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CHAPTER CHAPTER CHAPTER CHAPTER IIII
IntroductionIntroductionIntroductionIntroduction
andandandand
Literature ReviewLiterature ReviewLiterature ReviewLiterature Review
SECTION ISECTION ISECTION ISECTION I
► Studies onStudies onStudies onStudies on
� PyridonesPyridonesPyridonesPyridones
1.1.1 Introduction and literature review
The heterocyclic skeleton containing nitrogen atom is the basis of many
essential pharmaceuticals and of many physiologically active natural products.
Molecules containing heterocyclic substructures continue to be attractive targets for
synthesis since they often exhibit diverse and important biological properties.
Accordingly, novel strategies for the stereoselective synthesis of heteropolycyclic ring
systems continue to receive considerable attention in the field of synthetic organic
chemistry. 2(1H)-Pyridinone I is nitrogen containing synthetically designed scaffold
with a broad spectrum of biological activities. 2(1H)-Pyridinone moiety frequently
found in a variety of interesting compounds has received remarkable attention due to
its promising features as a key scaffold and in privileged building blocks. 2(1H)-
Pyridinone is an organic compound with the formula C5H4NH(O). This colourless
crystalline solid is used in peptide synthesis. It is well known to form hydrogen
bonded structures somewhat related to the base-pairing mechanism found in RNA and
DNA. It is also a classic case of a molecule that exists as tautomers. Other names of
2(1H)-pyridinone are 2-pyridones, 2(1H)-pyridone, 1-H-pyridine-2-one, 1,2-dihydro-
2-oxopyridine, 2-pyridinol, 1H-2-pyridone, 2-oxopyridone, 2-hydroxypyridine.
N O
H
I
The most prominent feature of 2-pyridone is the amide group; a nitrogen with
a hydrogen bound to it and a keto group next to it. In peptides, amino acids are linked
by this pattern, a feature responsible for some remarkable physical and chemical
properties. In this and similar molecules, the hydrogen bound to the nitrogen is
suitable to form strong hydrogen bonds to other nitrogen and oxygen containing
species. The structure of 2(H)-pyridinone in the crystalline state had been determined
by measuring the electron densities in two projections. The bond lengths and bond
angles are depicted in the following figure respectively.
II III
The pyridinone structure is the stable one, and there is a strong intermolecular
hydrogen bond between the nitrogen of one molecule and the oxygen of another
which is repeated throughout the structure linking molecules in endless helices. This
conclusion is based on the fact that the N-H distance is 1.02 A° II, very nearly the
normal covalent bond length of 1.00 A°, whereas the observed O-H distance greatly
exceeds the normal covalent distance. This obviates the possibility that 2(H)-
pyridinone exists as a hydrogen-bonded dimmer. The resonance structure of 2(H)-
pyridinone and their percent contribution as shown below were calculated to give the
best correspondence with the observed bond lengths and angles III.
IV
As expected on the basis of electro negativity trends, the dipolar forms IV
with negative charge on oxygen have much greater significance that those with the
negative charge on carbon. These latter forms, however, do account for electrophilic
substitutions at position ortho and para to the C=O group. The large contribution of
the dipolar forms with negatives charge on oxygen cause a high polarity on the N-H --
-O hydrogen bond. 2-Pyridone and 2-hydroxypyridine can form dimers with two
hydrogen bonds.
N
H
O N
H
+ O N
H
+ O N
H
O+
-
N
H
O +
-
50 % 15 % 20 % 10 % 5 %
- -
C
C
N
C
C
C
O
1.334
1.444
1.236
1.401
1.335
1.371
1.421
C
C
N
C
C
C
O
122.2
122.3
122.7 126
121.3
105 129
121.8
116.0
N
H
O
O
H
N
N
H
O
O
H
N
V
In solution the dimeric form V is present; the ratio of dimerisation is strongly
dependent on the polarity of the solvent. Polar and protic solvents interact with the
hydrogen bonds and more monomer is formed. Hydrophobic effects in non-polar
solvents lead to a predominance of the dimer. The ratio of the tautomeric forms is also
dependent on the solvent. All possible tautomers and dimers can be present and form
equilibrium, and the exact measurement of all the equilibrium constants in the system
is extremely difficult.
There are several reported methods for the synthesis of pyridone derivatives
likewise;
Synthesis from:
1. Aminopyridines [1-4]
2. Pyridine sulfonic acid [5-7]
3. Pyridinium quaternary salts [8-10]
4. N-oxides [11-13]
5. Halopyridines [14,15]
6. Direct hydroxylation [16]
7. Oxidation of thiol group [17]
8. Dealkylation of methoxy pyridine [18]
9. Thermal elimination of ethylene [19]
10. Furan derivatives [20-22]
11. Pyrones [23-27]
12. Cyclopentadiene derivatives [28]
13. Propaneoxidedione [29]
14. Cyclobutenedione [30]
15. Glutaconic acid derivatives [31-34]
16. β-Diketones and β-ketoacid derivaties with malonic acid derivatives [35-39]
17. β-Ketoamides and ketones [40, 41]
2-Pyridones constitute an important type of hyterocycles which have shown
variety of biological activities. In particular 2-pyridones containing H-bond acceptor
substituent in position-5 constitute a relatively new class of specific
phosphodiesterase 3 (PDE3) inhibitors [42]. They are good alternative to classic
digitalis glycosides for the acute treatment of congestive heart failure (CHF) i.e.
amrinone VI [43] and milrinone VII [44]. Substituted pyridones and their
dihydro/tetra hydro-derivatives are found in wide variety of naturally occurring
alkaloids and compounds with these structural motifs have been shown to exhibit
significant pharmacological properties [45].
NO
N
NH2
NO Me
NN
VI VII
Pyridones have been reported to possess non-nucleoside HIV type I specific
reserve transcriptase
inhibitors [46] and anti-inflammatory [47]
activities besides wide
range of pharmacological activities. 2-Pyridones have been also reported as fungicidal
agents [48]. 2-Pyridones were also reported as tissue factor VIIa inhibitor [49].
Cyclopenta[b]pyridin-2,5-dione constitutes also an interesting tensor of pharmaceutics
exemplified by the antibacterial product and a building-block for the access to 2-
cyclopenta[b]pyridin-5-one as seco analogues of 8-azasteroids [50] and antiviral
activity [51, 52]. This is nitrogen containing synthetically designed scaffold with a
broad spectrum of biological activities and play an important theoretical and practical
role in heterocyclic chemistry [53]. 2-Pyridones and their dihydro/tetrahydro-
derivatives have attracted considerable attention from synthetic organic chemists
since these scaffolds are found in a wide variety of naturally occurring alkaloids [54]
and compounds with these structural motifs exhibit significant pharmacological
properties [55]. 4-Hydroxy-1-β-D-ribofuranosyl-2-pyridone and 4-hydroxy-1-(β-D-
ribofuranosyl)-2-pyridones-5-carboxylic acid are biologically active and
therapeutically useful compounds. Substituted bicyclic 2-pyridones, termed pilicides,
are dipeptide mimetics that prevent pilus assembly in uropathogenic E coli [56]. 5-
Hydroxy 2-pyridone is an intermediate in the bacterial metabolism of a number of
pyridine derivatives including nicotinic acid [57]. It has been linked with damage to
DNA and show activity as an antitumor agent [58]. A wide range of biological
activities were also observed in compounds possessing a 2-pyridone motif which
includes anti-cancer [59], antifungal [60], antitumor [61], anti-inflammatory [62],
antiviral [63] and ant insecticidal properties [64].
The pyridine motif is also found in wide range of biologically active
compounds including pyridoxal, niacin and stimulant nicotine [65]. Many substituted
pyridines are used as pharmaceuticals i.e. isoniazid VIII for tuberculosis [66] and
indinavir IX as the HIV protease inhibitor [67]. 3,4-Dihydro-2-pyridones serve as
valuable building block in the construction of quinolizidines, perhydroquinolones,
piperidines, indolizidines, many alkaloids ring systems and have a wide range of
biological and pharmacological activities [68]. The N-aryl 2-pyridone moiety is an
important synthetic intermediate and structural motif that features in many
biologically active molecules (e.g. reverse transcriptase inhibitors, selective serotonin
reuptake inhibitors and HMG-CoA reductase inhibitors). More recently, pyridine-2-
one containing inhibitors of coagulation factor Xa have been also reported [69].
N
NHNH2
O
N
NN
NH
OH
OH
NH
O
CH3
CH3CH3
VIII IX
Its derivatives have been claimed to be non-nucleoside HIV type I specific
reserve transcriptase
inhibitors [70] and anti-inflammatory activities [71]. 3,4-
dihydro-2-pyridones have been reported to serve as valuable building block in the
construction of piperidines, perhydroquinolones, indolzidines, quinolizidines and
other alkaloid ring systems and have wide range of biological and pharmacological
activities [72]. (20S)-Camptothecin X is a well known anti-cancer natural product that
was first isolated from camptotheca acuminate in 1966 [73,74].
N O
N
O
O
OH
CH3
X
The 2-pyridone moiety frequently found in a variety of interesting
compounds has received remarkable attention due to its promising features as a key
scaffold and in privileged building blocks [75]. A wide range of biological activities
has been observed in compounds possessing a 2-pyridone motif which includes
antitumor [76], antifungal [77], antibacterial [78], anti-inflammatory [79], antiviral
[80] and antithrombotic properties [81]. In particular, the 3-amino-2-pyridone
template has considered as a peptidomimetic system which mimics the hydrogen-
bonding interaction compared with backbone of peptide inhibitors [82].
Ibrahim et al [83] have synthesized 2(1H)-pyridone derivatives XI by reaction
of 2-methyl-4-oxo-4H-1-benzopyrans with either cyanoacetamide or malononitrile
and explained it via opening of the pyrone ring.
NH
CH3
CN
OH
R
XI
A variety of novel N-arylsulfonylamino derivatives XII of 2-pyridones was
synthesized by Elgemeie and Sayed [84], by carrying out the reaction of N-
cyanoaceto- arylsulphonyl hydrazides with α, β-unsaturated nitriles.
X
N
ONC
NC Ph
SO
O
R
NH
XII
Lesniak and Pasternak [85] have thermolysed the enamides of α, β-unsaturated
acids in FVT conditions at 800 °C under pressure, which resulted in the formation of
1,2,3,4-tetrahydro-2-pyridones XIII as the exclusive products of the reaction in high
yield.
N
O
R1
R2
R3
R4
R5
XIII
Elgemeie and Elzanate [86] have carried out the reaction of oxime derivatives
of β-ketoesters with activated nitriles to produce the corresponding 6-hydroxy-5-
nitroso-2-oxopyridines XIV & XV.
N OOH
CNNO
R
NHSO2Ph
N OOH
CNNO
R
NHCHAr
XIV XV
Elgemeie and co-workers [87] have synthesized N-aroylamino-2-pyridones
XVI, XVII via reaction of ketene dithioacetal with cyanoaceto-N-aroylhydrazides.
NO
NC CN
NH2
NH
NHR
ArOC
O
CN
NH2
NH
NHN
COAr
NH2
XVI XVII
Stoyanov and Ivanov [88] have prepared some novel 2H-pyrano[3,2-
c]pyridine-2,5(6H)-dione XVIII by formylation of 4-hydroxy-6-methyl-2(1H)-
pyridones and subsequent cyclization with a Wittig reagent or with CH-acidic esters.
N
O
CH3OO
R
XVIII
Elgemee et al [89] have reported one-pot synthesis of 4-methylthio-N-aryl-2-
pyridone XIX and their deazapurine analogues by the reaction of ketene dithioacetals
with substituted acetanilides.
O
Z
NH
N
NH2
O
R1
R
XIX
By treatment of the nitrile in DMSO at 0 °C with a slight excess of 35%
hydrogen peroxide in the presence of potassium carbonate, the synthesis of 6-
ketoamides or 6-hydroxy-3,4,5,6- tetrahydro-2-pyridones XX have been reported by
Citterio et al [90].while Behrman and co-workers [91] have reported Improved
syntheses of 5-hydroxy-2-pyridones XXI , 6-chloro-5-hydroxy-2- pyridone and three
methyl-substituted 5-hydroxy-2- pyridones by an Elbs oxidation of 2-pyridone.
N
HO
R2
R1
N
HO
OH
R
XX XXI
Bowman and Bridge [92] have reported regioselective synthesis of N-alkyl
pyridines XXII, facilitated by alkylation of 2-methoxypyridines with activated
halides.
N OMeO
Ph
XXII
El-Essawy and co-workers [93] have carried out reaction of 4-hydroxy-6-
methyl-2(1H)-pyridones XXIII and 4-hydroxy-1,6- dimethyl-2(1H)-pyridones with
diethyl malonates to form pyrano[3,2-c]pyridines, which on degradation affords the
corresponding ketones while N-arylsulfonylamino-2-pyridones XXIV have been
synthesized by Elgemeiea et al [94] via reaction of arylmethylenemalononitriles with
cyanoacetyl-N-arylsulfonylhydrazides.
N OCH3
R
R1
NOH
OH
N ONH2
CNNC
Ar2
NHSO2Ar1
XXIII XXIV
Elgemeie et al [95] have synthesized substituted 4-alkylthio-N-
arylsulphonylamino- 2-pyridones XXV via the reaction of ketene-SS-acetals with N-
cyanoacetoaryl sulfonylhydrazides, which on treating with hydrazines yieled I-
arylsulfonylamino-pyrazolo[3,4-c]pyridine-2-(1H)-ones XXVI .
NO
NH2
N
H
N
NH2
O
Ar1HN
ArO2SNHSO2Ar
N ONH2
O
Ar1HN
NH
SCH3
CN
XXV XXVI
El-Shehawy and Adel Attia [96] have reported several new 2-oxo-, 2-thio-, as
well as 2-amino pyridines carrying the camphor sulfonylamino group XXVII as a
substituent in one step by Michael addition of several activated nitriles to compounds
4-[(+)-camphor-10'-sulfonylamino]acetophenone and some of its chalcones.
N
Ar1
OCH3CO
CNArO2SHN
XXVII
Insecticidal activity of some novel [1(2H).2'-bipyridin]-2-one XXVIII against
German cockroaches and houseflies has been reported by Sakamoto and co-workers
[97] and evaluated their electron withdrawing substituents at the 3, 3', 5 ,5'-positions
on both rings are required for the insecticidal activity.
N
N
O
CF3
R1
R2
R3
XXVIII
Amino-substituted 2-pyridones XXIX have been synthesized by Kim and co-
workers [98] through a two-step sequence of microwave-promoted, Buchwald-
Hartwig animation of 2-benzyloxy halo pyridines followed by debenzylation.
N
H
O
NR1R2
XXIX
Johnson et al [99] have synthesized some substituted 3-(benzyloxy)-1-
methoxyethyl)-2(1H)-pyridinones XXX, XXXI and carried out thermodynamic
evaluation of its gadolinium complex.
N
O
O
CH3BnO
O
N
S
SN
O
O
CH3BnO
O
OH
XXX XXXI
Pan and co-workers [100] have carried out an efficient one-pot synthesis of
highly substituted pyridin-2(1H)-ones of types XXXII and XXXIII from the
Vilsmeier-Haack reaction of readily available 1-acetyl, 1-carbamoyl cyclopropanes,
which involves sequential ring-opening, haloformylation, and intramolecular
nucleophilic cyclization reactions.
N
O
R
Cl
CHO
CH2CH2Cl
N
O
R
Cl
CH2CH2Cl
XXXII XXXIII
Ando et al [101] have synthesized difluoromethyl-2-pyridones XXXIV from
N-(pyridin-2-yl)acetamide. Hydrolysis of resultant 1,2-dihydro-2-acetimino-1-
ifluoromethylpyridines prepared proceeded under mild acidic conditions to afford the
corresponding N-difluoromethyl- 2-pyridones in moderate to good yields.
N O
CHF2
R
XXXIV
Pemberton [102] has prepared polycyclic ring-fused 2-pyridones XXXV via a
microwave-assisted acyl-ketene imine cyclocondensation from 3, 4-dihydroiso
quinolines or 3,4-dihydroharman in a one-step procedure.
N
O
R2
R1
XXXV
Sieburth and co-workers [103] have reported some 2-pyridones XXXVI and
studied their photo reactivity with Furan, Benzene, and naphthalene via inter and
intramolecular photocycloadditions.
N
O
R PhRO
XXXVI
Li and his co-workers [104] have discovered series of 3-urea-1-
(phenylmethyl)-pyridones XXXVII as novel EP3 antagonists via high throughput
screening and subsequent optimization and reported as selective EP3 receptor
antagonists.
R1
N
O NH
O
NH
OMe
XXXVII
Pemberton et al [105] have synthesized dihydroimidazolo and dihydrooxazolo
ring-fused 2-pyridones XXXVIII, XXXIX and biological evaluation revealed that
these compounds inhibit pilus assembly in uropathogenic E. coli.
