Design, synthesis and in vitro cytotoxicity studies of novel pyrrolo [2,1][1,4] benzodiazepine-glycosylated pyrrole and imidazole polyamide conjugates

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Design, synthesis and in vitro cytotoxicity studies of novel pyrrolo

[2,1][1,4] benzodiazepine-glycosylated pyrrole and imidazole

polyamide conjugates

Rohtash Kumar and J. William Lown*

Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2

Received 16th June 2003, Accepted 5th August 2003

First published as an Advance Article on the web 8th September 2003

The design, synthesis and biological evaluation of novel pyrrolo [2,1][1,4] benzodiazepine-water insoluble 31–38 and

water soluble 39–46 glycosylated pyrrole and imidazole polyamide conjugates are described that involved mercuric

chloride mediated cyclization of the corresponding amino diethyl thioacetals. The compounds were prepared with

varying numbers of pyrrole and imidazole containing polyamides and incorporating glucose moieties in order to

improve the water solubility of PBD-polyamide conjugates and probe the structural requirements for optimal in vitro

antitumor activity. These compounds were tested against a panel of 60 human cancer cells by the National Cancer

Institute, and demonstrated that the water soluble PBD-polyamide compounds exhibited a higher level of cytotoxic

activity than the existing natural and synthetic pyrrolo [2,1-c][1,4] benzodiazepines. The cytotoxic activities of these

compounds dramatically increase after hydrolysis of their acetylated counterparts. The activity data summarized in

Table 1 and Table 2 show that the solubility of the PBD-polyamides and also the type of heterocycle play important

roles inﬂuencing the cytotoxic activity of the PBD-polyamide conjugates. The PBD-glycosylated polyamide (water

soluble) conjugates 39–46 are highly cytotoxic against many human cancer cell lines in comparison with the

PBD-polyamide (water insoluble version) conjugates.

at either the C2–C3 (endocyclic) or C2 (exocyclic) positions.

Introduction

There is either an imine or carbinolamine methyl ether moiety

The biological activity of certain low molecular weight anti-

tumour compounds appears to be related to their mode and

speciﬁcity of interaction with particular DNA sequences. Such

small molecules are of considerable interest in chemistry, bio-

logy and medicine. Many of the anticancer drugs employed

clinically also exert their antitumour eﬀect by inhibiting nucleic

acid (DNA or RNA) or protein synthesis. Inhibition can occur

for example through cross-linking of bases in DNA or binding

to and inactivation of enzymes necessary for key processes. It is

evident that DNA is an important cellular target for many anti-

cancer agents. DNA is a well-characterized intracellular target

but its large size and sequential nature makes it an elusive target

for selective drug action. Binding of low molecular weight

ligands to DNA causes a wide variety of potential biological

responses. In this context PBDs (pyrrolo [2,1-c][1,4] benzo-

diazepines), a group of potent naturally occurring antitumor

antibiotics produced by various Streptomyces species,^1,2are one

of the promising types of lead compounds. They diﬀer in the

number, type and position of substituent in both their aromatic

A-ring and pyrrolidine C-rings, and in the degree of saturation

of the C-rings which can be either fully saturated or unsaturated

at the N10–C11 position.^3–6This latter is an electrophilic centre

responsible for alkylating DNA.

To date, 13 structures, including such compounds as anthra-

mycin, tomaymycin, chicamycin, neothramycin, and DC-81

(Fig. 1) have been isolated from various Streptomyces species.

Their common interaction with DNA has been extensively

investigated and it is considered unique since they bind within

the minor groove of DNA forming a covalent aminal bond

between the C11-position of the central B-ring and the N2

amino group of guanine base.⁷The cytotoxicity and antitumor

activity of PBDs are thus attributed to their ability to form

covalent DNA adducts. Molecular modeling, solution NMR,

ﬂourimetry experiment and DNA footprinting experiments have

shown that these molecules have a preferred selectivity for Pu–

G–Pu⁸sequences and are oriented with their A-rings pointed

either towards the 3Ј- or –5Ј end of the covalently bonded DNA

strand (as in the case of anthramycin and tomaymycin). The

PBDs have been shown to interfere with the action of endo-

nuclease enzymes on DNA⁹and to block transcription by

inhibiting DNA polymerase in a sequence speciﬁc manner,¹⁰

processes, which may be relevant for their biological activity.

Fig. 1 Compounds isolated from various Streptomyces species.

T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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In the search for compounds with better antitumour selec-

tivity and DNA sequence speciﬁcity many PBD analogues have

been synthesized in an attempt to increase their potency against

tumor cells. Confalone and coworkers¹¹have synthesized

PBD analogues with an epoxide group attached at the C-11a

position with the objective of producing a PBD structure with

DNA cross-linking activity. Recently, Thurston and coworkers,

in order to increase cytotoxicity through the production of

DNA cross-links, have designed and synthesized PBD dimers¹²

comprising two PBD units joined through their A-rings.

Similarly, Baraldi and coworkers¹³as well as Lown and co-

workers^14–19have prepared new PBD-pyrrole and imidazole

polyamide conjugates to explore their biological properties.

Kamal and coworkers²⁰recently designed and synthesized

non-cross-linking mixed imine–amide PBD dimers that have

signiﬁcant DNA-binding aﬃnity and potent anti-tumour

activity.

Recently a large number of structurally modiﬁed PBDs

compounds have also been prepared and evaluated for their

biological activity, particularly their antitumour potential.^21,22

A number of these compounds have been selected for

preclinical studies but unfortunately most of them did not

proceed beyond that stage, due to problems related to poor

bioavailability and low water solubility. Therefore Kamal

and coworkers^23,24recently designed and synthesized PBD-

naphthalimides, morpholine, N-methyl piperizine and N, N-di-

ethylamine hybrids in attempts to improve the water solubility

and cytotoxicity of the PBDs compounds.

Results and discussion

Synthesis

In our previous report the (2S)-N-[5-methoxy-4-[3-(carboxy)

propyloxy]-2-nitrobenzoyl] pyrrolidine-2-carboxaldehyde di-

ethyl thioacetal (1) and compounds 2–7 were synthesized.^15,19

by using convenient routes in good yield. The synthesis of a

pyrrole with a -glucose moiety attached at the 1-position of

the heterocycle was performed using the route outlined in

Scheme 1. The functionalization of the pyrrole ring was per-

formed at positions 2 and 4 by trichloroacetyl chloride and

fuming nitric acid, successively, to yield compound 8, which

when treated with methanol gave the methyl ester 9 in good

yield. Basic hydrolysis of compound 9 gave the corresponding

acid 10 which was then converted into an acidic labile tert-butyl

ester 11 by treating the acid with isobutylene under acidic con-

ditions according to Scheme 1. Bromination of the anomeric

acetate group of the 2,3,4,6-tetra-O-acetyl-α--glucose with

hydrobromic acid in acetic acid gave compound 2,3,4,6-tetra-

O-acetyl-α--bromoglucose (12) in 85% yield. The coupling of

the tert-butyl ester pyrrole unit 11 with the 2,3,4,6-tetra-O-

acetyl-α--bromoglucose 12 was achieved using KOH and a

phase transfer catalyst (18-crown-6-ether) to give compound 13

in 80% yield (Scheme 2).

In a complementary approach polyamides containing pyrrole

(Py) and imidazole (Im) moieties, that are based on the

naturally occurring compounds netropsin and distamycin,

constitute a class of compounds having DNA sequence

speciﬁcity.²⁵Polyamides show speciﬁc and high aﬃnity binding

for nucleotide sequences in the minor groove of DNA and

in favourable cases the binding strength is comparable to

sequence-speciﬁc DNA binding proteins. The biological

characterization of polyamides reveals that they function by

interfering with critical processes including, but not limited to,

the inhibition of DNA and RNA polymerases, topoisomerases,

HIV integrases, gyrases, human tumor helicases and reverse

transcriptases.^26–29Polyamides can block the activity of pro-

cessive enzymes complexes or interfere with the binding of

DNA-binding proteins. The binding of transcription factors

(TFs) to DNA cis elements is central to cellular regulation,

and the identiﬁcation of novel agents which can be targeted at

regulating this binding interaction would therefore be of great

therapeutic value.

Increasing the number of pyrrole (Py) and imidazole (Im)

groups in a polyamide compound results in a direct increase

in the length of base pairs recognized by the polyamide in the

minor groove of the DNA. The disadvantage to increasing

the number of such groups is that the aqueous solubility of the

drug is progressively decreased, often resulting in substantially

reduced cellular uptake or bioavailability. Earlier a large

number of polyamides that were synthesized and evaluated bio-

logically against various targets could not be developed further

because of their low aqueous solubility. Thus there is an urgent

need for water soluble polyamides which could overcome the

solubility problem of conventional polyamides.³⁰

In view of the commonly observed activity of polyamides

and PBDs, we have also been interested in structural modiﬁ-

cations of the PBD ring system and also towards the develop-

ment of new synthetic PBD hybrids with polyamides. Therefore

it was considered of interest to design and synthesize C-8 linked

PBD-water soluble polyamide conjugates and to investigate the

eﬀects of these structural changes on their biological properties.

In continuation of these eﬀorts, we herein report the design,

synthesis and in vitro antitumour cytotoxicity activities of novel

C-8 linked PBD-water soluble pyrrole and imidazole polyamide

hybrids.

Scheme 1 (i) Trichloroacetyl chloride, TEA CH₂Cl₂0 ЊC to RT, 6 h,

80%; (ii) fuming HNO₃, acetic anhydride, CH₂Cl₂, Ϫ40 ЊC to RT, 12 h,

70%; (iii) MeOH, DMAP, 60 ЊC, 10 h, 88%; (iv) 1 N NaOH, MeOH, 60

ЊC 20 h, 80%; (v) isobutylene, conc. H₂SO₄, diethylether, Ϫ40 ЊC, RT,

15 h, 83%.

The tert-butyl ester group of compound 13 was hydrolyzed

using 1 M TiCl₄solution in dichloromethane to aﬀord acid 14

in 78% yield. This acid 14 was then coupled with 3-dimethyl-

aminopropylamine using EDCI/HOBt as coupling reagents to

give compound 15 in 77% yield. The nitro group of compound

15 was reduced with hydrogen in the presence of Pd/C catalyst

into the corresponding amino compound which was then

coupled (for the chain elongation of the glucopyrrole carb-

oxamide peptide) with acid 14 using standard EDCI/HOBt

coupling conditions to aﬀord compound 16 in 80% yield. The

nitro group of compound 16 was converted into its amino

counterpart with hydrogen in the presence of Pd/C catalyst and

then treated with compounds 2 or 3 in the presence of triethyl-

amine in dry THF give polyamides 17 and 18, respectively in

good yields (Scheme 2).

The nitro groups of compound 4, 5, 6, and 7 were similarly

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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Scheme 2 (i) KOH, DMF, 18-crown-6-ether, RT, 4 h, 80%; (ii) 1.0 M TiCl₄solution in dichloromethane, CH₂Cl₂, RT, 12 h 78%; (iii) NH₂-

(CH₃)₃N(CH₃)₂, EDCI, HOBt, DMF, RT, 12 h, 77%; (iv) (a) H₂Pd/C, MeOH, RT, (b) EDCI, HOBt, DMF, RT, 12 h, 80% (v) (a) H₂Pd/C, MeOH,

RT, (b) 2 or 3, TEA, THF, RT, 6 h.

reduced with hydrogen in the presence of Pd/C catalyst into

their corresponding respective amino compounds which were

then coupled with acid 14 using standard EDCI/HOBt as

coupling reagents to give compounds 19–22, respectively in

good yields (Scheme 3).

hydrogen in the presence of Pd/C catalyst into their corre-

sponding respective amino compounds which were then sub-

jected to deprotective cyclization with HgCl₂/HgO in aqueous

acetonitrile at room temperature aﬀording the corresponding

imines 31–38 in 40–45% yield. Hydrolysis of compounds 31–38

with 0.1 N NaOH at room temperature for 2–3 h gave water

soluble PBD-glycosylated pyrrole and imidazole polyamide

conjugates 39–46 in good yield. Since the conjugation of the

polyamides with PBD resulted in highly polar imines, this

necessitated the use of methanol in combination with chloro-

form as eluent during the puriﬁcation of the imines by column

chromatography and therefore the product was obtained as a

mixture of imine and its methyl ether in approximately a 1 : 1

ratio. The presence of both the forms was conﬁrmed by NMR

and mass spectra. Since the methyl ether form is fully equivalent

to the imine form in terms of their reaction with DNA, the

compounds were isolated as the mixture of imines and methyl

ethers. This did not present any problems in evaluating their

biological activities. The ﬁnal compounds were isolated as pale

yellow crystalline compounds in 50–60% overall yields after

passing through an ion exchange column with methanol/water

(Schemes 4, 5, and 6).

Scheme 3 (i) (a) H₂Pd/C, MeOH, RT, (b) EDCI, HOBt, DMF, RT, 12

h, 75–81%.

Anticancer cytotoxicity

The pyrrolo [2,1][1,4] benzodiazepine-acetyl glycosylated

(water insoluble) 31–38 and glycosylated (water soluble) 39–46

pyrrole and imidazole polyamide conjugates, which contain

one or more pyrrole and imidazole units, were selected by the

US National Cancer Institute for evaluation in the in vitro

preclinical antitumor screening program against sixty human

tumour cell lines derived from nine cancer types, leukemia,

non-small cell lung cancer, colon cancer, CNS cancer, melan-

Coupling of the (2S)-N-[5-methoxy-4-[3-(carboxy) propy-

loxy]-2-nitrobenzoyl] pyrrolidine-2-carboxaldehyde diethyl

thioacetal (1) with the amine moiety of the polyamides 15–22,

using EDCI and HOBt as coupling agents in dry DMF

aﬀorded the corresponding coupled compounds 23–30,

respectively in good yields.

The nitro groups of compounds 23–50 were reduced with

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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Scheme 4 (i) (a) H₂Pd/C, MeOH, RT, (b) EDCI, HOBt, DMF, RT, 12 h, 73–74%; (ii) (a) H₂Pd/C, MeOH, RT, (b) HgCl₂, HgO, 75% aq CH₃CN,

41–43%; (iii) 0.1 N NaOH, MeOH/THF (1 : 1) RT, 53–60%.

oma, ovarian cancer, renal cancer, prostate cancer and breast

cancer. For each compound, dose response curves for each cell

line were measured at a minimum of ﬁve concentrations at 10

fold dilutions in a protocol of 48 h continuous drug exposure,

and a sulfurhodamine B (SRB) protein assay was used to

estimate cell viability or growth. The concentration causing

50% cell growth inhibition (GI₅₀), total cell growth inhibition

(TGI, 0% growth), and 50% cell death (LC₅₀, Ϫ50% growth)

compared with the control was calculated. The LC₅₀values

(concentration for killing 50% of the cells) for compounds

31–38 and 39–46 against the 60 diﬀerent tumor cells are given in

Table 1 (water insoluble) and Table 2 (water soluble).

