5-Amino-1-(chloromethyl)-1,2-dihydro-3H-benz[e]indoles: Relationships between structure and cytotoxicity for analogues bearing different DNA minor groove binding subunits

Article abstract of DOI:10.1021/jm990136b

A series of 5-amino-seco-CBI compounds, designed for use as effectors for prodrugs, were prepared to study structure-activity relationships for the cytotoxicity of side chain analogues. Compounds were prepared by coupling 1- (chloromethyl)-5-nitro-1,2-dih

Full text of DOI:10.1021/jm990136b

3400
J . Med. Chem. 1999, 42, 3400-3411
5-Am in o-1-(ch lor om eth yl)-1,2-d ih yd r o-3H-ben z[e]in d oles: Rela tion sh ip s betw een
Str u ctu r e a n d Cytotoxicity for An a logu es Bea r in g Differ en t DNA Min or Gr oove
Bin d in g Su bu n its
Graham J . Atwell, J ared J . B. Milbank, William R. Wilson, Alison Hogg, and William A. Denny*
Auckland Cancer Society Research Centre, Faculty of Medicine and Health Science, The University of Auckland,
Private Bag 92019, Auckland, New Zealand
Received March 22, 1999
A series of 5-amino-seco-CBI compounds, designed for use as effectors for prodrugs, were
prepared to study structure-activity relationships for the cytotoxicity of side chain analogues.
Compounds were prepared by coupling 1-(chloromethyl)-5-nitro-1,2-dihydro-3H-benz[e]indole
to appropriate carboxylic acids, followed by nitro group reduction, or by coupling suitable
5-amino-protected indolines to R,â-unsaturated acids, followed by deblocking. These AT-specific
DNA alkylating agents were evaluated for cytotoxicity in a series of tumor cell lines (AA8,
UV4, EMT6, SKOV3). For those analogues bearing an indolecarbonyl side chain, the 5′-methoxy
derivative was the most cytotoxic (IC50 1.3 nM in AA8 cells, 4 h exposure), comparable to that
of the parent CBI-TMI (5′,6′,7′-trimethoxyindole) derivative (IC50 0.46 nM in the above assay).
A subset of solubilized derivatives bearing O(CH2)2NMe2 substituents were about 10-fold less
potent. For compounds containing an acryloyl linker in the side chain, the 4′-methoxycinnamoyl
derivative proved the most cytotoxic (IC50 0.09 nM in the above assay). A number of these
5-amino-seco-CBI-TMI analogues (including the solubilized compounds) are of interest both
as cytotoxins and as components of amine-based prodrugs designed for tumor-specific activation.
The cyclopropanoindolinone class of DNA alkylating
agents are of current interest as cytotoxic anticancer
drugs.1-4 Both the natural products such as duocarmy-
cin SA (1)2 and the simpler synthetic analogues such
as CI-TMI (2)5 and CBI-TMI (3)5 are extremely cytotoxic
against a variety of cell lines, with some of the latter
class having IC50s in the low picomolar range. They
possess a novel mechanism of action that involves highly
sequence-specific alkylation at adenine N-3 sites in AT-
rich regions.5-7 The open-chain phenol seco forms of
these agents [e.g., seco-CI-TMI (4) and seco-CBI-TMI (5)]
have similar potencies8,9 to the parent cyclopropanoin-
dolinones, and undergo rapid ring closure to them. A
number of these compounds have been evaluated clini-
cally, including the CPI analogue adozelesin (6)10 and
the carbamate-type prodrugs carzelesin (7)11 and KW-
2189 (8).12 Both 7 and 8 are prodrugs of the correspond-
ing phenolic seco compounds and undergo rapid and
nonspecific hydrolysis to the phenols by plasma es-
terases (Chart 1).11,12
seco-CBI-TMI [(+)-10a ] showed high cytotoxic potency,
being very similar to that of the corresponding phenol
5 (IC50s both 0.21 nM in the above assay).19 Previous
work5 with analogues of the structurally related anti-
biotic (+)-CC-1065 showed that modification of the side
chain attached to the alkylating subunit can influence
sequence selectivity of DNA binding and toxicity, as well
as improving antitumor effectiveness. It has been sug-
gested5 that that the delayed fatal toxicity in mice
observed with (+)-CC-1065 is due in part to the strong
noncovalent binding provided by the side chain, which
renders DNA alkylation irreversible, and may be over-
come by side chains that allow stable but reversible
adduct formation.
We now report the synthesis of a series of amino-seco-
CBI analogues (10a-10r ), designed to explore structure-
activity relationships for cytotoxicity with varying DNA
binding side chains.
Ch em istr y
Such extremely potent compounds are also of interest
as potential effector components in tumor-specific pro-
drugs, for applications such as ADEPT and GDEPT.13
However, as shown above11,12 and elsewhere, ester and
other14 types of prodrugs of phenols are prone to rapid,
nonspecific hydrolysis. We have thus been interested in
amino analogues of the phenolic seco forms of cyclopro-
panoindolinones and have recently reported syntheses
of both 6-amino-seco-CI-TMI (9)15,16 and analogues,16,17
and 5-amino-seco-CBI-TMI (10a ).18,19 While the racemic
amino-seco-CI-TMI (9) was considerably less potent than
the corresponding racemate of phenol 4 (IC50s 320 and
6 nM respectively, AA8 cells, 4 h exposure),15 the amino-
We have previously reported the syntheses of the
racemate18 and enantiomers19 of 10a . The 5-amino-3-
(chloromethyl)benzindolines (10c-10k and 10n ) of Table
1 were prepared similarly, from the key NBOC inter-
mediate 11 (Scheme 1). NBOC deprotection of 11 in
HCl-saturated dioxane gave the unstable amine 12,
which was coupled with the required carboxylic acid side
chains using 1-(3-dimethylaminopropyl)-3-ethylcarbo-
diimide hydrochloride (EDCI‚HCl), to give the nitro
compounds 13. Examples 13c-13j were then reduced
with PtO2‚xH2O/H2 to give amines 10c-10j. The me-
sylate analogue 10b was prepared from the known19
intermediate 14 via the nitro compound 13b (Scheme
10.1021/jm990136b CCC: $18.00 © 1999 American Chemical Society
Published on Web 08/11/1999

5-Amino-1-(Chloromethyl)-1,2-dihydro-3H-benz[e]indoles
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17 3401
Ch a r t 1
Sch em e 1a
NFMOC compound 16. Selective NBOC deprotection
gave the unstable amine 17, which was then coupled
with the required acids to give intermediates 18-20.
These were deblocked in anhydrous base (piperidine/
DMF) to give the target compounds 10l, 10m , and 10r .
In a variant of this (Scheme 4), amine 15 was protected
as the NALLOC derivative 23, and then NBOC was
deprotected to give amine 24. EDCI-induced coupling
of this with the zwitterionic acid 22 gave 25, and
subsequent palladium-based removal of the ALLOC
group with Pd(PPh3)4 gave the desired 10q. Alterna-
tively (Scheme 5), 12 was protected as the NCOCF3
derivative 26. This was reduced (PtO2/H2/benzene) to
27, and then the 5-amino group was BOC-protected to
give 28. Hydrolysis of the NCOCF3 function with Cs2-
CO3, followed by immediate coupling of the resulting
unstable amine with cinnamic acids gave the intermedi-
ates 29 and 30, which were NBOC-deprotected to give
10o and 10p .
a
Reagents and conditions: (i) HCl-satd. dioxane/20 °C/2 h; (ii)
X-CO2H/EDCI‚HCl/DMA/20 °C/4 h; (iii) PtO2/H2/THF, or Raney
nickel/H2/EtOAc or Fe/H+.
Sch em e 2a
The acids for 10b, 10c, 10e-10i, 10k , and 10m -10p
were commercially available or were prepared by re-
ported methods (see Experimental Section). The acid 22
required for 10q was prepared, as outlined in Scheme
4, by etherification of methyl (E)-4-hydroxycinnamate
to give 21, followed by ester group hydrolysis. The indole
acid 46 for 10d was prepared from the known20 amine
44 via intermediate 45 (Scheme 6). The dipyrazole acid
34 for 10j was prepared as shown in Scheme 7. NCBZ
deprotection of the known21 ester 31 gave amine 32,
which was acetylated to provide 33, then subjected to
ester hydrolysis. The pyrazoleacrylic acid 40 for 10l was
synthesized from the known22 aminopyrazole 35 (Scheme
8). N-Acetylation gave 36, which was hydrolyzed to acid
37. Imidazolide formation followed by NaBH4 reduction
gave alcohol 38, which was oxidized (MnO2) to aldehyde
39. Condensation of this with malonic acid then gave
a
Reagents and conditions: (i) HCl/dioxane/20 °C/2 h, then 5,6,7-
triOMeindole-2-carboxylic acid/EDCI‚HCl/DMA/20 °C/2.5 h; (ii)
PtO2/H2/THF.
2). In general it was found that catalytic reduction of
nitro compounds 13 containing an acryloyl linker gave
extremely low yields of the required amines 10, due to
concomitant saturation of the double bond.
The pyrroleacryloyl analogue 10k was prepared by
Raney nickel reduction of the nitro compound 13k , but
in only 10% yield, while Fe/H+ reduction of 13n gave
the cinnamoyl analogue 10n in 54% yield (Scheme 1).
Some of the required amines 10 were therefore prepared
by other routes. In one alternative method (Scheme 3),
the 5-nitro-NBOC derivative 11 was catalytically re-
duced to give amine 15, and this was converted to the

3402 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17
Ta ble 1. Cytotoxicity of 5-Amino-seco-CBI Analogues
Atwell et al.
a
IC50 (nM)
no.
form.
R
ref/mp (°C)
AA8
UV4
EMT6
SKOV3
(()-10a
(-)-10a
(+)-10a
10b
10c
10d
10e
10f
10g
10h
10i
10j
10k
10l
10m
10n
10o
10p
10q
A
A
A
B
A
A
A
A
A
A
C
D
E
5′,6′,7′-triOMe
5′,6′,7′-triOMe
5′,6′,7′-triOMe
ref 19
ref 19
ref 19
0.46 ( 0.05
14 ( 3
0.29 ( 0.02
2.7 ( 0.2
0.27 ( 0.03
7.0 ( 0.6
1.04 ( 0.11
7.9 ( 1.6
0.54 ( 0.04
1.20 ( 0.12
3.0 ( 0.3
17.3 ( 0.2
1.86 ( 0.21
7.0 ( 0.9
5.3 ( 0.4
4.2 ( 1.2
3.5 ( 0.7
49 ( 9
0.21 ( 0.03
0.48 ( 0.18
2.5 ( 1.2
12.5 ( 0.2
1.3 ( 0.1
4.1 ( 0.8
3.6 ( 0.9
3.7 ( 1.4
2.0 ( 0.3
374 ( 20
31 ( 8
0.14 ( 0.01
0.46 ( 0.20
1.1 ( 0.6
0.13 ( 0.01
0.40 ( 0.16
0.83 ( 0.27
5.2 ( 2.3
>260
5′-NH2
5′-NHCOMe
5′-OMe
5′-O(CH2)2NMe2
5′-OMe, 6′-O(CH2)2NMe2
5′-OMe, 7′-O(CH2)2NMe2
>300
>300
7.6 ( 0.7
250-255
>250
0.84 ( 0.01
1.7 ( 0.3
0.98 ( 0.06
1.3 ( 0.2
130-133
109-111
>300
2.1 ( 0.2
2.0 ( 0.2
1.9 ( 0.4
1.9 ( 1.0
1.5 ( 0.1
1.3 ( 0.1
>250
253 ( 65
212 ( 120
5.9 ( 1.7
245-250
>300
16 ( 5
22
F
10.7 ( 1.5
2.7 ( 1.6
0.37 ( 0.01
2.6 ( 0.5
0.090 ( 0.008
1.5 ( 0.3
0.28 ( 0.03
5.4 ( 0.5
4.9 ( 1.4
13.0 ( 2.4
1.5 ( 0.4
0.68 ( 0.05
2.7 ( 0.3
0.24 ( 0.03
1.9
G
G
G
G
G
H
3′-NHCOMe
3′-OMe
4′-NHCOMe
4′-OMe
>250
1.5 ( 0.4
0.86 ( 0.31
0.63 ( 0.07
1.2 ( 0.3
>200
0.42 ( 0.13
1.4 ( 0.2
>250
114-116
147-150
>250
0.058 ( 0.002
0.56 ( 0.13
0.22 ( 0.02
0.089 ( 0.007
0.63 ( 0.07
0.23 ( 0.01
4′-O(CH2)2NMe2
10r
0.48 ( 0.01
a
IC50; concentration of drug to reduce cell numbers to 50% of controls, 4-5 days after a 4 h drug exposure. Average of 2-5 determinations
( SEM.
40. Finally, the indoleacrylic acid 43 for 10r was
UV4 ratio 6.8 ( 0.6), suggesting that the CBI adducts
are less efficiently repaired than CI adducts by ERCC1-
dependent nucleotide excision repair, which might
contribute to the higher cytotoxic potency of the CBI
compounds.
prepared (Scheme 9) by Wittig olefination of the known23
indole aldehyde 41 to give the acrylate ester 42, followed
by hydrolysis of this with Cs2CO3.
Resu lts a n d Discu ssion
The amino-seco-CBI compounds are much more po-
tent (up to 1000-fold) than the corresponding amino-
seco-CI analogues.17 It was shown previously19 that the
(+)- and (-)-enantiomers of 10a had widely differing
potencies (IC50s of 0.21 and 14 nM, respectively, in AA8),
similar to those (IC50s of 0.21 and 67.1) for the (+)- and
(-)-enantiomers of the corresponding phenolic seco
compounds (5 and its enantiomer).26 For both 10a and
5, the cytotoxicity of the racemate was approximately
half that of the more potent enantiomer, indicating that
the less toxic enantiomer does not significantly interfere
with cytotoxicity. Initial structure-activity relation-
ships for side chain variations were therefore explored
with the more readily available racemates.