N
O
R
N
H
COOLi
N
O
R
N
H
COOLi
XXXVIII XXXIX
Synthesis and biological evaluation of carboxylic acid isosteres, including, for
example, tetrazoles, acyl sulphonamides, and hydroxamic acids of two lead 2-
pyridones Xl have been carried out by Aberg and his co-workers [106] and concluded
that acyl sulphonamides and tetrazoles significantly improve pilicide activity against
uropathogenic E. coli.
N
O
R1
S
NH
N NN
XL
Singh et al [107] have reported the synthesis of substituted 3-methylene-2-
pyridones XLI via SN2 displacement reaction of nucleophiles bearing a keto group on
the acetyl derivative of Baylise Hillman adducts of acrylonitrile followed by
TFA/H2SO4-mediated intramolecular cyclization and illustrated the utility of these
pyridone derivatives for the synthesis of new spiroisoxazolines in highly regio- and
stereo-selective fashion.
NH
O
CH2
R
EtO2C
XLI
Tipparaju [108] have synthesized 2-pyridone derivatives XLII and evaluated
them for their BaENR inhibitory and antibacterial activities.
N
O
R1R2
R3
XLII
A series of 4-sulfonyl-2-pyridone activators XLIII have been reported by
Pfefferkorn and co-workers [109] and evaluated for in vitro biochemical activation
and pharmacokinetic properties.
N
O
NHHet
O
R1
S
R2
OO
XLIII
Smyth [110] has reported 3-amino-1H-pyrazolo [4,3-c]pyridin-4(5H)-ones
XLIV as potentially attractive heteroaromatic scaffold suitable for screening against
kinases and other cancer drug targets. The arrangement of hydrogen bond donor and
acceptor groups in the bicyclic core could fulfil the requirements for ATP competitive
binding to kinase enzymes.
N
H
O
NN
NH2
R3
R1
R2
XLIV
Abadi et al [111] have synthesized two series with the general formula of 4,6-
diaryl-2-oxo-1,2 dihydropyridine-3-carbonitriles XLV, XLVI and their isosteric 4,6-
diaryl-2-imino-1,2-dihydropyridine-3-carbonitrile through one pot reaction of the
appropriate acetophenone, aldehyde, ammonium acetate with ethyl cyanoacetate or
malononitrile, respectively and evaluated for their tumour cell growth inhibitory
activity against the human HT-29 colon tumour cell line, as well as their PDE3
inhibitory activity.
N
HO
S
R
N
N
HO
R
OH
Br
N
XLV XLVI
Pyrano[3,2-c]pyridone and pyrano[4,3-b]pyran derivatives have been
developed via an ionic liquid mediated by Fan and co-workers [112] and evaluated
as potential antiviral, antileishmanial agents and showed encouraging biological
activities.
NH
O
CH3
CH3
NHN
O
Cl
Cl
N
O
CH3
CH3 O
NO2
CN
NH2
X
O
CH3 O
R
CN
NH2
XLVII XLVIII XLIX
2-pyridone-containing imidazoline derivatives L have been synthesized by
Ando and co-workers [113] and evaluated as neuropeptide Y Y5 receptor antagonists
and concluded that 2-pyridone structure on the 2-position of the imidazoline ring led
to identification of 1-(difluoromethyl)-5-[(4S,5S)-4-(4-fluorophenyl)-4-(6-
fluoropyridin- 3-yl)-5-methyl-4,5-dihydro-1H-imidazol-2-yl]pyridin-2(1H)-one which
displayed statistically significant inhibition of food intake in an agonist-induced food
intake model in SD rats and no adverse cardiovascular effects in anesthetized dogs.
N
NH
N
F
F
CH3
R
L
Selby and co-workers [114] have reported the synthesis and complex II
inhibition for a series of synthetic atpenin analogs LI, LII against both mammalian
and fungal forms of the enzyme. Synthetic atpenin B provided optimum mammalian
and fungal inhibition with slightly higher potency than natural occurring atpenin A5.
N
H
O
OH
MeO
MeO
R
O
N
H
O
OH
MeO
MeO
CH(Me)(CH2)8Me
O
LI LII
The design and synthesis of an insulin receptor kinase family-targeted
inhibitor LIII template one pot was reported by Slavish et al [115] via Opatz
cyclization reaction using the inhibitor conformation observed in an IGF1R/inhibitor
co-crystal complex by application of a novel molecular design approach and some
compounds showed selective inhibition of anapaestic lymphoma kinase.
N
HO
CH3
N
Ph
R
LIII
Hanessian and co-workers [116] have synthesized a series of dihydropyrid-2-
ones LIV, LV and tested for inhibitory activity against serine protease enzymes.
Moderate to low nano molar inhibitory activities were obtained against thrombin and
excellent selectivity against tyrosine was observed.
N
O
NW
CH3
N
O
NH2
NH
R1
R2
R3
R4
R5
H H
LIV
N
O
NW
CH3
N
O
NH2
NH
R1
R2
R3
R4
R5
H H
LV
ABT-719 LVI, which represents the new 2-pyridone compound class for the
treatment of urinary tract infections has been reported by Meulbroek et al [117], as
suggested by the significant efficacy seen against experimental pyelonephritis caused
by E. coli, P. aeruginosa and resistant enterococci.
N
O O
OH
CH3
F
N
NH2
.HCl
LVI
Dihydropyrid-2-ones LVII-LX have been synthesized by Hanessian et al
[118] and tested for inhibitory activity against serine protease enzymes and reported
moderate to low nano molar inhibitory activities against thrombin and excellent
selectivity against trypsin was observed.
N
H
O
CN
CH3N
H
O
CN
CH3 N
H
O
CN
CH3
CH3
N
H
O
CN
CH3
CH3
CH3
LVII LVIII LIX LX
Some 2-pyridones LXI, LXII have been reported by Hartmann and co-
workers [119] as nonsteroidal inhibitors of 5α-reductase for the treatment of benign
prostatic hyperplasia using rat ventral prostate, as well as human BPH tissue as
enzyme source, 1b-2b-[3H]testosterone as substrate and a HPLC procedure for the
separation of dihydrotestosterone (DHT).
N
H
O (CH2)n
R
O
N
H
O (CH2)n
LXI LXII
Rodgers and co-workers [120] have reported trycyclic 2-pyridones LXIII,
LXIV useful as inhibitors of HIV reverse transcriptase.
NN
HO
R
R1
R2F3C
R3
NHN
HO
R2R3
R4
LXIII LXIV
Some 1-hydroxy-2-pyridones LXV have been reported by Bohn [121] for the
treatment of seborrheic dermatitis. Darvesh and co-workers [122] reported 2-
pyridones LXVI that modulate serine hydrolase activity and also inhibit activity of
BuChE or AChE and stimulate activity of trypsin.
N
OH
O
R2
R3R1
X
YZ
N
H
O
XR2R3
R1
R4
R5
LXV LXVI
Demuner and co-workers [123] have synthesized methylpyridin-2(1H)-one
derivatives LXVII and evaluated the effects of all methylpyridin- 2(1H)-ones on the
development of the dicotyledonous species Ipomoea grandifolia and Cucumis sativus
and the monocotyledonous species Sorghum bicolor.
N
HOCH3
OH R
N
HCH3
OH
O
LXVII
Dragovich et al [124] have reported various 2-pyridone LXVIII , comprised
of a peptidomimetic binding determinant and a Michael acceptor moiety, which forms
an irreversible covalent adduct with the active site cysteine residue of the 3C enzyme.
The 2-pyridone-containing inhibitors typically display improved 3CP inhibition
properties relative to related peptide-derived molecules along with more favourable
antiviral properties.
N
O
NHR3
O
NH CO2Et
O R1
R2
LXVIII
Banning et al [125] have synthesized some 2-pyridones LXIX showing phase
change ink composition comprising a phase change ink carriage. James D. Mayo et al
[85] reported some multi-chromophoric azo pyridone colourants LXX.
N O
CH3
CN
OH
R2
NN
NO2
OR1
N O
R3
CN
OH
R2
NN
O
R1X
Z
LXIX LXX
Li [126] has synthesized some 2-pyridones LXXI as inhibitors of bacterial
type III protein secreation systems.
O
NH
F3C
O
OH
O
LXXI
Tada and co-workers [127] have reported 2-pyridones LXXII, LXXIII having
affinity for cannabinoid 2-type receptor while Campbell [128] has reported 5-hetero
aryl-substituted-2-pyridines, useful as cardio tonic agents for treatment of congestive
heart failure.
N
OO
O
N
R
R1R2
R3
N
H
O
R1
R
F3C
N N
LXXII LXXIII
South [129] et al have reported some substituted polycyclic aryl and heteroaryl
pyridines LXXIV useful for selective inhibition of the coagulation cascade.
N
O
NHA
Z NR4
R
R1
R2O
H
LXXIV
Igata and Mikoda [130] have reported some 2-pyridone LXXV dyestuff for
thermal transfer recording and printing sheets.
N
ON
N
O
O
OR1
O CNCH3
OH R2
LXXV
Peukert et al [131] have synthesized some pyridines LXXVI and reported as
medicament as poly(ADP-ribose) polymerase (PARP) inhibitors in the treatment of
tissue damage or disease caused by necrosis or apoptosis while Nelson and Paquette
[132] have reported 6-(6-methoxy-l,2,3,4-tetrahydro-2-naphthyl)-l-methyl-2(1H )-
pyridone LXXVII (Xa) as steroidal hormone analogs.
N
H
O
CH3
CH3
NH
R
N
O
RO
CH3
LXXVI LXXVII
2-pyridones LXXVIII have been synthesized by transposition of the nitrogen
of 4-quinolones to the bridgehead reported as potent inhibitors of DNA gyrase by Qun
Li and co-workers [133] and also found active against resistant bacteria such as
methicillin-resistant Staphylococcus aureus, vancomycinresistant strains of
enterococci, and ciprofloxacin-resistant organisms.
N
O O
OHF
R2R3N
R1
LXXVIII
Zhiliang et al [134] have synthesized 2-pyridones LXXIX, LXXX and
evaluated for their antihepatitis B virus (HBV) activity and cytotoxicity in vitro,
moderate to good activity against HBV DNA replication was observed in these 2-
pyridone analogues.
N
O
R
OH
OCH3
O
N
O
R
OH
OCH3
NR
LXXIX LXXX
2-pyridones LXXXI have been synthesized by Parlow and co-workers [135]
from 2,6-dibromopyridine via a multistep synthesis via chemical transformations,
including regioselective nucleophilic addition, selective nitrogen alkylation, and a
Suzuki coupling, afforded the targeted tissue factor VIIa inhibitors. These compounds
were tested in several serine protease enzyme assays involved in the coagulation
cascade exhibiting modest activity on tissue Factor VIIa with excellent selectivity
over thrombin and Factor Xa.
N
O
NHCH3
CH3
NH2
R
O NH
NH
NH2
LXXXI
2-Pyridones LXXXII have been synthesized by Pierce et al [136] from N-
alkylacetoacetamides by self condensation and tested in a carrageenan-induced pedal
edema assay in rats in an attempt to develop nonacidic, nonsteroidal anti-
inflammatory agents.
N O
R
CH3
H
CH3
CN
O
R1H
LXXXII
1.1.2 Scope of the present work
2-Pyridones constitute an important type of hyterocycles which have shown
variety of biological activities. They work as specific phosphodiesterase 3 (PDE3)
inhibitors and are good alternative to classic digitalis glycosides for the acute
treatment of congestive heart failure (CHF) i.e. amrinone and milrinone. Compounds
with these structural motifs have been shown to exhibit significant pharmacological
properties. Triazoles have demonstrated activity against malarial, bronchospasm and
shown activity as coronary, vasodilators, antihypertensive agents, anti-depressants,
leishmanicides, antibiotics, adenosine antagonists, immunosuppressant, antitumor
agents, fungicides, xanthine oxidase inhibitors and anti-convulsant. Triazoles possess
significant antifungal and antiviral properties. Compounds with pyrrolidine core are
significant in treatment of many diseases like rheumatoid arthritis, allergies, asthma,
possess anti-influenzea virus and anticonvulsant activities and display versatile
pharmacological properties such as anticholinergics, histamine H3 receptor agonist,
antiarrhythmic, inhibitors of angiotensin converting enzyme and antihypertensive.
A number of methods have been previously developed for the synthesis of N-
aryl-pyridine-2-ones. A number of protocols have been successfully developed for
such C-N bond formation reactions. Literature survey reveals that no work has been
carried out on 2-pyridones substituted by 1,2,4-triazole and pyrrolidine. We have
previously reported the preparation of substituted 2-pyridones from the condensation
of β-glutaconic acid with aromatic amines which was prepared from citric acid. In
continuation of our work and because of the potent biological activities of 2-
pyridones, 1,2,4-triazole and pyrrolidines derivatives as described in part-I, we
thought that there is real need for straightforward and effective synthesis of these
classes of heterocyclic compounds as well as their analogues, which might be
important for pharmacological studies.
Pyridones have been a valuable addition to the array of antimicrobial agents
that are used to treat human infections. Combination of two biological active moieties
in one molecule might results in an overall enhanced the biological activity. Here, we
studied their antimicrobial activities as well as antitubercular activity against
Mycobacterium tuberculosis H37Rv.
1.1.3 References
1. Seide O.; Ber., 57, 1924, 791.
2. Chichibabin and Widonowa; J. Russ. Phys. Chem. Soc., 58, 1921, 238.
3. Chichibabin and Egorov A. F.; J. Russ. Phys. Chem. Soc., 50, 1928, 683,
Chem. Abstr., 23 : 1929, 21824.
4. Adarns and Schrecker; J. Am. Chem. Soc., 71, 1949, 1186.
5. Marion and Cockburn; J. Am. Chem. Soc., 71, 1949, 3402.
6. Brown and Miller; J. Org. Chem., 11, 1946, 388.
7. Jacobs and Sato; J. Biol. Chem., 191, 1951, 71.
8. Fargher and Furness; J. Chem. Soc., 107, 1915, 690.
9. Fischer and Chur, J. prakt. Chem., 93, 1916, 363.
10. Prill and McElavain; Org. Syntheses, 2, 1943, 419.
11. Katada; J. Pharm. Soc., 67, 1947, 51.
12. Boekelheide and linn; J. Am. Chem. Soc., 76, 1954, 1286.
13. Sgarshi; Japan Pat., 1951, 7672.
14. Wibaut J.P., Speakman B.W. and Wagtendonk H.M.; Rec. trav. Chim., 58,
1939,100.
15. Baurnler J., Sorkin E. and Erlenmeyer H; Helv. Chim. Acta, 34, 1951, 496.
16. Chichibabin; Ber., 56, 1923, 1879.
17. Caldwell and Kornfeld; J. Am. Chem. Soc., 64, 1942, 1695.
18. Zoltewicz J.A. and sale A.A.; J. Org. Chem., 35, 1970, 3462.
19. Roger T.; J. Chem. Soc., Chem. Commun., 17, 1978, 732; Chem. Abstr.,
90, 1979, 38372u.
20. Fischer E., Hess K. and Stahlschmidt A.; Ber., 38, 1905, 3824.
21. Neilsen J.T., E1ming N. and Clauson-Kass N.; Acta. Chem., Scand., 9,
1955, 30.
22. Clauson-kaas and Niels Elming; Acta Chem., Scand., 14, 1960, 938.
23. Von Pechmann and Welsh; Ber., 17, 1884, 2384.
24. Caldwell T. and Lauer; J. Am. Chem. Soc., 66, 1944, 1479.
25. Mitra; J. Ind. Chem. Soc., 15, 1938, 455.
26. Leben; Ber., 29, 1896, 1673.
27. Arndt F., Eistert B., Scholz H. and Aron E.; Ber., 69B, 1936, 2373.
28. Hong P. and Yamazaki H.; Synthesis, 50, 1977.
29. Wang C.S., Easterly J.P. and Skelly N.E.; Tetrahedron., 102, 1971, 848.
30. Reid W. and Batz F.; Ann., 230, 1969, 725.
31. Thorpe J.F.; J. Chem. Soc., 87, 1905, 1669.
32. Ruhemann S.; J. Chem. Soc., 75, 1899, 249.
33. Guthzeit; Ber., 32, 1899, 779.
34. Reynolds, Humph1ett, Swamer and Hauser; J. Org. Chem., 16, 1951, 165.
35. Stevens B. and Chamberlin; J. Am. Chem. Soc., 64, 1942, 1093.
36. Bobbith and Scola; J. Org. Chem., 25, 1959, 560.
37. Bardhan; J. Chem. Soc., 1929, 2223.
38. Plati and Wenner; J. Org. Chem., 15, 1950, 1165.
39. Coover and Bowman; US Pat. 2,523,612; Chem. Abstr., 45,1951, 2030.
40. Hauser and Eby; J. Am. Chem. Soc., 1959, 2554.
41. Wajons and Arens; Rec. trav. Chem., 76, 1957, 65.
42. Dorigo P., Gaion R.M., Belluco P., Fraccarollo D., Maragno I., Bobieri G.,
Benetoll F., Mosti and Orsini F.; J. Med. Chem., 36, 1993, 2475.
