Lise-Lotte Gundersen Department of Chemistry, University of Oslo, Norway

1

Synthesis directed towards Agelasines, Agelasimines, Asmarines and Analogs;

Bioactive Marine Natural Products

Lise-Lotte Gundersen

Department of Chemistry, University of Oslo, Norway

2

23. Organisk-kjemiske vintermøte, Geilo 2008

21:a Organikerdagarna, Åhus 2008

3

Marine organisms Algae and invertebrates (sponges, mollusks, tunicates etc)

Rich sources of bioactive compounds - Defence

•Antimicrobial

•Antineoplastic

4

Nature 2004, 430, 242

Nature 2004, 431, 892:

“Antibiotics are the worst

sort of pharmaceuticals

because they cure the

disease”

5

Agelasines Agelasimines Asmarines

N

N N

N

NHO

H

Asmarine A

N

N N

N

N

Agelasimine A

OH

H

Purine-Containing Natural Productsfrom Marine Sponges

•Total synthesis

•Synthesis of analogs

•Bioactivities

H

N

N N

N

NH2

Cl

Agelasine A

6

Marine Sponges?

7

Agelasines

•Isolated from marine sponges (Agelas sp.)

•11 comp. (Agelasine A - I, epiagelasine C and ageline B) known to date

•Total syntheses other groups: Agelasine A, B and C, and (±) agelasine F

•Bioactivities:

Cytotoxic

Antimicrobial

etc.

Brown Tube Sponge: Agelas sp. 2.5 feet long

H

N

N N

N

NH2

Cl

Agelasine A

7,9-dialkylated Adeninium salt

Terpenoid side chain at N-7

8

Synthesis of Trixagol and Agelasine E

Trixagol

OH

Isolated from Bellardia trixagoTL, 1978, 3491Isolated from Agelas sp.

Tetrahedron Lett. 1984, 2989

N

N N

N

NH2

CH3

CO2H

OH

Agelasine E

Geraniol

N

N NH

N

NH2

Helv. Chim. Acta, 1995, 539

Adenine

Cl

9

Synthesis of Trixagol and ent-Trixagol

Bakkestuen et al., Tetrahedron 2003, 59, 115

HO2C

HO2C

HO2C

O

H3CO2C

OOOCH3

OCH3

O

O

4 steps

+c.f. lit.

Synth. rac. acid: Helv. Chim. Acta, 1952, 1752 Resolution:Helv. Chim. Acta. 1995, 539

c.f. lit.

Trixagol

ent-Trixagol

Agelasine E

OH

3 steps

HO2C Litt. HOPhSSPh

Bu3P

pyridine

PhS

(S) 90%(R) 91%

oxone

MeOH, H2O0 oC

OTHP

OTHP

SO2Ph

PhSO2

OTs

OTHP

n-BuLiDMPU

THF

Na, Na2HPO4EtOH, THF

(S) 39%(R) 41%

two steps

PPTS

EtOH, 55 oC

OH

(S) 73% Trixagol(R) 82%

(S) 81%(R) 86%Tetrahedron 1997, 53, 3527

10

Synthesis of Agelasine E and ent-Agelasine E

N

N N

N

NH2

R

N

N N

N

NH

R

R'N

N N

N

NH2 R

N

N N

N

NH R

R'

Regioselectivity in dialkylation of adenines

R'X R'X

Bakkestuen et al., Org. Biomol. Chem. 2005, 3, 1025

N

N N

N

Cl

HN

N N

N

NMeO

N

N N

N

NMeO

N

N N

N

NMeO

+

MeONH3Cl, Et3N

n-BuOH, Δ63%

DMA, 50 oC

1) Zn, AcOHMeOH / H2O

2) NaCl(aq)Cl

(R) Enantiomer shown(S), Trixagol

OH

82% (R)96% (S)

BrPBr3

Et2O, 0 oC

N

N N

N

NH2

48% (R)44% (S)

32% (R)26% (S)

54% (R) Agelasine E89% (S)