The amino-seco-CBI compounds were evaluated for
growth inhibitory potency (measured as IC50 values for
a 4 h drug exposure) in a series of tumor cell lines (Table
1). These included two Chinese hamster ovary lines: the
wild-type AA8 and the repair-defective ERCC-1 mutant
UV4, which is hypersensitive to agents that form bulky
DNA adducts24 and particularly so to DNA cross-
linkers.25 A murine mammary carcinoma line EMT6,
and a human ovarian line SKOV3 were also used.
Overall, as seen previously17 with 6-amino-seco-CI
derivatives, there were no large differences in the
sensitivity of the wild-type cell lines AA8, EMT6, and
SKOV3, but most of the compounds were slightly (mean
2.0-fold) more cytotoxic in the UV4 line than in AA8, in
line with a mode of action involving DNA monoalkyla-
tion.25 These differentials for UV4 relative to AA8 are
lower than for the 6-amino-seco-CI compound 9 (AA8/
The first set of DNA binding side chains studied
(compounds 10a -10i) possessed substituted indolecar-
bonyl side chains and were variants of the 5′,6′,7′-
trimethoxyindole (TMI) subunit present in the natural

5-Amino-1-(Chloromethyl)-1,2-dihydro-3H-benz[e]indoles
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17 3403
Sch em e 3a
a
Reagents and conditions: (i) PtO2/H2/THF; (ii) 9-fluorenylmethyl chloroformate/CH2Cl2/N-Meimidazole/20 °C/4.5 h; (iii) HCl/dioxane/5
°C/4 h; (iv-vi) 40, (E)-3-(acetylamino)cinnamic acid or 43/EDCI‚HCl/DMA/20 °C/4 h; (vii) piperidine/DMF/20 °C/20 min.
Sch em e 4a
a
Reagents and conditions: (i) NaH/DMF/PhMe; (ii) NaOH/aq MeOH/reflux; (iii) allyl chloroformate/pyridine/-5 to 20 °C/2 h; (iv) HCl/
dioxane/5 °C/3 h; (v) 22/EDCI‚HCl/DMA; (vi) Pd(PPh3)4/PPh3/morpholine.
Sch em e 5a
Sch em e 6a
a
Reagents and conditions: (i) Ac2O/pyridine/20 °C; (ii) Cs2CO3/
EtOH/H2O/reflux.
Sch em e 7a
a
Reagents and conditions: (i) (CF3CO)2O/pyridine/0-20 °C; (ii)
PtO2/H2/benzene; (iii) (BOC)2O/dioxane/65 °C/12 h; (iv) Cs2CO3/
N-Mepyrrolidinone/water/20 °C/45 min, then (E)-4-(acetylamino)-
cinnamic acid/EDCI‚HCl/DMA/DMA‚HCl, or (E)-4-methoxycin-
namoyl chloride/pyridine/DMAP; (v) HCl/dioxane/20 °C/10 min.
products. Previous work in both the duocarmycin27 and
amino-seco-CI17 series showed that a single 5′-OMe
group on the indole side chain was sufficient to retain
potency. This was also seen in the present CBI series,
with the 5′-OMe analogue 10e showing IC50s in the cell
line panel only about 3-fold higher than the parent
compound (()-10a . The 5′-NH2 analogue 10c was also
slightly less potent than (-10a , while the 5′-NHCOMe
analogue 10d was significantly less effective. Deriva-
a
Reagents and conditions: (i) Pd-C/H2/MeOH; (ii) MeCOCl/
THF/reflux/30 min; (iii) Cs2CO3/water/reflux/2 h.
tives 10f-10h , bearing cationic side chains at the 5′-,
6′-, and 7′-positions, respectively, were about 5-10-fold
less cytotoxic than (()-10a in the cell panel. The
analogue 10i, bearing the adozelesin side chain, was

3404 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17
Atwell et al.
Sch em e 8a
Toxicity of the above compounds is currently being
investigated in C3H mice. Intraperitoneal doses of (()-
10a at above 5 µmol/kg resulted in death within 2-3
weeks, but at lower doses a delayed toxicity was
observed. Affected animals showed distended abdomens,
with extensive peritoneal masses at necropsy. Histologi-
cally, the peritoneal lesions showed inflammation and
fibrosis surrounding normal bowel, with signs of fatty
necrosis, presumably as a result of local toxicity at the
site of injection. At 3.16 µmol/kg, 3/10 mice died between
day 21 and day 30, and 6/7 of the remaining mice
showed large peritoneal masses by day 60. At 2.37 µmol/
kg, all mice survived to day 60, at which time 3/6 showed
peritoneal masses. The less cytotoxic enantiomer (-)-
10a showed similar toxicity: at 2.37 µmol/kg 2/6 mice
died before day 60, and two of the four survivors showed
peritoneal lesions. However, while the more cytotoxic
enantiomer (+)-10a also gave 2/6 deaths before day 60
at this dose, all the surviving animals were normal at
necropsy. These preliminary data indicate that (+)-10a ,
despite its greater cytotoxicity potency in culture, is not
the more toxic enantiomer in mice and suggest the
possibility of dissociating cytotoxicity against tumor cells
from chronic host toxicity within this series.
a
Reagents and conditions: (i) MeCOCl/THF/reflux; (ii) Cs2CO3/
water/reflux; (iii) CDl/THF, then NaBH4/water; (iv) MnO2/EtOAc/
reflux; (v) malonic acid/pyridine/piperidine/100 °C.
Sch em e 9a
a
Reagents and conditions: (i) Ph3PdCHCO2Me/PhH/reflux; (ii)
Cs2CO3/aq MeOH/reflux.
considerably less potent than (()-10a . This is somewhat
surprising, since studies with various cyclopropylindo-
line alkylating subunits, including CBI,5 show this
larger DNA-binding subunit usually moderately in-
creases potency.
Con clu sion s
The dipyrazole derivative 10j possesses a relatively
hydrophilic side chain that was used originally21 in the
design of a more stable analogue of the dipyrrolic AT-
selective minor groove binder netropsin. The side chain
of 10j was designed to avoid an NMe group adjacent to
the linking carbonyl function, as this was expected from
the results of a previous study20 to lower DNA binding.
However, 10j unexpectedly proved much less cytotoxic
(by about 800-fold) than (()-10a and was the least
potent analogue of the series.
The second set of compounds studied (10k -10r )
possessed an acryloyl linker in their DNA binding side
chain. The pyrroleacryloyl and pyrazoleacryloyl ana-
logues 10k and 101 were considerably less potent than
the parent (()-10a (IC50s in AA8 cells of 31, 9, and 0.46
nM, respectively). The reduced potency of 10k is in
contrast to a previous finding,28 in which the pyrrole-
acrylolyl side chain was claimed to confer extraordinary
potency on CPI analogues.
Previous work29 on duocarmycin derivatives bearing
cinnamoyl side chains showed that such agents were
also potent cytotoxins. In particular, among the 4′-
alkoxy derivatives, a 4′-OMe was the most cytotoxic,
with larger alkoxy groups causing a decrease in potency.
In the present study, cinnamoyl analogues also proved
to be effective cytotoxins. While the 3′- and 4′-NHCOMe
analogues 10m and 10o were somewhat less potent
than the parent TMI compound (()-10a , the 3′-OMe
compound 10n had comparable activity, and the 4′-OMe
analogue 10p was the most potent of the compounds
studied (IC50 0.09 nM in AA8). The corresponding 4′-
O(CH2)2NMe2 analogue 10q proved the most potent of
the cationic solubilized compounds although again
showed a lower cytotoxicity than the corresponding OMe
derivative. Finally, the 5′-methoxyindoleacryloyl deriva-
tive 10r provided a direct comparison with the 5′-
methoxyindolecarbonyl compound 10e and proved sig-
nificantly more cytotoxic (IC50s in AA8 cells of 0.3 and
1.3 nM, respectively).
These results show that the 5-amino-seco-CBI alkyl-
ating subunit remains a very potent cytotoxin (equiva-
lent to the corresponding phenol moiety) when substi-
tuted with a range of DNA binding side chains of
varying size and lipophilicity. TMI and 5′-methoxyindole
were the best of the carbonyl-linked side chains, provid-
ing the parent TMI compound (()-10a and 10e, respec-
tively, with the solubilized derivatives (10f-10h ) being
about 10-fold less potent. The best acryloyl-containing
analogues were those with cinnamoyl side chains. The
4′-OMe derivative 10p was the most cytotoxic of all the
compounds studied (about 5-fold more potent than (()-
10a ). A number of these latter agents, including the
solubilized analogues, are being explored as potent
effectors for prodrugs.12
Exp er im en ta l Section
Analyses were carried out in the Microchemical Laboratory,
University of Otago, Dunedin, NZ. Melting points were
determined on an Electrothermal 2300 melting point ap-
paratus. NMR spectra were obtained on a Bruker DRX-400
spectrometer and are referenced to Me4Si. Thin-layer chro-
matography was carried out on aluminum-backed silica gel
(Merck 60 F254) or alumina plates. Flash column chromatog-
raphy was carried out on Merck silica gel (230-400 mesh) or
alumina. Petroleum ether refers to the fraction boiling at 40-
60 °C. Mass spectra were determined using a VG 7070
spectrometer at nominal 5000 resolution. Compounds for
biological testing were judged to be >96% pure by reverse-
phase HPLC analysis with diode array detection.
5-Am in o-1-[(m eth a n esu lfon yloxy)m eth yl]-3-[(5,6,7-tr i-
m e t h oxyin d ol-2-yl)ca r b on yl]-1,2-d ih yd r o-3H -b e n z[e]-
in d ole (10b).
A solution of 3-(tert-butyloxycarbonyl)-1-
[(methanesulfonyloxy)methyl]-5-nitro-1,2-dihydro-3H-benz[e]-
indole19 (14) (265 mg, 0.63 mmol) was stirred in HCl-saturated
dioxane (12 mL) at 20 °C for 2 h and then evaporated to
dryness under reduced pressure below 30 °C. 5,6,7-Tri-
methoxyindole-2-carboxylic acid (165 mg, 0.66 mmol), EDCI‚
HCl (301 mg, 1.57 mmol), and DMA (2.5 mL) were then added,
and the mixture was stirred at 20 °C for 2.5 h. Addition of
dilute KHCO3 precipitated a solid which was collected, washed

5-Amino-1-(Chloromethyl)-1,2-dihydro-3H-benz[e]indoles
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17 3405
well with water, and chromatographed on silica gel. Elution
with CH2Cl2/EtOAc (4:1) and crystallization of the product
from EtOAc/petroleum ether gave 1-[(methanesulfonyloxy)-
methyl]-5-nitro-3-[(5,6,7-trimethoxyindol-2-yl)carbonyl]-1,2-di-
hydro-3H-benz[e]indole (13b) (264 mg, 76%): mp 213.5-214.5
°C; 1H NMR [(CD3)2SO] δ 11.61 (d, J ) 1.6 Hz, 1 H, NH), 9.11
(s, 1 H, H-4), 8.36 (d, J ) 8.7 Hz, 1 H, H-6), 8.21 (d, J ) 7.6
Hz, 1 H, H-9), 7.82-7.71 (m, 2 H, H-7,8), 7.17 (d, J ) 2.0 Hz,
1 H, H-3′), 6.98 (s, 1 H, H-4′), 4.88 (t, J ) 9.8 Hz, 1 H, H-2),
4.66-4.46 (m, 4 H, H-1,2, CH2O), 3.94 (s, 3 H, ArOCH3), 3.83
(s, 3 H, ArOCH3), 3.81 (s, 3 H, ArOCH3), 3.06 (s, 3 H, SO2-
CH3). Anal. (C26H25N3O9S) C, H, N.
H-3), 4.33 (q, J ) 7.1 Hz, 2 H, CH2CH3), 2.04 (s, 3 H, COCH3),
1.43 (t, J ) 7.0 Hz, 3 H, CH2CH3). Anal. (C13H14N2O3) C, H,
N.
Ester 45 was hydrolyzed in a hot 2 N solution of Cs2CO3 in
aqueous EtOH to give 5-(acetylaminoindole-2-carboxylic acid
(46) (91%): mp (EtOAc/MeOH 279-280 °C (dec); 1H NMR
[(CD3)2SO] δ 12.81 (br s, 1 H, CO2H), 11.65 (s, 1 H, indole NH),
9.81 (s, 1 H, NHCO), 7.99 (d, J ) 1.5 Hz, 1 H, H-4), 7.35 (d, J
) 8.9 Hz, 1 H, H-7), 7.30 (dd, J ) 8.9, 1.9 Hz, 1 H, H-6), 7.03
(d, J ) 1.6 Hz, 1 H, H-3), 2.04 (s, 3 H, COCH3). Anal.
(C11H10N2O3) C, H, N.