43. Farah A.E. and Alousi A.A.; Life Sci., 22, 1978, 1139.
44. Alousi A.A., Canter J.M., Monterano M.J., Fort D.J. and Ferrari R.A.; J.
Cardiovasc Pharmacol., 5, 1983, 792
45. Paulvannan K. and Chen T.; J. Org. Chem., 65, 2000, 6160.
46. Bristol-Myers Squibb Pharma, Princeton, NJ, US Pat., 2005, 104657:902.
47. Daniel L.F., Lawrence K.S., Peter A. and Arlington M.A., Deciphera
Pharma., LLC, Lawrence, KS; US Pat., 2007, 10886:329.
48. Pemberton N., Department of chemistry, umea university, Sweden,
synthesis and functionalization of ring fused 2-pyridones, 2007.
49. Prakash H.S. and Senthilkumar S.P.; Curr. Org. Chem., 8, 2004, 1521.
50. Misic-Vukovic M. and Radojkovic-Velickovic M.; J. Serb. Chem. Soc.,
Review, 63, 1998, 585.
51. Uscumlic G., Mijin D., Valentic N., Vajs V. and Susic B.; Chem. Phys.
Lett, 397, 2004, 148.
52. Forlani L., Gristoni G., Boga C., Todesco P.E., Del Vechio E., Salva S.
and Monari M., Arkivoc, 11, 2002, 198.
53. Katritzky A.R. and Rees W. Eds.; In comprehensive heterocyclic
chemistry, Pergamum Press, Oxford, 1984, 315.
54. Jones T.H. and Blum M.S.; In Alkaloids: Chemical and biological
perspective, Pelletier SW, Ed; Wiley: New York, 1, 1985, 33.
55. Paulvanan K. and Chen T.; J. Org. Chem.,65, 2000.
56. Berg V., Sellstedt M., Hedenstrom M., Pinkner J.S., Hultgren S.J. and
Almqvist F.; Bioorg. Med. Chem., 14, 2006, 7563.
57. Kaiser J.P., Feng Y. and Bollag J.M.; Microbiol Rev. 60, 1996, 483.
58. Kim S.G. and Navak R.F; Cancer Res., 50, 1990, 5333.
59. Du W.; Tetrahedron 59, 2003, 8649.
60. Cox R.J. and O’Hagan D.; J. Chem. Soc. Perkin Trans. 1 , 1991, 2537.
61. Hasvold L.A., Wang W., Gwaltney S.L., Rockway T.W., Nelson L.T.J.,
Mantei R.A., Fakhoury S.A., Sullivan G.M., Li Q., Lin N.H., Wang L.,
Zhang H., Cohen J., Gu W.Z., Marsh K., Bauch J., Rosenberg S. and Sham
H.L.; Bioorg. Med. Chem. Lett., 13, 2003, 4001.
62. Semple G., Andersson B.M., Chhajlani V., Georgsson J., Johansson M.J.,
Rosenquist A. and Swanson L.; Bioorg. Med. Chem. Lett., 13, 2003, 1141.
63. Parreira R.L.T., Abrahao O. and Galembeck S.E.; Tetrahedron, 57 , 2001,
3243.
64. Sakamoto N., Ishiwatari T. and Matsuo N.; J. Pesticide. Sci., 25, 2000,
373.
65. Warshakoon N.C., Wu S., Boyer A., Kawamoto R., Sheville J., Bhatt R.T.,
Renock S., Xu K., Pokross M., Zhou S., Wlter R., Mekel M., Evdokimov
A.G. and East S.; Bioorg. Med. Chem. Lett. 16 , 2006, 5616.
66. Wheate N., Vora V., Anthony N. and McInnes F.; J. Incl. Phenom.
Macrocycl. Chem., 68, 2010, 359.
67. Dorsey B.D., Levin R.B., McDaniel S.L., Vacca J.P., Guare J.P., Darke
P.L., Zugay J.A., Emini E.A., Schleif W.A., Quintero J.C., Lin J.H., Chen
I.W., Holloway M.K., Fitzgerald P.M., Axel M.G., Ostovic D., Anderson
P.S. and Huff J.R.; J. Med. Chem., 37, 1994, 3443.
68. Avenoza A., Busto J.H., Cativiela C., Corzana F., Peregrina J.M. and
Zurbano M.M.; J. Org. Chem. 67, 2002, 598.
69. Boehringer M., Groebke Z.K., Haap W., Pandey N., Ricklin F., Stahl M.
and Schmitz P.; WO, 2007, 2007054453; Chem Abstr., 146, 2007, 521676.
70. Dorigo P., Gaion R.M., Belluco P., Fraccarollo D., Maragno I., Bobieri
G., Benetoll F. and Mosti O.F.; J. Med. Chem., 36, 1993, 2475.
71. Farah A.E. and Alousi A.A.; Life Sci. 22, 1978, 1139.
72. Alousi A.A., Canter J.M., Monterano M.J., Fort D.J. and Ferrari R.A.; J.
Cardiovasc. Pharmacol., 1983, 5, 792.
73. Paulvannan K. and Chen T.; J. Org. Chem., 65, 2000, 6160.
74. Bristol-Myers; Squibb Pharma, Princeton, NJ; US Pat., 2005, 104657902.
75. Daniel L.F., Lawrence K.S., Peter A. and Arlington M.A.; Deciphera
Pharma., LLC, Lawrence, KS, ,US Pat., 2007, 10886329.
76. Nils P.; Department of chemistry, umea university, Sweden; Synthesis and
functionalization of ring fused 2-pyridones.
77. Prakash H.S. and Senthilkumar S.P.; Curr. Org. Chem., 8, 2004, 1521.
78. Vukovic M.and Radojkovic V.M.; J. Serb. Chem. Soc., Review, 63, 1998,
585.
79. Uscumlic G., Mijin D., Valentic N., Vajs V. and Susic B.; Chem. Phys.
Lett., 397, 2004, 148.
80. Forlani L., Gristoni G., Boga C., Todesco P.E., Del Vechio E., Salva S.
and Monari M.; Arkivoc, 11, 2002, 198.
81. Krick-Othmer; Encyclopedia of Chemical Technology, 2nd Ed. Wiley
Interscience Publication, JohnWiley Sons., 15, 1968, 638.
82. Aramrgo W.L.; Stereochemistry of Heterocyclic Compounds. 1969, Part-I,
190.
83. Ibrahim S.S., El-Shaaer H.M. and Hassan A.; Phosphorus, Sulfur and
Silicon, 177, 2002, 151.
84. Elgemeie G.H. and Sayed S.H.; Phosphorus, Sulfur and Silicon, 178,
2003, 465.
85. Lesniak S. and Pasternak B.; Syn. Comm., 32(6), 2002, 875.
86. Elgemeie G.H. and Sayed S.H. ; Syn. Comm., 33(12), 2003, 2087.
87. Elgemeie G.H., Elghandour A.H., Elzanate A.M. and Elaziz G.W.; Syn.
Comm., 33(2), 2003, 253.
88. Stoyanov E.V. and Ivanov I.C.; Syn. Comm., 28(10), 1998, 1755.
89. Elgemee G.H., Ali H.A., Elghandour A.H. and Elaziz G.W.; Phosphorus,
Sulfur and Silicon, 164, 2000, 189.
90. Citterio A., Carnevali E., Farina A., Meille V., Alini S. and Cotarca L.;
Organic Prep. Proced. Int., 29 (4), 1997, 465.
91. Behrman E.J.; Syn. Comm., 38, 2008, 1168.
92. Bowman W.R. and Bridge C.F.; Syn. Comm., 29(22), 1999, 4051.
93. EI-Essawy F.A., Khattab A.F., Zahran M.A. and Gomma S.A;. Syn.
Comm., 37, 2007, 3225.
94. Elgemeie G.H., Elghadour A.H., Elzanate A.M. and Masoud W.A.;
Phosphorus, Sulfur and Silicon, 163, 2000, 91.
95. Elgemeie G.H., Ali H.A., Elghadour A.H. and Abdel-aziz H.M.;
phosphorus, Sulfur and Silicon, 170, 2001, 171.
96. El-Shehawy A.A. and Attia A.M.E.; Phosphorus, Sulfur and Silicon, 178,
2003, 1129.
97. Sakamoto N., Ishiwatari T. and Matsuo N; J. Pesticide Sci., 25, 2000, 373.
98. Kim Y.H., Kim Y.J., Chang S.Y., Kim B.T. and Heo J.N.; Bull. Korean
Chem. Soc., 28(5), 2007, 777.
99. Johnson A.R., O’Sullivan B. and Raymond K.N.; Inorg. Chem., 39, 2000,
2652.
100. Pan W., Dong D., Wang K., Zhang J., Wu R., Xiang D. and Liu Q.; Org.
Lett., 9(12), 2007, 2421.
101. Ando M., Wada T. and Sato N.; Org. Lett., 8(17), 2006, 3805.
102. Pemberton N., Jakobsson L. and Almqvist F.; Org. Lett., 8(5), 2006, 935.
103. Sieburth S.M., McGee K.F., Zhang F. and Chen Y.; J. Org. Chem. 65,
2000, 1972.
104. Li Y.A., Tseng P.S., Evans K.S., Jaworski J.P., Morrow D.M., Fries H.E.,
Wu C.W., Edwards R.M. and Jin J.; Bioorg. Med. Chem. Lett., 20, 2010,
6744.
105. Pemberton N., Pinkner J.S., Edvinsson S., Hultgren S.J. and Almqvist F.;
Tetrahedron, 64, 2008, 9368.
106. Aberg V., Das P., Chorell E., Hedenstrom M., Pinkner J.S., Hultgren S.J.
and Almqvist F.; Bioorg. Med. Chem. Lett., 18, 2008, 3536.
107. Singh V., Yadav G.P., Maulik P.R. and Batra S.; Tetrahedron, 64, 2008,
2979.
108. Tipparaju S.K., Joyasawal S., Forrester S., Mulhearn D.C., Pegan S.,
Johnson M.E., Mesecar A.D. and Kozikowski A.P.; Bioorg. Med.Chem.
Lett., 18, 2008, 3565.
109. Pfefferkorn J.A., Lou J., Minich M.L., Filipski K.J., He M., Zhou R.,
Ahmed S., Benbow J., Perez A.G., Tu M., Litchfield J., Sharma R.,
Metzler K., Bourbonais F., Huang C.,Beebe D.A. and Oates P.J.; Bioorg.
Med. Chem. Lett., 19, 2009, 3247.
110. Abadi A.H., Abouel-Ella D.A., Lehmann J., Tinsley H.N., Gary B.D.,
Piazza G.A. and Abdel-Fattah M.A.O.; Eur. J. Med. Chem., 45, 2010, 90.
111. Fan X., Feng D., Qu Y., Zhang X., Wang J., Loiseau P.M., Andrei G.,
Snoeck R and Clercq E.D.; Bioorg. Med. Chem. Lett., 20, 2010, 809.
112. Ando M., Sato N., Nagase T., Nagai K., Ishikawa S., Takahashi H.,
Ohtake N., Ito J., Hirayama M., Mitobe Y., Iwaasa H., Gomori A.,
Matsushita H., Tadano K., Fujino N., Tanaka S., Ohe T., Ishihara A.,
Kanatani A. and Fukami T.; Bioorg. Med. Chem., 17, 2009, 6106.
113. Selby T.P., Hughes K.A., Rauh J.J. and anna W.S.; Bioorg. Med. Chem.
Lett., 20, 2010, 1665.
114. Slavish P.J., Jiang Q., Cui X., Morris S.W. and Webb T.R.; Bioorg. Med.
Chem. Lett., 17, 2009, 3308.
115. Hanessian S., Therrien E., Zhang J., Otterlo W.V., Xue Y., Gustafsson D.,
Nilsson I. and Fjellstom O.; Bioorg. Med. Chem. Lett., 19, 2009, 5429.
116. Meulbroek J.A., Oleksijew A., Tanaka S.K. and Alder J.D.; J. Antimicro.
Chemother.; 38, 1996, 641.
117. Hanessian S., Therrien E., Zhang J., Otterlo W.V., Xue Y., Gustafsson D.,
Nilson I. and Fjellstrom; Bioorg. Med. Chem. Lett., 19, 2009, 5429.
118. Hartmann R.W. and Reichert M.; Arch. Pharm. Pharm. Med. Chem. 333,
2000, 145.
119. Rodgers J.D., Wang H., Patel M., Arvanitis A. and Cocuzza A.J; US Pat.,
2004, 0023955 A1.
120. Bohn M., Kraemer K.T. and Astrid Markus; US Pat., 2004, 0039030 A1.
121. Darvesh S., Magee D., Valenta Z. and Martin E.; US Pat., 2003, 6544986
B2.
122. Demuner A.J., Valente V.M.M., Barbosa L.C.A., Rathi A.H., Donohoe
T.J. and Thompson A.L.; Molecules, 14, 2009, 4973;
doi:10.3390/molecules14124973.
123. Dragovich P.S., Prins T.J., Zhou R., Brown E.L., Maldonado F.C.,
Fuhrman S.A., Zalman L.S., Tuntland T., Lee C.A., Patick A.K., Matthews
D.A., Hendrickson T.F., Kosa M.B., Liu B., Batugo M.R., Gleeson J.R.,
Sakata S.K., Chen L., Guzman M.C., Meador J.W., Ferre R.A. and
Worland S.T.; J. Med. Chem., 45, 2002, 1607.
124. Banning J.H., Wo B., Mayo J.D., Duff J.M., Carlini R., Thomas J.W. and
Smith P.F.; US Pat., 2004, 6755902 B2.
125. Li X.; US Pat., 2006, 7087622 B2.
126. Tada Y., Iso Y. and Hanasaki K.; US Pat., 2005, 6977266 B2.
127. Campbell H.F.; US Pat., 1998, 4593028.
128. South M.S., Zeng Q., Hamme A.T. and Rueppel M.L.; US Pat., US 2005,
6867217 B1.
129. Igata A. and Mikoda T; US Pat., 1990, 4898850.
130. Peukert S., Guessregen S., Hofmeister A., Schreuder H. and Schwahn U.;
US Pat., 2007, 0281948 A1.
131. Nelson N.A. and Paquette L.A.; The department of Chemistry,
Massachusetts institute of technology, 27, 1961, 964.
132. Li Q, Chu D.T.W., Claiborne A, Cooper C.S., Lee C.M., Raye K., Berst
K.B., Donner P., Wang W., Hasvold L., Fung A., Ma Z., Tufano M.,
Flamm R., Shen L.L., Baranowski J., Nilius A., Alder J., Meulbroek J.,
Marsh K., Crowell D., Hui Y., Seif L., Melcher L.M., Henry R., Spanton
S., Faghih R., Klein L.L., Tanaka S.K. and Plattner J.J.; J. Med. Chem., 39,
1996, 3070.
133. Lv Z., Sheng C., Wang T., Zhang Y., Liu J., Feng J., Sun H., Zhong H.,
Niu C. and Li K.; J. Med. Chem., 53, 2010, 660.
134. Parlow J.J., Kurumbail R.G., Stegeman R.A., Stevens A.M., Stallings
W.C. and South M.S.; J. Med. Chem., 46, 2003, 4696.
135. Pierce J.B., Ariyan Z.S. and Ovenden G.S; J. Med. Chem., 25, 1982, 131.
SECTION IISECTION IISECTION IISECTION II
► Studies on Studies on Studies on Studies on
� 1,2,41,2,41,2,41,2,4----TriazolesTriazolesTriazolesTriazoles
� PyrrolidinePyrrolidinePyrrolidinePyrrolidine
1.2.1.1 Introduction and literature review of 1,2,4-triazole
Triazole is one of a class of organic heterocyclic compounds containing a five-
membered ring structure composed of three nitrogen atoms and two carbon atoms at
non adjacent positions. The simplest member of the triazole family is triazole I itself,
white to pale yellow crystalline solids with a weak characteristic odour; soluble in
water and alcohol, melts at 120°C, boils at 260
°C. Triazole and its derivatives are used
for biological activities such as antiviral, antibacterial, antifungal and antituberculous.
Mostly 1,2,4-triazole I and 1,2,3-triazole II are very important in pharmaceutical
industry. Heterocycles bearing symmetrical triazole ring I is reported to show a broad
spectrum of biological activities.
