Research Article One-Pot Synthesis of 2 -Aminobenzothiazolo-Arylmethyl-2 …downloads.hindawi.com/journals/tswj/2013/702929.pdf · 2 -Aminobenzothiazolo-Arylmethyl-2-Naphthols Catalyzed

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 702929 4 pageshttpdxdoiorg1011552013702929

Research ArticleOne-Pot Synthesis of21015840-Aminobenzothiazolo-Arylmethyl-2-Naphthols Catalyzed byNBS under Solvent-Free Conditions

Wei Lin Li1 Li Li Wang2 and Qiu Yan Luo2

1 Department of Medicinal Chemistry Pharmacy College of Xinxiang Medical University Xinxiang 453003 China2Department of Gynecological and Obstetric TheThird Affiliated Hospital of Xinxiang Medical College Xinxiang 453003 China

Correspondence should be addressed to Wei Lin Li linweilin1977163com

Received 6 April 2013 Accepted 13 May 2013

Academic Editors F A Attaby A Sacchetti and A K Saikia

Copyright copy 2013 Wei Lin Li et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

To develop a new facile protocol for the synthesis of 21015840-aminobenzothiazolo-arylmethyl-2-naphthol derivatives N-bromosuccinimide (NBS) was used as an efficient catalyst for the one-pot synthesis of 21015840-aminobenzothiazolo-arylmethyl-2-naphthols in excellent yields from 120573-naphthol (1mmol) aromatic aldehydes (1mmol) and 2-aminobenzothiazole (1mmol) at 60∘Cunder solvent-free conditions

1 Introduction

Organic reactions under solvent-free conditions haveattracted much interest of chemists particularly from theviewpoint of green chemistry Green chemistry approachesare significant due to the reduction in byproducts reductionin produced waste and reduction of energy cost Thepossibility of performing multicomponent reactions undersolvent-free conditions with a heterogeneous catalyst couldenhance their efficiency from an economic as well as anecological point of view [1ndash5]

The synthesis of new heterocyclic compounds has alwaysbeen a subject of great interest due to their wide applicabilityHeterocyclic compounds occur very widely in nature andare essential to life Amongst a large variety of hetero-cyclic compounds heterocycles containing benzothiazolemoiety are of interest because they show some pharmaco-logical and biological activities Benzothiazole derivativeswere reported to possess anti-inflammatory [6] anti-tumour[7ndash9] anticonvulsant [10 11] antibacterial [12] antifungal[13] and topoisomerase II inhibitory activities [14] Thusthe synthesis of benzothiazole is an important and usefultask in organic chemistry In recent years the synthesis

of 21015840-aminobenzothiazolo-arylmethyl-2-naphthols has beenreported using LiCl [15] and [Hnmp] HSO

4[16] as catalysts

The use of organic molecules as catalysts has become anattractive alternative to traditional metal catalysts Interestin the field of organocatalysis has increased spectacularly inthe last few years as the result of both the novelty of theconcept andmore importantly the fact that the efficiency andselectivity of many organocatalytic reactions meet the stan-dards of established organic reactions [17] NBS is one suchcatalyst which has recently received considerable attentionas a catalyst in various organic transformations [18ndash25] andis widely used as a brominating reagent Furthermore it isalso used in oxidation and free radical reactions under mildand convenient conditions to afford the desired products inexcellent yields andwith high selectivities However there areno examples of the use of NBS as a catalyst for the synthesisof 21015840-aminobenzothiazolo-arylmethyl-2-naphthols

In continuation of our efforts to explore newer reactionsfor the synthesis of heterocyclic compounds we wish toreport here a facile and improved protocol for preparationof 21015840-aminobenzothiazolo-arylmethyl-2-naphthols from 120573-naphthol aromatic aldehydes and 2-aminobenzothiazolein the presence of NBS as a catalyst under solvent-freeconditions (Scheme 1)

2 The Scientific World Journal

N

S

S

N

1 2 3 4

OH+ ArCHO + H2N

NBSNeat 60∘C

Ar NH

OH

Scheme 1

Table 1 The synthesis of 21015840-aminobenzothiazolo-phenyl-2-naphthol in various conditions

Entry Solvent NBS(mol)

Temperature(∘C)

Time(min)

Yield()

1 Water 10 25 90 592 Water 10 60 60 883 Ethanol-water 10 25 60 564 Ethanol-water 10 60 30 855 Neat 0 60 60 06 Neat 2 60 30 737 Neat 5 60 20 898 Neat 10 25 60 659 Neat 10 60 10 9410 Neat 15 60 10 9211 Neat 20 60 10 92