In general all the compounds are active against most of the

cell lines with the MG_MID (mean graph mid point) values

ranging from Ϫ4.00 to Ϫ6.23. Compound 31 which has one

acetyl glycosylated pyrrole unit shows almost the same cyto-

toxicity with the log₁₀LC₅₀values ranging from Ϫ5.05 to Ϫ5.27

against non-small cell lung, colon, melanoma, renal and breast

cancer cells, while its water soluble counterpart 39 shows

somewhat lower cytotoxicity against the same cell lines. Com-

pound 32, bearing two acetyl glycosylated pyrrole units dis-

played lower cytotoxicity compared with the compound 31

against the same cell lines, while its water soluble version com-

pound 40 displays much higher cytotoxicity against the same

cell lines with log₁₀LC₅₀values ranging from Ϫ5.07 to Ϫ5.23.

Compound 33, having two acetyl glycosylated pyrrole units

and one N-methyl pyrrole unit, displayed similar cytotoxic

potencies against the non-small cell lung, CNS, melanoma,

renal and breast cancer cell lines with log₁₀LC₅₀values ranging

from Ϫ5.04 to Ϫ5.41. Compound 34, bearing two acetyl

glycosylated pyrrole units and one N-methyl imidazole unit,

shows notably higher cytotoxicity against the melanoma cancer

cells M14 and SK-MEL-5 with log₁₀LC₅₀value Ϫ6.04 and

Ϫ6.25. This compound 34 has also shown promising activity

against colon cancer cells HCT-116 and KM-12 with log₁₀LC₅₀

value Ϫ5.71 and Ϫ6.08. On the other hand its water soluble

version, compound 42, shows somewhat lower cytotoxic

potency against the same cell lines but, in contrast the water

soluble version of compound 33 i.e. compound 41 the higher

cytotoxicity against the renal cancer cell 786-O (log₁₀LC₅₀value

Ϫ5.92). From the biological data from Table 1 and Table 2 we

can conclude that the compounds which bear two glycosylated

pyrrole units and one N-methyl pyrrole unit 33 and 41 are much

more potent compared with their counterparts the N-methyl

imidazole compounds 34 and 42.

Compound 35, with one acetyl glycosylated pyrrole unit and

one N-methyl pyrrole unit, displayed a higher potency against

colon cancer cells Colo-205 and HCT-116 with log₁₀LC₅₀values

Ϫ6.21 and Ϫ6.01. This compound 35 also shows higher cyto-

toxicity against renal cancer cell 786-O (log₁₀LC₅₀value Ϫ6.11)

and breast cancer cell T-47D (log₁₀LC₅₀value Ϫ6.01), while its

water soluble version compound 43 displayed somewhat lower

cytotoxicity against the same cell lines. Compound 37, which

has one acetyl glycosylated pyrrole unit and one N-methyl

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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Scheme 5 (i) (a) H₂Pd/C, MeOH, RT, (b) EDCI, HOBt, DMF, RT, 12 h, 75–77%; (ii) (a) H₂Pd/C, MeOH, RT, (b) HgCl₂, HgO, 75% aq CH₃CN,

40–42%; (iii) 0.1 N NaOH, MeOH/THF (1 : 1) RT, 50–57%.

imidazole unit, displayed higher potency against the colon

cancer cell Colo-205 (log₁₀LC₅₀value Ϫ6.10) and renal cancer

cell 786-O (log₁₀LC₅₀value Ϫ6.18), while its water soluble

version compound 45 displayed somewhat lower cytotoxicity

against the same cell lines. However compound 45 displays

higher cytotoxic potency against the CNS cancer cell line

SNB-75 (log₁₀LC₅₀value Ϫ5.13) and renal cancer cell ACHN

(log₁₀LC₅₀value Ϫ4.87).

Compound 36, bearing one acetyl glycosylated pyrrole unit

and two N-methyl pyrrole units displayed very good potencies

against the colon cancer cells Colo-205 and HCT-116 with the

log₁₀LC₅₀values Ϫ6.18 and Ϫ5.19, and also showed higher

cytotoxicity against the renal cancer cell line 786-O (log₁₀LC₅₀

value Ϫ6.24) and breast cancer cell T-47D (log₁₀LC₅₀value

Ϫ6.16). It is noteworthy that its water soluble counterpart

compound 44 is also more potent against non-small cell lung,

colon, melanoma, renal and breast cancer cell lines with the

log₁₀LC₅₀values ranging from Ϫ5.03 to Ϫ5.30. Compound 38,

having one acetyl glycosylated pyrrole unit and two N-methyl

imidazole units displayed almost the same cytotoxic potencies

against all the human cancer cell lines used by the NIH, and

this compound displayed log₁₀LC₅₀value Ϫ4.30 against the

colon cancer cell HCT-116. The water soluble version of this

compound i.e. 46 shows markedly higher cytotoxicities against

non-small cell lung cancer cell EKVX (log₁₀LC₅₀value Ϫ7.16),

colon cancer cells Colo-205 and HCT-116 (log₁₀LC₅₀values

< Ϫ8.00 and 7.13), melanoma cancer cells Malme-3M, M14,

SK-MEL-28, SK-MEL-5 with log₁₀LC₅₀values < Ϫ8.00,

Ϫ7.95, Ϫ7.15, Ϫ7.07. Compound 46 is also highly potent

against all the renal cancer cell lines with log₁₀LC₅₀values

ranging from Ϫ7.19 to < Ϫ8.00. In addition Compound 46

displayed higher cytotoxic potencies against the breast cancer

cell lines MDA-MB-231/ATCC, MDA-MB-435 and BT-549

with log₁₀LC₅₀value Ϫ7.30, 7.11 and 7.37. From these results

we can conclude that the water soluble compound 46 with one

glycosylated pyrrole unit and two N-methyl imidazole units, is

much more potent in comparision with the compounds 43, 44

and 45.

It can be seen from the comparison of the cytotoxic data

presented in Table 1 (water insoluble) and in Table 2 (water

soluble) that in individual cases certain PBD-acetyl glyco-

sylated polyamide conjugates are active in comparison to

their water soluble version. However, in general, most of the

PBD-glycosylated polyamide (water soluble) conjugates are

more highly potent compared with their water insoluble

counterparts. For example in the case of compounds 39,

40, 41, 44, and 46 these water soluble versions are signiﬁcantly

more highly potent then their water insoluble counterparts.

It is evident that the cytotoxic activity of these com-

pounds increases dramatically after hydrolysis of their acetyl

derivatives (Fig. 2). There are individual exceptions, e.g. in

the case of compounds 34, 35, and 37, where the water in-

soluble versions are more potent than the water soluble version.

Comparing the cytotoxic data among the PBD-polyamide

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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Scheme 6 (i) (a) H₂Pd/C, MeOH, RT, (b) EDCI, HOBt, DMF, RT, 12 h, 70–77%; (ii) (a) H₂Pd/C, MeOH, RT, (b) HgCl₂, HgO, 75% aq CH₃CN,

40–45%; (iii) 0.1 N NaOH, MeOH/THF (1 : 1) RT, 51–56%.

Table 1 In vitro, cytotoxic potencies (log₁₀LC₅₀) of novel pyrrolo [2,1][1,4] benzodiazepine-acetyl glycosylated pyrrole and imidazole polyamide

conjugates 31–38 (water insoluble) against nine panels of human cell lines

log₁₀LC₅₀/µM^a

Panels/cancer cell lines

31

32

33

34

35

36

37

38

Leukemia

CCRF-CEM

HL-60 (TB)

K-562

MOLT-4

RPMI-8226

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.28

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

—

Ϫ4.48

> Ϫ4.00

Non-small cell lung cancer

A549/ATCC

EKVX

HOP-62

> Ϫ4.00

Ϫ5.12

Ϫ5.14

Ϫ5.10

—

Ϫ5.19

> Ϫ4.00

Ϫ4.05

> Ϫ4.00

Ϫ4.13

Ϫ4.19

—

Ϫ4.04

Ϫ4.17

> Ϫ4.00

Ϫ4.24

Ϫ5.08

Ϫ5.07

Ϫ5.20

—

Ϫ5.12

Ϫ4.41

Ϫ4.33

> Ϫ4.00

—

Ϫ4.88

> Ϫ4.00

Ϫ5.06

Ϫ5.22

—

Ϫ5.26

Ϫ4.46

> Ϫ4.00

Ϫ5.09

Ϫ5.26

Ϫ5.28

—

Ϫ5.28

Ϫ4.30

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.12

Ϫ4.11

—

> Ϫ4.00

Ϫ4.04

> Ϫ4.00

Ϫ4.30

Ϫ5.19

Ϫ5.17

—

Ϫ5.28

Ϫ4.23

> Ϫ4.00

HOP-92

NCI-H226

NCI–H23

NCI–H322M

NCI–H460

NCI–H522

Colon cancer

COLO 205

HCC-2998

HCT-116

HCT-15

HT29

Ϫ5.17

Ϫ5.01

> Ϫ4.00

Ϫ5.01

Ϫ4.19

Ϫ4.12

> Ϫ4.00

Ϫ4.98

—

Ϫ4.74

—

Ϫ5.71

> Ϫ4.00

Ϫ6.21

—

Ϫ6.05

Ϫ5.23

Ϫ5.26

Ϫ6.18

—

Ϫ5.89

Ϫ5.24

Ϫ5.27

Ϫ6.10

—

Ϫ5.21

Ϫ5.19

Ϫ4.20

> Ϫ4.00

Ϫ4.30

> Ϫ4.00

—

Ϫ5.23

Ϫ4.59

> Ϫ4.00

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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Table 1 (Contd.)