HN

N N

N

N

R

CH3O

HN

N N

N

N

R

CH3OR'

R'X N

N N

N

N

R

CH3O R'

+X

11

Synthesis of Agelasine D

Agelasine D Manool

Sclareol

Salvia sclarea (Clary Sage)

Isolated from Agelas sp.Tetrahedron Lett. 1984, 2989

N

N N

N

NH2

H

H

X

H

HO

H

HO

OHCl

12

Synthesis of Agelasine D - Initial Approach

Drawbacks: Lack of selectivity

Utenova et al., Tetrahedron Lett. 2004, 45, 4233

H

Br

HN

N N

N

NMeO

N

N N

N

N

N

N N

N

NMeO

+

DMA, 50 oC

Zn, AcOH

MeOH, H2O

H

N

N N

N

NH2

H

MeO

H

60% E:Z 8:243% pure E after cryst.

27% E:Z 8:2

Cl

51%81% E:Z 8:2

PBr3, pyridine

Et2O, -35 oC

H

HO

(+) Manool

(+) Agelasine D

13

Improved Synthesis of Agelasine D

Synthesis of geometrically pure allyl bromide

Vik et al., J. Nat. Prod. 2006, 69, 381

H

AcO

90% E:Z 92:8

Ac2O, DMAP, Et3N

THF, Δ

H

AcO

PdCl2(MeCN)2

THF, 0 oC

K2CO3

MeOH

H

HO

76% Pure E

PBr3, pyridine

Et2O, 0 oC

H

Br

76% Pure E

Anticopalol

H

Br

81% E:Z 8:2

PBr3, pyridine

Et2O, -35 oC

H

HO

(+) Manool

14

Improved Synthesis of Agelasine D - Regioselective N-alkylation

Vik et al., J. Nat. Prod. 2006, 69, 381

H

Br

HN

N N

N

NMeO

N

N N

N

N

N

N N

N

NMeO

+DMA, 50 oC

H

MeO

H

60% E:Z 8:2 27% E:Z 8:2

H

Br

HN

N N

N

NO

N

N N

N

N

DMA, 50 oC

Zn, AcOH

MeOH, H2O

H

N

N N

N

NH2

H

O

Cl

49%

(+) Agelasine D

90%

Only isomer observed

HN

N N

N

NRO

DMA, 50 oC

PhCH2Br N

N N

N

NRO Ph

A

+ N

N N

N

NRO

Ph

B

R- Ratio A : B Yield (%) A Yield (%) B

CH3- 60 : 40 55 30

t-Bu- 90 : 10 86 9

PhCH2- 80 : 20 72 13

15

Synthesis of Agelasine F

Isolated from Agelas sp.Tetrahedron Lett. 1984, 2989J. Am. Chem. Soc. 1984, 106, 1819

N

N N

N

NH2

CH3

Agelasine F(Ageline A)

Cl

Asao et al., Synthesis 1990, 382Asao et al., Tetrahedron Lett. 1989, 30, 6397

Asao et al., Tetrahedron Lett. 1989, 30, 6401

O

CO2Me

BnOBr

+9 steps

(±)

HO

11 steps Br

(±)2 steps

(±) Agelasine F

16

Synthesis of Agelasine F

Isolated from Agelas sp.

Isolated from pennyroyal

(Mentha Pulegium)

N

N N

N

NH2

CH3

Agelasine F(Ageline A)

Cl OH

Geraniol

N

N NH

N

X

X(S)-Pulegone

17Proszenyak et al., Manuscript

BrO

(R)-Pulegone Side chain ent-Agelasine F

O

(R)-Pulegone

O TMSO

TMSCl, Et3N

DMF

1) LDA2) MeI

THF- 78 oC

O

KOH (aq)