Similar deprotection of 11 (300 mg, 0.83 mmol) and treat-
ment with 46 (181 mg, 0.83 mmol) and EDCI‚HCl (397 mg,
2.07 mmol) in DMA (3 mL) gave 3-[[5-(acetylamino)indol-2-
yl]carbonyl]-1-chloromethyl-5-nitro-1,2-dihydro-3H-benz[e]in-
dole (13d ) (301 mg, 79%): mp (THF/H2O) 252-253 °C; 1H
NMR [(CD3)2SO] δ 11.77 (d, J ) 1.2 Hz, 1 H, indole NH), 9.86
(s, 1 H, NHCO), 9.16 (s, 1 H, H-4), 8.35 (dd, J ) 7.1, 2.6 Hz,
1 H, H-6), 8.24 (dd, J ) 6.8, 2.5 Hz, 1 H, H-9), 8.10 (d, J ) 1.3
Hz, H-4′), 7.79-7.70 (m, 2 H, H-7,8), 7.43 (d, J ) 8.8 Hz, 1 H,
H-7′), 7.35 (dd, J ) 8.8, 1.8 Hz, 1 H, H-6′), 7.27 (d, J ) 1.8 Hz,
1 H, H-3′), 4.94 (t, J ) 10.2 Hz, 1 H, H-2), 4.71 (dd, J ) 11.0,
2.3 Hz, 1 H, H-2), 4.66-4.58 (m, 1 H, H-1), 4.13 (d, J ) 4.3
Hz, 2 H, CH2Cl), 2.06 (s, 3 H, COCH3). Anal. (C24H19ClN4O4)
C, H, N, Cl.
A solution of 13d (170 mg, 0.37 mmol) in THF (60 mL) was
hydrogenated over PtO2 at 50 psi for 2 h. After removal of the
catalyst, the solution was concentrated to a small volume
under reduced pressure below 25 °C and diluted with EtOAc/
iPr2O to give 10d (141 mg, 89%): mp >300 °C; 1H NMR [(CD3)2-
SO] δ 11.61 (d, J ) 1.4 Hz, 1 H, indole NH), 9.84 (s, 1 H,
NHCO), 8.08 (d, J ) 8.5 Hz, 1 H, H-6), 8.05 (d, J ) 1.4 Hz, 1
H, H-4′), 7.76 (d, J ) 8.2 Hz, 1 H, H-9), 7.71 (s, 1 H, H-4), 7.46
(t, J ) 7.5 Hz, 1 H, H-8), 7.42 (d, J ) 8.9 Hz, 1 H, H-7′), 7.33
(dd, J ) 8.8, 1.9 Hz, 1 H, H-6′), 7.29 (t, J ) 7.5 Hz, 1 H, H-7),
7.14 (d, J ) 1.7 Hz, 1 H, H-3′), 5.98 (s, 2 H, NH2), 4.74 (dd, J
) 10.8, 9.0 Hz, 1 H, H-2), 4.51 (dd, J ) 11.0, 1.6 Hz, 1 H, H-2),
4.17-4.08 (m, 1 H, H-1), 3.97 (dd, J ) 11.0, 3.0 Hz, 1 H,
CHHCl), 3.77 (dd, J ) 10.9, 7.8 Hz, 1 H, CHHCl), 2.06 (s, 3 H,
CH3). Anal. (C24H21ClN4O2) C, H, N, Cl.
5-Am in o-1-(ch lor om eth yl)-3-[(5-m eth oxyin d ol-2-yl)ca r -
bon yl]-1,2-d ih yd r o-3H-ben z[e]in d ole (10e). Similar depro-
tection of 11 (260 mg, 0.72 mmol) and reaction with 5-meth-
oxyindole-2-carboxylic acid (145 mg, 0.76 mmol) and EDCI‚
HCl (344 mg, 1.80 mmol) in DMA (3 mL) gave 1-(chloromethyl)-
3-[(5-methoxyindol-2-yl)carbonyl]-5-nitro-1,2-dihydro-3H-
benz[e]indole (13e) (237 mg, 76%): mp (2 × EtOAc/iPr2O):
241-243 °C; 1NMR [(CD3)2SO] δ 11.73 (d, J ) 1.3 Hz, 1 H,
NH), 9.16 (s, 1 H, H-4), 8.35 (dd, J ) 7.2, 2.5 Hz, 1 H, H-6),
8.23 (dd, J ) 6.9, 2.4 Hz, 1 H, H-9), 7.79-7.70 (m, 2 H, H-7,8),
7.42 (d, J ) 8.9 Hz, 1 H, H-7′), 7.20 (d, J ) 1.9 Hz, 1 H, H-3′),
7.17 (d, J ) 2.4 Hz, 1 H, H-4′), 6.94 (dd, J ) 9.0, 2.4 Hz, 1 H,
H-6′), 4.93 (dd, J ) 10.6, 9.2 Hz, 1 H, H-2), 4.70 (dd, J ) 10.9,
2.4 Hz, 1 H, H-2), 4.65-4.57 (m, 1 H, H-1), 4.18-4.07 (m, 2 H,
CH2Cl), 3.79 (s, 3 H, CH3). Anal. (C23H18ClN3O4) C, H, N, Cl.
A solution of 13b (162 mg, 0.29 mmol) in THF (25 mL) was
hydrogenated over PtO2 at 55 psi for 2 h. After removal of the
catalyst, the solution was concentrated to a small volume
i
under reduced pressure below 25 °C and diluted with Pr2O to
give a crude product. This was purified by precipitation from
a EtOAc solution with petroleum ether at 20 °C to give 10b
1
(116 mg, 76%): mp >260 °C; H NMR [(CD3)2SO] δ 11.41 (d,
J ) 1.6 Hz, 1 H, NH), 8.08 (d, J ) 8.5 Hz, 1 H, H-6), 7.76 (d,
J ) 8.3 Hz, 1 H, H-9), 7.67 (s, 1 H, H-4), 7.49 (t, J ) 7.6 Hz,
1 H, H-8), 7.30 (t, J ) 7.6 Hz, 1 H, H-7), 7.04 (d, J ) 2.0 Hz,
1 H, H-3′), 6.96 (s, 1 H, H-4′), 6.15 (v br s, 2 H, NH2), 4.66 (dd,
J ) 10.9, 8.5 Hz, 1 H, H-2), 4.47 (dd, J ) 9.9, 3.4 Hz, 1 H,
H-2), 4.41 (d, J ) 10.9 Hz, 1 H, CHHO), 4.17 (t, J ) 9.2 Hz, 1
H, CHHO), 4.13-4.04 (m, 1 H, H-1), 3.94 (s, 3 H, ArOCH3),
3.82 (s, 3 H, ArOCH3), 3.80 (s, 3 H, ArOCH3), 3.07 (s, 3 H,
SO2CH3). Anal. (C26H27N3O7S) C, H, N.
5-Am in o-3-[(5-a m in oin d ol-2-yl)ca r b on yl]-1-(ch lor o-
m eth yl)-1,2-d ih yd r o-3H-ben z[e]in d ole (10c). 3-(tert-Butyl-
oxycarbonyl)-1-(chloromethyl)-5-nitro-1,2-dihydro-3H-benz[e]-
indole18,19 (11) (280 mg, 0.77 mmol) was stirred in HCl-
saturated dioxane (10 mL) at 20 °C for 2 h and then evaporated
to dryness under reduced pressure below 30 °C to give crude
1-(chloromethyl)-5-nitro-1,2-dihydro-3H-benz[e]indole (12) as
the hydrochloride salt. 5-Nitroindole-2-carboxylic acid30 (167
mg, 0.81 mmol), EDCI‚HCl (370 mg, 1.93 mmol), and DMA (3
mL) were then added, and the mixture was stirred at 20 °C
for 4 h. Addition of dilute KHCO3 precipitated a yellow solid
which was collected, washed well with water, and recrystal-
lized from THF to give 1-(chloromethyl)-5-nitro-3-[(5-nitroin-
dol-2-yl)carbonyl]-1,2-dihydro-3H-benz[e]indole (13c) (282 mg,
81%): mp >300 °C; 1H NMR [(CD3)2SO] δ 12.56 (s, 1 H, NH),
9.14 (s, 1 H, H-4), 8.74 (d, J ) 2.2 Hz, 1 H, H-4′), 8.35 (dd, J
) 7.0, 2.7 Hz, 1 H, H-6), 8.24 (dd, J ) 6.8, 2.7 Hz, 1 H, H-9),
8.12 (dd, J ) 9.1, 2.3 Hz, 1 H, H-6′), 7.80-7.72 (m, 2 H, H-7,8),
7.64 (d, J ) 9.1 Hz, 1 H, H-7′), 7.58 (s, 1 H, H-3′), 4.96 (t, J )
10.1 Hz, 1 H, H-2), 4.71 (dd, J ) 10.8, 2.3 Hz, 1 H, H-2), 4.68-
4.61 (m, 1 H, H-1), 4.18-4.09 (m, 2 H, CH2Cl). Anal. (C22H15
ClN4O5) C, H, N, Cl.
-
A solution of 13c (170 mg, 0.38 mmol) in THF (120 mL) was
hydrogenated over PtO2 at 50 psi for 2 h. After removal of the
catalyst, the solution was concentrated to a small volume
i
under reduced pressure below 25 °C and diluted with Pr2O to
1
give 10c (136 mg, 92%): mp >300 °C; H NMR [(CD3)2SO] δ
Reduction of 13e in THF as for 13d gave 10e (95%): mp
11.23 (d, J ) 1.4 Hz, 1 H, NH), 8.07 (d, J ) 8.4 Hz, 1 H, H-6),
7.75 (d, J ) 8.2 Hz, 1 H, H-9), 7.70 (s, 1 H, H-4), 7.45 (t, J )
7.5 Hz, 1 H, H-8), 7.27 (t, J ) 7.7 Hz, 1 H, H-7), 7.21 (d, J )
8.6 Hz, 1 H, H-7′), 6.88 (d, J ) 1.8 Hz, 1 H, H-3′), 6.76 (d, J )
1.8 Hz, 1 H, H-4′), 6.68 (dd, J ) 8.6, 2.1 Hz, 1 H, H-6′), 5.96 (s,
2 H, 5-NH2), 4.70 (dd, J ) 10.9, 8.9 Hz, 1 H, H-2), 4.64 (br s,
2 H, 5′-NH2), 4.49 (dd, J ) 11.0, 1.6 Hz, 1 H, H-2), 4.15-4.07
(m, 1 H, H-1), 3.97 (dd, J ) 11.0, 3.0 Hz, 1 H, CHHCl), 3.74
(dd, J ) 11.0, 8.0 Hz, 1 H, CHHCl). Anal. (C22H19ClN4O) C,
N: H, found 5.5, calculated 4.9%.
1
(THF/H2O) 250-255 °C; H NMR [(CD3)2SO] δ 11.56 (d, J )
1.6 Hz, 1 H, NH), 8.08 (d, J ) 8.4 Hz, 1 H, H-6), 7.76 (d, J )
8.2 Hz, 1 H, H-9), 7.70 (s, 1 H, H-4), 7.46 (t, J ) 7.6 Hz, 1 H,
H-8), 7.40 (d, J ) 8.8 Hz, 1 H, H-7′), 7.28 (t, J ) 7.6 Hz, 1 H,
H-7), 7.16 (d, J ) 2.4 Hz, 1 H, H-4′), 7.08 (d, J ) 1.8 Hz, 1 H,
H-3′), 6.91 (dd, J ) 8.8, 2.5 Hz, 1 H, H-6′), 5.98 (s, 2 H, NH2),
4.73 (dd, J ) 10.8, 8.9 Hz, 1 H, H-2), 4.51 (dd, J ) 10.9, 1.7
Hz, 1 H, H-2), 4.17-4.08 (m, 1 H, H-1), 3.98 (dd, J ) 11.0, 3.1
Hz, 1 H, CHHCl), 3.78 (s, 3 H, CH3), 3.75 (dd, J ) 11.0, 8.1
Hz, 1 H, CHHCl). Anal. (C23H20ClN3O2) C, H, N, Cl.
3-[[5-(Ace t yla m in o)in d ol-2-yl]ca r b on yl]-5-a m in o-1-
(ch lor om eth yl)-1,2-d ih yd r o-3H-ben z[e]in d ole (10d ). Ethyl
5-aminoindole-2-carboxylate20 (44) was treated with Ac2O/
pyridine at 20 °C to give ethyl 5-(acetylamino)indole-2-car-
boxylate (45) (89%): mp (EtOAc/iPr2O) 216.5-217 °C; 1H NMR
[(CD3)2SO] δ 11.78 (s, 1 H, indole NH), 9,82 (s, 1 H, NHCO),
8.01 (d, J ) 1.6 Hz, 1 H, H-4), 7.37 (d, J ) 8.8 Hz, 1 H, H-7),
7.32 (dd, J ) 8.9, 1.9 Hz, 1 H, H-6), 7.09 (d, J ) 1.5 Hz, 1 H,
5-Am in o-1-(ch lor om et h yl)-3-[[5-[2-(d im et h yla m in o)-
e t h oxy]in d ol-2-yl]ca r b on yl]-1,2-d ih yd r o-3H -b e n z[e]-
in d ole (10f). Similar deprotection of 11 (260 mg, 0.72 mmol)
and reaction with 5-[2-(dimethylamino)ethoxy]indole-2-car-
boxylic acid hydrochloride17 (210 mg, 0.74 mmol) and EDCI‚
HCl (345 mg, 1.80 mmol) in DMA (3 mL), followed by addition
of the reaction mixture to saturated KHCO3, gave a crude
product. This was purified by precipitation from a CH2Cl2

3406 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17
Atwell et al.
solution with iPr2O (2×) to give 1-(chloromethyl)-3-[[5-[2-
(dimethylamino)ethoxy]indol-2-yl]carbonyl]-5-nitro-1,2-dihydro-
3H-benz[e]indole (13f) (237 mg, 67%): mp 224-227 °C; 1H
NMR [(CD3)2SO] δ 11.72 (d, J ) 1.5 Hz, 1 H, NH), 9.16 (s, 1
H, H-4), 8.35 (dd, 7.2, 2.5 Hz, 1 H, H-6), 8.23 (dd, J ) 6.9, 2.5
Hz, 1 H, H-9), 7.79-7.71 (m, 1 H, H-7,8), 7.41 (d, J ) 8.9 Hz,
1 H, H-7′), 7.21-7.16 (m, 2 H, H-3′,4′), 6.94 (dd, J ) 9.0, 2.4
Hz, 1 H, H-6′), 4.93 (dd, J ) 10.6, 9.8 Hz, 1 H, H-2), 4.70 (dd,
J ) 10.9, 2.4 Hz, 1 H, H-2), 4.65-4.58 (m, 1 H, H-1), 4.18-
4.09 (m, 2 H, CH2Cl), 4.07 (t, J ) 5.9 Hz, 2 H, OCH2), 2.66 (t,
J ) 5.8 Hz, 2 H, OCH2CH2), 2.24 (s, 6 H, N(CH3)2). Anal.