log₁₀LC₅₀/µM^a

Panels/cancer cell lines

31

32

Ϫ4.16

33

Ϫ4.46

34

Ϫ6.08

35

Ϫ5.29

36

Ϫ5.21

37

Ϫ4.02

38

KM12

SW-620

> Ϫ4.00

Ϫ4.92

> Ϫ4.00

Ϫ5.04

—

Ϫ5.05

CNS cancer

SF-268

SF-295

SF-539

SNB-19

SNB-75

U251

Ϫ4.41

> Ϫ4.00

Ϫ5.22

Ϫ4.23

Ϫ4.38

Ϫ4.05

Ϫ4.11

Ϫ4.51

Ϫ4.20

Ϫ4.07

Ϫ4.46

Ϫ4.05

Ϫ5.31

Ϫ4.38

Ϫ4.33

Ϫ5.28

> Ϫ4.00

Ϫ4.32

Ϫ4.44

Ϫ5.21

—

Ϫ5.09

Ϫ5.20

> Ϫ4.00

Ϫ5.24

—

Ϫ5.31

Ϫ5.28

Ϫ5.25

Ϫ5.16

Ϫ5.22

> Ϫ4.00

Ϫ4.09

—

Ϫ5.26

Ϫ5.24

Ϫ5.23

Ϫ5.27

Ϫ4.27

Ϫ5.24

Ϫ5.18

> Ϫ4.00

—

> Ϫ4.00

Melanoma

LOX IMVI

MALME-3M

M14

SK-MEL-2

SK-MEL-28

SK-MEL-5

UACC-257

UACC-62

Ϫ5.27

> Ϫ4.00

Ϫ5.10

> Ϫ4.00

Ϫ5.14

> Ϫ4.00

Ϫ5.16

> Ϫ4.00

Ϫ4.19

Ϫ4.12

> Ϫ4.00

Ϫ4.04

Ϫ4.13

Ϫ5.41

Ϫ5.04

Ϫ5.27

Ϫ4.00

Ϫ5.15

Ϫ5.16

Ϫ4.54

Ϫ5.10

Ϫ5.21

Ϫ5.16

Ϫ6.04

> Ϫ4.00

—

Ϫ6.25

> Ϫ4.00

Ϫ5.33

Ϫ5.21

Ϫ5.24

Ϫ5.18

Ϫ5.25

Ϫ5.22

Ϫ5.14

Ϫ5.23

Ϫ5.27

Ϫ5.30

Ϫ5.17

Ϫ5.23

Ϫ5.24

Ϫ5.15

Ϫ5.27

Ϫ5.19

Ϫ4.21

Ϫ5.26

Ϫ5.14

Ϫ4.41

Ϫ5.20

Ϫ5.21

Ϫ5.25

> Ϫ4.00

Ϫ4.04

Ϫ4.02

> Ϫ4.00

Ϫ4.17

> Ϫ4.00

Ϫ4.26

Ovarian cancer

IGROV 1

OVCAR-3

OVCAR-4

OVCAR-5

OVCAR-8

SK-OV-3

> Ϫ4.00

Ϫ5.07

Ϫ4.04

> Ϫ4.00

Ϫ4.10

> Ϫ4.00

Ϫ4.13

Ϫ4.20

Ϫ4.12

Ϫ4.43

> Ϫ4.00

Ϫ5.18

> Ϫ4.00

Ϫ5.27

Ϫ5.25

Ϫ5.20

> Ϫ4.00

Ϫ5.26

> Ϫ4.00

Ϫ5.31

Ϫ5.25

Ϫ5.28

> Ϫ4.00

Ϫ5.26

> Ϫ4.00

—

Ϫ4.22

Ϫ5.24

—

> Ϫ4.00

Ϫ4.17

—

Ϫ4.55

Ϫ4.78

Ϫ5.19

Ϫ4.31

Ϫ5.26

Renal cancer

786-0

A498

Ϫ5.25

Ϫ4.21

Ϫ5.18

Ϫ5.10

Ϫ5.05

Ϫ5.14

> Ϫ4.00

Ϫ4.22

Ϫ4.20

Ϫ4.03

Ϫ4.23

Ϫ4.16

Ϫ4.22

Ϫ4.09

> Ϫ4.00

Ϫ5.32

Ϫ4.89

Ϫ5.26

—

> Ϫ4.00

—

> Ϫ4.00

Ϫ6.11

Ϫ4.35

Ϫ5.24

Ϫ5.31

Ϫ5.11

—

Ϫ6.24

—

Ϫ6.18

—

Ϫ5.23

Ϫ5.27

Ϫ5.11

—

Ϫ4.14

> Ϫ4.00

Ϫ4.08

> Ϫ4.00

Ϫ4.12

ACHN

CAKI-1

RXF-393

SN12C

TK-10

UO-31

Ϫ5.27

Ϫ5.32

> Ϫ4.00

Ϫ5.23

Ϫ5.27

Ϫ5.32

—

Ϫ4.69

Ϫ5.24

—

Ϫ5.13

Ϫ5.24

Ϫ5.41

Ϫ4.56

Ϫ5.35

> Ϫ4.00

Ϫ4.06

Prostate cancer

PC-3

DU-145

> Ϫ4.00

Ϫ4.54

> Ϫ4.00

Ϫ4.12

Ϫ5.12

Ϫ5.26

> Ϫ4.00

—

Ϫ5.16

Ϫ5.18

Ϫ5.20

Ϫ5.26

Ϫ5.04

—

> Ϫ4.00

Ϫ4.08

Breast cancer

MCF 7

> Ϫ4.00

Ϫ5.19

Ϫ5.17

> Ϫ4.00

Ϫ5.05

Ϫ5.19

—

> Ϫ4.00

Ϫ4.01

Ϫ4.22

> Ϫ4.00

Ϫ4.14

Ϫ4.20

> Ϫ4.00

Ϫ5.14

Ϫ5.19

> Ϫ4.00

Ϫ4.13

Ϫ5.22

Ϫ4.72

Ϫ4.75

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.62

Ϫ4.38

> Ϫ4.00

Ϫ5.14

Ϫ5.22

> Ϫ4.00

Ϫ5.23

Ϫ5.19

Ϫ6.01

Ϫ5.00

> Ϫ4.00

Ϫ5.24

Ϫ5.30

> Ϫ4.00

Ϫ5.26

Ϫ5.25

Ϫ6.16

Ϫ4.99

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.06

NCI/ADR-RES

MDA-MB231/ATCC

HS578T

MDA-MB-435

BT-549

Ϫ5.17

> Ϫ4.00

Ϫ5.22

Ϫ5.14

Ϫ5.38

Ϫ4.84

T-24D

> Ϫ4.00

Ϫ4.09

> Ϫ4.00

Ϫ4.03

MGM^b

Ϫ4.53

^aThe cytotoxicity log₁₀LC₅₀values are the concentrations corresponding to 50% growth inhibition. ^bMean graph midpoint (µM) for growth

inhibition against all human cancer cell lines tested.

Table 2 In vitro, cytotoxic potencies (log₁₀LC₅₀) of novel pyrrolo [2,1][1,4] benzodiazepine-glycosylated (water soluble) pyrrole and imidazole

polyamide conjugates 39–46 ( water soluble) against nine panels of human cell lines

log₁₀LC₅₀/µM^a

Panels/cancer cell lines

Leukemia

39

40

41

42

43

44

45

46

CCRF-CEM

HL-60 (TB)

K-562

MOLT-4

RPMI-8226

—

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.10

—

Ϫ4.10

> Ϫ4.00

—

> Ϫ4.00

Non-small cell lung cancer

A549/ATCC

EKVX

Ϫ4.11

Ϫ4.19

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.16

> Ϫ4.00

Ϫ5.15

> Ϫ4.00

—

Ϫ7.16

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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Table 2 (Contd.)

log₁₀LC₅₀/µM^a

Panels/cancer cell lines

39

40

41

42

43

44

45

Ϫ4.47

> Ϫ4.00

Ϫ4.36

46

HOP-62

HOP-92

NCI–H226

NCI–H23

NCI–H322M

NCI–H460

NCI–H522

Ϫ4.28

Ϫ4.09

—

Ϫ4.21

> Ϫ4.00

Ϫ4.14

Ϫ5.14

Ϫ5.06

—

> Ϫ4.00

Ϫ5.18

> Ϫ4.00

—

> Ϫ4.00

Ϫ5.06

Ϫ5.22

—

Ϫ6.34

—

Ϫ4.27

—

Ϫ4.24

Ϫ5.25

—

> Ϫ4.00

Ϫ6.02

> Ϫ4.00

—

> Ϫ4.00

—

Colon cancer

COLO 205

HCC-2998

HCT-116

HCT-15

HT29

KM12

SW-620

Ϫ4.30

—

Ϫ4.69

Ϫ5.36

> Ϫ4.00

Ϫ5.15

> Ϫ4.00

Ϫ4.33

—

Ϫ4.25

> Ϫ4.00

Ϫ4.16

—

> Ϫ4.00

—

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.21

Ϫ5.16

> Ϫ4.00

Ϫ5.32

Ϫ5.24

> Ϫ4.00

Ϫ4.04

—

Ϫ4.33

—

Ϫ4.61

> Ϫ4.00

Ϫ4.52

Ϫ4.74

> Ϫ4.00

< Ϫ8.00

—

Ϫ7.13

> Ϫ4.00

—

Ϫ4.26

Ϫ4.14

Ϫ4.12

Ϫ4.15

> Ϫ4.00

—

CNS cancer

SF-268

SF-295

SF-539

SNB-19

SNB-75

U251

Ϫ4.19

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.19

Ϫ5.29

—

Ϫ4.64

Ϫ4.16

Ϫ5.23

> Ϫ4.00

Ϫ4.11

Ϫ4.29

> Ϫ4.00

—

> Ϫ4.00

—

Ϫ4.11

Ϫ4.55

—

> Ϫ4.00

Ϫ4.30

Ϫ4.02

Ϫ4.47

Ϫ5.13

Ϫ4.32

—

Ϫ6.20

< Ϫ8.00

Ϫ6.22

Ϫ6.18

—

Ϫ5.12

Ϫ5.11

Ϫ5.18

Melanoma

LOX IMVI

MALME-3M

M14

SK-MEL-2

SK-MEL-28

SK-MEL-5

UACC-257

UACC-62

—

Ϫ4.17

—

Ϫ4.20

Ϫ4.21

Ϫ4.29

> Ϫ4.00

Ϫ4.29

—

Ϫ5.10

—

> Ϫ4.00

Ϫ5.07

Ϫ5.11

> Ϫ4.00

Ϫ5.19

Ϫ4.59

Ϫ5.16

Ϫ5.21

Ϫ4.15

> Ϫ4.00

Ϫ5.16

> Ϫ4.00

Ϫ4.16

—

> Ϫ4.00

Ϫ4.24

> Ϫ4.00

Ϫ4.36

Ϫ5.24

> Ϫ4.00

Ϫ4.57

—

< Ϫ8.00

Ϫ7.95

—

Ϫ7.15

Ϫ7.07

> Ϫ4.00

Ϫ6.59

Ϫ5.29

Ϫ4.41

Ϫ5.19

Ϫ5.23

> Ϫ4.00

Ϫ5.26

> Ϫ4.00

Ϫ4.30

Ovarian cancer

IGROV 1

OVCAR-3

OVCAR-4

OVCAR-5

OVCAR-8

SK-OV-3

Ϫ4.07

Ϫ4.12

Ϫ4.09

Ϫ4.26

Ϫ4.20

Ϫ4.11

> Ϫ4.00

—

> Ϫ4.00

Ϫ5.15

> Ϫ4.00

Ϫ4.00

Ϫ5.07

Ϫ4.09

Ϫ5.24

Ϫ4.03

> Ϫ4.00

—

> Ϫ4.00

Ϫ4.46

Ϫ4.19

Ϫ4.18

> Ϫ4.00

Ϫ4.57

> Ϫ4.00

—

Ϫ4.06

—

Ϫ6.10

> Ϫ4.00

Renal cancer

786-0

A498

Ϫ4.26

Ϫ4.24

Ϫ4.25

Ϫ4.20

Ϫ4.27

Ϫ4.19

Ϫ4.24

Ϫ5.23

Ϫ4.41

Ϫ5.17

Ϫ5.15

Ϫ5.07

—

Ϫ5.92

Ϫ4.24

Ϫ4.63

Ϫ5.07

Ϫ5.14

Ϫ4.28

Ϫ4.39

Ϫ5.17

> Ϫ4.00

—

> Ϫ4.00

Ϫ5.36

Ϫ4.26

Ϫ5.26

Ϫ5.03

—

Ϫ4.61

—

Ϫ4.87

> Ϫ4.00

Ϫ4.03

—

< Ϫ8.00

Ϫ5.86

Ϫ7.34

Ϫ7.51

Ϫ7.19

Ϫ7.30

< Ϫ8.00

—

ACHN

CAKI-1

RXF-393

SN12C

TK-10

UO-31

> Ϫ4.00

—

> Ϫ4.00

Ϫ5.11

—

Ϫ5.21

Ϫ4.59

> Ϫ4.00

Prostate cancer

PC-3

DU-145

> Ϫ4.00

Ϫ4.27

> Ϫ4.00

Ϫ5.36

Ϫ4.30

Ϫ5.21

> Ϫ4.00

—

> Ϫ4.00

—

Ϫ5.25

> Ϫ4.00

—

Ϫ7.25

Breast cancer

MCF 7

> Ϫ4.00

Ϫ4.13

Ϫ4.29

> Ϫ4.00

Ϫ4.18

Ϫ4.27

> Ϫ4.00

—

> Ϫ4.00

Ϫ5.02

Ϫ5.20

> Ϫ4.00

Ϫ4.51

> Ϫ4.00

—

Ϫ4.35

—

Ϫ4.34

Ϫ5.22

> Ϫ4.00

Ϫ4.42

> Ϫ4.00

Ϫ4.00

> Ϫ4.00

Ϫ4.00

> Ϫ4.00

Ϫ5.22

> Ϫ4.00

Ϫ5.26

Ϫ5.30

> Ϫ4.00

Ϫ4.53

> Ϫ4.00

Ϫ4.25

> Ϫ4.00

Ϫ4.44

> Ϫ4.00

—

NCI/ADR-RES

MDA-MB231/ATCC

HS578T

MDA-MB-435

BT-549

Ϫ7.30

> Ϫ4.00

Ϫ7.11

Ϫ7.37

> Ϫ4.00

Ϫ6.23

T-24D

> Ϫ4.00

Ϫ4.16

MG_MID^b

Ϫ4.21

^aThe cytotoxicity log₁₀LC₅₀values are the concentrations corresponding to 50% growth inhibition. ^bMean graph midpoint (µM) for growth

inhibition against all human cancer cell lines tested.

conjugates in our group^15,19the activity data presented in

Table 1 and Table 2 show that the solubility of the PBD-

polyamides and also the nature of the heterocycles play impor-

tant roles in inﬂuencing the cytotoxic activities of the PBD-

polyamide conjugates. This study found that PBD-glycosylated

polyamide (water soluble) conjugates 39–46 in general are

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3334

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Fig. 2 Comparison between PBD-water insoluble acetylglycosylated polyamide compound 38 and PBD-water soluble glycosylated polyamide

compound 46.

highly potent against many human cancer cell lines and in

comparison with the PBD-polyamide (water insoluble version)

conjugates.

In summary, we have described the ﬁrst synthesis of the

PBD-water soluble pyrrole and imidazole polyamide con-

jugates and also their anticancer evaluation against 60 human

tumor cell lines in 9 cancer panels. More details of the bio-

physical, intracellular uptake and localization and additional

biological evaluation will be reported in due course.

Experimental

Kieselgel 60 (230–400 mesh) from E. Merck was used for ﬂash

column chromatography, and precoated silica gel 60F-254

sheets from E. Merck were used for TLC, with the solvent

system indicated in the procedure. TLC plates were visualized

by using UV light. All compounds obtained commercially were

used without further puriﬁcation unless otherwise stated.

Methanol and ethanol was freshly distilled over magnesium

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3335

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turnings; tetrahydrofuran was distilled over sodium benz-

ophenone ketyl under an atmosphere of dry argon, ether was

dried over sodium; methylene chloride was freshly distilled from

calcium hydride, triethylamine was treated with potassium

hydroxide then distilled from barium oxide and stored over 3 Å

molecular sieves, dry dimethylformamide and all commercially

available chemicals were purchased from Aldrich Chemical

Co. The ¹H NMR spectra were recorded on a Bruker WH-300

spectrometer. Proton chemical shifts are reported in parts per

million (δ) downﬁeld from tetramethylsilane (SiMe₄) as an

internal standard. Coupling constants (J values) are given in

hertz and spin multiplicates are described as follows: s (singlet),

d (doublet), dd (doublet of doublets), t (triplet), q (quartet),

p (pentet) or m (multiplet). FAB (fast atom bombardment)

mass spectra with glycerol as the matrix were determined on

Associate Electrical Ind. (AEI) MS-9 and MS-50 focusing high-

resolution mass spectrometers.

mixture was washed with saturated NaHCO₃repeatedly. The

crude product was further puriﬁed by column chromatography

using DCM as eluent to give 4-nitro-1H-pyrrole-2-carboxylic

acid tert-butyl ester (11) as a white solid in 83% yield (5.1 g). ¹H

NMR (300 MHz, DMSO-d₆): δ 1.59 (s, 9H, –C(CH₃)₃), 7.26

(d, 1H, J = 1.8 Hz, Py–H), 7.76 (d, 1H, J = 1.8 Hz, Py–H), 10.10

(brs, 1H, –NH–). HR-MS: m/z calculated for C₉H₁₂N₂O₄

212.07, found 212.15.