2 Results and Discussion

Initially we decided to explore the role of our catalyst in waterand ethanol-water (1 1) as solvent system for the synthesisof 21015840-aminobenzothiazolo-phenylmethyl-2-naphthol used asa model compound With respect to the solvent system thebest results were achieved using water (Table 1 Entry 2)In recent years the synthesis of compounds under solvent-free conditions is an important task in heterocyclic synthesisTherefore we decided to test this solvent-free reaction withvarious ratios of catalysts We found that the reaction wasrapid and gave excellent yields of the products when using10mol NBS

These results encouraged us to investigate the scope andgenerality of this new protocol for various aromatic aldehydesunder optimized conditions As shown in Table 2 a series ofaromatic aldehydes containing either electron-withdrawingor electron-donating substituents successfully react with 120573-naphthol and 2-aminobenzothiazole which afforded goodto high yields of products with high purity at 60∘C undersolvent-free conditions

It is likely that the reagent releases Br+ in situ whichcan act as an electrophilic species Therefore the mecha-nism shown in Scheme 2 can be suggested for the conver-sion of the 120573-naphthol 2-aminobenzothiazole and variousaromatic aldehydes to 21015840-aminobenzothiazolo-arylmethyl-2-naphthols

In summary we have developed a new facile proto-col for the synthesis of 21015840-aminobenzothiazolo-arylmethyl-2-naphthol derivatives from the reaction of 120573-naphthol

Table 2 Preparation of 21015840-aminobenzothiazolo-arylmethyl-2-naphtholsa

Entry Ar Time(min) Products Yield

()bmp

(lit) (∘C)c

1 C6H5 10 4a 94202ndash204(204-205)

[15]

2 4-Cl-C6H4 8 4b 95209-210(209-210)

[15]

3 4-Me-C6H4 10 4c 92 183-184(182-183) [15]

4 4-F-C6H4 10 4d 98 189-190(188-189) [16]

5 4-NO2-C6H4 5 4e 97 188-189(190-191) [16]

6 4-MeO-C6H4 10 4f 90 172-173(175-176) [16]

7 3-NO2-C6H4 8 4g 93 197ndash199(198-199) [15]

8 2-Cl-C6H4 8 4h 91 185-186(189-190) [16]

9 24-Cl2-C6H4 8 4i 96203-204(206-207)

[16]

10 4-OH-3-MeO-C6H3

15 4j 88 192ndash194(194-195) [16]

11 345-MeO3C6H2 15 4k 92 159-160aReaction conditions 120573-naphthol (1mmoL) aldehyde (1mmoL) 2-amino-benzothiazole (1mmoL) NBS (01mmoL) 60∘C and neatbIsolated yieldcTemperature value in the reference

aromatic aldehydes and 2-aminobenzothiazole compoundsusing NBS under solvent-free conditions

3 Experimental Part

General IR spectra were determined on FTS-40 infraredspectrometer NMR spectra were recorded on Bruker AV-400 spectrometer at room temperature using TMS as aninternal standard coupling constants (J) were measured inHz elemental analysis was performed by a Vario-III elemen-tal analyzer melting points were determined on an XT-4binocular microscope and were uncorrected commerciallyavailable reagents were used throughout without furtherpurification unless otherwise is stated

The Scientific World Journal 3

H

OO H

O

S

N

HN

S

N

N

O

O

Br

O

O

Nminus

Br

Br

Br

Br+

Br+

minusBr+

minusH2O Br+ O+

+

+

OH

OH

OHAr

Ar-CH

O

Ar-C

Ar

Ar Ar

NH2

Scheme 2

31 General Procedure for the Preparation of 4 A mix-ture of the 120573-naphthol (1mmol) aldehydes (1mmol) 2-aminobenzothiazole (1mmol) and NBS (01mmol) wasstirred at 60∘C for the appropriate time according to Table 2Completion of the reaction was indicated by TLC Thereaction was cooled to room temperature washed with waterand extracted with ethyl acetate (3 times 10mL) The combinedorganic layers were dried over sodium sulfate and concen-trated under reduced pressure to afford a white powder Thepure solid products were obtained by recrystallization fromethanol

32 Spectral Data of New Products

21015840-Aminobenzothiazolo-(3-nitrophenyl)methyl-2-naphthol(4g) IR (KBr) v 3335 (ndashOH) 1627 (C=N) 1597 (aromaticC=C) 1541 1531 (aromatic C=C) 1452 1436 1347 1312 12701252 1210 813 753 cmminus1 1H NMR (DMSO-d6 400MHz)120575 705ndash788 (m 15H ArH and CH) 890 (s 1H NH)1012 (brs 1H OH D2O exchangeable) Anal calcd forC24H17N3O3S C 6743 H 401 N 983 S 750 found C 6750H 400 N 987 S 742