I II
1,2,4-Triazole and its derivatives represent one of the most biologically active
classes of compounds, possessing a wide spectrum of biological and pharmacological
properties. The 1,2,4-triazole nucleus is associated with diverse pharmacological
activities such as antibacterial [1], antifungal [2], hypoglycaemic [3], antihypertensive
[4] and analgesic properties [5]. The substituted 1,2,4-triazole nucleus is particularly
common and examples can be found in marketed drugs such as triazolam III,
rizatriptan IV, fluconazole V, terconazole VI and alperazolame VII [6]. Some 1,2,4-
triazole derivarives bearing thiophene nucleus have been reported to possess potent
antitubercular and antimicrobial properties [7]. Synthesis of varieties of 1,2,4-
triazoles and study of their biological activities are also being pursued [8]. The title
compounds in the present are as follows:
N
H
N N
N
H
N
N
NN
N
CH3
N
Cl
Cl
NN
NN
H
N
CH3CH3
III Triazolam IV Rizatriptan
F
F
OH N N
N
NN
N
N
N
N
O O
ClCl
O
N
NCH3
CH3
V fluconazole VI terconazole
N
N N
CH3
N
Cl
VII alperazolame
Jean-Luc Girardet have synthesised and reported new series of 1,2,4-triazoles
and tested against several Non-nucleoside reverse transcriptase inhibitors (NNRTI)
resistant HIV-I isolutes [9]. They have demonstrated activity against malarial and
bronchospasm and shown activity as coronary, vasodilators, antihypertensive agents,
anti-depressants [10], leishmanicides, antibiotics, adenosine antagonists,
immunosuppressant, antitumor agents, fungicides, xanthine oxidase inhibitors and
anti-convulsant [11]. Triazoles possess significant antifungal and antiviral properties
[12]. They are strong CNS depressant and mild to moderate anti-inflammatory
hypocholesterimic and hypertensive activities. Triazoles act as antimicrobial and
antibactacterial agents [13, 14].
1,2,4-triazoles and their derivatives are found to be associated with various
biological activities such as anticonvulsant [15,16], antifungal [17-19], anticancer [20-
23], anti-inflammatory [24-26] and antibacterial properties [27-30]. Several
compounds containing 1,2,4-triazole rings are well known as drugs. For example,
fluconazole is used as an antimicrobial drug [31], while vorozole VIII, letrozole IX
and anastrozole X are non-steroidal drugs used for the treatment of cancer [32] and
loreclezole XI is used as an anticonvulsant [33]. Schiff base derivatives of 1,2,4-
triazoles and their reduced derivatives have been also found to possess
pharmacological activities [34-40].
N
NN
Cl
N
N
N
CH3
N
NN
ClNC
VIII IX
Cl
Cl
Cl
N
N
N
N N
N
NC
CH3CH3
CN
CH3
CH3
X XI
Mange and co-workers [41] have synthesized a series of new Schiff bases XII
by the condensation of N-[(4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-4-
substituted-benzamides with various substituted aromatic aldehydes in ethanol-
dioxane mixture using catalytic amount of sulphuric acid and evaluated for their
antibacterial and antifungal activity using the MIC method by serial dilution
technique.
N
NN
SH
NH
O
N
R1 R
XII
Odlo et al [42] have prepared cis-restricted 1,4 and 1,5-disubstituted 1,2,3-
triazole analogs of combretastatin and carried out their cytotoxicity and tubulin
inhibition studies which showed that 2-methoxy-5-[(5-(3,4,5-trimethoxyphenyl)- 1H-
1,2,3-triazol-1-yl)methyl]aniline XIII and 2-methoxy-5-(1-(3,4,5-trimethoxybenzyl)-
1H-1,2,3-triazol-5-yl)aniline XIV were two of the most active compounds.
NN
N
R
MeO
OMe
OMe
OMe
XIII
Some novel 1,2,4-triazoles XV have been synthesized by Mohd et al [43] by
cyclization of various benzoyl thiosemicarbazide in basic condition.
N N
N
R
MeOOMe
OMe
OMe
NN
N
SH
Ar
XIV XV
A series of 1,2,4-triazoles XVI have been synthesized by Desai and Mistry
[44] by the condensation of 1,3,4-oxadiazole and various amine using pyridine as
solvent whereas 3-amino-1H-1,2,4-triazoles XVII have been used as herbicides and
defoliants; meanwhile they were described as catalase inhibitors [45] and blockers for
certain ethanol-induced behaviour effects [46]. It has been reported that only certain
enantiomers of triazoles containing oxazolidine rings are active against C.albicans
infections in mice [47].
Cl
Cl
Cl
OCH2
NN
NAr
R
O
N
N
N N
H
H
OR
X
XVI XVII
Sheng-Jiao Yan and co-workers [48] have prepared heterocycle-fused 1,2,3-
triazoles XVIII by the 1,3-dipolar cycloaddition of heterocyclic ketene aminals or N,
O-acetals with sodium azide and polyhalo isophthalonitriles in a one pot reaction at
room temperature without a catalyst and evaluated in vitro against a panel of human
tumour cell lines. 4-Methoxyphenyl substituted 1,3-oxazoheterocycle fused 1,2,3-
triazole XIX was found to be the most potent derivative with IC50 values lower than
1.9 lg/mL against A431 and K562 human tumour cell lines.
N
N N
O
R
O
N
N N
O O
OMe
XVIII XIX
Bhatt et al [49] have synthesized 1,2,4-triazoles XX by elimination of H2S gas
during refluxing various potassium dithiocarbazinate and excess of hydrazine hydrate.
Some novel 1,2,4-triazoles XXI have been synthesized by Demirbas and Ahmet [50]
and proved that 1,2,4-triazol-3-one possess great antimicrobial activities.
NH
CH3
CH2
N N
N
NH2
SH
N
N
N
SH
CH2
N
N
N
NH2R O
NH2
XX XXI
S-triazolo[1,5-c]pyrimidines are important as potential therapeutic agents [51,
52], 3-amino-1,2,4-triazole (ATZ), 3-mercapto-1,2,4-triazole (MTZ) and 3-nitro-
1,2,4-triazole (NTZ) derivatives showed antithyroid activity [53]. In recent work [54]
thienopyrimido-1,2,4-triazoles XXII have been synthesized as pharmacologically
interesting compounds. Some acyclic 1,2,4-triazole C-nucleosides [55] lacked
antiviral properties against herpes simplex virus 1 and 2 (HSV-1 and -2) along with
other viruses.
S N
N
N N
R
XXII
Lucie Maingot et al [56] have synthesized new family of ADAMTS-5
inhibitors XXIII, XXIV and showed that these inhibitors display an original 1,2,4-
triazole-3-thiol scaffold as a putative zinc binding group. In vitro results are
rationalized by in silico docking of the compounds in ADAMTS-5’s crystal structure.
N
N N
R1
O
X
S
K+
N
H
N
N N
R1
O
X
S
K+
XXIII XXIV
Mishra et al [57] have synthesized some novel 1,2,4-triazoles XXV and
reported their pharmacological activities.
N
H
N
N
SH
NHC
O
Ar
Br
H3CO
XXV
Sangshetti and co-workers [58] have reported some novel substituted triazoles
XXVI and evaluated for their in vitro antifungal activity, in SAR compared their MIC
values with miconazole and fluconazole.
NN
N
NR
N
O
N
R1
XXVI
Veerendra and Shivananda [59] have reported 1,2,4-triazole XXVII as
significant antibacterial, antifungal, anthelminitic activity while Mohan and Kumar
[60] have reported some fused triazole XXVIII systems with other nitrogen ring
system increasing its biological importance as antibacterial agent and also possess
diuretic and naturiuretic activity.
N
NN
S
N
O
R
NCH
OCH3
O2N
N
N
N
S
N
RCl
F
XXVII XXVIII
Al-Masoudi et al [61] have synthesized new Schiff base ligand
derived from 5-amino-4-phenyl-4H-1,2,4-triazole-3-thiol XXIX and
evaluated in vitro anti-HIV activity.
Cl
N N
NN
S
NH
S
N
O
XXIX
Ribose N-glycoside XXX [62-66] is a broad spectrum antiviral agent
containing the 3-aminocarbonyltriazole and active against both RNA and DNA
viruses and is used in an aerosol for lower respiratory tract viral disease as well as in
the treatment of influenza, Lassa fever, and Hantaan virus [67, 68]. Amidine and
guanidine derivatives XXXI exhibiting a broad spectrum antiviral activity [69] have
been prepared.
O
OH
OHOH
N
N
N
CONH2
O
OH
OHOH
N
N
N
NH
NHR
XXX XXXI
Shi and Zhou [70] have designed, synthesized new coumarin-based 1,2,4-
triazoles XXXII and evaluated for their antimicrobial by two-fold serial dilution
technique. The bioactive assay showed that some synthesized coumarin triazoles
displayed comparable or even better antibacterial and antifungal efficacy in
comparison with reference drugs enoxacin, chloromycin and fluconazole. Coumarin
bis-triazole compounds exhibited stronger antibacterial and antifungal efficiency than
their corresponding mono-triazoles.
N
N
NROOO
CH3
XXXII
Wu and co-worker have synthesized 4-amino-3-(2-furyl)-5-mercapto-1,2,4-
triazole XXXIII as potential HIV-1 NNRTIs [71].
N
NN
R
N S
R
R1
XXXIII
Idrees et al have synthesized 2-(naphthalen-2-yl-oxy) propionic acid
derivatives XXXIV and XXXV as desmethyl fibrate analogous and evaluated
hypolipidemic activity [72].
O
CH3
N
N
NH
RS
O
CH3
N
N
N
RH5C2S
XXXIV XXXV
Boschelli et al have synthesized 1,2,4-triazole analogues of fenamates
XXXVI, XXXVII, XXXVIII, XXXIX as an in vitro inhibition of cyclooxygenease
and 5-lipoxygenase activities [73].
NH
N
N
H
N
H
S
R
NH
N
N
H
N
H
CF3
O
XXXVI XXXVII
NH
N
N
N
H
O
R
CH3
NH
N
N
N
H
S
R
CH3
XXXVIII XXXIX
Tripathi and co-workers [74] have synthesized 1,4-disubstituted-1,2,3-
triazoles XL by cycloaddition of different 2-(azidomethyl)-dihydronaptho(benzo)
furans with different alkynes and screened for antitubercular activity against
Mycobacterium tuberculosis H37Rv, reported antitubercular activities with MIC
ranging from 12.5 to 3.12 mg/ml. The other method for synthesis of novel 1,2,4-
triazole XLI was reported by S. giri and Nizamuddin [75] while Desai and Mistry
[76] also prepared 1,2,4-triazole XLI by refluxing various 1,2,4-triazole with excess
hydrazine hydrate in absolute ethanol.
N
N N
RO
R1
N
N
N
SHAr
NH2
XL XLI
Some novel 1,2,4-triazole XLII have been synthesized by Faidallah et al [77],
while Papakonstantinou-Garoufalias et al [78] have synthesized substituted 4-(2,4-
dichlorophenyl)-5-adamantyl-1H-1,2,4-triazoles XLIII and found as potential
antimicrobial agents.
NN
R
N
NN
PhSH
N
N N
Cl
Cl
SCH2CONHN
R1
R2
XLII XLIII
Siddiqui and co-workers [79] have reported 6-(substituted phenyl)-2-(4-
substituted phenyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-4,5-dihydropyridazin-
3(2H)-ones XLIV by a sequence of reactions starting from respective aryl
hydrocarbons and evaluated for antihypertensive activities by non-invasive method
using Tail Cuff method and compared with that of standard hydralazine and
propranolol.
N
N
H
N
S
R1N
N
R
O
XLIV
El-Sayed has synthesized new 1,2,4-triazoles XLV-XLIX and studied their
surface activity and evaluated as antibacterial agent [80].
N
O
O
NN
N
R
SH
NN
N
R
N
H
S
S
XLV XLVI
N
N N
R
N
R1
S
N
S
N
NN
R
SH
Ph
O
N
N
N
R
SHN
Ph
XLVII XLVIII XLIX
Song and co-workers [81] have synthesized triazole-linked glycosyl
acetophenone L, benzoic acid, and a-ketocarboxylic acid derivatives via Cu(I)-
catalyzed azide-alkyne cycloaddition (‘click’ reaction) and a docking simulation was
conducted to propose a plausible binding mode of the glucosyl α-ketocarboxylic acid
triazole with the enzymatic target. While Kumar et al [82] have synthesized 2-
substituted-5-[isopropylthiazole] clubbed 1,2,4-triazoles LI and evaluated for their
preliminary cytotoxicity, antimicrobial and antitubercular activity against
Mycobacterium tuberculosis H37Rv strain by broth dilution assay method.
Antimycobacterial activity tested against M. tuberculosis showed that many analogues
showed twofold enhanced potency than parent compound
NN
N
R
O
RO
N N
NSH
NN
R
S
N
CH3
CH3
L LI
Aytac and his co-workers have synthesized 3,6-disubstituted-4H-1,2,4-
triazolo[3,4-b]-1,3,4-thiadiazines LII, LIII and found as potent analgesic and anti-
inflammatory agents [76].
(CH2)n
R
R
O
CH3
N
N
H
S
NN
R1
(CH2)n
R
R
O
CH3 N
N
N
H
NH2
S
LII LIII
Some novel 1,2,4-triazole and 4,5-dihydro-1H-1,2,4-triazol-5-ones LIV have
been reported as antifungal, antimicrobial, hypoglycemic, antihypertensive, analgesic,
antiparastic, hypocholestermic, antiviral, anti-inflammatory, antitumor and anti-HIV
activities [83-86] proved by Haydar and Zafer.
NC
NN
R
O
N
C
O X
H
H
LIV
Palaska and co-worker [87] have synthesized 1,2,4-triazole-3-thiones LV; 5-
(3,5-ditertbutyl-4-hydroxyphenyl)-1,2,4-triazoles LVI have been synthesized by
Mullican and co-workers [88] and evaluated as potential anti-inflammatory activity.
Turan-Zitouni et al have synthesized triazoles LVII and triazolothiadiazines
LVIII and evaluated their analgesic activity [89].
N
N N
H
OCH2
R
S
N
N N
H
Ph
S
NH2
LV LVI
OCH2
NN
N
H
N
S
R2
OCH2
N
N
N
H
N
S
R1
R2
R3
LVII LVIII
Some 1,2,4-triazoles LIX have been derived by Udaupi and co-workers [90]
possess wide range of biological activities while Sun and co-workers [91] have
synthesized 3-(phenylcyclobutyl)-1,2,4-triazoles LX as inhibitors of 11-β-
hydroxysteroid dehydrogenase type 1 (HSD1). They were shown to be active in the
mouse in vivo pharmacodynamic model (PD) for HSD1 but exhibited a potent off-
target activation of the Pregnane X Receptor (PXR), SAR studies and synthesis of
analogues led to the discovery of a selective HSD1 inhibitor.
N
CN
N
Ar SH
NH2
NN
N
PhR
Cl
CH3
LIX LX
Shiradkar et al [92] have synthesized thiazolyl triazole derivatives LXI
under microwave; 3-alkylsulfanyl-1,2,4-triazole derivatives LXII have been
synthesized by Kalpancikli et al [93] and evaluated as potential antitubercular agents.
S
N
N N
S
O
S
NH2R
LXI LXII
Reddy et al [94] have synthesized novel 1,2,3-triazoles LXIII by click
reaction of sugar-derived azides with acetylenes and evaluated antifungal activity
against C. albicans, C. neoformans, S. schenckii, T. mentagrophytes, A. fumigatus,
and C. Parapsilosis (ATCC 22019) and antibacterial activity against E. coli, P.
Aeruginosa (ATCC BAA-427), S. aureus (ATCC 25923), and K. pneumoniae (ATCC
27736).
N
NN
R
O
OH
OBn
LXIII
Ciocoiu and co-workers [95] have prepared 1,4-disubstituted 1,2,3-triazoles
LXIV and tested for their ability to increase oleic acid oxidation in human myotubes
using a high-throughput multiwell assay. Some of them exhibited powerful agonist
effects for both PPARa and PPARd in a luciferase-based assay and also categorized
as dual PPAR agonists.
NN
NR1
R2
S O
OH
O
LXIV
S
N
N
NN
R
NH2SH
Recently we have evaluated the antimycobacterial and antimicrobial activities of
newly synthesized 3-(3-pyridyl)-5-(4-methoxyphenyl)-4-(N-substituted-1,3-
benzothiazol-2-amino)-4H-1,2,4-triazole LXV in good yields. In-vitro
antimycobacterial activity was carried out against Mycobacterium tuberculosis H37Rv
strain using Lowenstein-Jensen medium and antimicrobial activity against two Gram
positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), two Gram
negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and three fungal
species (Candida albicans, Aspergillus niger, Aspergillus clavatus) using the broth
microdilution method by Patel et al [96].