4-Nitro-1-(3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-

2-yl)-1H-pyrrole-2-carboxylic acid tert-butyl ester (13)

4-Nitro-1H-pyrrole-2-carboxylic acid tert-butyl ester (11)

(2.5 g, 11.79 mmol) was taken in dry DMF and to it crushed

potassium hydroxide (0.86 g, 15.35 mmol) was added and the

reaction mixture was stirred at room temperature for 30 min

and the yellow colored potassium salt was obtained. The reac-

tion mixture was then treated with the acetyl bromo-sugar

compound 12 (7.25 g, 17.68 mmol) followed by the addition of

a catalytic amount of 18-crown-6-ether (10 mg). The reaction

mixture was stirred for 3 h at room temperature. TLC exami-

nation showed the consumption of all the starting material. The

reaction mixture was concentrated under reduced pressure and

the residue was dissolved in ethyl acetate and washed with

water. The organic was removed and dried over sodium sulfate,

ﬁltered and concentrated in vacuo, to give crude compound 13

which was puriﬁed by column chromatography using ethyl

acetate/dichloromethane (2 : 98) as a white colored foam in

2,2,2-Trichloro-1-(4-nitro-1H-pyrrol-2-yl)-ethanone (8)

To a solution of 2,2,2-trichloro-1-(1H-pyrrol-2-yl)-ethanone

(5.3 g, 24.94 mmol) in acetic anhydride (40.0 ml) at Ϫ40 ЊC was

added fuming nitric acid 8.0 ml over a period of 30 min while a

temperature of Ϫ40 ЊC was maintained. The reaction mixture

was carefully allowed to warm to room temperature and stirred

for an additional 6 h. After being stirred for 6 h the solvent and

acetic anhydride were removed under reduced pressure and the

residue was puriﬁed by column chromatography eluting with

EtOAc/DCM (2 : 98) to give compound 8 4.5 g in 70% yield as a

1

80% yield (5.15 g). H NMR (300 MHz, CDCl₃): δ 1.70 (s,

1

solid. H NMR (300 MHz, CDCl₃): δ 7.26 (d, 1H, J = 1.8 Hz,

9H, C(CH₃)₃), 1.85 (s, 3H, COCH₃), 2.00 (s, 3H, COCH₃), 2.12

(s, 3H, COCH₃), 2.16 (s, 3H, COCH₃), 4.00 (ddd, 1H, J = 10.1,

4.4, 12.1 Hz), 4.20 (m, 2H), 4.56 (dd, 1H, J = 10.1, 9.5 Hz), 5.19

(t, 1H, J = 9.5 Hz), 5.62 (t, 1H, J = 9.5 Hz), 6.64 (d, 1H, J = 3.85

Hz), 7.30 (d, 1H, J = 1.8 Hz, Py–H), 7.90 (d, 1H, J = 1.8 Hz,

Py–H). HR-MS: m/z calculated for C₂₃H₃₀N₂O₁₃542.174, found

565.40 (M ϩ Na).

Py–H), 7.76 (d, 1H, J = 1.8 Hz, Py–H), 10.10 (brs, 1H, –NH–).

MS: m/z calculated for C₆H₃Cl₃N₂O₃257.50, found 280.15

(M ϩ Na).

4-Nitro-1H-pyrrole-2-carboxylic acid methyl ester (9)

A solution of the 2,2,2-trichloro-1-(4-nitro-1H-pyrrol-2-yl)-

ethanone (8) (4.5 g, 17.47 mmol) in MeOH and DMAP (cata-

lyst) was stirred at 60 ЊC temperature until all the starting

material disappeared. After completion the reaction mixture

was cooled and concentrated to dryness under reduced pressure

(at RT) and crystallized to aﬀord the ester 9 in 88% yield (2.41

4-Nitro-1-(3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-

2-yl)-1H-pyrrole-2-carboxylic acid (14)

A solution of the compound 13 (4.0 g, 7.38 mmol) was pre-

pared in dry dichloromethane (50 ml) and to it 1.0 M TiCl₄

solution in dichloromethane (10 ml) was added dropwise slowly

with constant stirring at room temperature. After complete

addition the stirring was continued for 24 h. TLC observation

at this time indicated completion of the reaction. The reaction

mixture was concentrated in vacuo and puriﬁed by column

chromatography. Elution with EtOAC/DCM (3 : 7) gave pure

4-nitro-1-(3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-

2-yl)-1H-pyrrole-2-carboxylic acid (14) as a white solid in 78%

1

g). H NMR (300 MHz, CDCl₃): δ 3.98 (s, 1H, –COOCH₃),

7.20 (d, 1H, J = 1.8 Hz, Py–H), 7.72 (d, 1H, J = 1.8 Hz, Py–H),

10.15 (brs, 1H, –NH–). MS: m/z calculated for C₆H₆N₂O₄

170.00, found 171.03 (M ϩ 1).

4-Nitro-1H-pyrrole-2-carboxylic acid (10)

A mixture of 4-nitro-1H-pyrrole-2-carboxylic acid methyl ester

(9) (2.0 g, 28.84 mmol) methanol (100 ml) and 10 ml of 1 N

NaOH was placed in a ﬂask, then the reaction mixture was

stirred at 60 ЊC temperature until the ester completely dis-

appeared as shown by TLC. The reaction mixture was cooled in

ice with stirring and neutralized with 0.5 N HCl to pH 2 when a

solid separated out from the solution. The solid was collected

and washed with water and dried under reduced pressure to

give acid 10 in 80% yield (1.45 g). ¹H NMR (300 MHz, DMSO-

d₆): δ 7.25 (d, 1H, J = 1.8 Hz, Py–H), 7.78 (d, 1H, J = 1.8 Hz,

Py–H), 10.15 (brs, 1H, –NH–), 12.98 (brs, 1H, –COOH). MS:

m/z calculated for C₅H₄N₂O₄156.00, found 156.10.

1

yield (2.8 g). H NMR (300 MHz, DMSO-d₆): δ 1.92 (s, 3H,

COCH₃), 2.05 (s, 3H, COCH₃), 2.08 (s, 3H, COCH₃), 2.12 (s,

3H, COCH₃), 4.06 (ddd, 1H, J = 10.1, 4.4, 12.1 Hz), 4.15 (m,

2H), 4.36 (dd, 1H, J = 10.1, 9.5 Hz), 5.21 (t, 1H, J = 9.5 Hz),

5.56 (t, 1H, J = 9.5 Hz), 6.62 (d, 1H, J = 3.85 Hz), 7.58 (d, 1H,

J = 1.8 Hz, Py–H), 7.98 (d, 1H, J = 1.8 Hz, Py–H), 12.95 (brs,

1H, –COOH). HR-MS: m/z calculated for C₁₉H₂₂N₂O₁₃486.12,

found 509.12 (M ϩ Na).

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-[2-(3-dimethyl-

amino-propylcarbamoyl)-4-nitro-pyrrol-1-yl]-tetrahydro-pyran-

3-yl ester (15)

4-Nitro-1H-pyrrole-2-carboxylic acid tert-butyl ester (11)

4-Nitro-1H-pyrrole-2-carboxylic acid (10) (4.5 g, 28.84 mmol)

was added to 200 ml of diethyl ether and 6 ml of concentrated

sulfuric acid in a round bottom pressure bottle. The colloidal

solution was cooled to Ϫ60 ЊC and a slow stream of isobutylene

was bubbled through this solution for several minutes. The solu-

tion was capped tightly with a teﬂon cork and allowed to warm

to room temperature and stirred for 36 h. The crude reaction

3-Dimethylaminopropylamine (0.46 g, 4.50 mmol) was dis-

solved in dry DMF and added to a mixture of the 4-nitro-1-

(3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-2-yl)-1H-

pyrrole-2-carboxylic acid (14) (2.0 g, 4.11 mmol), hydroxy-

benzotriazole (0.55 g, 4.07 mmol), and EDCI (1.97 g, 10.27

mmol), in dry DMF. This mixture was stirred at RT for 12 h

and after completion of the reaction the solvent was removed

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3336

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under reduced pressure to aﬀord a dark oil which was puriﬁed

by ﬂash column chromatography on silica gel by using meth-

anol/dichloromethane (5 : 95) as eluent to aﬀord the acetic acid

4,5-diacetoxy-6-acetoxymethyl-2-[2-(3-dimethylamino-propyl-

carbamoyl)-4-nitro-pyrrol-1-yl] tetrahydro-pyran-3-yl ester (15)

nitrogen atmosphere. The reaction mixture was brought to

room temperature and stirred for 2 h. After completion of the

reaction the residue was concentrated to dryness under reduced

pressure and the residue was puriﬁed by column chromato-

graphy eluting with NH₄OH/MeOH/DCM 0.2 : 1 : 9; to give

compound 17, 1.10 g in 82% yield. ¹H NMR (300 MHz,

DMSO-d₆): δ 1.55 (q, 2H, J = 6.8 Hz, –CH₂–), 1.78 (s, 3H,

COCH₃), 1.85 (s, 3H, COCH₃), 1.95 (s, 3H, COCH₃), 1.99

(s, 3H, COCH₃), 2.04 (s, 3H, COCH₃), 2.06 (s, 3H, COCH₃),

2.08 (s, 3H, COCH₃), 2.09 (s, 3H, COCH₃), 2.26 (s, 6H,

–N(CH₃)₂), 2.30 (t, 2H, J = 7.0 Hz, –CH₂N–), 3.18 (dt, 2H, J =

6.0, 7.0 Hz, –NHCH₂–), 3.85 (s, 3H, –NCH₃), 3.90–4.33 (m,

8H, sugar proton), 5.22–5.56 (m, 4H, sugar proton), 6.71

(d, 2H, J = 3.85 Hz), 6.81 (d, 1H, J = 1.8 Hz, Py–H), 6.96 (d,

1H, J = 1.8 Hz, Py–H), 7.18 (d, 1H, J = 1.8 Hz, Py–H), 7.25

(d, 1H, J = 1.8 Hz, Py–H), 7.45 (d, 1H, J = 1.8 Hz, Py–H), 7.86

(d, 1H, J = 1.8 Hz, Py–H), 8.18 (t, 1H, J = 6.5 Hz, –NHCH₂–),

9.61 (s, 1H, –NH–), 9.95 (s, 1H, –NH–). HR-MS: m/z cal-

culated for C₄₉H₆₂N₈O₂₃1130.39, found 1153.40 (M ϩ Na).

1

as a white solid in 77% yield (1.89 g). H NMR (300 MHz,

DMSO-d₆): δ 1.55 (q, 2H, J = 6.8 Hz, –CH₂–), 1.95 (s, 3H,

COCH₃), 2.08 (s, 3H, COCH₃), 2.10 (s, 3H, COCH₃), 2.12

(s, 3H, COCH₃), 2.18 (s, 6H, –N(CH₃)₂), 2.25 (t, 2H, J = 7.0 Hz,

–CH₂N–), 3.15 (dt, 2H, J = 6.0, 7.0 Hz, –NHCH₂–), 4.15 (ddd,

1H, J = 10.1, 4.4, 12.1 Hz), 4.18 (m, 2H), 4.32 (dd, 1H, J = 10.1,

9.5 Hz), 5.20 (t, 1H, J = 9.5 Hz), 5.50 (t, 1H, J = 9.5 Hz), 6.61

(d, 1H, J = 3.85 Hz), 7.62 (d, 1H, J = 1.8 Hz, Py–H), 8.08

(d, 1H, J = 1.8 Hz, Py–H), 8.45 (t, 1H, J = 6.5 Hz, –NHCH₂–).

HR-MS: m/z calculated for C₂₄H₃₄N₄O₁₂570.21, found 593.20

(M ϩ Na).

General procedure A

A solution of the nitropolyamides 15 and 4–7 in MeOH or

DMF was hydrogenated over 10% Pd/C at 50 psi pressure for

2 h and the catalyst was removed by ﬁltration through a Celite

pad. The ﬁltrate was concentrated to dryness under reduced

pressure (at RT) to aﬀord the corresponding amine. Owing

to the sensitivity of the amine to oxidation, it was used for the

next reaction immediately. It was dissolved in dry DMF and a

mixture of the acid 14 (1.0 equivalent), hydroxybenzotriazole

(1.0 equivalent), and EDCI (2.5 equivalent), in dry DMF was

added. This mixture was stirred at RT for 12 h and after com-

pletion of the reaction the solvent was removed under reduced

pressure to aﬀord a dark oil which was puriﬁed by ﬂash column

chromatography on silica gel by using methanol–dichloro-

methane as eluent to aﬀord the polyamides 16, and 19–22

respectively in good yields.

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-[2-(3-dimethyl-

amino-propylcarbamoyl)-4-({1-(3,4,5-triacetoxy-6-acetoxy-

methyl-tetrahydro-pyran-2-yl)-4-[(1-methyl-4-nitro-1H-imid-

azole-2-carbonyl)-amino]-1H-pyrrole-2-carbonyl}-amino)-pyr-

rol-1-yl]-tetrahydro-pyran-3-yl ester (18)

This compound was prepared according to the method

described for the compound 17, employing compound 16 (1.2 g,

1.19 mmol) and 4-nitro-2-(trichloroacetyl)-1-methylimidazole

1

(3) (0.356 g, 1.30 mmol) in 78% yield (1.05 g). H NMR (300

MHz, DMSO-d₆): δ 1.56 (q, 2H, J = 6.8 Hz, –CH₂–), 1.76 (s,

3H, COCH₃), 1.86 (s, 3H, COCH₃), 1.97 (s, 3H, COCH₃), 1.99

(s, 3H, COCH₃), 2.02 (s, 3H, COCH₃), 2.04 (s, 3H, COCH₃),

2.06 (s, 3H, COCH₃), 2.09 (s, 3H, COCH₃), 2.28 (s, 6H,

–N(CH₃)₂), 2.29 (t, 2H, J = 7.0 Hz, –CH₂N–), 3.18 (dt, 2H, J =

6.0, 7.0 Hz, –NHCH₂–), 3.86 (s, 3H, –NCH₃), 3.90–4.33 (m,

8H, sugar proton), 5.22–5.56 (m, 4H, sugar proton), 6.70

(d, 2H, J = 3.85 Hz), 6.96 (d, 1H, J = 1.8 Hz, Py–H), 7.20 (d,

1H, J = 1.8 Hz, Py–H), 7.40 (d, 1H, J = 1.8 Hz, Py–H), 7.68

(s, 1H, Im–H), 7.79 (d, 1H, J = 1.8 Hz, Py–H), 8.15 (t, 1H, J =

6.5 Hz, –NHCH₂–), 9.51 (s, 1H, –NH–), 9.93 (s, 1H, –NH–).

HR-MS: m/z calculated for C₄₈H₆₁N₉O₂₃1131.39, found

1154.45 (M ϩ Na).