21015840-Aminobenzothiazolo-(345-trimethoxyphenyl)methyl-2-naphthol (4k) IR (KBr) v 3347 (ndashOH) 2936 2836 25991627 (C=N) 1595 (aromatic C=C) 1544 1507 (aromaticC=C) 1436 1417 1332 1268 1233 1129 1006 816 753 cmminus11H NMR (DMSO-d

6 400 MHz) 120575 362 (s 9H OCH

3)

680ndash781 (m 13H ArH and CH) 881 (s 1H NH) 1015 (s1H OH D

2O exchangeable) Anal calcd for C

27H24N2O4S

C 6862 H 512 N 593 S 679 found C 6870 H 504 N 600S 682

Acknowledgment

This research program was supported by Foundation ofHersquonan Educational Committee China (no 12B350005)

References

[1] A Kumar and R A Maurya ldquoSynthesis of polyhydroquino-line derivatives through unsymmetric Hantzsch reaction usingorganocatalystsrdquoTetrahedron vol 63 no 9 pp 1946ndash1952 2007

[2] L F Tietze T Kinzel and C C Brazel ldquoThe domino multi-component allylation reaction for the stereoselective synthesisof homoallylic alcoholsrdquoAccounts of Chemical Research vol 42no 2 pp 367ndash378 2009

[3] L F Tietze and U Beifuss ldquoSequential transformations inorganic chemistry a synthetic strategy with a futurerdquo Ange-wandte ChemiemdashInternational Edition vol 32 no 2 pp 131ndash163 1993

[4] H Bienayme C Hulme G Oddon and P Schmitt ldquoMaximiz-ing synthetic efficiency multi-component transformations leadthe wayrdquo Chemistry vol 6 no 18 pp 3321ndash3329 2000

[5] U C Reddy S Bondalapati and A K Saikia ldquoStereoselectiveone-pot three-component synthesis of 4-aryltetrahydropyranvia Prins-Friedel-Crafts reactionrdquo Journal of Organic Chemistryvol 74 no 6 pp 2605ndash2608 2009

[6] A N El-Shorbagi S I Sakai M A El-Gendy N Omar and HH Farag ldquoImidazo[21-b]benzothiazoles II Synthesis and anti-inflammatory activity of some imidazo[21-b]benzothiazolesrdquoChemical and Pharmaceutical Bulletin vol 37 no 11 pp 2971ndash2975 1989


[7] D F Shi T D Bradshaw S Wrigley et al ldquoAntitumor benzoth-iazoles 3 Synthesis of 2-(4-aminophenyl)benzothiazoles andevaluation of their activities against breast cancer cell lines invitro and in vivordquo Journal of Medicinal Chemistry vol 39 no 17pp 3375ndash3384 1996

[8] G Wells T D Bradshaw P Diana et al ldquoAntitumourbenzothiazolesmdashpart 10 the synthesis and antitumour activityof benzothiazole substituted quinol derivativesrdquo Bioorganic andMedicinal Chemistry Letters vol 10 no 5 pp 513ndash515 2000

[9] I Hutchinson M S Chua H L Browne et al ldquoAntitumorbenzothiazoles 141 synthesis and in vitro biological propertiesof fluorinated 2-(4-aminophenyl)benzothiazolesrdquo Journal ofMedical Chemistry vol 44 no 9 pp 1446ndash1455 2001

[10] R S Chopade R H Bahekar P B Khedekar K P Bhusariand A R Rao ldquoSynthesis and anticonvulsant activity of 3-(6-substituted-benzothiazol-2-yl)-6-phenyl-[1 3]-xazinane-2-thionesrdquo Archiv Der Pharmazie vol 335 no 8 pp 381ndash3882002

[11] N D Amnerkar and K P Bhusari ldquoSynthesis anticonvulsantactivity and 3D-QSAR study of some prop-2-eneamido and 1-acetyl-pyrazolin derivatives of aminobenzothiazolerdquo EuropeanJournal of Medicinal Chemistry vol 45 no 1 pp 149ndash159 2010

[12] M Palkar M Noolvi R Sankangoud V Maddi A Gadadand L V G Nargund ldquoSynthesis and antibacterial activ-ity of a novel series of 23-diaryl-substituted-imidazo(21-b)-benzothiazole derivativesrdquo Archiv der Pharmazie vol 343 no6 pp 353ndash359 2010