N N
N
O
CH3
N NH
S
N
R
LXV
1.2.1.2 References
1. Jones D. H., Slack R., Squires S. and Woolridge K. R. H.; J. Med. Chem., 8,
1965, 676.
2. Goswami B. N., Kataky J. C. S. and Baruah J .N.; J. Het. Chem., 2, 1984, 225.
3. Holla B. S., Kalluraya B. and Sridhar K. R.; Curr. Sci., 56, 1987, 236.
4. Abdon N. A., Amin F. M. and Mansoura A.; J. Pharm. Sci., 6, 1990, 25.
5. Mishra R. K., Tewari R. K., Srivastava S. K. and Bahel S. C.; J. Ind. Chem.
Soc., 68, 1991, 110.
6. Street L. J., Baker R., Baker W. B., Davey, W. B., Guiblin A. R. and Jelley R.
A., J. Med. Chem., 38, 1995, 1799.
7. Vasoya S. L., Chovatia P.T., Paghdar D. J. and Joshin H. S.; J. Ind. Chem.
Soc., 84, 2007, 709.
8. Manjunath G. D. and Sreenivasa A.; Ind. J. Het. Chem., 11, 2002, 255.
9. Jean-Luc G.; Bio.Org. Med. Chem. Lett., 16, 2006, 4444.
10. Dudley M.W., Soremen S.M. and Miller J.M.; J. Med. Chem., 91, 1988, 1253.
11. John M.K., Bruce M.B. and Mark W.D.; J. Med. Chem., 33, 1990, 2772.
12. Huffman J.M., Sidwell R.W., Khare G.P., Witkowski J.T., Allen L.B. and
Robins R.K.; Antimicrob. Agents Chemother., 3, 1973, 235.
13. Wujec M.; Acta Pharm., 54, 2004, 251.
14. Katsuhide M., Fukushima A., Hiroshi. A and Yamazaki T.; Chem. Bull., 27,
1979, 242.
15. Kane J.M.; Baron B.M.; Dudley M.W.; Sorensen S.M.; Staeger M.A. and
Miller F.P; J. Med. Chem., 33, 1990, 2772.
16. Kucukguzel I., Kucukguzel S.G., Rollas S., Otuk-Sanis G., Ozdemir O.,
Bayrak I.; Altug T. and Stables J.P; Il Farmaco, 59, 2004, 893.
17. Rollas S., Kalyoncuoglu N., Sur-Altiner D. and Yegenoglu Y.; Pharmazie ,
48, 1993, 308.
18. Chollet J.F., Bonnemain J.L., Miginiac L. and Rohr O.; J. Pestic. Sci., 29,
1990, 427.
19. Murabayashi A., Masuko M., Niikawa M., Shirane N., Futura T., Hayashi Y.
and Makisumi Y.; J. Pestic. Sci. 16, 1991, 419.
20. Gilbert B.E. and Knight V.; Antimicrob. Agents Chemother., 30, 1986, 201.
21. Holla B.S., Veerendra B., Shivananda M.K. and Poojary B.; Eur. J. Med.
Chem., 38, 2003, 759.
22. Turan-Zitouni G., Sıvacı M.F., Kilic S., Erol K.; Eur. J. Med. Chem., 36, 2001
685. Molecules, 11, 2006, 477.
23. Bekircan O., Kucuk M., Kahveci B and Kolaylı S.; Arch. Pharm., 338, 2005,
365.
24. Wade P.C., Vogt B.R., Kissick T.P., Simpkins L.M., Palmer D.M. and
Millonig R.C.; J. Med. Chem., 25, 1982, 331.
25. Gruta A.K., Bhargava K.P.; Pharmazie, 33, 1978, 430.
26. Modzelewska B., Kalabun J.; Pharmazie, 54, 1999, 503.
27. Malbec F., Milcent R., Vicart P. and Bure A.M.; J. Het. Chem., 21, 1984,
1769.
28. Milcent R., Vicart P., Bure A.M.; Eur. J. Med. Chem. 18, 1983, 215.
29. Gulerman N., Rollas S., Kiraz M., Ekinci A.C. and Vidin A.; Il Farmaco, 52,
1997, 691.
30. Ikizler A.A., Johansson C.B., Bekircan O. and Celik C.; Acta Polon Pharm-
Drug Res., 56, 1999, 283.
31. Shujuan S., Hongxiang L., Gao Y., Fan P., Ma B., Ge W. and Wang X.; J.
Pharm. Miomed. Anal.; 34, 2004, 1117.
32. Clemons M., Coleman R.E., and Verma S.; Cancer Treat. Rev., 30, 2004, 325.
33. Johnstonn G.A.R.; Curr. Top.Med. Chem., 2, 2002, 903.
34. Bhat A.R., Bhat G.V. and Shenoy G.G.; J. Pharm. Pharmacol., 53, 2001, 267.
35. Demirbas N., Ugurluoglu R. and Demirbas A.; Bioorg. Med. Chem., 10, 2002,
3717.
36. Kahveci B., Bekircan O., Serdar M. and Ikizler A.A.; Ind. J. Chem., 42B,
2003, 1527.
37. Bhat K.I., Kumar V.and Kalluraya B.; Asian J. Chem., 16, 2004, 96.
38. Bekircan O. and Gumrukcuoglu N.; Ind. J. Chem., 44B, 2005, 2107.
39. Kahveci B., Bekircan O. and Karaoglu S.A.; Ind. J. Chem., 44B, 2005, 2614.
40. Bekircan O., Kahveci B. and Kucuk M.; Turk J. Chem., 30, 2006, 29.
41. Mange Y.J., Isloo A.M., Malladi S. and Isloor S.; Arab. J. Chem.,
doi:10.1016/j.arabjc.2011.01.033.
42. Odlo K., Fournier-Dit-Chabert J., Ducki S., Gani O., Sylte I. And Hansen
T.V.; Bioorg. Med. Chem., 18, 2010, 6874.
43. Amir M. and Kumar S., Ind. J. Chem., 43(B), 2004, 2189.
44. Desai K.R and Mistri B.D., J. Ind. Chem. Soc., 79, 2002, 964.
45. Konorev E. A., Struck A. T., Baker J. E., Ramanujam S., Thomas J. P., Radi
R. and Kalyanaraman B.; Free Rad. Res. Commun., 19, 1993, 397.
46. Aspberg A., Soderback M. and Tottmar O.; Biochem. Pharmacol., 46, 1993,
1873.
47. Konosu T., Tajima Y., Miyaoka T. and Oida S.; Tetrahedron Lett., 32, 1991,
7545.
48. Yan S.J., Liu Y.J.,Chen Y.L, Liu L. and Lin J.; Bioorg. Med. Chem. Lett., 20,
2010, 5225.
49. Bhatt A.R., Ind. J. Het. Chem., 13, 2004, 237.
50. Demirbas N., Demirbas A. and Celik E., Arkivoc., 1, 2005, 75.
51. Eid F. A., Abd El-Wahab A. H. F., El-Hag Ali G. A. M. and Khafagy M. M.;
Acta Pharma., 54, 2004, 13.
52. Shankar R.B. and Pews R.G.; Heterocycles, 53, 2000, 1151.
53. Takaoka M., Manabe S., Yamoto T., Matsunuma N., Masuda H. and Goto N.;
J. Vet. Med. Sci., 56, 1994, 341.
54. El-Gazzar A.B.A., Hegab M.I., Swelam S. A. and Aly A. S.; Phosphorus,
Sulfur and Silicon, 177, 2002, 123.
55. Schneller S. W., May J. I. and De Clercq E.; Croat. Chem. Acta, 596, 1986,
307.
56. Maingot L., Leroux F., Landry V., Dumont J., Nagase H., Villoutreix
B.,Sperandio O., Deprez-Poulain R. and Deprez B.; Bioorg. Med. Chem. Lett.,
20, 2010, 6213.
57. Mishra J., Freddy H. and Havaldar., Ind. J. Het. Chem., 13, 2003, 167.
58. Sangshetti J.N., Chabukswar A.R. and Shinde D.B.; Bioorg. Med. Chem. Lett.,
21, 2011, 444.
59. Veerendra B. and Shivananda M. K.; Ind. J. Het. Chem., 13, 2003, 61.
60. Mohan J. and Kumar A.; Ind. J. Het. Chem., 14, 2003, 97.
61. Al-Masoudi N.A., Aziz N.M. and Mohammed A.T.; Phosphorus, Sulfur and
Silicon, 184, 2009, 2891.
62. Witkowski J.T., Robins R.K., Sidwell R.W. and Simon L.N.; J. Med. Chem.,
15, 1972, 1150.
63. Sidwell R.W., Hoffmann J.H., Khare G.P., Allene L. B., Witkowski J. T. and
Robins R. K.; Science, 177, 1972, 705.
64. Smith R.A. and Kirkpatrick R.A.; Ribavirin. A Broad Spectrum Antiviral
Agent, Acad. Press, New York, 1985, 49.
65. Smith R.W., Revankar G.R. and Robins R.K.; In Viral Chemotherapy; D.
Shugar (ed.); Pergamon Press, New York, 1985, 13.
66. Smith A., Knight V. and Smith J.A.D.; Clinical Applications of Ribavirin;
Acad. Press, New York, 1984.
67. Hanna N.B., Dimitrijevich S., Larson S.B., Robins R.K. and Ravankar G.R.; J.
Het. Chem., 25, 1988, 1857.
68. Jenkins T.C., Stratford I.J. and Stephens M.A.; Anticancer Drug Res., 4, 1989,
145.
69. Kini G.D., Robins R.K. and Avery T.L.; J. Med. Chem., 32, 1989, 1447.
70. Shi Y. and Zhou C.; Bioorg. Med.Chem. Lett., 21, 2011, 956.
71. Wu J., Liu X., Cheng X., Cao Y., Wang D., Li Z., Xu W., Pannecouque C.,
Witvrouw M. and Clercq E. D.; Molecules, 12, 2007, 2003.
72. Idrees G.A., Aly O.M., Abuo-Rahma G.A.A. and Radwan M.F.; Eur. J. Med.
Chem., 44(10), 2009, 3973.
73. Boschelli D.H., Connor D.T., Bornemeier D.A., Dyer R.D., Kennedy J.A.,
Kuipers P.J., Okonkwo G.C., Schrier D.J. and Wright C.D.; J. Med. Chem.,
36, 1993, 1802.
74. Tripathi R.P., Yadav A.K., Ajay A., Bisht S.S., Chaturvedi V. and Sinha S.K.;
Eur. J. Med. Chem., 45, 2010,142.
75. Giri S. and Nizammuddin.; Ind. J. Chem., 32(B), 1993, 399.
76. Desai K.R. and Mistri B.D., J. Ind. Chem. Soc.; 79, 2002, 964.
77. Faidalla H.M,. Sharshir E.M., Basaif S.A. and A-Ba-Oum A. E.; Phosphorus,
Sulfur and Silicon, 177, 2002, 67.
78. Papakonstantinou-Garoufalias S., Pouli N., Marakos P. and Chytyroglou-
Ladas A.; Farmaco, 57, 2002, 973.
79. Siddiqui A.A., Mishra R., Shaharyar M., Husain A., Rashid M. and Pal P.;
Bioorg. Med. Chem. Lett., 21, 2011, 1023.
80. Al-Sayed; Grasas Y Aceites, 57, 2006, 180.
81. Song Z., He X., Li C., Gao L., Wang Z.,Tang Y., Xie Y.,Xie J., Li J. and Chen
G.; Carbohydrate Research, 346, 2011, 140.
82. Kumar G.V.S., Prashad Y.R., Mallikarjuna B.P., Chandrashekhar S.M. and
Kistayya C.; Eur. J. Med. Chem., 45, 2010, 2063.
83. Erol K. and Turan-Zitouni G., Eur. J. Med. Chem., 36, 2001, 685.
84. Demirbas N., Demirbas A. and Celik E.; Arkivoc.,1, 2005, 75.
85. Modze B., Banachiewicz E. and Jagiello-Wojtowicz E.; Acta. Pol. Pharma.-
Drug Res. 57, 2000, 199.
86. Ulusoy N., Gurosy A. and Otuk G., Pharmaco., 56, 2001, 947.
87. Palaska E., Sahin G., Kelicen P., Durlu N. T. and Altinok G.; Farmaco, 57,
2002, 101.
88. Mullican M.D., Wilson M.W., Connor D.T., Kostlan C.R., Schrier D.J. and
Dyer R.D.; J. Med. Chem., 36, 1993, 1090.
89. Turan-Zitouni G., Kaplancikli Z. A., Erol K. and Kilic F. S.; Farmaco, 54,
1999, 218.
90. Udupi R.H., Pasha T.Y. and Agarwal M.; Ind. J. Het. Chem., 12, 2003, 361.
91. Sun W., Maletic M., Mundt S.S., Shah K., Zokian H.,Lyons K.,Wadell S.T.
and Balkovec J.; Bioorg. Med.Chem. Lett., doi:10.1016/j.bmcl.2011.01.125.
92. Shiradkar M.R., Murahari K.K., Gangadasu H.R., Suresh T., Kalyan C.A.,
Panchal D., Kaur R., Burange P., Ghogare J., Mokale V. and Raut M.; Bioorg.
Med. Chem., 15, 2007, 3997.
93. Kaplancikli Z.A., Turan-Zitouni Z. and Chevallet V.; J. Enzm. Inhib. Med.
Chem., 20(2), 2005, 179.
94. Reddy L.V., Reddy P.V., Mishra N.N., Shukla P.K., Yadav G., Srivastava R.
and Shaw A.K.; Carbohydrate Research, 345, 2010, 1515.
95. Ciocoiu C.C., Nikolic N., Nguyen H.H., Thoresen G.H., Aasen A. and Hansen
T.V.; Eur. J. Med.Chem., 45, 2010 ,3047.
96. Patel N.B., Khan I.H.and Rajani S.D.; Arch. Pharm. Chem. Life Sci., 10, 2010,
692.
1.2.2.1 Introduction and literature review of pyrrolidine
Pyrrolidine is a colourless or slightly yellow liquid, miscible with water and
almost all common organic solvents. Intermediate used in the production of ·
pharmaceuticals, crop protection agents, pesticides, plasticizers, photographic
chemicals, emulsifiers, corrosion inhibitors, rubber auxiliaries. In addition,
pyrrolidine can be used as a catalyst for manufacturing polyurethane and as a curing
agent for epoxy resins.
N
H
I
Compounds with pyrrolidine core are significant in treatment of many diseases
like rheumatoid arthritis, allergies, asthma, anti-influenzea virus [1,2] and the
compounds showed good inhibition towards AR with 1-cyclohexyl-3-[2'(4"-
aminophenyl) ethyl] pyrrolidine-2,5-dione [3]. It has been reported that various
substituted pyrrolidines display versatile pharmacological properties such as
antihypertensive [4], anticholinergics [5], antihistaminics [6, 7] and CNS stimulants
[8]. Also, among these, analgesic activity in dextromoramide is more potent than
morphine [9].