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-{2-[5-(3-di-

methylamino-propylcarbamoyl)-1-(3,4,5-triacetoxy-6-acetoxy-

methyl-tetrahydro-pyran-2-yl)-1H-pyrrol-3-ylcarbamoyl]-4-

nitro-pyrrol-1-yl}-tetrahydro-pyran-3-yl ester (16)

This compound was prepared starting from acetic acid 4,5-di-

acetoxy-6-acetoxymethyl-2-[2-(3-dimethylamino-propylcarb-

amoyl)-4-nitro-pyrrol-1-yl] tetrahydro-pyran-3-yl ester (15)

(1.5 g, 2.63 mmol) and the acid 14 (1.27 g, 2.61 mmol) according

to the general procedure A (2.1 g, 80% yield) as a light yellow

1

solid. H NMR (300 MHz, DMSO-d₆): δ 1.55 (q, 2H, J = 6.8

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-{2-[5-(3-dimethyl-

amino-propylcarbamoyl)-1-methyl-1H-pyrrol-3-ylcarbamoyl]-4-

nitro-pyrrol-1-yl}-tetrahydro-pyran-3-yl ester (19)

Hz, –CH₂–), 1.79 (s, 3H, COCH₃), 1.86 (s, 3H, COCH₃), 1.96

(s, 3H, COCH₃), 1.99 (s, 3H, COCH₃), 2.03 (s, 3H, COCH₃),

2.05 (s, 3H, COCH₃), 2.07 (s, 3H, COCH₃), 2.08 (s, 3H,

COCH₃), 2.26 (s, 6H, –N(CH₃)₂), 2.30 (t, 2H, J = 7.0 Hz,

–CH₂N–), 3.18 (dt, 2H, J = 6.0, 7.0 Hz, –NHCH₂–), 3.90–4.32

(m, 8H, sugar proton), 5.20–5.50 (m, 4H, sugar proton), 6.71

(d, 2H, J = 3.85 Hz), 6.96 (d, 1H, J = 1.8 Hz, Py–H), 7.20

(d, 1H, J = 1.8 Hz, Py–H), 7.56 (d, 1H, J = 1.8 Hz, Py–H), 7.95

(d, 1H, J = 1.8 Hz, Py–H), 8.15 (t, 1H, J = 6.5 Hz, –NHCH₂–),

9.62 (s, 1H, –NH–). HR-MS: m/z calculated for C₄₃H₅₆N₆O₂₂

1008.34, found 1031.40 (M ϩ Na).

This compound was prepared starting from compound 4

(0.574 g, 2.25 mmol) and the acid 14 (1.0 g, 2.05 mmol) accord-

ing to the general procedure A (1.15 g, 81% yield) as a light

1

yellow solid. H NMR (300 MHz, CDCl₃): δ 1.56 (q, 2H, J =

6.8 Hz, –CH₂–), 1.85 (s, 3H, COCH₃), 2.00 (s, 3H, COCH₃),

2.04 (s, 3H, COCH₃), 2.09 (s, 3H, COCH₃), 2.20 (s, 6H,

–N(CH₃)₂), 2.27 (t, 2H, J = 7.0 Hz, –CH₂N–), 3.18 (dt, 2H,

J = 6.0, 7.0 Hz, –NHCH₂–), 3.85 (s, 3H, –NCH₃), 4.15 (ddd,

1H, J = 10.1, 4.4, 12.1 Hz), 4.18 (m, 2H), 4.34 (dd, 1H, J = 10.1,

9.5 Hz), 5.22 (t, 1H, J = 9.5 Hz), 5.56 (t, 1H, J = 9.5 Hz), 6.63

(d, 1H, J = 3.85 Hz), 6.89 (d, 1H, J = 1.8 Hz, Py–H), 7.25 (d,

1H, J = 1.8 Hz, Py–H), 7.42 (d, 1H, J = 1.8 Hz, Py–H), 7.82 (d,

1H, J = 1.8 Hz, Py–H), 8.25 (t, 1H, J = 6.5 Hz, –NHCH₂–), 9.59

(s, 1H, –NH–). HR-MS: m/z calculated for C₃₀H₄₀N₆O₁₃692.27,

found 693.30 (M ϩ 1).

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-[2-(3-dimethyl-

amino-propylcarbamoyl)-4-({1-(3,4,5-triacetoxy-6-acetoxy-

methyl-tetrahydro-pyran-2-yl)-4-[(1-methyl-4-nitro-1H-pyrrole-

2-carbonyl)-amino]-1H-pyrrole-2-carbonyl}-amino)-pyrrol-1-yl]-

tetrahydro-pyran-3-yl ester (17)

To a solution of compound 16 (1.2 g, 1.19 mmol) in 25.0 ml

of methanol was added 0.200 g of 10% Pd–C. The reaction

mixture was hydrogenated in a Parr shaker at 50 psi for 2 h.

The catalyst was removed by ﬁltration and the solvent was

evaporated in vacuo. The residue was dissolved in dry THF

(10.0 ml), triethylamine (2.0 ml) and a solution of 4-nitro-2-

(trichloroacetyl)-1-methylpyrrole (2) (0.354 g, 1.30 mmol) in

THF (10 ml), was added slowly with stirring at 0 ЊC under

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-(2-{5-[5-(3-di-

methylamino-propylcarbamoyl)-1-methyl-1H-pyrrol-3-ylcarb-

amoyl]-1-methyl-1H-pyrrol-3-ylcarbamoyl}-4-nitro-pyrrol-1-yl)-

tetrahydro-pyran-3-yl ester (20)

The title compound was prepared according to the general

procedure A by using compound 5 (0.851 g, 2.26 mmol) and the

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

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acid 14 (1.0 g, 2.05 mmol) in 80% yield (1.35 g) as a yellow solid.

¹H NMR (300 MHz, CDCl₃): δ 1.55 (q, 2H, J = 6.8 Hz, –CH₂–),

1.87 (s, 3H, COCH₃), 2.01 (s, 3H, COCH₃), 2.03 (s, 3H,

COCH₃), 2.06 (s, 3H, COCH₃), 2.19 (s, 6H, –N(CH₃)₂), 2.28

(t, 2H, J = 7.0 Hz, –CH₂N–), 3.15 (dt, 2H, J = 6.0, 7.0 Hz,

–NHCH₂–), 3.85 (s, 3H, –NCH₃), 3.88 (s, 3H, –NCH₃), 4.12

(ddd, 1H, J = 10.1, 4.4, 12.1 Hz), 4.17 (m, 2H), 4.32 (dd, 1H,

J = 10.1, 9.5 Hz), 5.21 (t, 1H, J = 9.5 Hz), 5.53 (t, 1H, J =

9.5 Hz), 6.61 (d, 1H, J = 3.85 Hz), 6.83 (d, 1H, J = 1.8 Hz,

Py–H), 6.96 (d, 1H, J = 1.8 Hz, Py–H), 7.20 (d, 1H, J = 1.8 Hz,

Py–H), 7.35 (d, 1H, J = 1.8 Hz, Py–H), 7.45 (d, 1H, J = 1.8 Hz,

Py–H), 7.80 (d, 1H, J = 1.8 Hz, Py–H), 8.20 (t, 1H, J = 6.5 Hz,

–NHCH₂–), 9.59 (s, 1H, –NH–), 9.97 (s, 1H, –NH–). HR-MS:

m/z calculated for C₃₆H₄₆N₈O₁₄814.31, found 837.40 (M ϩ Na).

silica gel by using methanol–dichloromethane–aq ammonia

as eluent to aﬀord the PBD-nitro dithioacetal glycosylated

polyamides 23–30 in good yield.

Compound 23

This compound was prepared according to the general pro-

cedure B, using compound 15 (1.28 g, 2.24 mmol) and the

(2S)-N-[5-methoxy-4-[3-(carboxy) propyloxy]-2-nitrobenzoyl]

pyrrolidine-2-carboxaldehyde diethyl thioacetal (1) (1.0 g,

2.05 mmol), as a yellow solid in 73% yield (1.5 g). IR: (Nujol)

ν_max3289, 2855, 2420, 2061, 1721, 1703, 1640, 1156, 889, 810,

756 cm^Ϫ1¹H NMR (DMSO-d₆, 300 MHz): δ 1.24 (s, 6H,

.

–(CH₃)₂), 1.56–1.61(m, 4H), 1.69 (m, 2H), 1.95 (m, 2H), 2.01 (s,

3H, –COCH₃), 2.03 (s, 3H, –COCH₃), 2.05 (s, 3H, –COCH₃),

2.09 (s, 3H, –COCH₃), 2.18 (m, 2H), 2.28 (s, 6H, –N(CH3)₂),

2.36 (m, 2H), 2.48 (m, 4H), 2.95 (m, 2H), 3.30 (m, 2H), 3.75 (s,

3H, –OCH₃), 3.89 (m, 1H), 3.95 (m, 2H), 4.12 (m, 1H), 4.16–

4.35 (m, 4H, sugar proton), 5.21–5.60 (m, 2H, sugar proton),

6.56 (m, 1H, sugar proton), 6.91 (d, 1H, J = 1.7 Hz, Py–H), 7.12

(d, 1H, J = 1.7 Hz, Py–H), 7.61 (s, 1H, Ar–H), 7.75 (s, 1H,

Ar–H), 8.20 (t, J = 6.5 Hz, 1H), 9.98 (s, 1H, –NH–). HR-MS:

m/z calculated for C₄₅H₆₄N₆O₁₆S₂, 1008.35 found 1009.10

(M ϩ 1).

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-{2-[2-(3-dimethyl-

amino-propylcarbamoyl)-1-methyl-1H-imidazol-4-ylcarbamoyl]-

4-nitro-pyrrol-1-yl}-tetrahydro-pyran-3-yl ester (21)

This compound was prepared according to the method

described for compound 20, employing compound 6 (0.577 g,

2.26 mmol) and the acid 14 (1.0 g, 2.05 mmol), in 77% yield

1

(1.10 g) as a light yellow solid. H NMR (300 MHz, CDCl₃):

δ 1.55 (q, 2H, J = 6.8 Hz, –CH₂–), 1.90 (s, 3H, COCH₃), 2.00

(s, 3H, COCH₃), 2.05 (s, 3H, COCH₃), 2.10 (s, 3H, COCH₃),

2.20 (s, 6H, –N(CH₃)₂), 2.29 (t, 2H, J = 7.0 Hz, –CH₂N–), 3.15

(dt, 2H, J = 6.0, 7.0 Hz, –NHCH₂–), 3.87 (s, 3H, –NCH₃), 4.14

(ddd, 1H, J = 10.1, 4.4, 12.1 Hz), 4.19 (m, 2H), 4.32 (dd, 1H,

J = 10.1, 9.5 Hz), 5.21 (t, 1H, J = 9.5 Hz), 5.55 (t, 1H, J = 9.5

Hz), 6.60 (d, 1H, J = 3.85 Hz), 7.15 (d, 1H, J = 1.8 Hz, Py–H),

7.35 (s, 1H, Im–H), 7.75 (d, 1H, J = 1.8 Hz, Py–H), 8.18 (t, 1H,

J = 6.5 Hz, –NHCH₂–), 9.65 (s, 1H, –NH–). HR-MS: m/z cal-

culated for C₂₉H₃₉N₇O₁₃693.26, found 716.20 (M ϩ Na).

Compound 24

This compound was prepared according to the method

described for the compound 23, employing glycosylated poly-

amide 16 (2.06 g, 2.04 mmol) and the acid 1 (1.0 g, 2.05 mmol)

in 74% yield (2.21 g) as a yellow solid. IR: (Nujol) ν_max3285,

1

2850, 2415, 2161, 1720, 1640, 1155, 890, 810, 756 cm^Ϫ1. H

NMR (DMSO-d₆, 300 MHz): δ 1.25 (s, 6H, –(CH₃)₂), 1.56–1.60

(m, 4H), 1.65 (m, 2H), 1.98 (m, 2H), 2.00–2.12 (8 singlets, 24H,

COCH₃), 2.16 (m, 2H), 2.30 (s, 6H, –N(CH3)₂), 2.35 (m, 2H),

2.50 (m, 4H), 2.97 (m, 2H), 3.30 (m, 2H), 3.78 (s, 3H, –OCH₃),

3.89 (m, 1H), 3.97 (m, 2H), 4.15 (m, 1H), 4.16–4.41 (m, 8H,

sugar proton), 5.20–5.65 (m, 4H, sugar proton), 6.61 (m,

2H, sugar proton), 6.83 (d, 1H, J = 1.7 Hz, Py–H), 6.96 (d, 1H,

J = 1.7 Hz, Py–H), 7.12 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (d, 1H,

J = 1.7 Hz, Py–H), 7.60 (s, 1H, Ar–H), 7.76 (s, 1H, Ar–H), 8.25

(t, J = 6.5 Hz, 1H), 9.98 (s, 1H, –NH–), 10.05 (s, 1H, –NH–).

MS: m/z calculated C₆₄H₈₆N₈O₂₆S₂1446.51, found 1447.50

(M ϩ 1).

Acetic acid 4,5-diacetoxy-6-acetoxymethyl-2-(2-{2-[2-(3-di-

methylamino-propylcarbamoyl)-1-methyl-1H-imidazol-4-ylcar-

bamoyl]-1-methyl-1H-imidazol-4-ylcarbamoyl}-4-nitro-pyrrol-1-

yl)-tetrahydro-pyran-3-yl ester (22)

The title compound was prepared according to the general pro-

cedure A, using compound 7 (0.855 g, 2.26 mmol), and the acid

14 (1.0 g, 2.05 mmol) in 75% yield (1.25 g) as a yellow solid. ¹H

NMR (300 MHz, CDCl₃): δ 1.56 (q, 2H, J = 6.8 Hz, –CH₂–),

1.89 (s, 3H, COCH₃), 2.03 (s, 3H, COCH₃), 2.07 (s, 3H,

COCH₃), 2.10 (s, 3H, COCH₃), 2.15 (s, 6H, –N(CH₃)₂), 2.26

(t, 2H, J = 7.0 Hz, –CH₂N–), 3.18 (dt, 2H, J = 6.0, 7.0 Hz, –

NHCH₂–), 3.86 (s, 3H, –NCH₃), 3.89 (s, 3H, –NCH₃), 4.15

(ddd, 1H, J = 10.1, 4.4, 12.1 Hz), 4.19 (m, 2H), 4.32 (dd, 1H, J =

10.1, 9.5 Hz), 5.21 (t, 1H, J = 9.5 Hz), 5.55 (t, 1H, J = 9.5 Hz),

6.62 (d, 1H, J = 3.85 Hz), 6.89 (d, 1H, J = 1.8 Hz, Py–H), 7.25 (s,

1H, Im–H), 7.45 (d, 1H, J = 1.8 Hz, Py–H), 7.95 (s, 1H, Im–H),

8.18 (t, 1H, J = 6.5 Hz, –NHCH₂–), 9.56 (s, 1H, –NH–), 9.95 (s,

1H, –NH–). HR-MS: m/z calculated for C₃₄H₄₄N₁₀O₁₄816.30,

found 839.37 (M ϩ Na).