[13] T Singh V K Srivastava K K Saxena S L Goel and AKumar ldquoSynthesis of new thiazolylthiazolidinylbenzothiazolesand thiazolylazetidinylbenzothiazoles as potential insecticidalantifungal and antibacterial agentsrdquo Archiv der Pharmazie vol339 no 8 pp 466ndash472 2006

[14] S J Choi H J Park S K Lee S W Kim G Han and H Y PChoo ldquoSolid phase combinatorial synthesis of benzothiazolesand evaluation of topoisomerase II inhibitory activityrdquo Bioor-ganic and Medicinal Chemistry vol 14 no 4 pp 1229ndash12352006

[15] A Shaabani A Rahmati and E Farhangi ldquoWater promotedone-pot synthesis of 21015840-aminobenzothiazolomethyl naphtholsand 5-(21015840-aminobenzothiazolomethyl)-6-hydroxyquinolinesrdquoTetrahedron Letters vol 48 no 41 pp 7291ndash7294 2007

[16] Y Yu and H Guo ldquoOne-pot synthesis of 21015840-aminob-enzothiazolo-arylmethyl-2-naphthols in ionic liquid of[Hnmp]HSO4under solvent-free conditionsrdquo Chinese Journalof Organic Chemistry vol 31 no 1 pp 96ndash100 2011

[17] P I Dalko and LMoisan ldquoIn the golden age of organocatalysisrdquoAngewandte ChemiemdashInternational Edition vol 43 no 39 pp5138ndash5175 2004

[18] B Karimi H Seradj and G R Ebrahimian ldquoMild and efficientconversion of aldehydes to 11-diacetates catalyzed with N-bromosuccinimiderdquo Synlett no 5 pp 0623ndash0624 2000

[19] H Hazarkhani and B Karimi ldquoN-bromosuccinimide as analmost neutral catalyst for efficient synthesis of dihydropyrim-idinones under microwave irradiationrdquo Synthesis no 8 pp1239ndash1242 2004

[20] CW Kuo S VMore and C F Yao ldquoNBS as an efficient catalystfor the synthesis of 15-benzodiazepine derivatives under mildconditionsrdquo Tetrahedron Letters vol 47 no 48 pp 8523ndash85282006

[21] A R Hajipour S A Pourmousavi and A E Ruoho ldquoChemos-elective and solvent-free thioacetalization of aldehydes by a

catalytic amount of NBSrdquo Synthetic Communications vol 36no 19 pp 2807ndash2811 2006

[22] A Khazaei A Rostami A Raiatzadeh and M MahboubifarldquoN-bromosuccinimide (NBS)-selective and effective catalystfor trimethylsilylation of alcohols and phenols using hexam-ethyldisilazane and their regeneration under mild and neutralreaction conditionsrdquoCanadian Journal of Chemistry vol 85 no5 pp 336ndash340 2007

[23] A Khazaei A Rostami and A Raiatzadeh ldquoN-bromosuccinimide (NBS) a mild and efficient catalyst fortetrahydropyranylation of alcohols and phenols under solvent-free conditionsrdquo Journal of the Chinese Chemical Society vol54 no 4 pp 1029ndash1032 2007

[24] A Rostami and H Jafari ldquoNBS as a powerful catalyst forthe synthesis of 120573-hydroxysulphides with thiolysis of epoxidesunder mild reaction conditionsrdquo South African Journal ofChemistry-suid-afrikaanse Tydskrif vir Chemie vol 61 article115 2008

[25] H R Shaterian H Yarahmadi M Ghashang andMM SafarildquoN-bromosuccinimide catalyzed one-pot and rapid synthesisof acetamidobenzyl naphthols under mild and solvent-freeconditionsrdquo Chinese Journal of Chemistry vol 26 no 11 pp2093ndash2097 2008

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


N

S

S

N

1 2 3 4

OH+ ArCHO + H2N

NBSNeat 60∘C

Ar NH

OH

Scheme 1

Table 1 The synthesis of 21015840-aminobenzothiazolo-phenyl-2-naphthol in various conditions

Entry Solvent NBS(mol)

Temperature(∘C)

Time(min)

Yield()

1 Water 10 25 90 592 Water 10 60 60 883 Ethanol-water 10 25 60 564 Ethanol-water 10 60 30 855 Neat 0 60 60 06 Neat 2 60 30 737 Neat 5 60 20 898 Neat 10 25 60 659 Neat 10 60 10 9410 Neat 15 60 10 9211 Neat 20 60 10 92