A novel molecular modelling study is described for the fitting of non-steroidal
1-substituted-3-[2'(4"-aminophenyl) alkyl] pyrrolidine-2,5-dione based reversible
inhibitors of the Aromatase (AR) enzyme to the natural substrate androstenedione
[10]. Several novel pyrrolidine-2,5-dione based compounds have been synthesised
and evaluated for their biological activity against human placental aromatase (AR), rat
testicular 17 alpha-hydroxylase/17,20-lyase (P450(17) alpha) and bovine cholesterol
side chain cleavage (CSCC) [11]. (R,S)3-(N,N-[bis-(2-chloroethyl)]-amino)-1-(2'-
methoxyphenyl)- pyrrolidine-2,5-dione hydrochloride has shown antitumor activity
against P388 and L1210 leukaemias and Sarcoma 180 (ascites) and effect of it , when
co-administered with anticancer drugs, was studied in these murine tumours [12]. A
series of (3R,4R)-pyrrolidine-3,4-dicarboxylic acid amides was investigated with
respect to their factor Xa inhibitory activity, selectivity, pharmacokinetic properties,
and ex vivo antithrombotic activity [13]. The in vitro antibacterial and antifungal
activities of the compounds synthesised from some 1,2,3,5-tetrahalogeno benzenes in
presence of sodium piperidide and sodium pyrrolidide (2,6-dipiperidino-1,4-
dihalogenobenzenes; 2,6-dipyrrolidino-1,4-dibromobenzene; 2,4,6-tripyrrolidino
chlorobenzene; and 1,3-dipyrrolidino benzene) were investigated [14]. Novel alpha-
mannosidase inhibitors of the type (2R,3R,4S)-2-[{9(1R)-2-hydroxy-1-
arylethyl)amino}methyl]pyrrolidine-3,4-di ol have been prepared and assayed for
their anticancer activities [15]. The modulatory effects and molecular mechanisms of
pyrrolidine dithiocarbamate (PDTC) on the cytotoxicity of luteolin to HL-60 cells was
studied and it was revealed that PDTC was able to inhibit luteolin-induced cell
apoptosis in a dose-dependent manner [16]. A series of novel pyrrolidine derivatives
were designed, synthesized and assayed for their inhibitory activities on matrix
metalloproteinase 2 (MMP-2) and aminopeptidase N (AP-N). The results showed that
these pyrrolidine derivatives exhibited highly selective inhibition against MMP-2 as
compared with AP-N. The hydroxamates were equally or more potent MMP-2
inhibitors than the positive control LY52 [17]. Pyrrolidine and isoxazolidine
benzamidines were reported as novel and potent inhibitors of factor Xa [18]. Gamma-
secretase is a key enzyme involved in the production of beta-amyloid peptides which
are believed to play a critical role in the onset and progression of Alzheimer's disease
(AD). The design, synthesis, and evaluation of tetrahydroquinoline and pyrrolidine
sulfonamide carbamates as gamma-secretase inhibitors are described [19]. Synthetic
and biological evaluation of novel diphenyloxazole derivatives containing a
pyrrolidine ring, as a prostacyclin mimetic without the PG skeleton, are described
[20]. Study was carrried out to evaluate the role of the inducible nitric oxide synthase
(iNOS), selective nuclear factor-kappa B (NF-kappaB) and p38-mitogene-activated
protein kinase (p38-MAPK) on oxalate-induced crystal deposition in renal tubules
[21]. Pyrrolidine dithiocarbamate (PDTC) is a stable anti-oxidant or pro-oxidant,
depending on the situation, and it is widely used to inhibit the activation of NF-kappa
B [22]. Pyrrolidine dithiocarbamate, an antioxidant and a potent inhibitor of nuclear
factor-kappa B (NF-kappa B), is known to have protective effect against ischemia and
reperfusion injury and was examined the cytoprotective mechanism of pyrrolidine
dithiocarbamate against the microcirculatory failure caused by hepatic ischemia and
reperfusion [23]. A novel series of pyrrolidine heterocycles was prepared and found to
show potent inhibitory activity of CCR1 binding and CCL3 mediated chemotaxis of a
CCR1-expressing cell line [24]. Pyrrolidine dithiocarbamate (PDTC) can form a
complex with metal ions and act as a proteasome inhibitor, which leads to tumor cell
apoptosis, and act as an anticancer agent [25]. The rational design of a novel series of
pyrrolidine derivatives as neurokinin-3 receptor antagonists is reported starting from a
selective neurokinin-1 receptor antagonist [26]. Coxsackievirus B3 (CVB3) is one of
the most common pathogens for viral myocarditis. The lack of effective therapeutics
for CVB3-caused viral diseases underscores the importance of searching for antiviral
compounds. Pyrrolidine dithiocarbamate (PDTC) is an antioxidant and is recently
reported to inhibit ubiquitin-proteasome-mediated proteolysis [27]. A series of 3-
[(alpha-hydroxy-substituted) benzylidene]pyrrolidine-2,4-dione derivatives were
synthesized as candidate herbicides by reacting different aroyl acetates with N-
substituted glycine esters [28].
Kumar and Siddiqi [29] have synthesized pyrrolidine carboxamide analogues
II by using Leapfrog and showed better predicted activity using the CoMFA model
with respect to reported systems; hence suggesting that newlyproposed molecules in
this series of compounds may be more potent and selective toward EACP reductase
inhibition.
N
O
O
NH
R1R2
II
Abdalla et al [30] synthesized N-(p-substituted phenyl)-4-cyanopyrrolidin-3-
ones and their corresponding hydrazines and corresponding Schiff bases serotonin
antagonist, antianexity agents and screened for their serotonin antagonistic and
antianexity activities, compared to buspirone and diazepam as controls.
N
CN
NH
N
PhR
CH3
H3CO
III
Lee and co-workers [31] have characterized N-(4-amino)butyl 3-
phenylpyrrolidine derivatives IV as a selective and potent 5-HT1A receptor agonist
and evaluated its anxiolytic and antidepressant activities. LB50016-induced
pharmacological activities are mediated by activation of 5-HT1A receptors, offering
an effective therapeutic candidate in the management of anxiety and depression in
humans.
NN
S
O
OO
IV
Kudryavtsev and Tsentalovich [32] have reported methyl esters of 5-
phenylprolines V with the vinylsulfonyl or cyano group in the 4- position of the
pyrrolidine VI. By ring X-ray crystallography they showed that all substituents in the
vinylsulfonyl derivatives are cis to each other and are inhibitors of S. aureus sortase
SrtA.
N
N
R
R1
COOR2
R3
N
S
R
R1
COOR2
R3
CH2
O
O
V VI
Poschenrieder and co-workers [33] have prepared a series of oximes deriving
from 5-arylidene-pyrrolidine-2,3,4-triones VII and pyridine-2,3,4-triones. The
binding affinity of the new oximes toward the N-methyl-D-aspartate (glycine site)
receptor has been measured as a basis for more detailed structure-activity relationship
studies. Some oxime showed the highest binding potency acting as glycine antagonist
in nanomolar concentration while Doddi and co-workers [34] have synthesized
hybrids of D-Glucose and D-Galactose with pyrrolidine VIII based iminosugars and
found to be moderate glycosidase.
N
HH3CO O
O
NOH
X
N
H
O
OH
OH
OH
R
R1
H
H
VII VIII
Synthesis and Glycosidase Inhibitory activities of 5-(1',4'-dideoxy-1',4'-imino-
D-erythrosyl)-2-methyl-3-furoic acid derivatives have been synthesized by Vargas
and co-workers [35] which leads as selective α-L-fucosidase and β-galactosidase
Inhibitors
N
H
OH
OH
NH
Ph
N
H
OH
OH
NH
S
Me
IX X
Thamotharan et al [36] have reported N-(2-naphthyloxymethylcarbonyl)
pyrrolidine XI as a potential antiamnesic agent and was determined as a continuation
of the investigation of a new class of antiamnesic agents while Quintard and co-
workers [37] have disclosed the synthesis and use of highly efficient aminal–
pyrrolidine organocatalysts XII. A careful design of the pyrrolidine substituents led to
a considerable increase in enantioselectivity. A cooperative effect between the bulky
aminal on the 2-position of the pyrrolidine ring and a phenoxy group on the 4-position
led to two different catalysts, giving high reactivity and some of the highest
enantioselectivities
ON
O
N
H
N
N
PhO
R1
R1
R2
R2
XI XII
Oh et al [38] synthesized a new series of β-methylcarbapenems containing the
substituted thiazolidinopyrrolidine moiety XIII and in vitro antibacterial activities
against both Gram positive and Gram negative bacteria were tested, the effect of
substituent on the thiazolidine ring was investigated and compound having a 2-amide
substituted thiazolidine moiety showed the most potent antibacterial activity.
NH
S
N
H
R
S
NO
OHCH3
CH3
HOOC
XIII
Gao and co-workers [39] have reported catalytic properties of a series of chiral
(pyrrolidine salen)Mn(III) complexes XIV for asymmetric oxidation of aryl methyl
sulfides. Moderate activity, good chemical selectivity and low enantioselectivity were
attained with iodosylbenzene as a terminal oxidant. Enantioselectivity of sulfide
oxidation was affected slightly by polar solvent and the sulfoxidation carried out in
THF for thioanisole and in CH3CO2Et for electron-deficient sulfides gave better
enatioselctivities.
N
R
N+
OMn
3-
Cl
N+
O t-But
-Bu
XIV
Oh et al [40] have prepared new series of 1β-methylcarbapenems containing a
substituted imidazolino pyrrolidine moiety XV and evaluated their in vitro
antibacterial activities against both Gram positive and Gram negative bacteria, the
effect of the substituent on the imidazoline ring was investigated. Compound having a
N-sulfonylmethyl substituted imidazoline moiety showed the most potent antibacterial
activity.
NH
N
N
S
NO
OHCH3
CH3
HOOC
R
R1R2
XV
A new series of β-methylcarbapenems with a substituted
oxadiazolopyrrolidine moiety XVI have been reported by Oh and co-workers [41] and
in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria
were tested and the compounds with ester and carbamoyl substituted oxadiazole
moieties showed the most potent antibacterial activity.
NH
S
NO
OHCH3
CH3
HOOC
N
N
O
R
XVI
The synthesis of a new series of 2-alkyl-4-pyrrolidinylthio-β-
methylcarbapenems containing the substituted heteroaromatic moieties XVII have
been described by Cho et al [42] and in vitro antibacterial activities against both Gram
positive and Gram negative bacteria were tested.
NH
S
N
HS
N
O
OHCH3
CH3
HOOCR
H
H
XVII
Some novel diastereomeric, erythritol and threitol polyhydroxylated
pyrrolidine imine scaffolds XVIII, XXI have been synthesized by Chapman and co-
workers [43] and screening of a representative selection of these hydrophobically-
modified aza-sugars against a diverse panel of 12 non-mammalian and human
carbohydrate-processing enzymes.
N
H
OH
R
OH
N
H
OH
R
OH
N
H
OH
R
OH
N
H
OH
R
OH
XVIII XIX XX XXI
Simmonds and co-workers [44] have tested polyhydroxy alkaloids XXII-
XXIV of plant origin for antifeedant effects against larvae of the lepidopterans
Spodoptera littoralis, Spodoptera frugiperda, Heliothis virescens and Helicoverpa
armigera.
N
H
OH OH
CH2OHHOH2C
N
H
OH OH
CH2OH N
H
OH
CH2OH
XXII XXIII XXIV
Kulig and Malawska [45] have investigated the lipophilicity (RMO and log k’)
of some antiarrhythmic and antihypertensive active 1-[2-hydroxy- or 1-[2-acetoxy-3-
(4-aryl-1-piperazinyl)propyl]pyrrolidin-2-ones XXV by reversed-phase thin-layer
chromatography and reversed-phase high-performance liquid chromatography with
mixtures of acetonitrile and tris buffer as mobile phases.
N
X
N
N
R
OR
XXV
Arndt et al have reported [46] 2,5-trans-substituted oligopyrrolidines novel
RNA-binding agents XXVI as well as potential building blocks for artificial anion
channels and screened for RNA cleavage activity in which p-nitrosulfonamide was
found to induce cleavage at mm concentrations under physiologically relevant
conditions while Sun et al [47] reported Michael addition of cyclohexanone with
trans-b-nitrostyrene catalyzed by a chiral ionic liquid (CIL) pyrrolidine-imidazolium
bromide XXVII which represents a prototype of CIL-promoted asymmetric
syntheses, has been investigated by performing density functional theory calculations.
N
HN
HN
OROR
H H
HH H
H
H
NN
N
CH3
BrH
XXVI XXVII
Planar 2(5H)-furanones substituted at C-4 with a chiral pyrrolidinyl group
XXVIII, XXIX, XXX have been studied by Gawronski and co-workers [48] which
showed CD spectra which are apparently due to the distortion of the C4-N1 bond of
SP2 character from the plane defined by the 2(5H)-furanone ring atoms and due to the
presence of substituents in the pyrrolidine ring and the chiroptical properties of 2(5H)-
furanones were studied and emerging from the analysis of X-ray diffraction data and
quantum mechanical DFT computations.
NO
O
R
NO
O
RCH3
CH3
R1
NO
O
R
R1
R4R2 OR3
XXVIII XXIX XXX
A novel disubstituted pyrrolidine acid XXXI has reported by Freedman et al
[49] as a new class of agents that are potentially useful for the treatment of diabetes
and dyslipidemia.
N
O O
OH
O
HHO
N
O CH3
XXXI
Chiral C2-symmetric 2,5-disubstituted pyrrolidine derivatives having a β-
aminoalcohol moiety XXXII have been successfully synthesized by Shi and co-
workers [50] and their catalytic abilities of chiral induction have been examined in the
reactions of diethylzinc with aryl aldehydes. The production of secondary alcohols
having R absolute configuration was achieved in very high chemical yield when N-
(2',2'-diphenyl-2'-hydroxyethyl)-(2R,5R)-bis(methoxymethyl)-pyrrolidine XXXIII is
used as achiral ligand
N
R
ROH
MeOH2C C(O)OMe
N
Me OHOH
R
RR
R
XXXII XXXIII
Isoherranen et al [51] have reported a antiepileptic drug, levetiracetam
XXXIX (LEV, ucb LO59), a chiral molecule with one asymmetric carbon atom
whose anticonvulsant activity is highlyenantioselective and to evaluate and compare
the pharmacokinetics (PK) of LEV [(S)-a-ethyl-2-oxo-pyrrolidine acetamide] and its
enantiomer (R)-α-ethyl-2- oxo-pyrrolidine acetamide XL (REV) after i.v.
administration to dogs.
N
O
NH2
CH3
O
N
O
NH2
CH3
O
N
O
OH
CH3
O
XXXIX XL XLI
Kang and co-workers [52] have reported antibacterial activity of pyrrolidine
dithiocarbamate XLII PDTC and have evaluated in vitro by the broth microdilution
method against Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans,
Staphylococcus aureus, and Escherichia coli. Bacterial growth was inhibited by
PDTC, where a wide range of sensitivity was demonstrated among the tested bacteria
and Kabay and co-workers [53] reported the effect of PDTC on lung reperfusion
injury induced by superior mesenteric occlusion.
N
SH
S
XLII
A group of m-[3-alkyl-l-(cyclopropylmethyl)-3-pyrrolidinyl] phenols XLIII
and related compounds has been synthesized by Bowman et al [54] and evaluated for
potential nonaddicting analgesic drugs. New 2-(aminomethyl)-5-(hydroxymethyl)
pyrrolidine-3,4-diol derivatives XLIV were synthesized from (5S)-5-
[(trityloxy)methyl]pyrrolidin-2-one and their inhibitory activities toward 25
glycosidases were reported by Popowycz et al [55].
N
R1
R2
OR
N
H
OH
OH
NH
ROH
XLIII XLIV
Dispiro[1H-indene-2,3'-pyrrolidine-2',3''-[3H]indole]-1,2'' (1H)-diones XLV
were generated by 1,3-Dipolar cycloaddition reaction of 2-(arylmethylene)-2,3-
dihydro-1H-inden-1-ones with non-stabilized azomethine yield, in situ via
decarboxylative condensation of isatins and sarcosine afforded and not the isomeric
forms dispiro[1H-indene-2,4’-pyrrolidine-2',3''-[3H]indole]-1,2''(1''H)-diones in a
highly regioselective manner. Anti-tumor activity screening for the synthesized
compounds XLV at a dose of 10 mM utilizing 56 different human tumour cell lines
representing, leukemia, melanoma and cancers of the lung, colon, brain, ovary, breast,
prostate and kidney have been carried out by Girgis [56].
N
N
CH3
OR
R1
O
XLV
Obniska and Zagorska [57] have synthesized a series of N-[(4-arylpiperazin-
1-yl)-methyl] derivatives of 3-arylpyrrolidine-2,5-diones XLVI and tested for
anticonvulsant activity in the maximum electroshock seizure (MES) and metrazole
seizure threshold (sc.MET) tests while Brunel and co-workers [58] have studied the
complexes formed by copper (II) XLVII with potential non-steroidal anti-
inflammatory agents (NSAIDs) under physiological conditions.
N
N N (CH2)n
R
O
O
N
Cu+2
N
N
R
R
N
XLVI XLVII
1.2.2.2 References
1. Mituaki O., Toshiyuki K., Fumihiko W. and Koaru S.; Chem Abstr, 1997, 126,
22529u.
2. Galeazzi R., Geremia S., Mobbili G. and Orena M.; Tetrahedron Asymmetry,
10, 1999, 587.
3. Ahmed S., Smith J.H., Nicholls P.J., Whomsley R. and Cariuk P.; Drug Des.
Discov., 12, 1995, 275.
4. Malawska B., Kulig K., Filipek B., Sapa J., Maciag D. and Zygmunt M.; Eur.
J. Med. Chem., 37, 2002, 183.
5. Adamson B.W., Barret P.A. and Wilkison S; J. Chem. Socv., 1951, 52.
6. Weidmann H., Grauwiler J., Griffith R., Roemer D., Taeschler M. and
Zehnder Z.; Boll Chim. Form. 106, 1967, 467.
7. Ondetti M.A. and Cushman D.W.; US pat., 1977, 4,053,651; Chem. Abstr.,
1977, 88, 136977.
8. Seeger E. and Kottler A.; Ger. Pat., 1, 093, 709, 1960; Chem. Abstr., 1961,
55, 19950.
9. Keats A.S., Telford J. and Kurosu Y.; J. Pharma. Exp. Therap., 212, 1982,
130.
10. Ahmed S ; Drug Des. Discov., 14(1), 1996, 77.
11. Ahmed S., Smith J.H., Nicholls P.J.,Whomsley R. and Cariuk P; Drug Des.
Discov., 12(4) ,1995, 275.