(C26H25ClN4O4) C, H, N, Cl.
Reduction of 13f in THF as for 13d gave 10f (98%): mp
(THF/iPr2O) >250 °C; 1H NMR [(CD3)2SO] δ 11.56 (d, J ) 1.4
Hz, 1 H, NH), 8.08 (d, J ) 8.5 Hz, 1 H, H-6), 7.76 (d, J ) 8.2
Hz, 1 H, H-9), 7.70 (s, 1 H, H-4), 7.46 (t, J ) 7.4 Hz, 1 H, H-8),
7.39 (d, J ) 8.9 Hz, 1 H, H-7′), 7.28 (t, J ) 7.7 Hz, 1 H, H-7),
7.17 (d, J ) 2.2 Hz, 1 H, H-4′), 7.07 (d, J ) 1.8 Hz, 1 H, H-3′),
6.91 (dd, J ) 8.9, 2.4 Hz, 1 H, H-6′), 5.98 (s, 2 H, NH2), 4.73
(dd, J ) 10.6, 9.1 Hz, 1 H, H-2), 4.51 (dd, J ) 10.9, 1.4 Hz, 1
H, H-2), 4.16-4.08 (m, 1 H, H-1), 4.06 (t, J ) 5.9 Hz, 2 H,
OCH2), 3.98 (dd, J ) 10.9, 3.0 Hz, 1 H, CHHCl), 3.75 (dd, J )
10.9, 8.1 Hz, 1 H, CHHCL), 2.65 (t, J ) 5.9 Hz, 2 H, OCH2CH2),
2.24 (s, 6 H, N(CH3)2). Anal. (C26H27ClN4O2) C, H, N, Cl.
5-Am in o-1-(ch lor om et h yl)-3-[[6-[2-(d im et h yla m in o)-
eth oxy]-5-m eth oxyin d ol-2-yl]ca r bon yl]-1,2-d ih yd r o-3H-
ben z[e]in d ole (10g). Similar deprotection of 11 (261 mg, 0.72
mmol) and reaction with 6-[2-(dimethylamino)ethoxy]-5-meth-
oxy-1H-indole-2-carboxylic acid hydrochloride17 (230 mg, 0.73
mmol) and EDCI‚HCl (345 mg, 1.80 mmol), in DMA (3 mL) at
20 °C for 3 h gave a solidified mixture. This was shaken with
dilute KHCO3, and the resulting gelatinous solid was collected
and chromatographed on alumina-90. Elution with EtOAc/
MeOH (10:1) provided a crude product which was recrystal-
lized from EtOAc/iPr2O, followed by CH2Cl2/petroleum ether,
to give 1-(chloromethyl)-3-[[6-[2-(dimethylamino)ethoxy]-5-
methoxyindol-2-yl]carbonyl]-5-nitro-1,2-dihydro-3H-benz[e]in-
dole (13g) (180 mg, 48%): mp 224-234 °C (dec); 1H NMR
[(CD3)2SO] δ 11.54 (d, J ) 1.6 Hz, 1 H, NH), 9.17 (s, 1 H, H-4),
8.34 (dd, J ) 7.5, 2.2 Hz, 1 H, H-6), 8.22 (dd, J ) 7.1, 1.8 Hz,
1 H, H-9), 7.79-7.69 (m, 2 H, H-7,8), 7.17 (d, J ) 1.6 Hz, 1 H,
H-3′), 7.16 (s, 1 H, H-4′ or 7′), 6.99 (s, 1 H, H-4′ or 7′), 4.91 (t,
J ) 10.2 Hz, 1 H, H-2), 4.68 (dd, J ) 10.9, 2.4 Hz, 1 H, H-2),
4.65-4.57 (m, 1 H, H-1), 4.17-4.09 (m, 2 H, CH2Cl), 4.06 (t, J
) 6.0 Hz, 2 H, OCH2), 3.79 (s, 3 H, OCH3), 2.69 (t, J ) 5.9 Hz,
2 H, OCH2CH2), 2.26 (s, 6 H, N(CH3)2). Anal. (C27H27ClN4O5)
C, H, N, Cl.
A solution of 13g (130 mg, 0.25 mmol) in THF (20 mL) was
hydrogenated over PtO2 (30 mg) at 55 psi for 2 h. The catalyst
was removed, and the solution was concentrated under
reduced pressure below 30 °C. The residue was dissolved in a
small volume of CH2Cl2, the solution was diluted with petro-
leum ether to precipitate impurities which were removed by
filtration, and then further addition of petroleum ether
precipitated 10g (87 mg, 71%): mp 130-133 °C; 1H NMR
[(CD3)2SO] δ 11.38 (d, J ) 1.6 Hz, 1 H, NH), 8.07 (d, J ) 8.5
Hz, 1 H, H-6), 7.75 (d, J ) 8.3 Hz, 1 H, H-9), 7.72 (s, 1 H,
H-4), 7.45 (t, J ) 7.4 Hz, 1 H, H-8), 7.27 (t, J ) 7.7 Hz, 1 H,
H-7), 7.15 (s, 1 H, H-3′), 7.05 (s, 1 H, H-4′ or 7′), 6.99 (s, 1 H,
H-4′ or 7′), 5.96, 5.94 (2 × s, 2 H, NH2), 4.71 (dd, J ) 10.6, 9.1
Hz, 1 H, H-2), 4.50 (dd, J ) 10.9 Hz, 1.6 Hz, 1 H, H-2), 4.16-
4.08 (m, 1 H, H-1), 4.05 (t, J ) 6.0 Hz, 2 H, OCH2), 3.98 (dd,
J ) 11.0, 3.0 Hz, 1 H, CHHCl), 3.79 (s, 1 H, OCH3), 3.74 (dd,
J ) 10.9, 8.2 Hz, 1 H, CHHCl), 2.68 (t, J ) 5.9 Hz, 2 H,
OCH2CH2), 2.25 (s, 6 H, N(CH3)2). Anal. (C27H29ClN4O3‚
0.5H2O) C, H, N. Treatment of the free base with EtOAc/
petroleum ether/HCl gave the dihydrochloride salt.
precipitated a solid. This was recrystallized from CH2Cl2/iPr2O
followed by CH2Cl2/EtOAc to give 1-chloromethyl)-3-[[7-[2-
(dimethylamino)ethoxy]-5-methoxyindol-2-yl]carbonyl]-5-nitro-
1,2-dihydro-3H-benz[e]indole (13h ) (193 mg, 84%): mp 230-
240 °C (dec); 1H NMR [(CD3)2SO] δ 11.64 (s, 1 H, NH), 9.11 (s,
1 H, H-4), 8.36 (dd, J ) 7.1, 2.7 Hz, 1 H, H-6), 8.23 (dd, J )
6.7, 2.6 Hz, 1 H, H-9), 7.79-7.71 (m, 2 H, H-7,8), 7.14 (s, 1 H,
H-3′), 6.75 (d, J ) 2.0 Hz, 1 H, H-4′ or 6′), 6.50 (d, J ) 2.0 Hz,
1 H, H-4′ or 6′), 4.89 (dd, J ) 10.6, 9.6 Hz, 1 H, H-2), 4.65-
4.55 (m, 2 H, H-1,2), 4.19 (t, J ) 5.7 Hz, 2 H, OCH2), 4.16-
4.05 (m, 2 H, CH2Cl), 3.78 (s, 3 H, OCH3), 2.74 (t, J ) 5.7 Hz,
2 H, OCH2CH2), 2.28 (s, 6 H, N(CH3)2). Anal. (C27H27ClN4O5)
C, H, N, Cl.
A solution of 13h (120 mg, 0.23 mmol) in THF (45 mL) was
hydrogenated over PtO2 (30 mg) at 55 psi for 1.5 h. After
removal of the catalyst, the solution was concentrated to a
small volume under reduced pressure below 30 °C and then
diluted with petroleum ether to give 10h (104 mg, 92%): mp
1
109-111 °C; H NMR [(CD3)2SO] δ 11.41 (s, 1 H, NH), 8.07
(d, J ) 8.8 Hz, 1 H, H-6), 7.75 (d, J ) 8.2 Hz, 1 H, H-9), 7.64
(s, 1 H, H-4), 7.45 (t, J ) 7.5 Hz, 1 H, H-8), 7.28 (t, J ) 7.6 Hz,
1 H, H-7), 7.00 (d, J ) 1.2 Hz, 1 H, H-3’), 6.73 (d, J ) 1.9 Hz,
1 H, H-4′ or 6′), 6.48 (d, J ) 2.0 Hz, 1 H, H-4′ or 6′), 5.98, 5.96
(2 × s, 2 H, NH2), 4.66 (dd, J ) 10.7, 9.0 Hz, 1 H, H-2), 4.41
(dd, J ) 11.0, 1.4 Hz, 1 H, H-2), 4.19 (t, J ) 5.7 Hz, 2 H, OCH2),
4.12-4.04 (m, 1 H, H-1), 3.96 (dd, J ) 10.9, 3.0 Hz, CHHCl),
3.77 (s, 3 H, OCH3), 3.72 (dd, J ) 11.0, 8.2 Hz, 1 H, CHHCl),
2.73 (t, J ) 5.7 Hz, 2 H, OCH2CH2), 2.28 (s, 6 H, N(CH3)2).
Anal. (C27H29ClN4O3‚1.5H2O) C, H, N, Cl. Treatment of the
free base with EtOAc/petroleum ether/HCl gave the dihydro-
chloride salt.
5-Am i n o -3-[[5-[(b e n z o fu r a n -2-y l)c a r b o x a m i d o ]-
in d ol-2-yl]ca r b on yl]-1-(ch lor om et h yl)-1,2-d ih yd r o-3H -
ben z[e]in d ole (10i). Deprotection of 11 (300 mg, 0.83 mmol)
as above, and reaction of the product with 5-[(benzofuran-2-
yl)carboxamido]indole-2-carboxylic acid31 (278 mg, 0.87 mmol)
and EDCI‚HCl (397 mg, 2.07 mmol) in DMA (10 mL) at 20 °C
for 4 h, followed by addition of dilute KHCO3, precipitated a
solid. This was collected, washed with water, and recrystallized
from THF/iPr2O followed by EtOAc to give 3-[[5-[(benzofuran-
2-yl)carboxamido]indol-2-yl]carbonyl]-1-(chloromethyl)-5-nitro-
1,2-dihydro-3H-benz[e]indole (13i) (341 mg, 73%): mp 277 °C
1
(dec); H NMR [(CD3)2SO] δ 11.88 (d, J ) 1.5 Hz, 1 H, indole
NH), 10.50 (s, 1 H, NHCO), 9.18 (s, 1 H, H-4), 8.36 (dd, J )
7.0, 2.8 Hz, 1 H, H-6), 8.27 (d, J ) 1.5 Hz, 1 H, H-4′), 8.25 (dd,
J ) 6.7, 2.6 Hz, 1 H, H-9), 7.84 (d, J ) 7.7 Hz, 1 H, H-4′′),
7.80-7.71 (m, 3 H, H-7,8,7′′), 7.78 (d, J ) 0.6 Hz, 1 H, H-3′′),
7.65 (dd, J ) 8.9, 1.9 Hz, 1 H, H-6′), 7.55-7.48 (m, 1 H, H-6′′),
7.52 (d, J ) 8.8 Hz, 1 H, H-7′), 7.38 (t, J ) 7.5 Hz, 1 H, H-5′′),
7.34 (d, J ) 1.6 Hz, 1 H, H-3′), 4.97 (dd, J ) 10.6, 9.9 Hz, 1 H,
H-2), 4.74 (dd, J ) 11.0, 2.3 Hz, 1 H, H-2), 4.68-4.60 (m, 1 H,
H-1), 4.15 (d, J ) 4.3 Hz, 2 H, CH2Cl). Anal. (C31H21ClN4O5)
C, H, N, Cl.
A solution of 13i (200 mg, 0.35 mmol) in THF (35 mL) was
hydrogenated over PtO2 at 50 psi for 2 h. THF was added to
dissolve the precipitated product, and after removal of the
catalyst the solution was concentrated to a small volume below
i
25 °C under reduced pressure and diluted with Pr2O to give
10i (187 mg, 99%): mp >300 °C; 1H NMR [(CD3)2SO] δ 11.72
(d, J ) 1.3 Hz, 1 H, indole NH), 10.48 (s, 1 H, NHCO), 8.22 (d,
J ) 1.4 Hz, 1 H, H-4′), 8.09 (d, J ) 8.5 Hz, 1 H, H-6), 7.84 (d,
J ) 7.8 Hz, 1 H, H-4′′), 7.80-7.69 (m, 3 H, H-4,9,7′′), 7.77 (s,
1 H, H-3′′), 7.62 (dd, J ) 8.9, 1.9 Hz, 1 H, H-6′), 7.54-7.43 (m,
2 H, H-8,6′′), 7.50 (d, J ) 8.6 Hz, 1 H, H-7′), 7.38(t, J ) 7.5
Hz, 1 H, H-5′′), 7.29 (t, J ) 7.7, 1 H, H-7), 7.21 (d, J ) 0.9 Hz,
1 H, H-3′), 6.00, 5.98 (2 × s, 2 H, NH2), 4.77 (dd, J ) 10.9, 9.0
Hz, 1 H, H-2), 4.54 (dd, J ) 10.8, 1.3 Hz, 1 H, H-2), 4.19-4.10
(m, 1 H, H-1), 3.99 (dd, J ) 10.9, 2.9 Hz, 1 H, CHHCl), 3.79
(dd, J ) 10.9, 7.8 Hz, 1 H, CHHCl). Anal. (C31H23ClN4O3‚0.5
H2O) C, H, N.