2 Results and Discussion

Initially we decided to explore the role of our catalyst in waterand ethanol-water (1 1) as solvent system for the synthesisof 21015840-aminobenzothiazolo-phenylmethyl-2-naphthol used asa model compound With respect to the solvent system thebest results were achieved using water (Table 1 Entry 2)In recent years the synthesis of compounds under solvent-free conditions is an important task in heterocyclic synthesisTherefore we decided to test this solvent-free reaction withvarious ratios of catalysts We found that the reaction wasrapid and gave excellent yields of the products when using10mol NBS

These results encouraged us to investigate the scope andgenerality of this new protocol for various aromatic aldehydesunder optimized conditions As shown in Table 2 a series ofaromatic aldehydes containing either electron-withdrawingor electron-donating substituents successfully react with 120573-naphthol and 2-aminobenzothiazole which afforded goodto high yields of products with high purity at 60∘C undersolvent-free conditions

It is likely that the reagent releases Br+ in situ whichcan act as an electrophilic species Therefore the mecha-nism shown in Scheme 2 can be suggested for the conver-sion of the 120573-naphthol 2-aminobenzothiazole and variousaromatic aldehydes to 21015840-aminobenzothiazolo-arylmethyl-2-naphthols

In summary we have developed a new facile proto-col for the synthesis of 21015840-aminobenzothiazolo-arylmethyl-2-naphthol derivatives from the reaction of 120573-naphthol

Table 2 Preparation of 21015840-aminobenzothiazolo-arylmethyl-2-naphtholsa

Entry Ar Time(min) Products Yield

()bmp

(lit) (∘C)c

1 C6H5 10 4a 94202ndash204(204-205)

[15]

2 4-Cl-C6H4 8 4b 95209-210(209-210)

[15]

3 4-Me-C6H4 10 4c 92 183-184(182-183) [15]

4 4-F-C6H4 10 4d 98 189-190(188-189) [16]

5 4-NO2-C6H4 5 4e 97 188-189(190-191) [16]

6 4-MeO-C6H4 10 4f 90 172-173(175-176) [16]

7 3-NO2-C6H4 8 4g 93 197ndash199(198-199) [15]

8 2-Cl-C6H4 8 4h 91 185-186(189-190) [16]

9 24-Cl2-C6H4 8 4i 96203-204(206-207)

[16]

10 4-OH-3-MeO-C6H3

15 4j 88 192ndash194(194-195) [16]

11 345-MeO3C6H2 15 4k 92 159-160aReaction conditions 120573-naphthol (1mmoL) aldehyde (1mmoL) 2-amino-benzothiazole (1mmoL) NBS (01mmoL) 60∘C and neatbIsolated yieldcTemperature value in the reference

aromatic aldehydes and 2-aminobenzothiazole compoundsusing NBS under solvent-free conditions

3 Experimental Part

General IR spectra were determined on FTS-40 infraredspectrometer NMR spectra were recorded on Bruker AV-400 spectrometer at room temperature using TMS as aninternal standard coupling constants (J) were measured inHz elemental analysis was performed by a Vario-III elemen-tal analyzer melting points were determined on an XT-4binocular microscope and were uncorrected commerciallyavailable reagents were used throughout without furtherpurification unless otherwise is stated


H

OO H

O

S

N

HN

S

N

N

O

O

Br

O

O

Nminus

Br

Br

Br

Br+

Br+

minusBr+

minusH2O Br+ O+

+

+

OH

OH

OHAr

Ar-CH

O

Ar-C

Ar

Ar Ar

NH2

Scheme 2





6 400 MHz) 120575 362 (s 9H OCH

3)



27H24N2O4S

C 6862 H 512 N 593 S 679 found C 6870 H 504 N 600S 682

Acknowledgment


References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


H

OO H

O

S

N

HN

S

N

N

O

O

Br

O

O

Nminus

Br

Br

Br

Br+

Br+

minusBr+

minusH2O Br+ O+

+

+

OH

OH

OHAr

Ar-CH

O

Ar-C

Ar

Ar Ar

NH2

Scheme 2





6 400 MHz) 120575 362 (s 9H OCH

3)



27H24N2O4S

C 6862 H 512 N 593 S 679 found C 6870 H 504 N 600S 682

Acknowledgment


References





































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

Research Article One-Pot Synthesis of 2 -Aminobenzothiazolo-Arylmethyl-2 …downloads.hindawi.com/journals/tswj/2013/702929.pdf · 2 -Aminobenzothiazolo-Arylmethyl-2-Naphthols Catalyzed