12. Ambaye R.Y., Indap M. A. and Naik S.D.; J. Cancer Res. Clin. Oncol.,
115(4),1989, 379.
13. Anselm L., Banner D.W., Benz J., Zbinden K.G., Himber J., Hilpert H., Huber
W., Kuhn B., Mary J.L., Otteneder M.B., Panday N., Ricklin F., Stahl M.,
Thomi S. and Haap W.; Bioorg. Med. Chem. Lett., 20(17), 2010, 5313.
14. Arslan S., Logoglu E. and Oktemer A.; J. Enzyme Inhib. Med. Chem., 21(2),
2006, 211.
15. Bello C., Cea M, Dal Bello G.,Garuti A., Rocco I., Cirmena G., Moran E.,
Nahimana A., Duchosal M.A., Fruscione F., Pronzato P., Grossi F., Patrone
F., Ballestrero A., Dupuis M., Sordat B., Nencioni A. and Vogel P.; Bioorg.
Med. Chem., 18(9), 2010, 3320.
16. Cheng A. C.,Huang T. C., Lai C.S., Kuo J.M., Huang Y.T., Lo C.Y., Ho C.T.
and Pan M.H.; J. Agric Food Chem., 54(12), 2006, 4215.
17. Cheng X.C., Wang Q., Fang H., Tang W. and Xu W.F.; Eur. J. Med. Chem.,
43(10), 2008, 2130.
18. Fevig J.M., Buriak J., Stouten P.F., Knabb R.M., Lam G.N., Wong P.C. and
Wexler R.R.; Bioorg. Med. Chem. Lett., 9(8), 1999, 1195.
19. Guo T., Gu H., Hobbs D.W., Rokosz L.L., Stauffer T.M., Jacob B. And Clader
J.W.; Bioorg. Med. Chem. Lett., 17(11), 2007, 3010.
20. Hattori K., Okitsu O., Tabuchi S., Taniguchi K., Nishio M., Koyama S., Seki
J. and Sakane K.; Bioorg. Med. Chem. Lett,. 15(13), 2005, 3279.
21. Ilbey Y.O., Ozbek E., Simsek A., Cekmen M., Somay A. and Tasci A.I.; Arch
Ital. Urol. Androl., 82(2), 2010, 87.
22. Kim Y.E., Park J.A., Nam K.H., Kwon H.J. and Lee Y.; BMB Rep., 42(3),
2009, 148.
23. Lee C.H., Kim S.H. and Lee S.M.; Eur. J. Pharmacol., 595, 2008, 100.
24. Merritt J.R., James R., Paradkar V.M., Zhang C., Liu R., Liu J., Jacob B.,
Chiriac C., Ohlmeyer M.J., Quadros E., Wines P., Postelnek J., Hicks C.M.,
Chen W., Kimble E.F., O’Brien L., White N., Desai H., Appell K.C. and
Webb M.L.; Bioorg. Med. Chem. Lett., 20(18), 2010, 5477.
25. Oh da H., Bang J.S., Choi H.M., Yang H.I., Yoo M.C. and Kim K.S.; Eur. J.
Pharmacol., 649, 2010, 135.
26. Ratni H., Ballard T.M., Bissantz C., Hoffmann T., Jablonski P., Knoflach F.,
Knust H., Malherbe P., Netttekoven M., Patiny-Adam A., Riemer C., Scmitt
M. and Spooren W.; Bioorg. Med. Chem. Lett., 20(22), 2010, 6735.
27. Si X., McManus B.M., Zhang J., Yuan J., Cheung C.,Esfandiarei M., Suarez
A., Morgan A. and Luo H.; J. Virol., 79(13), 2005, 8014.
28. Zhu Y., Zou X., Hu F., Yao C., Liu B. and Yang H.; J. Agric Food Chem.,
53(24), 2005, 9566.
29. Kumar A.and Siddiqi M.I.; J. Mol. Model 14, 2008, 923.
30. Abdalla M.M., Abdel-Wahab B.F. and Amr A.E.; Monatsh Chem. ,140, 2009,
129.
31. Lee C.H., Oh J.I., Park H.D., Kim H.J., Park T.K., Kim J.S., Hong C.Y., Lee
S. J., Ahn K.H. and Kim Y.; Arch Pharm.. Res., 22(2), 1999, 157.
32. Kudryavtsev K.V. and Tsentalovich M.Y.; Moscow Uni. Chem. Bulletin,
62(5), 2007, 34; doi: 10.3103/S0027131407050069.
33. Poschenrieder H., Hofner G. and Stachel H.; Arch. Pharm. Pharm. Med.
Chem. 332, 1999, 309.
34. Doddi V.R., Kokatla H.P., Pal A.P., Basak R.K. and Vankar Y.D.; Eur. J.
Org. Chem. 2008, 5731; doi: 10.1002/ejoc.200800770.
35. Moreno-Vargas A.J., Robina I., Demange R. and Vogel P.; Helvetica Chimica
Acta, 86, 2003.
36. Thamotharan S.,Parthasarathi V., Gupta P., Jindal D.P., Piplani P. and Linden
A.; Acta Cryst., 59, 2003, 1334.
37. Quintard A., Belot S., Marchal E. and Alexakis A.; Eur. J. Org. Chem., 2010,
927; doi: 10.1002/ejoc.200901283.
38. Oh C., Cho H., Lee I., Gong J., Choi J. and Cho J.; Arch. Pharm. Pharm. Med.
Chem., 4, 2002, 152.
39. Gao A., Mei Wang, Shi J., Wang D., Tian W. and Sun L.; Appl. Organometal.
Chem., 20, 2006; 830.
40. Oh C., Lee C., Lee J. and Cho J.; Arch. Pharm. Pharm. Med. Chem., 336,
2003, 504.
41. Oh C., Dong H., Lee J., Lee S. and Hong J.; Arch. Pharm. Pharm. Med.
Chem., 336, 2003, 567.
42. Cho H., Oh C., Lee J., Lee S., Choi J. and Cho J.; Arch. Pharm. Pharm. Med.
Chem., 336, 2003, 495.
43. Chapman T.M., Courtney S., Hay P. and Davis B.; Chem. Eur. J., 9, 2003,
3397.
44. Simmonds M.S.J., Blaney W.M. and Fellows L.E.; J. Chem. Ecology, 16(11),
1990, 3167.
45. Kulig K. and Malawska B.; Biomed. Chromatogr.,17, 2003, 318.
46. Arndt H., Welz R., Muller S., Ziemer B. and Koert U.; Chem. Eur. J., 10,
2004, 3945.
47. Sun H., Zhang D. and Liu C.; Chirality, 2010; doi 10.1002/chir.
48. Gawronski J., Gawronska K., Kwit M., Kacprzak K. and Rychlewska U;
Chirality, 16, 2004, 405.
49. Freedman T.B., Cao X., Phillips P.T., Dalterio R., Shu Y., Zhao N., Shukla
R.B., Tymiak A., Gozo S.K., Nafie L.A. and Gougoutas J.Z.; Chirality, 18,
2006, 746.
50. Shi M., Satoh Y. and Masaki Y.; J. Chem. Soc., Perkin Trans., 1, 1998, 2547.
51. Isoherranen N., Yagen B., Soback S., Roeder M., Schurig V. and Bailer M;
Epilepsia, 42(7), 2001, 825.
52. Kang M., Choi E., Choi D., Ryu S., Lee H, Kang H., Koh J., kim O., Hawang
Y., Yoon S., Kim S., Yang K. and Kang I.; FEMS Microbiol. Lett., 280, 2008,
250.
53. Kabay B., Teke Z., Aytekin F.O., Yenisey C.,Bir F., Sacar M., Erdem E. and
Ozden A.; World J. Surg. 31, 2007, 1707; doi: 10.1007/s00268-007-9112-5.
54. Bowman R.E., Collier H.O.J., Hattersley P.J., Lockhart I.M., Peters D.J.,
Schneider N.C., Webb N.E. and Wright M.; J. Med. Chem., 16(10), 1973,
1177.
55. Popowyez F., Gerber-Lemaire S., Schutz C. and Vogel P.; Helvetica Chemica
Acta , 87, 2004.
56. Girgis A.S.; Eur. J. Med.Chem., 44, 2009, 91.
57. Obniska J. and Zagorska A; Il Farmaco, 58, 2003, 1227.
58. Brunel S., Brumas V. and Fiallo M.M.L.; Inorganica Chimica Acta, 362,
2009, 4043.
SECTION IIISECTION IIISECTION IIISECTION III
► Studies on Studies on Studies on Studies on
� ChromatographicChromatographicChromatographicChromatographic
TechniquesTechniquesTechniquesTechniques
1.3.1 Introduction and literature review
Chromatography, firstly introduced in 1906 by the Russian botanist Micharl
Tswett, is a method for separating the components of a mixture by differential
distribution of the components of the mixture between a stationary phase and a mobile
(moving) phase. Tswett used a glass columns packed with finely divided CaCO3 to
separate plant pigments extracted by hexane. The pigments after separation appeared
as colour bands that can come out of the column one by one. He was the first to use
the term "Chromatography" derived from two Greek words "Chroma" means colour
and "graphein” meaning to write. Initially, it was used for the separation of coloured
substances from the plants (Greek, Chromos meaning coloured) is now the most
extensive technique of separation and purification of coloured and colourless organic
compounds. Chromatography is the physical separation of a mixture into its
individual components.
Chromatography is a standard method used in preparative laboratories to
isolate and purify substances. In the early days of chromatography simple glass
columns were chiefly used, operated by means of the hydrostatic pressure of the
solvent acting as an eluent. Clark W.S explored the possibility of accelerating the
separation process in simple glass columns in 1978, which was until then the
commonly used method, and thereby considerably increasing the efficiency of the
technique. The results were convincing and the foundations of modern flash
chromatography were laid. It triumphantly established itself in laboratories as an
indispensable purification method in preparative chemistry. Flash chromatography
has since undergone constant development, and has been adapted to meet present day
expectations in terms of equipment and convenience.
According to IUPAC definition (International Union of pure and applied
Chemistry) (1993): Chromatography is a physical method of separation in which the
components to be separated are distributed between two phases, one of which is
stationary while the other moves in a definite direction. The stationary phase may be
a solid, or a liquid supported on a solid or gel, the mobile phase may be either a gas or
a liquid. Different affinity of the different components towards stationary phase
causes the separation. They are then flushed through the system at different rates. The
differential rates of migration as mixture moves over adsorptive materials provide
separation. Repeated sorption/ desorption acts that take place during the movement of
the sample over the stationary bed determine the rates. The smaller the affinity a
molecule has for the stationary phase, the shorter the time spent in a column.
Chromatography is a powerful technique for separating mixtures. There are
different types of chromatography, such as paper, thin layer, or column
chromatography (amongst others), each with its own strengths and weaknesses.
Chromatography systems have a stationary phase (which can be solid or liquid) and a
mobile phase (usually liquid or gas). In column chromatography both phases are
placed in a column container. Chromatographic separation is based on a balanced
state among the components to be separated, an adsorbent agent in the column
(stationary phase) and a solvent flowing through it (mobile phase). When a
component settles on the stationary phase this is defined as adsorption, while
detachment by the mobile phase is defined as desorption. A high adsorption capacity
between the components of interest and the stationary phase means that there is a high
retention of these components and that there is a considerable delay in elution from
the column. The separation of a mixture into its individual components is only
possible if the individual components in a combination of stationary and mobile
phases have different adsorption/desorption properties.
Types of Chromatography:
Liquid/Solid Chromatography (adsorption chromatography)
Adsorption chromatography is one of the oldest types of chromatography
around. It utilizes a mobile liquid or gaseous phase that is adsorbed onto the surface of
a stationary solid phase. The equilibration between the mobile and stationary phase
accounts for the separation of different solutes. The separation mechanism in LSC is
based on the competition of the components of the mixture sample for the active sites
on an absorbent such as silica gel e.g. thin layer chromatography (tlc) and column
chromatography.
Liquid/Liquid Chromatography (partition chromatography)
This form of chromatography is based on a thin film formed on the surface of
a solid support by a liquid stationary phase. Solute equilibrates between the mobile
phase and the stationary liquid. Mobile phase may be either a liquid or a gas. The
stationary solid surface is coated with a second liquid (the Stationary Phase) which is
immiscible in the solvent (mobile phase). Partitioning of the sample between two
phases delays or retains some components more than others to effect separation. E.g.
paper chromatography. Paper Chromatography is one of the most common types of
this chromatography in which filter paper serves as a support for immobile liquid
phase. Removing liquid flows between the fibers of the cellulose but these are not the
stationary phase. The true stationary phase is the very thin film of liquid usually water
adhering o the surface of the fibers. (Water is adsorbed on the fibers/ cellulose by
strong hydrogen bonds with –OH of the cellulose). The substrate to be separated is
distributed between the two liquids, stationary liquid that is held on the fibers of the
paper and moving liquid in developing solvent. It uses a strip of paper and capillary
action is used to pull the solvents up through the paper to separate the solutes. A small
concentrated spot of solution that contains the sample is applied to a strip of
chromatography paper about 2 cm away from the base of the plate, usually using a
capillary tube for maximum precision. This sample is absorbed onto the paper and
may form interactions with it. Any substance that reacts or bonds with the paper
cannot be measured using this technique. The paper is then dipped in to a suitable
solvent, such as ethanol or water, taking care that the spot is above the surface of the
solvent, and placed in a sealed container. The solvent moves up the paper by capillary
action, which occurs as a result of the attraction of the solvent molecules to the paper,
this can also be explained as differential absorption of the solute components into the
solvent. As the solvent rises through the paper it meets and dissolves the sample
mixture, which will then travel up the paper with the solvent. Different compounds in
the sample mixture travel at different rates due to differences in solubility in the
solvent, and due to differences in their attraction to the fibers in the paper. This
method has been largely replaced by thin layer chromatography.
Chromatographic techniques which are most commonly used in the synthetic
organic laboratory are thin layer chromatography and column chromatography. These
techniques may be variously used as analytical tools to establish the complexity of
mixtures and the purity of samples, and as preparative tools for the separation of
mixtures in to individual components.
1.3.2 Thin layer chromatography
The surface of the plate consists of a very thin layer of silica gel on a plastic or
aluminium backing. Silica gel is a form of silicon dioxide (silica). At the surface of
the silica gel, the silicon atoms are attached to -OH groups. The silica gel, stationary
phase is very polar and, because of the -OH groups, can form hydrogen bonds with
suitable compounds around it as well as Van der Waals dispersion forces and dipole-
dipole attractions. The other commonly used stationary phase is alumina, aluminium
oxide. The aluminium atoms on the surface of this also have -OH groups attached.
Basic TLC is carried out as follows:
A spot of mixture (components A & B) in a proper solvent is placed near one
end of the stationary phase known as origin as shown in the diagram. The sample spot
is dried. Place the end of the stationary phase with the initial zone is placed into a
mobile phase, usually a mixture of pure solvents, inside a closed chamber. This
solvent acts as the moving phase. The components of the mixture migrate at different
rates during movement of the mobile phase through the stationary phase, which is
termed as the development of the chromatogram. When the mobile phase has moved
an appropriate distance, the stationary phase is removed from the chamber, the mobile
phase is rapidly dried and the zones are detected by application of a suitable
visualization reagent. Differential migration is the result of varying degrees of affinity
of the mixture components for the stationary and mobile phases. Non-polar
compounds are less strongly attracted to the plate and spend more time in the moving
phase. This compound will move faster and will appear closer to the top of the plate.
Polar compounds will be more strongly attracted to the plate and will spend less time
in the moving phase and appear lower on the plate. Different separation mechanisms
are involved, the predominant forces depending upon the exact nature of the two
phases and the solutes. The interactions involved in determining chromatographic
retention and selectivity include hydrogen bonding, electron-pair donor/electron-pair
acceptor (charge transfer), ion-ion, ion-dipole, and van der Waals interactions. Among
the latter are dipole-dipole (Keesom), dipole-induced dipole (Debeye), and
instantaneous dipole-induced dipole (London) interactions. The two spots at different
retention time will be observed at the plate. If the distance travelled by solvent front is
dS, by component A is dA and by component B is dB.
Visualization Methods
Most of the time, the spots don’t show unless they are visualized.
Visualization is a method that is used to render the TLC spots visible.
A visualization method can be:
• Ultraviolet light: Absorption of UV light is common for many compounds, e.g.,
aromatics and those with conjugated double bonds. This leads to a simple, rather
universal detection method on layers impregnated with a fluorescence indicator
(fluorescence quench detection).
• Iodine vapours to stain spots
• Coloured reagents to stain spots e.g. the chromatogram is allowed to dry and is
then sprayed with a solution of ninhydrin. Ninhydrin reacts with amino acids to give
coloured compounds, mainly brown or purple. Reagents selectively stain spots by
spraying leaving others unaffected.