5-Am in o-1-(ch lor om et h yl)-3-[[7-[2-(d im et h yla m in o)-
eth oxy]-5-m eth oxyin d ol-2-yl]ca r bon yl]-1,2-d ih yd r o-3H-
ben z[e]in d ole (10h ). Deprotection of 11 (160 mg, 0.44 mmol)
as above, and reaction of the product with EDCI‚HCl (211 mg,
1.10 mmol) and 7-[2-(dimethylamino)ethoxy]-5-methoxyindole-
2-carboxylic acid hydrochloride17 (145 mg, 0.46 mmol) in DMA
(2 mL) at 20 °C for 3 h, followed by addition of dilute KHCO3,
3-[[5-[[5-(Acet yla m in o)-1-m et h ylp yr a zol-3-yl]ca r b ox-
a m i d o ]-1 -m e t h y l p y r a z o l -3 -y l ]c a r b o n y l ]-5 -a m i n o -
1-(ch lor om eth yl)-1,2-d ih yd r o-3H-ben z[e]in d ole (10j). A
solution of methyl 5-[[5-(benzyloxycarbonylamino)-1-meth-

5-Amino-1-(Chloromethyl)-1,2-dihydro-3H-benz[e]indoles
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17 3407
ylpyrazol-3-yl]carboxamido]-1-methylpyrazole-3-carboxy-
late21 (31) in MeOH was hydrogenated over Pd-C at 55 psi
for 2 h. Recrystallization of the product from a small volume
of EtOAc gave methyl 5-[(5-amino-1-methylpyrazol-3-yl)car-
boxamido]-1-methylpyrazole-3-carboxylate (32) (93%): mp
167-168 °C; 1H NMR [(CD3)2SO] δ 10.01 (s, 1 H, NH), 6.62 (s,
1 H, H-4), 5.77 (s, 1 H, H-4′), 5.49 (s, 2 H, NH2), 3.78 (s, 3 H,
CH3), 3.74 (s, 3 H, CH3), 3.64 (s, 3 H, CH3). Anal. (C11H14N6O3)
C, H, N.
crystallization of the product from CH2Cl2/iPr2O, gave 3-[(E)-
3-[4-(butyrylamino)-1-methylpyrrol-2-yl]acryloyl]-1-(chlorom-
ethyl)-5-nitro-1,2-dihydro-3H-benz[e]indole (13k ) (246 mg,
62%): mp 216 °C; 1H NMR [(CD3)2SO] δ 9.79 (s, 1 H, NH),
9.22 (s, 1 H, H-4), 8.32 (d, J ) 8.7 Hz, 1 H, H-6), 8.17 (d, J )
8.1 Hz, 1 H, H-9), 7.76-7.65 (m, 2 H, H-7,8), 7.64 (d, J ) 14.9
Hz, 1 H, COCHdCH), 7.25 (d, J ) 1.6 Hz, 1 H, H-5′), 6.81 (d,
J ) 1.6 Hz, 1 H, H-3′), 6.71 (d, J ) 15.0 Hz, 1 H, COCHdCH),
4.65-4.50 (m, 3 H, 2 × H-2, H-1), 4.08 (d, J ) 3.6 Hz, 2 H,
CH2Cl), 3.71 (s, 3 H, NCH3), 2.22 (t, J ) 7.3 Hz, 2 H, COCH2),
1.65-1.54 (m, 2 H, CH2CH3), 0.90 (t, J ) 7.4 Hz, 3 H, CH2CH3).
Anal. (C25H25ClN4O4) C, H, N.
A suspension of the powdered amine 32 (0.39 g, 1.40 mmol)
in THF (20 mL) containing MeCOCl (2 mL) was heated at
reflux with stirring for 30 min. The mixture was cooled and
i
then diluted with Pr2O, and the resulting solid was recrystal-
A solution of 13k (100 mg, 0.21 mmol) in EtOAc was
hydrogenated over EtOAc-washed Raney nickel (ca. 100 mg)
at 40 psi for 3 h. The filtered solution was evaporated to
dryness below 30 °C, and the residue was chromatographed
on silica gel. Later EtOAc eluates gave a yellow oil which was
crystallized from EtOAc/iPr2O/petroleum ether to give 10k (9
lized from MeOH/EtOAc to give methyl 5-[(5-acetylamino-1-
methylpyrazol-3-yl)carboxamido]-1-methylpyrazole-3-carbox-
ylate (33) (0.35 g, 78%): mp 215-216 °C; 1H NMR [(CD3)2SO]
δ 10.28 (s, 1 H, NH), 10.19 (s, 1 H, NH), 6.73 (s, 1 H, H-4 or
H-4′), 6.65 (s, 1 H, H-4 or H-4′), 3.80 (s, 3 H, CH3), 3.79 (s, 3
H, CH3), 3.76 (s, 3 H, CH3), 2.11 (s, 3 H, COCH3). Anal.
(C13H16N6O4) C, H, N.
A mixture of the ester 33 (0.38 g, 1.19 mmol) and Cs2CO3
(3.26 g) in water (10 mL) was heated at reflux for 2 h, then
concentrated, cooled to 0 °C, and acidified with concentrated
HCl. After prolonged cooling, the crude product was collected
and recrystallized from MeOH/EtOAc to give 5-[(5-acety-
lamino-1-methylpyrazol-3-yl)carboxamido]-1-methylpyrazole-
3-carboxylic acid (34) (0.19 g, 52%): mp 263-264 °C (dec); 1H
NMR [(CD3)2SO] δ 12.62 (s, 1 H, CO2H), 10.24 (s, 1 H, NH),
10.18 (s, 1 H, NH), 6.72 (s, 1 H, H-4 or H-4′), 6.59 (s, 1 H, H-4
or H-4′), 3.80 (s, 3 H, N-CH3), 3.74 (s, 3 H, N-CH3), 2.11 (s,
3 H, COCH3). Anal. (C12H14N6O4) C, H, N.
1
mg, 10%): mp 245-250 (dec); H NMR [(CD3)2SO] δ 9.76 (s,
1 H, NH), 8.04 (d, J ) 8.4 Hz, 1 H, H-6), 7.79 (v br s 1 H, H-4),
7.71 (d, J ) 8.1 Hz, 1 H, H-9), 7.55 (d, J ) 15.0 Hz, 1 H,
COCHdCH), 7.43 (t, J ) 7.3 Hz, 1 H, H-8), 7.28-7.20 (m, 2
H, H-7,5′), 6.75-6.65 (m, 2 H, COCHdCH, H-3′), 5.94 (br s, 2
H, NH2), 4.47-4.34 (m, 1 H, H-2), 4.33 (dd, J ) 10.9, 2.1 Hz,
1 H, H-2), 4.13-4.04 (m, 1 H, H-1), 3.95 (dd, J ) 10.9, 3.0 Hz,
1 H, CHHCl), 3.73 (dd, J ) 11.0, 8.3 Hz, 1 H, CHHCl), 3.69 (s,
3 H, NCH3), 2.21 (t, J ) 7.3 Hz, 2 H, COCH2), 1.64-1.53 (m,
2 H, CH2CH3), 0.90 (t, J ) 7.4 Hz, 3 H, CH2CH3). Anal. (C25H27
ClN4O2) C, H, N.
-
3-[(E )-3-[3-(Ac e t y la m i n o )-1-m e t h y lp y r a z o l-5-y l]-
a c r yloyl]-5-a m in o-1-(c h lor om e t h yl)-1,2-d ih yd r o-3H -
ben z[e]in d ole (10l). A solution of methyl 3-amino-1-meth-
ylpyrazole-5-carboxylate22 (35) (2.50 g, 16.1 mmol) in THF (90
mL) was treated at 20 °C with acetyl chloride (2.29 mL, 32.2
mmol) and heated at reflux for 15 min. The mixture was
concentrated under reduced pressure, and the residue was
dissolved in warm EtOAc (250 mL). The solution was filtered
through a short column of silica gel, concentrated to a small
Deprotection of 11 (153 mg, 0.42 mmol) as above, followed
by reaction with the acid 34 (135 mg, 0.44 mmol) and EDCI‚
HCl (201 mg, 1.05 mmol) in DMA (2 mL) gave a solid which
was collected, washed with water, and dried. This was dis-
solved in THF (10 mL), and the solution was diluted with
EtOAc (5 mL) and then filtered through a column of silica gel,
eluting with further THF/EtOAc (2:1). The solution was
concentrated under reduced pressure to a small volume and
i
volume, and diluted with Pr2O to precipitate methyl 3-(acety-
i
lamino)-1-methylpyrazole-5-carboxylate (36) (3.09 g, 97%): mp
(EtOAc) 202-203 °C; 1H NMR [(CD3)2SO] δ 10.60 (s, 1 H, NH),
7.01 (s, 1 H, H-4), 3.99 (s, 3 H, NCH3 or CO2CH3), 3.83 (s, 3 H,
NCH3 or CO2CH3), 2.01 (s, 3 H, CH3CO). Anal. (C8H11N3O3)
C, H, N.
diluted with Pr2O to precipitate the crude product which was
twice recrystallized from THF/EtOAc/iPr2O to give 3-[[5-[(5-
acetylamino-1-methylpyrazol-3-yl)carboxamido]-1-methylpyra-
zol-3-yl]carbonyl]-1-(chloromethyl)-5-nitro-1,2-dihydro-3H-benz-
[e]indole (13j) (125 mg, 54%): mp 158-160 °C; 1H NMR
[(CD3)2SO] δ 10.35 (s, 1 H, NH), 10.20 (s, 1 H, NH), 9.19 (s, 1
H, H-4), 8.35 (dd, J ) 7.1, 2.7 Hz, 1 H, H-6), 8.21 (dd, J ) 6.8,
2.6 Hz, 1 H, H-9), 7.79-7.70 (m, 2 H, H-7,8), 6.78 (s, 1 H, H-4
or H-4′), 6.75 (s, 1 H, H-4 or H-4′), 4.92 (dd, J ) 11.9, 1.6 Hz,
1 H, H-2), 4.79 (dd, J ) 12.0, 9.4 Hz, 1 H, H-2), 4.59-4.50 (m,
1 H, H-1), 4.16-4.05 (m, 2 H, CH2Cl), 3.84 (s, 3 H, N-CH3),
A mixture of 36 (3.04 g, 15.4 mmol) and Cs2CO3 (8.0 g) in
water (24 mL) was heated at reflux for 45 min, then concen-
trated to 10 mL, and acidified in the cold with 0.5 N HCl. The
precipitated solid was recrystallized from MeOH to give
3-(acetylamino)-1-methylpyrazole-5-carboxylic acid (37) (2.44
1
g, 86%): mp 286 °C (dec); H NMR [(CD3)2SO] δ 13.2 (br s, 1
3.82 (s, 3 H, N-CH3), 2.12 (s, 3 H, COCH3). Anal. (C25H23
ClN8O5) C, H, N.
-
H, CO2H), 10.54 (s, 1 H, NH), 6.96 (s, 1 H, H-4), 3.98 (s, 3 H,
NCH3), 2.00 (s, 3 H, CH3CO). Anal. (C7H9N3O3) C, H, N.
A solution of 13j (77 mg, 0.14 mmol) in THF (50 mL) was
hydrogenated over PtO2 at 55 psi for 2.5 h. After removal of
the catalyst, the solution was concentrated to a small volume
A suspension of 37 (751 mg, 4.10 mmol) in THF (20 mL)
was treated with 1,1′-carbonyldiimidazole (864 mg, 5.33 mmol).
The mixture was stirred at 45 °C for 15 min and at 20 °C for
15 min, and it was then was added to a stirred freshly prepared
solution of NaBH4 (620 mg, 16.4 mmol) in water (10 mL) at 5
°C. This mixture was stirred at 20 °C for 30 min, then treated
slowly with AcOH (2.5 mL), and evaporated to complete
dryness under reduced pressure. The residue was extracted
with boiling EtOAc (2 × 125 mL), and the combined extracts
were concentrated to a small volume and cooled at 0 °C for 24
h. The resulting solid was collected and recrystallized from
EtOAc/iPr2O to give 3-(acetylamino)-5-(hydroxymethyl)-1-me-
thylpyrazole (38) (468 mg, 67%): mp 148 °C; 1H NMR [(CD3)2-
SO] δ 10.24 (s, 1 H, NH), 6.38 (s, 1 H, H-4), 5.23 (br s, 1 H,
OH), 4.42 (d, J ) 4.2 Hz, 2 H, CH2), 3.66 (s, 3 H, NCH3), 1.96
(s, 3 H, CH3CO). Anal. (C7H11N3O2) C, H, N.
i
under reduced pressure below 25 °C and diluted with Pr2O to
1
give 10j (63 mg, 87%) as an unstable solid: mp >250 °C; H
NMR [(CD3)2SO] δ 10.30 (s, 1 H, NH), 10.19 (2, 1 H, NH), 8.06
(d, J ) 8.5 Hz, 1 H, H-6), 7.75 (br s, 1 H, H-4), 7.73 (d, J ) 8.3
Hz, 1 H, H-9), 7.44 (t, J ) 7.5 Hz, 1 H, H-8), 7.27 (t, J ) 7.6
Hz, 1 H, H-7), 6.75 (s, 1 H, H-4 or H-4′), 6.69 (s, 1 H, H-4 or
H-4′), 5.95, 5.93 (2 × s, 2 H, NH2), 4.69 (d, J ) 11.5 Hz, 1 H,
H-2), 4.56 (dd, J ) 11.9, 8.8 Hz, 1 H, H-2), 4.10-4.03 (m, 1 H,
H-1), 3.94 (dd, J ) 10.9, 3.0 Hz, 1 H, CHHCl), 3.82 (s, 3 H,
N-CH3), 3.80 (s, 3 H, N-CH3), 3.69 (dd, J ) 10.9, 8.3 Hz, 1
H, CHHCl), 2.12 (s, 3 H, COCH3). Anal. (C25H25ClN8O3) C, H,
N, Cl.