Compound 25

This compound was prepared starting from the polyamide 17

(1.27 g, 1.12 mmol) and the acid 1 (0.50 g, 1.02 mmol), accord-

ing to the general procedure described for compound 24, as a

yellow solid (1.21 g, 75% yield). IR: (Nujol) ν_max3288, 2960,

2690, 1720, 1640, 1578, 1523, 1405, 1220, 1156, 1098, 886, 810,

756 cm^Ϫ1¹H NMR (DMSO-d₆, 300 MHz): δ 1.24 (s, 6H,

.

–(CH₃)₂), 1.56–1.61 (m, 4H), 1.65 (m, 2H), 1.95 (m, 2H), 2.01–

2.12 (8 singlets, 24H, COCH₃), 2.16 (m, 2H), 2.32 (s, 6H,

–N(CH3)₂), 2.35 (m, 2H), 2.48 (m, 4H), 2.95 (m, 2H), 3.31 (m,

2H), 3.76 (s, 3H, –OCH₃), 3.85 (s, 3H, –NCH₃), 3.89 (m, 1H),

3.95 (m, 2H), 4.10 (m, 1H), 4.16–4.39 (m, 8H, sugar proton),

5.21–5.59 (m, 4H, sugar proton), 6.60 (m, 2H, sugar proton),

6.84 (d, 1H, J = 1.7 Hz, Py–H), 6.96 (d, 1H, J = 1.7 Hz, Py–H),

7.12 (d, 1H, J = 1.7 Hz, Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H),

7.45 (d, 1H, J = 1.7 Hz, Py–H), 7.56 (d, 1H, J = 1.7 Hz, Py–H),

7.60 (s, 1H, Ar–H), 7.76 (s, 1H, Ar–H), 8.28 (t, J = 6.5 Hz, 1H),

9.95 (s, 1H, –NH–), 10.05 (s, 1H, –NH–), 10.08 (s, 1H, –NH–).

MS: m/z calculated for C₇₀H₉₂N₁₀O₂₇S₂1568.52, found 1569.60

(M ϩ 1).

General procedure B

Solution of the respective nitropolyamides 15–22 in MeOH or

DMF were hydrogenated over 10% Pd/C at 50 psi pressure for 2

h and the catalyst was removed by ﬁltration through a Celite

pad. The ﬁltrate was concentrated to dryness under reduced

pressure (at RT) to aﬀord the corresponding amine. Owing to

the sensitivity of the amine to oxidation, it was used for the

next reaction immediately. It was dissolved in dry DMF and a

mixture of the (2S)-N-[5-methoxy-4-[3-(carboxy) propyloxy]-2-

nitrobenzoyl] pyrrolidine-2-carboxaldehyde diethyl thioacetal

(1) (1.0 equivalent), hydroxybenzotriazole (1.0 equivalent), and

EDCI (2.5 equivalent), in dry DMF was added. This mixture

was stirred at RT for 12 h and after completion of the reaction

the solvent was removed under reduced pressure to aﬀord a

dark oil which was puriﬁed by ﬂash column chromatography on

Compound 26

This compound was prepared according to the method

described for the compound 23, employing the polyamide 18

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3338

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(1.27 g, 1.12 mmol) and the thio acid 1 (0.50 g, 1.02 mmol), in

77% yield (1.25 g) as a yellow solid. IR: (Nujol) ν_max3288, 2960,

2H), 4.12 (m, 1H), 4.16–4.35 (m, 4H, sugar proton), 5.21–5.60

(m, 2H, sugar proton), 6.61 (m, 1H, sugar proton), 6.94 (d,

1H, J = 1.7 Hz, Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.61

(s, 1H, Ar–H), 7.75 (s, 1H, Ar–H), 7.80 (s, 1H, Im–H), 8.20 (t,

J = 6.5 Hz, 1H), 9.98 (s, 1H, –NH–), 10.06 (s, 1H, –NH–). MS:

m/z calculated for C₅₀H₆₉N₉O₁₇S₂1131.43 found 1132.25

(M ϩ 1).

1

1730, 1640, 1578, 1523, 1405, 1156, 886, 810, 756 cm^Ϫ1. H

NMR (DMSO-d₆, 300 MHz): δ 1.25 (s, 6H, –(CH₃)₂), 1.56–1.61

(m, 4H), 1.65 (m, 2H), 1.95 (m, 2H), 2.01–2.12 (8 singlets, 24H,

COCH₃), 2.16 (m, 2H), 2.30 (s, 6H, –N(CH3)₂), 2.34 (m, 2H),

2.48 (m, 4H), 2.95 (m, 2H), 3.31 (m, 2H), 3.75 (s, 3H, –OCH₃),

3.87 (s, 3H, –NCH₃), 3.90 (m, 1H), 3.95 (m, 2H), 4.12 (m, 1H),

4.16–4.39 (m, 8H, sugar proton), 5.20–5.59 (m, 4H, sugar

proton), 6.62 (m, 2H, sugar proton), 6.96 (d, 1H, J = 1.7 Hz,

Py–H), 7.12 (d, 1H, J = 1.7 Hz, Py–H), 7.20 (d, 1H, J = 1.7 Hz,

Py–H), 7.56 (d, 1H, J = 1.7 Hz, Py–H), 7.60 (s, 1H, Ar–H), 7.76

(s, 1H, Ar–H), 7.82 (s, 1H, Im–H), 8.25 (t, J = 6.5 Hz, 1H), 9.97

(s, 1H, –NH–), 10.06 (s, 1H, –NH–), 10.08 (s, 1H, –NH–). MS:

m/z calculated for C₆₉H₉₁N₁₁O₂₇S₂1569.52, found 1570.68

(M ϩ 1).

Compound 30

Prepared according to the general procedure B using com-

pound 22 (1.38 g, 1.69 mmol) and the acid 1 (0.75 g, 1.54 mmol)

in 72% yield (1.40 g) as a yellow solid. IR: (Nujol) ν_max3290,

2980, 2650, 1720, 1640, 1578, 1415, 1156, 1110, 886, 810, 756

cm^Ϫ1. ¹H NMR (DMSO-d₆, 300 MHz): δ 1.24 (s, 6H, –(CH₃)₂),

1.56–1.61 (m, 4H), 1.66 (m, 2H), 1.95 (m, 2H), 2.01 (s, 3H,

–COCH₃), 2.03 (s, 3H, –COCH₃), 2.06 (s, 3H, –COCH₃), 2.08

(s, 3H, –COCH₃), 2.15 (m, 2H), 2.27 (s, 6H, –N(CH3)₂), 2.35

(m, 2H), 2.48 (m, 4H), 2.95 (m, 2H), 3.30 (m, 2H), 3.75 (s, 3H,

–OCH₃), 3.86 (s, 3H, –NCH₃), 3.88 (s, 3H, –NCH₃), 3.90 (m,

1H), 3.95 (m, 2H), 4.12 (m, 1H), 4.15–4.38 (m, 4H, sugar

proton), 5.20–5.55 (m, 2H, sugar proton), 6.60 (m, 1H, sugar

proton), 6.84 (d, 1H, J = 1.7 Hz, Py–H), 6.96 (d, 1H, J = 1.7 Hz,

Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.65 (s, 1H, Im–H), 7.70

(s, 1H, Ar–H), 7.75 (s, 1H, Ar–H), 7.84 (s, 1H, Im–H), 8.21 (t,

J = 6.5 Hz, 1H), 9.95 (s, 1H, –NH–), 9.99 (s, 1H, –NH–), 10.04

(s, 1H, –NH–). MS: m/z calculated for C₅₅H₇₄N₁₂O₁₈S₂1254.47,

found 1255.35 (M ϩ 1).

Compound 27

This compound was prepared according to the general pro-

cedure C, using compound 19 (1.17 g, 1.69 mmol) and the acid

1 (0.75 g, 1.54 mmol) in 77% yield (1.35 g), as a yellow solid. IR:

(Nujol) ν_max3288, 2960, 1640, 1578, 1410, 1205, 1156, 1098,

1

890, 810, 756 cm^Ϫ1. H NMR (DMSO-d₆, 300 MHz): δ 1.23

(s, 6H, –(CH₃)₂), 1.56–1.61 (m, 4H), 1.65 (m, 2H), 1.95 (m,

2H), 2.00 (s, 3H, –COCH₃), 2.04 (s, 3H, –COCH₃), 2.05 (s, 3H,

–COCH₃), 2.10 (s, 3H, –COCH₃), 2.17 (m, 2H), 2.25 (s, 6H,

–N(CH3)₂), 2.37 (m, 2H), 2.50 (m, 4H), 2.97 (m, 2H), 3.30 (m,

2H), 3.76 (s, 3H, –OCH₃), 3.85 (s, 3H, –NCH₃), 3.89 (m, 1H),

3.95 (m, 2H), 4.12 (m, 1H), 4.15–4.38 (m, 4H, sugar proton),

5.21–5.55 (m, 2H, sugar proton), 6.60 (m, 1H, sugar proton),

6.86 (d, 1H, J = 1.7 Hz, Py–H), 6.91 (d, 1H, J = 1.7 Hz, Py–H),

7.12 (d, 1H, J = 1.7 Hz, Py–H), 7.26 (d, 1H, J = 1.7 Hz, Py–H),

7.61 (s, 1H, Ar–H), 7.75 (s, 1H, Ar–H), 8.22 (t, J = 6.5 Hz, 1H),

9.95 (s, 1H, –NH–), 10.05 (s, 1H, –NH–). MS: m/z calculated

for C₅₁H₇₀N₈O₁₇S₂1130.40, found 1131.30 (M ϩ 1).

General procedure C

Nitrodithioacetal glycosylated polyamides 23–30 were dis-

solved in methanol (50.0 ml) respectively and hydrogenated

over 10% Pd–C at 50 psi pressure for 2 h and then the catalyst

was removed by ﬁltration through a Celite pad. The ﬁltrate was

concentrated to dryness under reduced pressure. The resultant

amino compounds were dissolved in CH₃CN/H₂O (4 : 1) and

HgCl₂(1.5 equivalent) and HgO (1.5 equivalent) were

added and the mixture was stirred slowly at RT for 12 h. When

TLC (CHCl₃/MeOH/ammonia) indicated the complete dis-

appearance of starting materials, the reaction mixtures were

charged directly on to a short silica column and ﬁrst eluted

with ethyl acetate to remove HgCl₂. After complete removal of

HgCl₂, the column was eluted with CHCl₃/MeOH system by

which all other impurities were removed. Then the column was

further eluted with CHCl₃/MeOH/ammonia and the ammonia

concentration were slowly increased from 1% through 2%. The

imine compounds were collected at diﬀerent percentage of

ammonia from 1–3%. The imine and corresponding methyl

ether move together as they have close Rf values. Evaporation

of the solvents under high vacuum, at RT, aﬀorded an insepar-

able mixture of imines and methyl ethers 31–38 in almost 1 : 1

ratio in 40–45% yield.

Compound 28

This compound was prepared according to the general pro-

cedure B, using compound 20 (1.37 g, 1.68 mmol) and the acid

1 (0.75 g, 1.54 mmol), in 77% yield (1.49 g) as a yellow solid. IR:

(Nujol) ν_max3288, 2960, 2650, 1710, 1640, 1578, 1523, 1405,

1210, 1156, 1090, 886, 810, 756 cm^Ϫ1. ¹H NMR (DMSO-d₆, 300

MHz): δ 1.24 (s, 6H, –(CH₃)₂), 1.56–1.61(m, 4H), 1.66 (m, 2H),

1.95 (m, 2H), 2.01 (s, 3H, –COCH₃), 2.03 (s, 3H, –COCH₃),

2.06 (s, 3H, –COCH₃), 2.08 (s, 3H, –COCH₃), 2.15 (m, 2H),

2.27 (s, 6H, –N(CH₃)₂), 2.35 (m, 2H), 2.48 (m, 4H), 2.95 (m,

2H), 3.30 (m, 2H), 3.75 (s, 3H, –OCH₃), 3.84 (s, 3H, –NCH₃),

3.86 (s, 3H, –NCH₃), 3.90 (m, 1H), 3.95 (m, 2H), 4.12 (m,

1H), 4.15–4.38 (m, 4H, sugar proton), 5.20–5.76 (m, 2H, sugar

proton), 6.61 (m, 1H, sugar proton), 6.84 (d, 1H, J = 1.7 Hz,

Py–H), 6.96 (d, 1H, J = 1.7 Hz, Py–H), 7.15 (d, 1H, J = 1.7 Hz,

Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (d, 1H, J = 1.7 Hz,

Py–H), 7.65 (d, 1H, J = 1.7 Hz, Py–H), 7.71 (s, 1H, Ar–H), 7.77

(s, 1H, Ar–H), 8.20 (t, J = 6.5 Hz, 1H), 9.95 (s, 1H, –NH–), 9.98

(s, 1H, –NH–), 10.05 (s, 1H, –NH–). MS: m/z calculated for

C₅₇H₇₆N₁₀O₁₈S₂1252.48, found 1253.35 (M ϩ 1).

Compound 31

This was prepared according to the general procedure C by

using compound 23 (1.1 g, 1.09 mmol) in 43% yield (0.40 g) as a

yellow solid after puriﬁcation. ¹H NMR (DMSO-d₆, 300 MHz):

δ 1.59–1.62 (m, 4H), 1.65 (m, 2H), 1.98 (m, 2H), 2.01–2.10

(4 singlets, 12H, 4× –COCH₃), 2.16 (m, 2H), 2.27 (s, 6H,

–N(CH₃)₂), 2.36 (m, 2H), 2.96 (m, 2H), 3.30 (m, 1H), 3.35 (m,

2H), 3.73 (s, 3H, –ArOCH₃), 3.89 (m, 3H, –OCH₃for its methyl

ether), 3.95 (m, 2H), 4.16–4.35 (m, 4H, sugar proton), 5.20–

5.62 (m, 2H, sugar proton), 6.50 (m, 1H, sugar proton), 6.80

(s, 1H, Ar–H), 6.92 (d, 1H, J = 1.7 Hz, Py–H), 7.10 (d, 1H, J =

1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H), 7.50 (d, 1H, J = 4.2 Hz,

imine proton), 8.21 (t, J = 6.5 Hz, 1H), 9.95 (s, 1H, –NH–). MS:

m/z calculated for C₄₁H₅₄N₆O₁₄854.37, found 855.30 (M ϩ 1)

for its imine compound and 887.10 (M ϩ 1) for its methyl ether

compound.