Calculation of Rf values:
If, dA= distance travelled by component A from the origin.
dB= distance travelled by component B from the origin.
dS= distance travelled by mobile phase or eluent from the origin.
Solvent front
Component B
dS
dB Component A
dA
Origin
Figure 01: Thin layer chromatography: Determination of Rf value
Rf value = Distance travelled by the substance / Distance travelled by the solvent
front
Rf value of compound A= dA/dS and Rf value of compound B= dB/dS
Compound identification in TLC is based initially on Rf values compared to
authentic standards. Rf values are generally not exactly reproducible from laboratory
to laboratory or even in different runs in the same laboratory, so they should be
considered mainly as guides to relative migration distances and sequences. Factors
causing fly values to vary include: dimensions and type of chamber, nature and size of
the layer, direction of mobile phase flow, the volume and composition of the mobile
phase, equilibration conditions, humidity, and sample preparation methods preceding
chromatography. Further characterization of separated substances can be obtained by
scraping the layer and elution of the analyte followed by infrared (IR), nuclear
magnetic resonance (NMR), or mass spectrometry (MS) if sufficient compound is
available.
1.3.3 Column chromatography
In any chemical or bio-processing industry, the need to separate and purify a
product from a complex mixture is a necessary and important step in the production
line. Chromatography is a very special separation process for a multitude of reasons.
It can separate complex mixtures with great precision. Even very similar components,
such as proteins that may only vary by a single amino acid, can be separated with
chromatography; it can purify basically any soluble or volatile substance if the right
adsorbent material, carrier fluid, and operating conditions are employed.
Chromatography can be used to separate delicate products since the conditions under
which it is performed are not typically severe. For these reasons, chromatography is
quite well suited to a variety of uses in the field of biotechnology. Chromatography to
separate the components of inks and dyes, such as those found in pens, markers,
clothing, and even candy shells. Chromatography can also be used to separate the
coloured pigments in plants.
Column chromatography is an extremely valuable technique for purification of
synthetic or natural products. Compounds are separated by column chromatography
through the same mechanism as TLC; through differential intermolecular forces
between the components of the mixture with the mobile phase and the stationary
phase. A variety of adsorbents can be used as the stationary phase; silica gel (which is
very polar) is most commonly used in organic chemistry.
Adsorption is based on the following interactions:
• Dipole interactions
During bonding between two atoms of different electronegativities, there is an
asymmetric arrangement of the bonding electron pair. The most electronegative atom
pulls the bonding electron pair closer to itself; a bond dipole is formed, the strength of
which can be measured. The charge distribution in the polar atom bond is marked
with the symbols δ+ and δ–. In the periodic table of elements, the positive charge on
the nucleus, and hence the electronegativity, increases from left to right and decreases
from top to bottom.
• Hydrogen bridge bonds
Hydrogen bridges are bonds of a predominantly electrostatic nature between
an H atom of one molecule and a strongly electronegative element of a second
molecule (F, O, N, S). Such associates are stable in the solid state but unstable in the
liquid phase, i.e. some of them break up while others re-form.
• π-Complex
The π-complex is formed when an electrophilic partner with an electron hole
(X+) attacks a C = C double bond. The resulting loose adduct is called a π-complex.
In the case of silica gel, the active partner in the adsorption chromatography is the
silanol group, while in alumina this function is fulfilled by the Al centers and the
linking O atoms.
• Charge-transfer complex
π-Complexes in particular are referred to as charge transfer complexes. In this
case, there is an interaction between systems in which the electron content has been
greatly reduced (for example as a result of ionization effects) and another suitable π-
electron system.
• Steric effects
Apart from the mechanisms and interactions described above, spatial aspects
of the molecules also play a role. Hence, molecules with sterically differing structures
(isomers) can generally easily be separated by adsorption chromatography.
Selection of stationary phase and mobile phase
Generally, in the synthetic organic laboratories, during the comprehensive
study of a mixture having unknown chromatographic characteristics it is frequently
desirable to be initially guided in the selection of adsorbents and solvent from
information obtained by thin layer chromatography(TLC) analysis using alumina or
silica gel on microscope slides. It should be noted that the resolution obtained on TLC
plate is rather better than obtained on the conventional adsorption column. In the
column chromatography, amount of stationary phase i.e. silica is usually packed 50
times (by weight) that of compound to be applied to the column. For easy separations,
10-30 times is sufficient, while, for difficult separations may require 100 times that of
compound to be applied to the column.
If the chromatographic behaviour of the substance is unknown, a series of
solvent systems with increasing polarity are set up for example, hexane, toluene,
carbon tetrachloride, dichloromethane, diethyl ether, ethyl acetate, acetone, methanol
and identically loaded micro-plates are developed separately using the chosen solvent,
dried and sprayed with appropriate reagent and chromatographic mobility of the
individual components are noted. If it is seen that no single solvent gives a
satisfactory chromatogram, with well spaced compact spots, it is necessary to
examine the effect of using mixtures of solvents to provide systems having a range of
intermediate polarity. For example, mixtures of toluene and methanol or hexane and
ethyl acetate, are often suitable when the pure solvents are unsatisfactory. The mobile
phase or eluent in which compound has a Rf value of approx. 0.25-0.30 (based on the
result of TLC) is appropriate for the column chromatography. If small column is used
, a eluent which gives Rf value of 0.15-0.20 is more appropriate. Polarity of the
stationary phase and mobile phase for TLC or column chromatography is given in
increasing order as shown below:
Stationary Phase
INCREASIN
G POLARITY
Carbowax
C18 (hydrocarbon coated silica)
reverse phase
Paper
Cellulose
Starch
Calcium sulphate
Silica
Florosil (magnesium silicate)
Magnesium oxide
Alumina (aluminium oxide)
Activated carbon
Figure 02: Increasing Polarity of the stationary phase and mobile phase for TLC
or column chromatography
Stationary Phase Mobile phase
Carbowax (polyethylene glycol)
C18 (hydrocarbon coated silica)-
reverse phase
Cellulose
Calcium sulphate
Florosil (magnesium silicate)
Magnesium oxide
Alumina (aluminium oxide)
Activated carbon
Helium
Nitrogen
Petroleum ether
Ligroin (hexanes)
Cyclohexane
Carbon tetrachloride
Toluene
Chloroform
Dichloromethane
t-butyl methyl ether
Diethyl ether
Ethyl acetate
Acetone
2-propanol
Pyridine
Ethanol
Methanol
Water
Acetic acid
Increasing Polarity of the stationary phase and mobile phase for TLC
or column chromatography
le phase
Nitrogen
Petroleum ether (Pentanes)
Ligroin (hexanes)
Cyclohexane
Carbon tetrachloride
Chloroform
Dichloromethane
butyl methyl ether
Diethyl ether
Ethyl acetate
propanol
Methanol
Acetic acid
Increasing Polarity of the stationary phase and mobile phase for TLC
The order in which components of a mix
related to their relative polarity.
polarity, e.g. a hydrocarbon and a ketone separation
polar ketone is adsorbed more strongly on the adsorbent and hence the hydrocarbon
may be eluted with a relatively non
a more polar solvent. The ease of elution of the adsorbate may be broadly in the
following order:
INCREASIN
G FUNCTIO
NAL GROUP POLARITY
Figure 03: Elution sequence by functional group
TLC & Column Chromatography
In the column chromatography, a glass or plastic, generally glass column
a diameter from 5 mm to 50
of a filter (a glass frit or glass wool plug
The order in which components of a mixture are eluted from a column is
related to their relative polarity. Thus with a mixture of two components of differing
e.g. a hydrocarbon and a ketone separation is achieved because the more
polar ketone is adsorbed more strongly on the adsorbent and hence the hydrocarbon
may be eluted with a relatively non-polar solvent; the ketone is eluted by changing to
olar solvent. The ease of elution of the adsorbate may be broadly in the
Fast
Alkane hydrocarbons
Alkenes (olefins)
Aromatic hydrocarbons
Ethers
Esters
Ketones
Aldehydes
Amines
Alcohols
Phenols
Carboxylic acids
Slow
Elution sequence by functional groups on silica or alumina (polar)
TLC & Column Chromatography
In the column chromatography, a glass or plastic, generally glass column
a diameter from 5 mm to 50 mm and a height of 5 cm to 1 m with a tap and some kind
glass frit or glass wool plug to prevent the loss of the stationary phase) at
are eluted from a column is
Thus with a mixture of two components of differing
is achieved because the more
polar ketone is adsorbed more strongly on the adsorbent and hence the hydrocarbon
the ketone is eluted by changing to
olar solvent. The ease of elution of the adsorbate may be broadly in the
on silica or alumina (polar)
In the column chromatography, a glass or plastic, generally glass column with
cm to 1 m with a tap and some kind
to prevent the loss of the stationary phase) at
the bottom. Two methods are generally used to prepare a column; the dry method, and
the wet method. For the dry method, the column is first filled with dry stationary
phase powder, followed by the addition of mobile phase, which is flushed through the
column until it is completely wet, and from this point is never allowed to run dry. For
the wet method, a slurry is prepared of the eluent with the stationary phase powder
and then carefully poured into the column. Care must be taken to avoid air bubbles. A
solution of the organic material is pipetted on top of the stationary phase. This layer is
usually topped with a small layer of sand or with cotton or glass wool to protect the
shape of the organic layer from the velocity of newly added eluent. Eluent is slowly
passed through the column to advance the organic material. Often a spherical eluent
reservoir or an eluent-filled and stoppered separating funnel is put on top of the
column.
Usually the dry method is used. The stationary phase is equilibrated with a
small amount of the eluent, then a mixture of compounds i.e. A and B are dissolved in
the proper solvent and applied to the top of the column as a narrow layer.(i) If the
stopcock of the column is carefully opened, a layer of the mobile phase or eluent will
start to move down the packed column by gravity (ii & iii).As the eluent moves
through the column, compounds in the mixture partition between the moving (mobile)
phase and adsorbent (stationary phase) due to the difference between the physical
properties (e.g., polarity, molecular weight, vapour pressure etc.) of the compounds
and therefore the different interactions the compounds have with the stationary phase
and mobile phase (e.g., hydrogen bonding, dipole dipole interactions, London
dispersion forces etc.). Two band at different Rf value are observed (iv) and as the
time passes the distance between the two bands increases (v & vi). The component A
reaches the column end firstly and it is collected (vi). After having eluted component
A, by passing the eluent, later component B is also collected in different
fraction.(viii).
Figure 04: Separation of components by Column Chromatography
The mobile phase or eluent is passed through the column until the compound
of interest have eluted. As the chromatography proceeds, generally, the liquid exiting
the column is collected in the test tubes (called fractions) and analysed using TLC to
determine which fraction contains the desired compound and all fractions containing
the desired product are combined and solvent is removed by rotary evaporator or by
simple evaporation.
The stationary phase is pre-loaded into the column above a plug of glass wool
(to prevent solid material from contaminating products) and a thin layer of sand (to
provide a uniform bed for the stationary phase). Careless addition of sample can
disturb the stationary phase and lead to poor separation. For this reason, a second bed
of sand is added above the column as a “shock absorber.” Nevertheless, you must be
very careful when adding sample or mobile phase to the top of the column. Most
importantly, no part of the stationary phase must ever be dry. Air bubbles trapped in
the stationary phase can severely impair your separation. To avert disaster, always
keep the stationary phase covered with the mobile phase. Because the silica or
alumina gel that makes up the stationary phase is quite dense, column
chromatography tends proceed very slowly if gravity is the only force pulling the
mobile phase through the gel. The process can be sped up if high gas pressure at the
top of the column or a vacuum at the bottom of the column is used to push or pull the
mobile phase more quickly. This method is called flash column chromatography. In
your food dye experiment, you will have the option of performing flash column
chromatography by using a syringe attached to the bottom of the column to provide
vacuum suction and thereby quicken elution.
Advantages of Column Chromatography
Column chromatography is advantageous over most other chromatographic
techniques because it can be used in both analytical and preparative applications. Not
only can column chromatography be used to determine the number of components of
a mixture, but it can also be used to separate and purify substantial quantities of those
components for subsequent analysis. This is in contrast to paper chromatography,
which is solely an analytical method. For example, while paper chromatography is
easily applied to see whether a purple coloured beverage contains a mixture of dyes, it
is not practical to further analyze the separated dyes because of very small size of the
initial sample. A preparative method like column chromatography allows you to do
just that. Separating the purple food dye on an appropriately set up column with good
technique will leave you with cleanly separated blue and red dyes in large enough
amounts for further investigation. Thus, column chromatography should be used any
time you want to separate a mixture of liquids or solutes in to its components, and
work with these components individually. In fact, it is the most frequently used
method of purifying mixtures of products in research laboratories. Chromatographic
separation can be carried out on both polar and a polar stationary phases and suitable
sorbents are available from various manufacturers. Chromatography requires the use
of polar stationary phases such as silica gel and non polar solvents. The individual
components are delayed as a result of a reaction between the polar function
component groups and the polar groups of the sorbent. Low polarity substances are
eluted first, followed by components of increasing size. In “reversed phase”
chromatography, however, the stationary phase is non polar and elution is by means
of polar solvents. These stationary phases are produced by modifying silica gel with
non polar groups such as C-18 or similar substances. Substances are eluted in order of
decreasing polarity from reversed phase columns, i.e. the substance with the highest
polarity appears first. Reversed phase materials are considerably more expensive than
standard stationary phases, and this is one of the reasons why standard stationary
phases are primarily used in flash chromatography. If the substance classes to be
separated allow, modified stationary phases can nonetheless be used without
restrictions or problems
Disadvantages of Column Chromatography
With all its advantages and preparative power, column chromatography does
have its complications. Properly setting up the column (something that will be done
for you prior to experiment) requires some technical skill and manual dexterity, and
takes some time. Column chromatography is less fool proof than paper
chromatography and requires constant attention while the experiment is being
performed: collection vessels must be frequently switched and solvent levels need to
be topped up. In short, running a column is time-consuming and tedious, especially
for large samples. If it is unnecessary to preparatively separate large quantities of
sample, analytical methods such as paper chromatography may be more suitable and
easier to perform. The stationary phase and mobile phase are chosen based on the
nature of the sample mixture in order to achieve the best possible separation of its
components. In most applications in the chemistry laboratory, the stationary phase is
either silica (SiO2) or alumina (Al2O3), which is mixed with the solvent being used as
the mobile phase to yield thick white slurry. The mobile phase is a liquid that is
chosen to maximize the separation of the sample. This can be water or any organic
solvent. A final note is necessary about the versatility of column chromatography.
While most organic chemistry laboratories restrict themselves to the usual silica or
alumina stationary phase, this is not the case in biochemical applications. Biochemists
have been incredibly creative in adapting the column technique for separating
macromolecules. For example, by coating the stationary phase with anionic groups, it
is possible to selectively adsorb positively charged sample molecules to the column.
or, in an even more advanced application, a stationary phase of cellulose coated with
antibodies against a particular molecule can be used to isolate that molecule from a
cell extract. There are few separations that column chromatography can't perform.
1.3.4 References
1. Furniss B.S., Hannaford A.J., Smith P.W.G. and Tatchell A.R..; Vogel’s
Textbook of practical organic chemistry, 5th Ed., John Wiley Sons, New
York, 1989, p. 197.
2. Cassidy H.G. and Weissberger A; Fundamental of Chromatography in
Technique of Organic Chemistry, Interscience, 10, 1963.
3. Heftmann E.; Chromatography, 3rd Ed., Reinhold, Newyork, 1974.
4. Karger B.L., Snyder L.R. and Horvath; An introduction to separation
Science, 3rd Ed., Wiley-Interscience, New York, 1973.
5. Braithwaite A. and Smith F.J.; Chromatographic Methods, 4th Ed.,
Chapman Hall, New York, 1985.
6. Touchstone J.C. and Dobbins M.F.; Practice of Thin- Layer
Chromatography, 2nd Ed., Wiley, New York, 1983.
7. Fried B. and Sherma S.H.; Thin-Layer Chromatography,
Chromatographic Science Series, 2nd Ed., Dekker, New York, 35, 1986.
8. Strain H.H.; Chromatographic Adsorption Analysis, 2nd Ed., Interscience,
New York, 1945.
9. Perry J.A. and Cazes G.; Introduction to Analytical Gas Chromatography,
Chromatographic Science Series, Dekker, New York, 14, 1981.
10. Stahl E.; Thin-Layer Chromatography-A Laboratory Handbook, Springer-
Verlag, New York, 1965.
11. Gasparic J. and Churacek J.; Laboratory Handbook of Paper and Thin-
Layer Chromatography, Wiley: New York, 1978.
12. Zlatkis A., Kaiser R. E.; High Performance Thin-Layer Chromatography;
Elsevier: Amsterdam, 1977.