5-Am in o-3-[(E)-3-[4-(bu tyr ylam in o)-1-m eth ylpyr r ol-2-yl]-
a c r y lo y l]-1-(c h lo r o m e t h y l)-1,2-d ih y d r o -3H -b e n z[e]-
in d ole (10k ). Deprotection of 11 (300 mg, 0.83 mmol) as above
and reaction with (E)-3-[4-(butyrylamino)-1-methylpyrrol-2-
yl]acrylic acid17 (197 mg, 0.83 mmol) and EDCI‚HCl (397 mg,
2.07 mmol) in DMA gave a product that was chromatographed
on silica gel. Elution with CH2Cl2/EtOAc (1:1), followed by
A mixture of 38 (450 mg, 2.66 mmol) and activated MnO2
(1.36 g, 85%, 13.3 mmol) in EtOAc (30 mL) was heated under
reflux for 2 h. The mixture was filtered, passed through a short
column of silica gel, and concentrated under reduced pressure
to give 3-(acetylamino)-1-methylpyrazole-2-carboxaldehyde (39)
(382 mg, 86%): mp (iPr2O) 148 °C; 1H NMR [(CD3)2SO] δ 10.65

3408 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17
Atwell et al.
(s, 1 H, NH), 9.85 (s, 1 H, CHO), 7.17 (s, 1 H, H-4), 4.00 (s, 3
H, NCH3), 2.02 (s, 3 H, CH3CO). Anal. (C7H9N3O2) C, H, N.
Hz, 1 H, CHHCl), 2.02 (s, 3 H, CH3CO). Anal. (C22H22ClN5O2‚
0.25H2O) C, H, N, Cl.
3-[(E)-3-(Acet yla m in o)cin n a m oyl]-5-a m in o-1-(ch lor o-
m eth yl)-1,2-d ih yd r o-3H-ben z[e]in d ole (10m ). Deprotection
of 16 (94 mg, 0.17 mmol) as above, followed by reaction with
EDCI‚HCl (81 mg, 0.42 mmol) and (E)-3-(acetylamino)cin-
namic acid (37 mg, 0.18 mmol) in DMA (2 mL), gave a solid
that was dissolved in EtOAc. Addition of petroleum ether
precipitated impurities that were removed by filtration. The
solution was then concentrated to small volume and diluted
A mixture of 39 (425 mg, 2.54 mmol) and malonic acid (396
mg, 3.81 mmol) in pyridine (5 mL) containing piperidine (1
drop) was heated at 100 °C for 2 h and then heated at reflux
for 5 min. The mixture was concentrated under reduced
pressure, the residue was shaken with 0.5 N HCl, and the
resulting solid was recrystallized from DMF/H2O to give (E)-
3-[3-(acetylamino)-1-methylpyrazol-5-yl]acrylic acid (40) (454
mg, 85%): mp 286-287 °C; 1H NMR [(CD3)2SO] δ 12.56 (br s,
1 H, CO2H), 10.43 (s, 1 H, NH), 7.49 (d, J ) 15.9 Hz, 1 H,
CHdCHCO2H), 6.91 (s, 1 H, H-4), 6.36 (d, J ) 15.8 Hz, 1 H,
CHdCHCO2H), 3.82 (s, 3 H, NCH3), 1.99 (S, 3 H, CH3CO).
Anal. (C9H11N3O3‚0.25H2O) C, H, N.
A solution of 11 (200 mg, 0.55 mmol) in THF (15 mL) was
hydrogenated over PtO2 at 55 psi for 1.5 h. The catalyst was
removed, the solvent was evaporated, and the resulting solid
was triturated with petroleum ether to give 5-amino-3-(tert-
butyloxycarbonyl)-1-(chloromethyl)-1,2-dihydro-3H-benz[e]in-
dole (15) (166 mg, 90%) as an unstable solid: mp >200 °C; 1H
NMR [(CD3)2SO] δ 8.01 (d, J ) 8.4 Hz, 1 H, H-6), 7.64 (d, J )
8.3 Hz, 1 H, H-9), 7.45-7.25 (underlying br, 1 H, H-4), 7.40
(t, J ) 7.4 Hz, 1 H, H-8), 7.20 (t, J ) 7.4 Hz, 1 H, H-7), 5.91
(s, 2 H, NH2), 4.11-3.87 (m, 4 H, H-1,2, CHHCl), 3.66 (dd, J
) 10.5, 8.3 Hz, 1 H, CHHCl), 1.53 (s, 9 H, C(CH3)3). Anal.
(C18H21ClN2O2) C, H, N, Cl.
i
with Pr2O to give crude 3-[(E)-3-(acetylamino)cinnamoyl]-1-
(chloromethyl)-5-(9-fluorenylmethyloxycarbonylamino-1,2-di-
hydro-3H-benz[e]indole (19) (47 mg, 43%): mp 208-209 °C,
which was used without further purification; 1H NMR [(CD3)2-
SO] δ 10.06 (s, 1 H, NHCO), 9.75 (s, 1 H, NHCO2), 8.65 (s, 1
H, H-4), 8.01-7.87 (m, 4 H, ArH), 7.85 (s, 1 H, H-2′), 7.77 (br
s, 2 H, ArH), 7.69-7.30 (m, 9 H, ArH), 7.62 (d, J ) 15.5 Hz, 1
H, PhCHdCH), 7.14 (d, J ) 15.4 Hz, 1 H, PhCHdCH), 4.65-
4.27 (m, 6 H, aliphatic H), 4.06 (dd, J ) 11.1, 3.0 Hz, 1 H,
CHHCl), 3.96 (dd, J ) 11.0, 7.2 Hz, 1 H, CHHCl), 2.07 (s, 3 H,
CH3).
A solution of 19 (31 mg, 0.048 mmol) in dry DMF (0.4 mL)
was treated at 20 °C with piperidine (0.04 mL). After 20 min
the mixture was poured into water and the precipitated solid
was collected, dried, and dissolved in EtOAc. The solution was
filtered through a short column of silica gel, and the eluates
i
were concentrated to small volume and diluted with Pr2O. The
resulting solid was recrystallized from EtOAc/iPr2O/petroleum
ether to give 10m (17 mg, 84%): mp >250 °C; 1H NMR [(CD3)2-
SO] δ 10.06 (s, 1 H, NH), 8.06 (d, J ) 8.5 Hz, 1 H, H-6), 7.86
(s, 1 H, H-2’), 7.83 (br s, 1 H, H-4), 7.72 (d, J ) 8.3 Hz, 1 H,
H-9), 7.65 (d, J ) 8.0 Hz, 1 H, H-4′), 7.59 (d, J ) 15.3 Hz, 1 H,
PhCHdCH), 7.50 (d, J ) 7.6 Hz, 1 H, H-6′), 7.44 (t, J ) 7.6
Hz, 1 H, H-8), 7.38 (t, J ) 7.9 Hz, 1 H, H-5’), 7.26 (t, J ) 7.7
Hz, 1 H, H-7), 7.11 (d, J ) 15.4 Hz, 1 H, PhCHdCH), 5.97 (s,
2 H, NH2), 4.54-4.42 (m, 1 H, H-2), 4.39 (d, J ) 9.5 Hz, 1 H,
H-2), 4.18-4.07 (m, 1 H, H-1), 3.96 (dd, J ) 10.9, 2.9 Hz, 1 H,
CHHCl), 3.75 (dd, J ) 10.9, 8.3 Hz, 1 H, CHHCl), 2.07 (s, 3 H,
CH3). Anal. (C24H22ClN3O2) C, H, N, Cl.
5-Am in o-1-(ch lor oet h yl)-3-[(E)-3-(5-m et h oxyin d ol-2-
yl)a cr yloyl]-1,2-d ih yd r o-3H-ben z[e]in d ole (10r ). A mix-
ture of 5-methoxyindole-2-carboxaldehyde23 (41) (601 mg, 3.43
mmol) and methyl (triphenylphosphoranylidene)acetate (1.43
g, 4.28 mmol) in dry benzene (30 mL) was heated at reflux for
1 h and then concentrated under reduced pressure. The residue
was chromatographed on silica gel, eluting with CH2Cl2/EtOAc
(9:1), to give methyl (E)-3-(5-methoxyindol-2-yl)acrylate (42)
(613 mg, 77%): mp (EtOAc/iPr2O) 180-181 °C; 1H NMR
[(CD3)2SO] δ 11.45 (s, 1 H, NH), 7.61 (d, J ) 16.0 Hz, 1 H,
CHdCHCO), 7.27 (d, J ) 8.8 Hz, 1 H, H-7), 7.04 (d, J ) 2.4
Hz, 1 H, H-4), 6.85 (dd, J ) 8.8, 2.5 Hz, 1 H, H-6), 6.83 (s, 1
H, H-3), 6.50 (d, J ) 15.9 Hz, 1 H, CHdCHCO), 3.75 (s, 3 H,
CH3), 3.72 (s, 3 H, CH3). Anal. (C13H13NO3) C, H, N.
A stirred mixture of 42 (0.55 g, 2.38 mmol), CsCO3 (3.26 g,
10.0 mmol), MeOH (8 mL), and water (2 mL) was heated at
reflux until homogeneous and then for a further 30 min. The
mixture was diluted with water (60 mL), concentrated under
reduced pressure, and acidified with aqueous HCl. The result-
ing precipitate was recrystallized from MeOH/H2O and then
EtOAc/iPr2O to give (E)-3-(5-methoxyindol-2-yl)acrylic acid (43)
(0.47 g, 91%), mp 213-215 °C (dec); 1H NMR [(CD3)2SO] δ
12.28 (br s, 1 H, CO2H), 11.41 (s, 1 H, NH). 7.53 (d, J ) 16.0
Hz, 1 H, CHdCHCO), 7.26 (d, J ) 8.8 Hz, 1 H, H-7), 7.04 (d,
J ) 2.4 Hz, 1 H, H-4), 6.83 (dd, J ) 8.8, 2.4 Hz, 1 H, H-6),
6.77 (s, 1 H, H-3), 6.41 (d, J ) 16.0 Hz, 1 H, CHdCHCO), 3.75
(s, 3 H, CH3). Anal. (C12H11NO3) C, H, N.
A solution of 9-fluorenylmethyl chloroformate (97%, 270 mg,
1.01 mmol) in dry CH2Cl2 (20 mL) was treated with 1-meth-
ylimidazole (90 mg, 1.10 mmol), followed by 15 (280 mg, 0.84
mmol). The mixture was stirred at 20 °C for 1.5 h and then
treated with additional 1-methylimidazole (18 mg, 0.22 mmol)
and 9-fluorenylmethyl chloroformate (54 mg, 0.20 mmol). The
mixture was stirred for a further 3 h and was then concen-
trated under reduced pressure, and the residue was chromato-
graphed on silica gel. Elution with CH2Cl2/petroleum ether (9:
i
1) gave a gum that was recrystallized from Pr2O/petroleum
ether to give give 3-(tert-butyloxycarbonyl)-1-(chloromethyl)-
5-(9-fluorenylmethyloxycarbonylamino)-1,2-dihydro-3H-benz-
[e]indole (16) (417 mg, 89%): mp 103-106 °C; 1H NMR
[(CD3)2SO] δ 9.73 (s, 1 H, NHCO2), 8.21 (br s, 1 H, H-4), 7.98
(d, J ) 8.5 Hz, 1 H, ArH), 7.95-7.85 (m, 3 H, ArH), 7.76 (br s,
2 H, ArH), 7.54 (t, J ) 7.5 Hz, 1 H, ArH), 7.48-7.27 (m, 5 H,
ArH), 4.46 (d, J ) 7.0 Hz, 2 H, aliphatic H), 4.32 (t, J ) 6.8
Hz, 1 H, aliphatic H), 4.26-4.11 (m, 2 H, aliphatic H), 4.11-
3.97 (m, 2 H, CHHCl, aliphatic H), 3.88 (dd, J ) 10.7, 6.9 Hz,
1 H, CHHCl), 1.52 (s, 9 H, C(CH3)3). Anal. (C33H31ClN2O4) C,
H, N, Cl.
A solution of 16 (234 mg, 0.42 mmol) in HCl-saturated
dioxane (12 mL) was stirred at 5 °C for 4 h and then
evaporated to dryness under reduced pressure below 30 °C to
give crude 17. Acid 40 (92 mg, 0.44 mmol), EDCI‚HCl (202
mg, 1.05 mmol), and DMA (2.5 mL) were then added, and the
mixture was stirred at 20 °C for 4 h. Basification by the slow
addition of dilute KHCO3 gave a precipitate that was collected,
washed with water, dried, dissolved in EtOAc, and filtered
through a short column of silica gel. The eluate was concen-
trated to a small volume under reduced pressure below 30 °C
i
and then diluted with Pr2O to complete the separation of crude
3-[(E)-3-[3-(acetylamino)-1-methylpyrazol-5-yl]acryloyl]-1-(chlo-
romethyl)-5-(9-fluorenylmethyloxycarbonylamino)-1,2-dihydro-
3H-benz[e]indole (18) (87 mg, 32%): mp 256 °C (dec) as an
unstable solid that was used without further characterization.