48% from pulegone

Cl SPh

O

PhS

57%

O

PhS

33%

+TiCl4, CH2Cl2, -23 oC

TMSO

Cl SO2Ph

O

PhS

O

PhS

oxone

MeOH, H2OO

PhSO2

O

PhSO2

87%

85%

oxone

MeOH, H2O

X-ray; minor isomer sulfone

18Proszenyak et al., Manuscript

PhSO2

PhSO2

Agelasine E Agelasine F

More reactive

O

PhSO21) MeMgI

Et2O, 0 oC - rt

82%

2) HCO2H, 80 oC

PhSO2

1) BuLi

2) THPO

THF, 50 oC

THPO

SO2Ph

THPONa, Na2HPO4

EtOH, THF

PPTs

EtOH, 55 oC

HO

I

54%(Two steps)

82%

PBr3

Et2O, 0 oCBr

93%

O

(R)-Pulegone

19

Intermediate in synthesis of other natural products ?

O

(S)-Pulegone

O

O

O

OculatolideO

Subersin

S

NHH2N

HN

OO

(-) Agelasidine CAgelasidine D

OH

S

NHH2N

HN

O

O

PhSO2

O

(R)-Pulegone

O

O

O

Sollasin D

O

Sollasin A(Fulvanin 1)

O

S

NHH2N

HN

OO

S

HN

H2NNH

OO

(+) Agelasidine C

Agelasidine B

PhSO2

O

O

Microcionin 2

O

O

O

O

Striatol

OH

20

Proszenyak et al., Manuscript

Asao et al., Synthesis 1990, 382Asao et al., Tetrahedron Lett. 1989, 30, 6397

Asao et al., Tetrahedron Lett. 1989, 30, 6401

BrO

10 steps

O

CO2Me

BnOBr

+9 steps

(±)

HO

11 steps Br

(±)

21Proszenyak et al., Manuscript

O

(R)-Pulegone

Br

HN

N N

N

NRO

N

N N

N

NRO

76%, R = t-Bu

49%, R = Me

+ N

N N

N

NRO

11%, , R = t-Bu

23%, R = Me

N

N N

N

NH2

48%

Cl

DMA, 50 oC

ent-Agelasine F

Zn, AcOH

MeOH, H2O75 oC

22

Bakkestuen et al., Org. Biomol. Chem. 2005, 3, 1025

Vik et al., J. Nat. Prod. 2006, 69, 381

Vik et al., Bioorg. Med. Chem. 2007, 15, 4016

Proszenyak et al., Arch. Pharm. Chem. Life Sci. 2007, 340, 625

HN

N N

N

N

R''

RO

orHN

N N

N

N

R''

OR

syn anti

HN

N N

N

NMeO

H2N

OHO

HO

NOE

Hill et al. Nucl. Acids Res. 1998, 26, 1144

HN

N N

N

N

R''

RO

HN

N N

N

N

R''

RO R'

N

N N

N

NH2

R''

R'

ClR'-CH2-Br

N

N N

N

NH

R''

RO

A

B

RONH2N

N N

N

Cl

R''

R''XN

N NH

N

Cl[red]

Base

N

N N

N

N

R''

RO R'

X

HX

1H NMR: A : B, ca 8 : 2 (CDCl3, CD3OD, DMSO-d6), 25 oC

Only minor variations depending on R and R''