Compound 29

This compound was prepared starting from compound 21 (1.17

g, 1.68 mmol) and the acid 1 (0.75 g, 1.54 mmol) according to

the general procedure B (1.22 g, 70% yield) as a yellow solid.

IR: (Nujol) ν_max3289, 2980, 2640, 1640, 1578, 1415, 1156, 1098,

810, 756 cm^Ϫ1. ¹H NMR (DMSO-d₆, 300 MHz): δ 1.24 (s, 6H,

–(CH₃)₂), 1.56–1.61 (m, 4H), 1.65 (m, 2H), 1.95 (m, 2H), 2.02

(s, 3H, –COCH₃), 2.05 (s, 3H, –COCH₃), 2.08 (s, 3H, –COCH₃),

2.10 (s, 3H, –COCH₃), 2.16 (m, 2H), 2.27 (s, 6H, –N(CH3)₂),

2.36 (m, 2H), 2.48 (m, 4H), 2.95 (m, 2H), 3.30 (m, 2H), 3.75

(s, 3H, –OCH₃), 3.86 (s, 3H, –NCH₃), 3.89 (m, 1H), 3.94 (m,

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3339

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Compound 32

1H, sugar proton), 6.80 (s, 1H, Ar–H), 6.86 (d, 1H, J = 1.7 Hz,

Py–H), 6.92 (d, 1H, J = 1.7 Hz, Py–H), 7.22 (d, 1H, J = 1.7 Hz,

Py–H), 7.38 (s, 1H, Ar–H), 7.42 (d, 1H, J = 1.7 Hz, Py–H), 7.50

(d, 1H, J = 4.2 Hz, imine proton), 8.20 (t, J = 6.5 Hz, 1H), 9.97

(s, 1H, –NH–), 10.05 (s, 1H, –NH–). MS: m/z calculated for

C₄₇H₆₀N₈O₁₅976.40, found 977.01 (M ϩ 1) for its imine com-

pound and 1009.07 (M ϩ 1) for its methyl ether compound.

This compound was prepared starting from compound 24

(1.5 g, 1.03 mmol) according to the general procedure C (0.55 g,

41% yield) as a yellow solid. H NMR (DMSO-d₆, 300 MHz):

1

δ 1.56–1.62 (m, 4H), 1.65 (m, 2H), 1.95 (m, 2H), 1.98–2.12 (8

singlets, 24H, COCH₃), 2.15 (m, 2H), 2.28 (s, 6H, –N(CH₃)₂),

2.35 (m, 2H), 2.95 (m, 2H), 3.30 (m, 1H), 3.34 (m, 2H), 3.75 (s,

3H, –ArOCH₃), 3.89 (m, 3H, –OCH₃for its methyl ether), 3.95

(m, 2H), 4.15–4.45 (m, 8H, sugar proton), 5.21–5.65 (m, 4H,

sugar proton), 6.52 (m, 2H, sugar proton), 6.80 (s, 1H, Ar–H),

6.86 (d, 1H, J = 1.7 Hz, Py–H), 6.96 (d, 1H, J = 1.7 Hz, Py–H),

7.18 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H), 7.45 (d, 1H,

J = 1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz, imine proton), 8.22

(t, J = 6.5 Hz, 1H), 9.95 (s, 1H, –NH–), 10.05 (s, 1H, –NH–).

MS: m/z calculated for C₆₀H₇₆N₈O₂₄1292.48, found 1293.25

(M ϩ 1) for its imine compound and 1325.33 (M ϩ 1) for its

methyl ether compound.

Compound 36

This compound was prepared according to the method

described for the compound 34, employing compound 28 (1.2 g,

1

0.958 mmol) in 44% yield (0.47 g) as a yellow solid. H NMR

(DMSO-d₆, 300 MHz): δ 1.56–1.60 (m, 4H), 1.66 (m, 2H), 1.95

(m, 2H), 2.00–2.10 (4 singlets, 12H, 4× –COCH₃), 2.14 (m, 2H),

2.27 (s, 6H, –N(CH₃)₂), 2.34 (m, 2H), 2.95 (m, 2H), 3.30 (m,

1H), 3.34 (m, 2H), 3.75 (s, 3H, –ArOCH₃), 3.84 (s, 3H, –NCH₃),

3.86 (s, 3H, –NCH₃), 3.89 (m, 3H, –OCH₃for its methyl ether),

3.96 (m, 2H), 4.15–4.40 (m, 4H, sugar proton), 5.21–5.55 (m,

2H, sugar proton), 6.50 (m, 1H, sugar proton), 6.81 (s, 1H,

Ar–H), 6.84 (d, 1H, J = 1.7 Hz, Py–H), 6.95 (d, 1H, J = 1.7 Hz,

Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H), 7.45

(d, 1H, J = 1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz, imine

proton), 7.75 (d, 1H, J = 1.7 Hz, Py–H), 8.21 (t, J = 6.5 Hz, 1H),

9.94 (s, 1H, –NH–), 10.00 (s, 1H, –NH–), 10.05 (s, 1H, –NH–).

MS: m/z calculated for C₅₃H₆₆N₁₀O₁₆1098.45, found 1099.12

(M ϩ 1) for its imine compound and 1131.15 (M ϩ 1) for its

methyl ether compound.

Compound 33

This compound was prepared according to the general pro-

cedure C by using compound 25 (1.5 g, 0.956 mmol) in 42%

yield (0.57 g) as a yellow solid. ¹H NMR (DMSO-d₆, 300

MHz): δ 1.55–1.60 (m, 4H), 1.65 (m, 2H), 1.95 (m, 2H), 1.98–

2.12 (8 singlets, 24H, COCH₃), 2.15 (m, 2H), 2.28 (s, 6H,

–N(CH₃)₂), 2.35 (m, 2H), 2.96 (m, 2H), 3.30 (m, 1H), 3.34 (m,

2H), 3.75 (s, 3H, –ArOCH₃), 3.84 (s, 3H, –NCH₃), 3.89 (m,

3H, –OCH₃for its methyl ether), 3.95 (m, 2H), 4.15–4.45 (m,

8H, sugar proton), 5.21–5.65 (m, 4H, sugar proton), 6.52 (m,

2H, sugar proton), 6.80 (s, 1H, Ar–H), 6.84 (d, 1H, J = 1.7 Hz,

Py–H), 6.96 (d, 1H, J = 1.7 Hz, Py–H), 7.15 (d, 1H, J = 1.7 Hz,

Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H), 7.43

(d, 1H, J = 1.7 Hz, Py–H), 7.52 (d, 1H, J = 4.2 Hz, imine

proton), 7.72 (d, 1H, J = 1.7 Hz, Py–H), 8.20 (t, J = 6.5 Hz, 1H),

9.95 (s, 1H, –NH–), 10.00 (s, 1H, –NH–), 10.05 (s, 1H, –NH–).

MS: m/z calculated for C₆₆H₈₂N₁₀O₂₅1414.50, found 1415.41

(M ϩ 1) for its imine compound and 1447.42 (M ϩ 1) for its

methyl ether compound.

Compound 37

This compound was prepared starting from compound 29

(1.2 g, 1.06 mmol) according to the general procedure C (0.42 g,

1

40% yield) as a yellow solid. H NMR (DMSO-d₆, 300 MHz):

δ 1.58–1.62 (m, 4H), 1.66 (m, 2H), 1.95 (m, 2H), 2.03–2.12

(4 singlets, 12H, 4× –COCH₃), 2.15 (m, 2H), 2.27 (s, 6H,

–N(CH₃)₂), 2.36 (m, 2H), 2.96 (m, 2H), 3.30 (m, 1H), 3.35 (m,

2H), 3.73 (s, 3H, –ArOCH₃), 3.85 (s, 3H, –NCH₃), 3.89 (m, 3H,

–OCH₃for its methyl ether), 3.95 (m, 2H), 4.15–4.35 (m, 4H,

sugar proton), 5.20–5.62 (m, 2H, sugar proton), 6.50 (m, 1H,

sugar proton), 6.80 (s, 1H, Ar–H), 6.92 (d, 1H, J = 1.7 Hz,

Py–H), 7.22 (d, 1H, J = 1.7 Hz, Py–H), 7.38 (s, 1H, Ar–H), 7.50

(d, 1H, J = 4.2 Hz, imine proton), 7.80 (s, 1H, Im–H), 8.25 (t,

J = 6.5 Hz, 1H), 9.95 (s, 1H, –NH–), 10.04 (s, 1H, –NH–). MS:

m/z calculated for C₄₆H₅₉N₉O₁₅977.41, found 978.02 (M ϩ 1)

for its imine compound and 1010.04 (M ϩ 1) for its methyl

ether compound.

Compound 34

This compound was prepared according to the method

described for the compound 33, by employing compound 26

(1.5 g, 0.956 mmol) in 40% yield (0.54 g) as a yellow solid. H

1

NMR (DMSO-d₆, 300 MHz): δ 1.56–1.62 (m, 4H), 1.65 (m,

2H), 1.95 (m, 2H), 1.98–2.10 (8 singlets, 24H, –COCH₃), 2.12

(m, 2H), 2.27 (s, 6H, –N(CH₃)₂), 2.35 (m, 2H), 2.96 (m, 2H),

3.31 (m, 1H), 3.36 (m, 2H), 3.77 (s, 3H, –ArOCH₃), 3.85 (s, 3H,

–NCH₃), 3.90 (m, 3H, –OCH₃for its methyl ether), 3.96 (m,

2H), 4.15–4.49 (m, 8H, sugar proton), 5.21–5.60 (m, 4H, sugar

proton), 6.55 (m, 2H, sugar proton), 6.81 (s, 1H, Ar–H), 6.83

(d, 1H, J = 1.7 Hz, Py–H), 6.96 (d, 1H, J = 1.7 Hz, Py–H), 7.17

(d, 1H, J = 1.7 Hz, Py–H), 7.32 (s, 1H, Ar–H), 7.47 (d, 1H, J =

1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz, imine proton), 7.80

(s, 1H, Im–H), 8.21 (t, J = 6.5 Hz, 1H), 9.96 (s, 1H, –NH–),

10.01 (s, 1H, –NH–), 10.05 (s, 1H, –NH–). MS: m/z calculated

for C₆₅H₈₁N₁₁O₂₅1415.52, found 1416.40 (M ϩ 1) for its imine

compound and 1448.44 (M ϩ 1) for its methyl ether compound.

Compound 38

This compound was prepared according to the general pro-

cedure C by using compound 30 (1.2 g, 0.956 mmol) in 44%

yield (0.44 g) as a yellow solid. ¹H NMR (DMSO-d₆, 300

MHz): δ 1.56–1.65 (m, 4H), 1.70 (m, 2H), 1.95 (m, 2H), 2.00–

2.10 (4 singlets, 12H, 4× –COCH₃), 2.14 (m, 2H), 2.26 (s, 6H,

–N(CH₃)₂), 2.35 (m, 2H), 2.95 (m, 2H), 3.30 (m, 1H), 3.34 (m,

2H), 3.74 (s, 3H, –ArOCH₃), 3.84 (s, 3H, –NCH₃), 3.86 (s, 3H,

–NCH₃), 3.88 (m, 3H, –OCH₃for its methyl ether), 3.95 (m,

2H), 4.15–4.38 (m, 4H, sugar proton), 5.21–5.62 (m, 2H, sugar

proton), 6.51 (m, 1H, sugar proton), 6.82 (s, 1H, Ar–H), 6.92

(d, 1H, J = 1.7 Hz, Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.35

(s, 1H, Ar–H), 7.47 (s, 1H, Im–H), 7.52 (d, 1H, J = 4.2 Hz,

imine proton), 7.80 (s, 1H, Im–H), 8.25 (t, J = 6.5 Hz, 1H), 9.95

(s, 1H, –NH–), 10.00 (s, 1H, –NH–), 10.04 (s, 1H, –NH–). MS:

m/z calculated for C₅₁H₆₄N₁₂O₁₆1100.42, found 1101.13 (M ϩ

1) for its imine compound and 1133.15 (M ϩ 1) for its methyl

ether compound.

Compound 35

This compound was prepared according to the general pro-

cedure C, using compound 27 (1.2 g, 1.06 mmol) in 43% yield

(0.45 g) as a yellow solid. H NMR (DMSO-d₆, 300 MHz):

δ 1.59–1.62 (m, 4H), 1.65 (m, 2H), 1.98 (m, 2H), 2.01–2.10

(4 singlets, 12H, 4× –COCH₃), 2.16 (m, 2H), 2.27 (s, 6H,

–N(CH₃)₂), 2.36 (m, 2H), 2.96 (m, 2H), 3.30 (m, 1H), 3.35 (m,

2H), 3.73 (s, 3H, –ArOCH₃), 3.84 (s, 3H, –NCH₃), 3.89 (m, 3H,

–OCH₃for its methyl ether), 3.95 (m, 2H), 4.16–4.35 (m,

4H, sugar proton), 5.20–5.62 (m, 2H, sugar proton), 6.51 (m,

1

General procedure D

A mixture of the respective compounds 31–38 in methanol/

THF (1 : 1) and 0.1 N NaOH was placed in a ﬂask, then the

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3340

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reaction mixture was stirred at room temperature until the

starting materials completely disappeared as shown by TLC.

The crude reaction mixtures were passed through small ion

exchange resin (Amberlite-15) columns using MeOH/H₂O (80

: 20). The solvent was removed under reduced pressure and the

ﬁnal water soluble PBD-glycosylated polyamides 39–46 dried

by lyophilization in 50–60% yield.

3.85 (s, 3H, –NCH₃), 3.90 (m, 3H, –OCH₃for its methyl ether),

3.96 (m, 2H), 5.90 (m, 2H, sugar proton), 6.81 (s, 1H, Ar–H),

6.83 (d, 1H, J = 1.7 Hz, Py–H), 6.96 (d, 1H, J = 1.7 Hz, Py–H),

7.17 (d, 1H, J = 1.7 Hz, Py–H), 7.32 (s, 1H, Ar–H), 7.47 (d,

1H, J = 1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz, imine proton),

7.80 (s, 1H, Im–H). HR-MS: m/z calculated for C₄₉H₆₅N₁₁O₁₇

1079.45, found 1080.10 (M ϩ 1) for its imine compound and

1112.12 (M ϩ 1) for its methyl ether compound.