A solution of 18 (77 mg, 0.12 mmol) in DMF (1.0 mL) was
treated with piperidine (0.1 mL), stirred at 20 °C for 20 min,
i
and then diluted with Pr2O. The resulting crude product was
collected, washed with iPr2O, and purified by dissolving in
warm DMA and precipitating by addition of EtOAc/iPr2O,
giveing 10l (44 mg, 87%): mp >300 °C; 1H NMR [(CD3)2SO] δ
10.45 (s, 1 H, NH), 8.06 (d, J ) 8.5 Hz, 1 H, H-6), 7.81 (s, 1 H,
H-4), 7.72 (d, J ) 8.3 Hz, 1 H, H-9), 7.55 (d, J ) 15.2 Hz, 1 H,
CHdCHCO), 7.44 (t, J ) 7.5 Hz, 1 H, H-8), 7.26 (t, J ) 7.7
Hz, 1 H, H-7), 7.11 (d, J ) 15.1 Hz, 1 H, CHdCHCO), 7.10 (s,
1 H, pyrazole H-4), 5.95 & 5.94 (2 × s, 2 H, NH2), 4.50-4.37
(m, 2 H, H-2), 4.17-4.08 (m, 1 H, H-1), 3.95 (dd, J ) 11.0, 2.8
Hz, 1 H, CHHCl), 3.86 (s, 3 H, NCH3), 3.76 (dd, J ) 10.9, 7.9
Deprotection of 16 (361 mg, 0.65 mmol) as above was
followed by reaction with acid 43 (148 mg, 0.68 mmol) and
EDCI‚HCl (312 mg, 1.63 mmol) in DMA (2.5 mL) at 20 °C for
4 h. The mixture was diluted with KHCO3 solution, and the
precipitated solid was collected, washed with KHCO3 solution
and water, and dried to give crude, unstable 1-(chloromethyl)-
5-(9-fluorenylmethyloxycarbonylamino)-3-[(E)-3-(5-methoxyin-
dol-2-yl)acryloyl]-1,2-dihydro-3H-benz[e]indole (20) (360 mg).
A solution of this in DMF (2 mL) was treated at 20 °C with
piperidine (0.2 mL), left at 20 °C for 30 min, and then diluted

5-Amino-1-(Chloromethyl)-1,2-dihydro-3H-benz[e]indoles
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17 3409
with iPr2O/petroleum ether (1:1) (350 mL). After prolonged
cooling at 5 °C, the precipitated solid was collected and
chromatographed on silica gel, eluting with CH2Cl2/EtOAc (3:
2), to give a crude product which was recrystallized from CH2-
Cl2/EtOAc/iPr2O to give 10r (114 mg, 41% overall): mp >250
7.7 Hz, 1 H, H-7), 6.14 (s, 2 H, NH2), 4.45 (dd, J ) 11.0, 8.7
Hz, 1 H, H-2), 4.33 (d, J ) 11.2 Hz, 1 H, H-2), 4.24-4.16 (m,
1 H, H-1), 4.03 (dd, J ) 11.0, 3.0 Hz, 1 H, CHHCl), 3.84 (dd,
J ) 11.0, 7.1 Hz, 1 H, CHHCl). Anal. (C15H12ClF3N2O) C, H,
N, Cl. When catalytic reductions of the nitro compound were
conducted in a more polar solvent than benzene (e.g., THF),
more than one product was obtained.
1
°C; H NMR [(CD3)2SO] δ 11.53 (s, 1 H, NH), 8.06 (d, J ) 8.4
Hz, 1 H, H-6), 7.85 (br s, 1 H, H-4), 7.72 (d, J ) 8.3 Hz, H-9),
7.62 (d, J ) 15.2 Hz, 1 H, PhCHdCH), 7.45 (t, J ) 7.6 Hz, 1
H, H-8), 7.31 (d, J ) 8.8 Hz, 1 H, H-7′), 7.26 (t, J ) 7.6 Hz, 1
H, H-7), 7.16 (d, J ) 15.3 Hz, 1 H, PhCHdCH), 7.06 (d, J )
2.2 Hz, 1 H, H-4′), 6.85 (dd, J ) 8.8, 2.4 Hz, 1 H, H-6′), 6.82 (s,
1 H, H-3′), 5.97 & 5.95 (2 × s, 2 H, NH2), 4.50-4.38 (m, 2 H,
H-2), 4.19-4.10 (m, 1 H, H-1), 3.98 (dd, J ) 10.9, 2.8 Hz, 1 H,
CHHCl), 3.77 (s, 3 H, CH3), 3.73 (dd, J ) 10.9, 9.2 Hz, 1 H,
CHHCl). Anal. (C25H22ClN3O2) C, H, N, Cl.
5-Am in o-1-(ch lor om eth yl)-3-[(E)-3-m eth oxycin n am oyl]-
1,2-d ih yd r o-3H-ben z[e]in d ole (10n ). Deprotection of 11 (250
mg, 0.69 mmol) as above and reaction of the product with
EDCI‚HCl (331 mg, 1.73 mmol) and (E)-3-methoxycinnamic
acid (129 mg, 0.72 mmol) in DMA (3 mL) at 20 °C for 3 h,
followed by addition of dilute KHCO3, gave a solid. This was
recrystallized from CH2Cl2/iPr2O followed by EtOAc to give
1-(chloromethyl)-3-[(E)-3-methoxycinnamoyl]-5-nitro-1,2-dihy-
dro-3H-benz[e]indole (13n ) (215 mg, 74%): mp 200 °C; 1H
NMR [(CD3)2SO] δ 9.22 (s, 1 H, H-4), 8.33 (dd, J ) 7.9, 1.8
Hz, 1 H, H-6), 8.19 (dd, J ) 7.5, 1.7 Hz, 1 H, H-9), 7.78-7.68
(m, 2 H, H-7,8), 7.72 (d, J ) 15.4 Hz, 1 H, PhCHdCH), 7.45-
7.34 (m, 2 H, H-5′,6′), 7.39 (s, 1 H, H-2′), 7.26 (d, J ) 15.4 Hz,
1 H, PhCHdCH), 7.02 (dt, J ) 7.2, 2.2 Hz, 1 H, H-4′), 4.71-
4.56 (m, 3 H, H-1,2), 4.11-4.05 (m, 2 H, CH2Cl), 3.84 (s, 3 H,
CH3). Anal. (C23H19ClN2O4) C, H, N, Cl.
MeOH (5 mL), H2O (2 mL), AcOH (0.2 mL), and Fe powder
(0.5 g) were added sequentially to a hot solution of 13n (110
mg, 0.26 mmol) in THF (10 mL). The mixture was heated at
reflux for 1 h, then basified with CaO (1 g), filtered, concen-
trated to a small volume under reduced pressure below 30 °C,
and diluted with water. The resulting precipitate was chro-
matographed on silica gel, eluting with CH2Cl2/EtOAc (9:1),
to give a solid which was recrystallized from CH2Cl2/petroleum
ether to give 10n (55 mg, 54%): mp >200 °C; 1H NMR [(CD3)2-
SO] δ 8.06 (d, J ) 8.5 Hz, 1 H, H-6), 7.83 (br s, 1 H, H-4), 7.72
(d, J ) 8.3 Hz, 1 H, H-9), 7.63 (d, J ) 15.4 Hz, 1 H, PhCHd
CH), 7.44 (t, J ) 7.4 Hz, 1 H, H-8), 7.40-7.34 (m, 3 H, PhH),
7.26 (t, partially obscured, J ) 7.9 Hz, 1 H, H-7), 7.22 (d, J )
15.4 Hz, 1 H, PhCHdCH), 7.04-6.97 (m, 1 H, PhH), 5.95 (br
s, 2 H, NH2), 4.53-4.38 (m, 2 H, H-2), 4.19-4.08 (m, 1 H, H-1),
3.95 (dd, J ) 11.0, 2.9 Hz, 1 H, CHHCl), 3.83 (s, 3 H, OCH3),
3.76 (dd, J ) 10.9, 8.1 Hz, 1 H, CHHCl). Anal. (C23H21ClN2O2)
C, H, N, Cl.
3-[(E)-4-(Acet yla m in o)cin n a m oyl]-5-a m in o-1-(ch lor o-
m eth yl)-1,2-d ih yd r o-3H-ben z[e]in d ole (10o). Deprotection
of 11 (302 mg, 0.83 mmol) as above and evaporation of the
reaction to dryness under reduced pressure gave 12 that was
dissolved in pyridine (5 mL). The stirred solution was treated
dropwise at 0 °C with trifluoroacetic anhydride (0.14 mL, 0.99
mmol). The mixture was stirred for a further 10 min at 20 °C
and then poured into water, and the precipitated solid was
dissolved in CH2Cl2 and filtered through a column of silica gel.
The solvent was removed under reduced pressure, and the
residue was crystallized from EtOAc/petroleum ether to give
1-(chloromethyl)-5-nitro-3-(trifluoroacetyl)-1,2-dihydro-3H-ben-
z[e]indole (26) (241 mg, 81%): mp 182 °C; 1H NMR (CDCl3) δ
9.10 (s, 1 H, H-4), 8.49-8.43 (m, 1 H, H-6), 7.93-7.87 (m, 1
H, H-9), 7.76-7.68 (m, 2 H, H-7,8), 4.70 (dt, J ) 11.4, 1.4 Hz,
1 H, H-2), 4.51 (dd, J ) 11.5, 8.6 Hz, 1 H, H-2), 4.35-4.28 (m,
1 H, H-1), 3.97 (dd, J ) 11.7, 3.4 Hz, 1 H, CHHCl), 3.64 (dd,
J ) 11.7, 8.8 Hz, 1 H, CHHCl). Anal. (C15H10ClF3N2O3) C, H,
N, Cl.
A mixture of 27 (200 mg, 0.61 mmol) and di-tert-butyl
dicarbonate (266 mg, 1.22 mmol) in dioxane (20 mL) was
stirred at 65 °C under N2 with the exclusion of light for 4 h.
Additional di-tert-butyl dicarbonate (200 mg, 0.92 mmol) was
added, and the mixture was stirred for a further 8 h at 70 °C
and then concentrated under reduced pressure. The residue
was chromatographed on silica gel, eluting with petroleum
ether/CH2Cl2 (1:3), to provide a solid which was recrystallized
from iPr2O/petroleum ether to give 5-(tert-butyloxycarbony-
lamino)-1-(chloromethyl)-3-(trifluoroacetyl)-1,2-dihydro-3H-
benz[e]indole (28) (192 mg, 74%): mp 185 °C; 1H NMR
[(CD3)2SO] δ 9.41 (s, 1 H, NH), 8.48 (s, 1 H, H-4), 8.10 (d, J )
8.4 Hz, 1 H, H-6), 8.01 (d, J ) 8.2 Hz, 1 H, H-9), 7.61 (t, J )
7.1 Hz, 1 H, H-8), 7.52 (t, J ) 7.7 Hz, 1 H, H-7), 4.56 (dd, J )
11.1, 9.7 Hz, 1 H, H-2), 4.47-4.37 (m, 2 H, H-1,2), 4.12 (dd, J
) 11.1, 2.8 Hz, 1 H, CHHCl), 4.01 (dd, J ) 11.2, 5.8 Hz, 1 H,
CHHCl), 1.50 (s, 9 H, C(CH3)3). Anal. (C20H20ClF3N2O3) C, H,
N, Cl.
A stirred solution of 28 (180 mg, 0.42 mmol) in N-meth-
ylpyrrolidone (4.5 mL) was treated dropwise at 20 °C with a
solution of Cs2CO3 (1.2 g) in water (2.7 mL). The mixture was
stirred for a further 45 min at 20 °C, then diluted with water
(35 mL), and extracted with benzene (2 × 25 mL). The
combined organic extracts were washed with water (2×), dried
(Na2SO4), and concentrated under reduced pressure below 30
°C. The residue was treated sequentially with EDCI‚HCl (201
mg, 1.05 mmol), (E)-4-(acetylamino)cinnamic acid (86 mg, 0.42
mmol), DMA (2 mL), and DMA‚HCl (52 mg, 0.42 mmol). The
mixture was stirred at 20 °C for 30 min and then diluted with
KHCO3 solution. The precipitated solid was collected, washed
with water, dried, and dissolved in warm EtOAc. This solution
was filtered through
a short column of silica gel, then
concentrated to a small volume, and diluted with iPr2O/
petroleum ether to give 3-[(E)-4-(acetylamino)cinnamoyl]-5-
(tert-butyloxycarbonylamino)-1-(chloromethyl)-1,2-dihydro-3H-
benz[e]indole (29) (97 mg, 44%): mp >300 °C, that was used
1
without further purification; H NMR [(CD3)2SO] δ 10.15 (br
s, 1 H, NHCO), 9.28 (br s, 1 H, NHCO2), 8.64 (br s, 1 H, H-4),
8.02 (d, J ) 8.1 Hz, 1 H, H-6), 7.92 (d, J ) 8.3 Hz, 1 H, H-9),
7.76 (d, J ) 8.6 Hz, 2 H, H-3′,5′), 7.67 (d, J ) 9.1 Hz, 2 H,
H-2′,6′), 7.64 (d, J ) 15.6 Hz, 1 H, PhCHdCH), 7.55 (t, J )
7.3 Hz, 1 H, H-8), 7.43 (t, J ) 7.5 Hz, 1 H, H-7), 7.13 (br d, J
) 15.3 Hz, 1 H, PhCHdCH), 4.60-4.45 (m, 2 H, H-2), 4.35
(br s, 1 H, H-1), 4.02 (dd, J ) 11.1, 3.0 Hz, 1 H, CHHCl), 3.92
(dd, J ) 11.0, 7.2 Hz, 1 H, CHHCl), 2.08 (s, 3 H, CH3CO), 1.51
(s, 9 H, C(CH3)3.