23

X % Amine B in DMSO-d6

40 oC25 oC 70 oC

H 20 25 32

Me 18 21 29

CF3 100 100 100

Cl 100 100 100

NO2 100 100 100

OMe 92 92 92

OEt 94 93 94

NHMe 28 33 37

NMe2 100 100 100

1H NMR data Roggen et al. Manuscript

N

N

Cl

X N

N

Me

N

N

NH

X N

N

Me

MeO

HN

N

N

X N

N

Me

MeO

H, CH3, CF3, Cl, NO2 H, CH3, CF3, Cl, NO2

OMe, OEt, NHMe, NMe2

A B

MeONH2

HXR

24Roggen et al. Manuscript

X Yield (%) 1 Yield (%) 2

H 51 35

Me 57 29

CF3 <2 _

Cl 4 _

NO2_ _

OMe _11

OEt 52 20

NHMe 61 7

NMe2 56 22

Yields of isolated compounds

% Start. mat. recov

8

5

66

86

95

14

22

12

_

N

N

NH

X N

N

Me

MeO

HN

N

N

X N

N

Me

MeO

H, Me, CF3, Cl, NO2

OMe, OEt, NHMe, NMe2

A B

HN

N N

N

N

Me

MeO

N

N N

N

N

Me

MeO

+

X X

Ph

BrBnBr

DMA, 50 oC

1 2

Ph

N

N N

N

NH

Me

MeO

19%

O

Ph**

25

Bioactivities•Antibacterial (incl. Mycobacterium tuberculosis)•Antifungal•Antiprotozoal (incl. several causing tropical diseases;

i.e. Chagas disease, Viceral Leichmaniasis)•Antifouling•Antineoplastic

HN

N N

N

N

R''

RO

HN

N N

N

N

R''

RO R'

N

N N

N

NH2

R''

R'

ClR'-CH2-Br [red]

Base

N

N N

N

N

R''

RO R'

X

HX

X X X

X

Bakkestuen et al., Org. Biomol. Chem. 2005, 3, 1025

Vik et al., J. Nat. Prod. 2006, 69, 381

Vik et al., Bioorg. Med. Chem. 2007, 15, 4016

Proszenyak et al., Arch. Pharm. Chem. Life Sci. 2007, 340, 625Sjögren et al., Biofouling. 2008, 24, 251

26

•Generally broad spectrum activity

•Type A more active than type B structure ( otherwise same subst.)

•R’ must be relatively long and preferably contain unsaturation(s)

•R, R’’ and X; some modifications of activity spectrum

Structure - Activity Relationships

HN

N N

N

N

R''

RO R'

N

N N

N

NH2

R''

R'

XX X

Type A Type B

X

HN

N N

N

N

CH3

MeO

HO

geranylgeraniol

Agelasine analog

X

27

WHO (1993): Tuberculosis - TB a “global emergency”

•AIDS

•Resistant strains

•Migration

•Powerty

Ca. 3 mill deaths / year

R MIC M. tuberculosis (μg/mL)

Type A Type B

3.13

1.56

3.13

3.13

n.d.

>6.25(38% inhib. at 6.25 μg/mL)

>6.25(21% inhib. at 6.25 μg/mL)

>6.25(30% inhib. at 6.25 μg/mL)Agelasine E

>6.25(38% inhib. at 6.25 μg/mL)

3.13Agelasine F

MIC Rifampin 0.25 μg/mL Bakkestuen et al., Org. Biomol. Chem. 2005, 3, 1025Mangalindan et al. Planta Med. 2000, 66, 364; Agelasine F

N

N N

N

NH2

Cl

R

N

N N

N

N RMeO

Type A Type B

28Bakkestuen et al., Org. Biomol. Chem. 2005, 3, 1025Vik et al., Bioorg. Med. Chem. 2007, 15, 4016

N

N N

N

N

CH3

MeO

Staphylococcus aureus

MIC (μg/mL)

Mycobacterium tuberculosisMIC (μg/mL)

4.0 3.13

N

N N

N

N

CH3

MeO > 32 >6.25(86% inhib. at 6.25 μg/mL)

N

N N

N

NHMeO > 32 >6.25

(74% inhib. at 6.25 μg/mL)

N

N N

N

NH2

CH3

Cl

32 >6.25(38% inhib. at 6.25 μg/mL)

N

N N

N

NH2 > 32 1.56

29Bakkestuen et al., Org. Biomol. Chem. 2005, 3, 1025Vik et al., Bioorg. Med. Chem. 2007, 15, 4016Vik et al., Planta Med. 2007, 73, 1410

N

N N

N

N

CH3

MeO

Staphylococcus aureus

MIC (μg/mL)

Mycobacterium tuberculosisMIC (μg/mL)

HO

(Geranylgeraniol)

O

O

O

4.0 3.1

3.1n.d.