Compound 39

Compound 43

This compound was prepared according to the general pro-

cedure D employing compound 31 (0.35 g, 1.48 mmol) and

0.1 N NaOH in 53% yield (0.15 g) as a yellow solid. H NMR

This compound was prepared according to general procedure

1

D using compound 35 (0.4 g, 0.409 mmol) 0.1 N NaOH in 56%

1

(D₂O, 300 MHz): δ 1.59–1.60 (m, 4H), 1.65 (m, 2H), 1.98 (m,

2H), 2.18 (m, 2H), 2.26 (s, 6H, –N(CH₃)₂), 2.35 (m, 2H), 2.95

(m, 2H), 3.30 (m, 1H), 3.35 (m, 2H), 3.40–3.49 (m, 3H, sugar

proton), 3.65 (m, 2H, –CH₂OH), 3.73 (s, 3H, –ArOCH₃), 3.76

(m, 1H, sugar proton), 3.89 (m, 3H, –OCH₃for its methyl

ether), 3.95 (m, 2H), 5.89 (m, 1H, sugar proton), 6.81 (s, 1H,

Ar–H), 6.92 (d, 1H, J = 1.7 Hz, Py–H), 7.12 (d, 1H, J = 1.7 Hz,

Py–H), 7.32 (s, 1H, Ar–H), 7.50 (d, 1H, J = 4.2 Hz, imine pro-

ton). HR-MS: m/z calculated for C₃₃H₄₆N₆O₁₀686.30, found

687.20 (M ϩ 1) for its imine compound and 719.65 (M ϩ 1) for

its methyl ether compound.

yield (0.185 g) as a yellow solid. H NMR (D₂O, 300 MHz):

δ 1.59–1.62 (m, 4H), 1.65 (m, 2H), 1.98 (m, 2H), 2.15 (m, 2H),

2.27 (s, 6H, –N(CH₃)₂), 2.36 (m, 2H), 2.95 (m, 2H), 3.30 (m,

1H), 3.35 (m, 2H), 3.40–3.51 (m, 3H, sugar proton), 3.65 (m,

2H, –CH₂OH), 3.73 (s, 3H, –ArOCH₃), 3.76 (m, 1H, sugar

proton), 3.84 (s, 3H, –NCH₃), 3.89 (m, 3H, –OCH₃for its

methyl ether), 3.95 (m, 2H), 5.89 (m, 1H, sugar proton), 6.80

(s, 1H, Ar–H), 6.86 (d, 1H, J = 1.7 Hz, Py–H), 6.92 (d, 1H, J =

1.7 Hz, Py–H), 7.22 (d, 1H, J = 1.7 Hz, Py–H), 7.38 (s, 1H, Ar–

H), 7.42 (d, 1H, J = 1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz,

imine proton). HR-MS: m/z calculated for C₃₉H₅₂N₈O₁₁808.36,

found 809.30 (M ϩ 1) for its imine compound and 841.46

(M ϩ 1) for its methyl ether compound.

Compound 40

This compound was prepared starting from compound 32 (0.45

Compound 44

g, 0.348 mmol) and 0.1 N NaOH according to the general

1

procedure D (0.20 g, 60% yield) as a yellow solid. H NMR

This compound was prepared according to the method

described for the compound 42, employing compound 36

(0.41 g, 0.373 mmol) 0.1 N NaOH in 54% yield (0.19 g) as a

(D₂O, 300 MHz): δ 1.56–1.60 (m, 4H), 1.65 (m, 2H), 1.95 (m,

2H), 2.15 (m, 2H), 2.28 (s, 6H, –N(CH₃)₂), 2.35 (m, 2H), 2.95

(m, 2H), 3.30 (m, 1H), 3.34 (m, 2H), 3.40–3.50 (m, 6H, sugar

proton), 3.66 (m, 4H, 2× –CH₂OH), 3.74 (s, 3H, –ArOCH₃),

3.78 (m, 2H, sugar proton), 3.89 (m, 3H, –OCH₃for its methyl

ether), 3.95 (m, 2H), 5.90 (m, 2H, sugar proton), 6.82 (s, 1H,

Ar–H), 6.86 (d, 1H, J = 1.7 Hz, Py–H), 6.95 (d, 1H, J = 1.7 Hz,

Py–H), 7.15 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H), 7.42

(d, 1H, J = 1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz, imine

proton). HR-MS: m/z calculated for C₄₄H₆₀N₈O₁₆956.40, found

957.00 (M ϩ 1) for its imine compound and 989.03 (M ϩ 1)

for its methyl ether compound.

1

yellow solid. H NMR (D₂O, 300 MHz): δ 1.56–1.60 (m, 4H),

1.66 (m, 2H), 1.95 (m, 2H), 2.14 (m, 2H), 2.27 (s, 6H,

–N(CH₃)₂), 2.34 (m, 2H), 2.95 (m, 2H), 3.30 (m, 1H), 3.34 (m,

2H), 3.40–3.49 (m, 3H, sugar proton), 3.65 (m, 2H, –CH₂OH),

3.73 (s, 3H, –ArOCH₃), 3.75 (m, 1H, sugar proton), 3.84 (s, 3H,

–NCH₃), 3.87 (s, 3H, –NCH₃), 3.89 (m, 3H, –OCH₃for its

methyl ether), 3.96 (m, 2H), 5.90 (m, 1H, sugar proton), 6.81 (s,

1H, Ar–H), 6.84 (d, 1H, J = 1.7 Hz, Py–H), 6.95 (d, 1H, J = 1.7

Hz, Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H),

7.45 (d, 1H, J = 1.7 Hz, Py–H), 7.50 (d, 1H, J = 4.2 Hz, imine

proton), 7.75 (d, 1H, J = 1.7 Hz, Py–H). HR-MS: m/z cal-

culated for C₄₅H₅₈N₁₀O₁₂930.40, found 931.21 (M ϩ 1) for its

imine compound and 963.04 (M ϩ 1) for its methyl ether

compound.

Compound 41

This compound was prepared according to the general pro-

cedure D using compound 33 (0.45 g, 0.318 mmol) and 0.1 N

NaOH in 55% yield (0.19 g) as a yellow solid. ¹H NMR (D₂O,

300 MHz): δ 1.56–1.60 (m, 4H), 1.65 (m, 2H), 1.95 (m,

2H), 2.17 (m, 2H), 2.27 (s, 6H, –N(CH₃)₂), 2.36 (m, 2H), 2.95

(m, 2H), 3.30 (m, 1H), 3.35 (m, 2H), 3.41–3.51 (m, 6H, sugar

proton), 3.66 (m, 4H, 2× –CH₂OH), 3.74 (s, 3H, –ArOCH₃),

3.77 (m, 2H, sugar proton), 3.84 (s, 3H, –NCH₃), 3.89 (m, 3H,

–OCH₃for its methyl ether), 3.95 (m, 2H), 5.89 (m, 2H, sugar

proton), 6.81 (s, 1H, Ar–H), 6.83 (d, 1H, J = 1.7 Hz, Py–H),

6.96 (d, 1H, J = 1.7 Hz, Py–H), 7.16 (d, 1H, J = 1.7 Hz, Py–H),

7.21 (d, 1H, J = 1.7 Hz, Py–H), 7.36 (s, 1H, Ar–H), 7.45 (d, 1H,

J = 1.7 Hz, Py–H), 7.51 (d, 1H, J = 4.2 Hz, imine proton), 7.72

(d, 1H, J = 1.7 Hz, Py–H). HR-MS: m/z calculated for

C₅₀H₆₆N₁₀O₁₇1078.46, found 1079.10 (M ϩ 1) for its imine

compound and 1111.15 (M ϩ 1) for its methyl ether compound.

Compound 45

This compound was prepared starting from compound 37 (0.40

g, 0.409 mmol) 0.1 N NaOH according to the general procedure

D (0.17 g, 51% yield) as a yellow solid. H NMR (D₂O, 300

1

MHz): δ 1.58–1.62 (m, 4H), 1.66 (m, 2H), 1.95 (m, 2H), 2.15 (m,

2H), 2.27 (s, 6H, –N(CH₃)₂), 2.36 (m, 2H), 2.96 (m, 2H), 3.30

(m, 1H), 3.35 (m, 2H), 3.40–3.49 (m, 3H, sugar proton), 3.65

(m, 2H, –CH₂OH), 3.74 (s, 3H, –ArOCH₃), 3.77 (m, 1H, sugar

proton), 3.85 (s, 3H, –NCH₃), 3.89 (m, 3H, –OCH₃for its

methyl ether), 3.95 (m, 2H), 5.89 (m, 1H, sugar proton), 6.80 (s,

1H, Ar–H), 6.92 (d, 1H, J = 1.7 Hz, Py–H), 7.22 (d, 1H, J = 1.7

Hz, Py–H), 7.38 (s, 1H, Ar–H), 7.50 (d, 1H, J = 4.2 Hz, imine

proton), 7.80 (s, 1H, Im–H). HR-MS: m/z calculated for

C₃₈H₅₁N₉O₁₁809.37, found 810.57 (M ϩ 1) for its imine com-

pound and 842.40 (M ϩ 1) for its methyl ether compound.

Compound 42

This compound was prepared according to the method

described for the compound 40 employing compound 34

(0.48 g, 0.339 mmol) and 0.1 N NaOH in 57% yield (0.21 g) as

Compound 46

This compound was prepared according to the general pro-

cedure D using compound 38 (0.4 g, 0.363 mmol) 0.1 N NaOH

in 53% yield (0.18 g) as a yellow solid. H NMR (D₂O, 300

MHz): δ 1.56–1.65 (m, 4H), 1.70 (m, 2H), 1.95 (m, 2H), 2.15 (m,

2H), 2.26 (s, 6H, –N(CH₃)₂), 2.35 (m, 2H), 2.95 (m, 2H), 3.30

(m, 1H), 3.34 (m, 2H), 3.41–3.50 (m, 3H, sugar proton), 3.65

1

a yellow solid. H NMR (D₂O, 300 MHz): δ 1.56–1.62 (m,

1

4H), 1.65 (m, 2H), 1.95 (m, 2H), 2.12 (m, 2H), 2.27 (s, 6H,

–N(CH₃)₂), 2.35 (m, 2H), 2.96 (m, 2H), 3.31 (m, 1H), 3.36 (m,

2H), 3.41–3.51 (m, 6H, sugar proton), 3.66 (m, 4H, 2×

–CH₂OH), 3.74 (s, 3H, –ArOCH₃), 3.78 (m, 2H, sugar proton),

O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3341

View Article Online

11 P. N. Confalone, E. M. Huie, S. S. Ko and G. M. Cole, J. Org. Chem.,

1988, 53, 482.

(m, 2H, –CH₂OH), 3.73 (s, 3H, –ArOCH₃), 3.77 (m, 1H, sugar

proton), 3.84 (s, 3H, –NCH₃), 3.86 (s, 3H, –NCH₃), 3.88 (m,

3H, –OCH₃for its methyl ether), 3.95 (m, 2H), 5.89 (m, 1H,

sugar proton), 6.82 (s, 1H, Ar–H), 6.92 (d, 1H, J = 1.7 Hz,

Py–H), 7.20 (d, 1H, J = 1.7 Hz, Py–H), 7.35 (s, 1H, Ar–H), 7.47

(s, 1H, Im–H), 7.52 (d, 1H, J = 4.2 Hz, imine proton), 7.80

(s, 1H, Im–H). HR-MS: m/z calculated for C₄₃H₅₆N₁₂O₁₂

932.41, found 933.15 (M ϩ 1) for its imine compound and

965.02 (M ϩ 1) for its methyl ether compound.

12 (a) D. S. Bose, A. S. Thompson, J. A. Ching, M. D. Berardini,

T. C. Jenkins, S. Neidle, L. H. Hurley and D. E. Thurston, J. Am.

Chem. Soc., 1992, 114, 4939; (b) D. E. Thurston, D. S. Bose,

A. S. Thompson, P. W. Howard, A. Leoni, S. J. Croker, T. C. Jenkins,

S. Neidle, J. A. Hartley and L. H. Hurley, J. Org. Chem., 1996,

61, 8141.

13 P. G. Baraldi, G. Balboni, B. Cacciari, A. Guiotto, S. Manfridini,

R. Romagnoli, G. Spalluto, D. E. Thurston, P. W. Howard,

N. Bianchi, C. Rutigliano, C. Mischiati and R. Gambari, J. Med.

Chem., 1999, 42, 5131.

14 Y. Damayanthi, B. S. P. Reddy and J. W. Lown, J. Org. Chem., 1999,

64, 290.

15 B. S. P. Reddy, Y. Damayanthi, B. S. N. Reddy and J. W. Lown, Anti-

Cancer Drug Des., 2000, 15, 225.

16 B. S. P. Reddy, Y. Damayanthi and J. W. Lown, Synth. Lett., 1999,

1112.

17 R. Kumar, B. S. N. Reddy and J. W. Lown, Heterocycl. Commun.,

2002, 8, 19–26.

Acknowledgements

We thank the National Cancer Institute, Maryland for the

anticancer assay in human cell lines. This research was sup-

ported by a grant (to J.W.L.) from the Natural Sciences and

Engineering Research Council of Canada.

18 R. Kumar and J. W. Lown, Heterocycl. Commun., 2002, 8, 115–122.

19 R. Kumar and J. W. Lown, Oncol. Res., 2002, 13(4), 221–233.

20 A. Kamal, G. Ramesh, N. Laxman, P. Ramulu, O. Srinivas,

K. Neelima, A. K. Kondapi, V. B. Sreenu and H. A. Nagarajaram,

J. Med. Chem., 2002, 45(21), 4679.

21 S. J. Gregson, P. W. Howard, K. E. Corcoran, T. C. Jenkins,

L. R. Kelland and D. E. Thurston, Bioorg. Med. Chem. Lett., 2001,

11, 2859.

22 N. Langlois, A. R. Rousseau, C. Gaspard, G. H. Werner, F. Darro

and R. Kiss, J. Med. Chem., 2001, 44, 3754.

23 A. Kamal, N. Laxman, G. Ramesh, O. Srinivas and P. Ramulu,

Bioorg. Med. Chem. Lett., 2002, 12, 1917.

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O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 3 2 7 – 3 3 4 2

3342

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Design, synthesis and in vitro cytotoxicity studies of novel pyrrolo [2,1][1,4] benzodiazepine-glycosylated pyrrole and imidazole polyamide conjugates

DOI: 10.1039/b306685a

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