> 32 1.6

n.d. n.d.(0% inhib. at 6.25 μg/mL)

30

N

N N

N

NH2

H

Cl Sjögren et al., Biofouling. 2008, 24, 251

Antifouling activity - Barnacles

Agelasine D and analogs inhibit settlement of Balanus improvisus cypris larvae,

low tox. to cyprids

31

Agelasines Agelasimines Asmarines

N

N N

N

NHO

H

Asmarine A

N

N N

N

N

Agelasimine A

OH

H

Purine-Containing Marine Natural Productsfrom Marine Sponges

H

N

N N

N

NH2

Cl

Agelasine A

32

Asmarines

•Isolated from marine sponges (Raspailia sp.)

•11 comp. (Asmarine A - J)

•No total syntheses

•Bioctivities: Cytotox.

N

N N

N

NR

H

Asmarine A: R = OHAsmarine B: R = OH (epi at C'-5)Asmarine G: R = OMeAsmarine H: R = HAsmarine K: R = H (epi at C'-5)

N

N N

N

NR

H

O

* *

Asmarine D: R = OHAsmarine C: R = OH (epi at C'-5)Asmarine E: R = OMe (epi at C'-5)Asmarine F: R = OMe

N

N N

N

NR

H

Asmarine I: R = OHAsmarine J: R = H

33

Previous strategies for construction of the 7-membered ring

No ex. of formation of bond c or d

N

N

N

N

NX

R1R2

a

b cd

e

N

N

N

N

Cl

HNMOM

N

HN

N

N

NRO

N

N

NH

N

NX

OH

N

N

N

N

NR

SOCl2Et3N, BuOH

R1Br

N

HN

N

N

NRO

R1R2

R1 = R2 = H

R2

1. I2, NaHCO32. Bu3Sn

HBr, AcOH

34

Formation of bond d - Initial attempts

Vik et al.Tetrahedron. Lett. 2007, 48, 1931

Co-complex

NCo

N

N

N

OH2

O O

O

H

OH

N

N N

N

NR

R'' R'

N

N N

N

NR

R'' R'

RCM ?

7

d

N

N N

N

Cl

HXCH2CH=CH2

Pyridine, 100 oCN

N N

N

X

a: X = NH, 89%b: X = NMe, 92%c: X = Od: X = NBoc, 65%

(Boc)2ODMAP, CH2Cl2

N

N N

N

NBocGrubbs II or

Hoveyda-Grubbs II

DCE, Δ

54% (Grubbs II) 73% (How.-Grubbs II) Compds a-c: n.r.

N

N N

N

HN

HCl(aq)

MeOH81%

N

N N

N

HN

N

N NH

N

Cl I-CH2CH=CH2, K2CO3, Co-complex, CH3CN

(c.f. Dalby et al. Angew. Chem. Int. Ed. Engl. 1993, 32, 1696)

8

H2, Pd/C

H2SO2MeOH

85%

35

N

N N

N

NR

R'' R'

N

N N

N

NR

R'' R'

RCM ?

7

N

N N

N

NH

(Boc)2O, DMAP

MeCN

Hoveyda-Grubbs II

DCE, ΔN

N N

N

NH

N

N N

N

NBoc

68%

N

N N

N

NBoc7

95%

K2CO3

MeCN, Δ

100%

N

N N

N

HN

76%

1) H2, Pd/C, EtOAc

2) HCl, MeOH

Vik et al.

Tetrahedron. Lett. 2007, 48, 1931

N

N N

N

HN

H

Asmarine H

36

Acknowledgements

Synthesis•Dr. Anne Kristin Bakkestuen

•Anthony James

•Dr. Agnes Prozenyak

•Heidi Roggen

•Linda W. Tangen

•Dr. Bibigul T. Utenova

•Dr. Anders Vik

Bioactivities•Prof. Lars Bohlin & co-workers

•Dr. Colin Charnock•Tuberculosis Antimicrobial Acquisition & Coordinating Facility (TAACF)

•WHO - TDR

Financial Support•NFR (FRINAT & KOSK)

•UiO