A cold suspension of 29 (83 mg, 0.16 mmol) in dioxane (8
mL) was saturated with HCl gas and left at 20 °C for 10 min.
The mixture was diluted with EtOAc/petroleum ether, and the
product was collected and partitioned between dilute KHCO3
and EtOAc. The organic layer was washed with water, dried
(Na2SO4), and filtered through a short column of silica gel. The
solution was concentrated to small volume under reduced
pressure below 30 °C and then diluted with petroleum ether
to give 10o (54 mg, 81%): mp >250 °C; 1H NMR [(CD3)2SO] δ
10.14 (s, 1 H, NH), 8.05 (d, J ) 8.5 Hz, 1 H, H-6), 7.83 (br s,
1 H, H-4), 7.74 (d, J ) 8.8 Hz, 2 H, H-3′,5′), 7.72 (d, J ) 9.1
Hz, 1 H, H-9), 7.66 (d, J ) 8.5 Hz, 2 H, H-2′,6′), 7.60 (d, J )
15.3 Hz, 1 H, PhCHdCH), 7.44 (t, J ) 7.5 Hz, 1 H, H-8), 7.26
(t, J ) 7.6 Hz, 1 H, H-7), 7.10 (d, J ) 15.3 Hz, 1 H, PhCHd
CH), 5.97 (br s, 2 H, NH2), 4.50-4.35 (m, 2 H, H-2), 4.12 (br
s, 1 H, H-1), 3.95 (dd, J ) 10.9, 2.6 Hz, 1 H, CHHCl), 3.74 (dd,
A solution of 26 (175 mg, 0.49 mmol) in benzene (30 mL)
was hydrogenated over PtO2 (45 mg) at 50 psi for 1 h. Removal
of the catalyst and solvent provided a solid which was
J ) 10.6, 8.5 Hz, 1 H, CHHCl), 2.07 (s, 3 H, CH3). Anal. (C24H22
ClN3O2) C, H, N, Cl.
-
i
recrystallized from Pr2O/petroleum ether to give 5-amino-1-
5-Am in o-1-(ch lor om eth yl)-3-[(E)-4-m eth oxycin n am oyl]-
1,2-d ih yd r o-3H-ben z[e]in d ole (10p ). A stirred solution of
28 (100 mg, 0.23 mmol) in N-methylpyrrolidone (2.5 mL) was
hydrolyzed with Cs2CO3 as above, and the resulting crude
product was dissolved in pyridine (2 mL), cooled to -5 °C, and
(chloromethyl)-3-(trifluoroacetyl)-1,2-dihydro-3H-benz[e]in-
dole (27) (143 mg, 89%): mp 177 °C; 1H NMR [(CD3)2SO] δ
8.11 (d, J ) 8.4 Hz, 1 H, H-6), 7.80 (d, J ) 8.3 Hz, 1 H, H-9),
7.60 (s, 1 H, H-4), 7.50 (t, J ) 7.7 Hz, 1 H, H-8), 7.35 (t, J )

3410 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17
Atwell et al.
treated with (E)-4-methoxycinnamoyl chloride (46 mg, 0.23
mmol) followed by DMAP (5 mg). The mixture was stirred at
20 °C for 45 min and then diluted with KHCO3 solution. The
precipitated solid was collected, washed with water, dried, and
chromatographed on silica gel. Elution with CH2Cl2/EtOAc
gave a crude product that was recrystallized from CH2Cl2/
petroleum ether to give 5-(tert-butyloxycarbonylamino)-1-
(chloromethyl)-3-[(E)-4-methoxycinnamoyl]-1,2-dihydro-3H-
benz[e]indole (30) (55 mg, 48%): mp 185-185.5 °C, that was
used without further purification; 1H NMR [(CD3)2SO] δ 9.28
(br s, 1 H, NH), 8.64 (br s, 1 H, H-4), 8.01 (d, J ) 8.1 Hz, 1 H,
H-6), 7.92 (d, J ) 8.3 Hz, 1 H, H-9), 7.78 (d, J ) 8.6 Hz, 2 H,
H-2′,6′), 7.66 (d, J ) 15.3 Hz, 1 H, PhCHdCH), 7.54 (t, J )
7.6 Hz, 1 H, H-8), 7.42 (t, J ) 7.7 Hz, 1 H, H-7), 7.10 (d, J )
15.2 Hz, 1 H, PhCHdCH), 7.01 (d, J ) 8.7 Hz, 2 H, H-3’,5’),
4.60-4.44 (m, 2 H, H-2), 4.41-4.28 (m, 1 H, H-1), 4.02 (dd, J
) 11.1, 3.0 Hz, 1 H, CHHCl), 3.92 (dd, J ) 11.1, 7.2 Hz, 1 H,
CHHCl), 3.82 (s, 3 H, OCH3), 1.51 (s, 9 H, C(CH3)3).
4.42 (t, J ) 5.1 Hz, 2 H, OCH2CH2), 3.51 (t, J ) 5.1 Hz, 2 H,
OCH2CH2), 2.83 (s, 6 H, N(CH3)2). Anal. (C13H17NO3.HCl) C,
H, N, Cl.
A stirred solution of 15 (456 mg, 1.37 mmol) in pyridine (5
mL) was treated dropwise at -5 °C with allyl chloroformate
(0.29 mL, 2.74 mmol). The mixture was stirred at 0 °C for 1
h, at 20 °C for a further 1 h, then concentrated under reduced
pressure below 30 °C. The residue was shaken with water,
the precipitated oil was collected and dissolved in CH2Cl2, and
the solution was washed with water, dried, and concentrated
under reduced pressure. The residue was extracted with hot
petroleum ether, and treated with decolorizing charcoal, and
the filtered solution was evaporated to give 5-(allyloxycarbo-
nylamino)-3-(tert-butyloxycarbonyl)-1-(chloromethyl)-1,2-dihy-
dro-3H-benz[e]indole (23) (479 mg, 84%) as a foam: 1H NMR
[(CD3)2SO] δ 9.67 (s, 1 H, NH), 8.24 (br s, 1 H, H-4), 8.03 (d,
J ) 8.5 Hz, 1 H, H-6), 7.87 (d, J ) 8.3 Hz, 1 H, H-9), 7.52 (t,
J ) 7.5 Hz, 1 H, H-8), 7.39 (td, J ) 7.7, 0.9 Hz, 1 H, H-7),
6.07-5.95 (m, 1 H, CHdCH2), 5.39 (d, J ) 14.1 Hz, 1 H, CHd
CHH), 5.25 (dd, J ) 10.4, 1.2 Hz, 1 H, CHdCHH), 4.65 (d, J
) 5.3 Hz, 2 H, OCH2), 4.25-4.12 (m, 2 H, H-1,2), 4.07 (d, J )
9.3 Hz, 1 H, H-2), 4.01 (dd, J ) 11.0, 2.4 Hz, 1 H, CHHCl),
3.87 (dd, J ) 10.8, 6.7 Hz, 1 H, CHHCl). Anal. (C22H25ClN2O4)
C, H, N.
A cold suspension of 30 (46 mg, 0.09 mmol) in dioxane (5
mL) was saturated with HCl gas and left at 20 °C for 10 min.
The mixture was diluted with EtOAc/petroleum ether, and the
product was collected and partitioned between dilute KHCO3
and EtOAc. The organic layer was washed with water, dried
(Na2SO4), and concentrated under reduced pressure below 30
°C, and the residue was chromatographed on silica gel. Elution
with CH2Cl2/EtOAc (2:1) gave a solid which was recrystallized
from CH2Cl2/petroleum ether to give 10p (26 mg, 71%): mp
A solution of 23 (489 mg, 1.17 mmol) in HCl-saturated
dioxane (8 mL) was stirred at 5 °C for 3 h and then evaporated
to dryness under reduced pressure below 25 °C to give 24. Acid
22 (335 mg, 1.23 mmol), EDCI‚HCl (562 mg, 2.93 mmol), and
DMA (5 mL) were then added, and the mixture was stirred at
20 °C in the dark for 12 h and then poured into dilute KHCO3.
The precipitated solid was collected, washed with water, and
dissolved in CH2Cl2. The solution was washed with water,
dried, and concentrated under reduced pressure below 25 °C
to give crude 5-(allyloxycarbonylamino)-1-(chloromethyl)-3-
[(E)-4-[2-(dimethylamino)ethoxy]cinnamoyl]-1,2-dihydro-3H-
benz[e]indole (25). This intermediate (346 mg, 0.65 mmol) was
immediately dissolved in THF (15 mL), and the solution was
treated with morpholine (0.40 mL, 4.59 mmol), PPh3 (8 mg, 5
mol %), and Pd(PPh3)4 (75 mg, 10 mol %). The mixture was
stirred at 20 °C under N2 for 1.5 h and then concentrated under
reduced pressure below 25 °C. The residue was dissolved in
EtOAc, and the solution was diluted with iPr2O/petroleum
ether (1:1), precipitating a solid that was chromatographed
on alumina-90. Elution with EtOAc/MeOH (19:1) provided a
crude product that was crystallized twice from EtOAc/iPr2O/
petroleum ether to give 10q (79 mg, 15% over two steps): mp
1
114-116 °C; H NMR [(CD3)2SO] δ 8.05 (d, J ) 8.4 Hz, 1 H,
H-6), 7.82 (br s, 1 H, H-4), 7.76 (d, J ) 8.7 Hz, 2 H, H-2′,6′),
7.71 (d, J ) 8.3 Hz, 1 H, H-9), 7.62 (d, J ) 15.3 Hz, 1 H,
PhCHdCH), 7.44 (t, J ) 7.5 Hz, 1 H, H-8), 7.01 (d, J ) 8.7
Hz, 2 H, H-3′,5′), 5.96 (br s, 2 H, NH2), 4.49-4.36 (m, 2 H,
H-2), 4.17-4.06 (m, 1 H, H-1), 3.94 (dd, J ) 11.0, 2.9 Hz, 1 H,
CHHCl), 3.82 (s, 3 H, OCH3), 3.74 (dd, J ) 10.9, 8.3 Hz, 1 H,
CHHCl). Anal. (C23H21ClN2O2) C, H, N, Cl.
5-Am in o-1-(ch lor om eth yl)-3-[(E)-4-[2-(d im eth yla m in o)-
eth oxy]cin n a m oyl]-1,2-d ih yd r o-3H-ben z[e]in d ole (10q).
An ice-cold solution of 2-(dimethylamino)ethyl chloride hydro-
chloride (5.0 g, 34.7 mmol) in water (16 mL) was treated with
an ice-cold solution of NaOH (1.67 mL, 41.75 mmol) in water
(8 mL) and then saturated by addition of solid NaCl. The
mixture was extracted with toluene (16 mL × 4), and the
combined extracts were dried over KOH pellets. A stirred
solution of methyl (E)-4-hydroxycinnamate (4.12 g, 23.1 mmol)
in DMF (10 mL) was treated portionwise at 0 °C with NaH
(925 mg, 23.1 mmol, 60% in oil) and then stirred at 20 °C for
a further 1 h. The above toluene solution of 2-(dimethylamino)-
ethyl chloride was added, and the mixture was stirred at reflux
for 2 h, then treated with AcOH (1 mL), and concentrated
under reduced pressure. The residue partitioned between
dilute KHCO3 and EtOAc (125 mL). The organic layer was
washed with water and then extracted with 1 N HCl (2 × 50
mL). The combined acidic layers were washed with EtOAc,
treated with excess solid KHCO3, then extracted with EtOAc
(50 mL × 2). The combined organic layers were dried and
concentrated under reduced pressure to give methyl (E)-4-[2-
(dimethylamino)ethoxy]cinnamate (21) (4.02 g, 70%): mp
1
147-150 °C; H NMR [(CD3)2SO] δ 8.05 (d, J ) 8.5 Hz, 1 H,
H-6), 7.82 (br s, 1 H, H-4), 7.74 (d, J ) 8.7 Hz, 2 H, H-2′,6′),
7.71 (d, J ) 8.6 Hz, 1 H, H-9), 7.61 (d, J ) 15.3 Hz, 1 H,
PhCHdCH), 7.44 (H, J ) 7.3 Hz, 1 H, H-8), 7.25 (t, J ) 7.6
Hz, 1 H, H-7), 7.07 (d, J ) 15.3 Hz, 1 H, PhCHdCH), 7.01 (d,
J ) 8.7 Hz, 2 H, H-3′,5′), 5.94, 5.92 (2 × s, 2 H, NH2), 4.47-
4.37 (m, 2 H, H-2), 4.16-4.06 (m, 3 H, H-1, OCH2), 3.95 (dd,
J ) 11.0, 3.0 Hz, 1 H, CHHCl), 3.73 (dd, J ) 10.9, 8.3 Hz, 1
H, CHHCl), 2.64 (t, J ) 5.8 Hz, 2 H, OCH2CH2), 2.22 (s, 6 H,
N(CH3)2). Anal. (C26H28ClN3O2) C, H, N, Cl. Treatment of the
free base with HCl/EtOAc/petroleum ether, followed by crys-
tallization from MeOH/EtOAc, gave the hydrochloride salt.
1
(petroleum ether) 47-48 °C; H NMR [(CD3)SO] δ 7.66 (d, J
Gr ow th In h ibition Assa y. Cell lines were maintained as
monolayers in exponential phase growth using R-MEM con-
taining fetal bovine serum (5% v/v) without antibiotics. Drug
stock solutions were stored frozen in DMSO and diluted into
culture medium (with adjustment of pH to 7.4 under 5% CO2
if necessary) immediately before use to give final DMSO
concentrations <1%. Drug concentrations were checked rou-
tinely by spectrophotometry in 0.1 N HCl, or by HPLC. Growth
inhibitory potency under aerobic conditions was determined
using log-phase cultures in 96-well plates. Cultures were
initiated using 200 AA8 cells, 300 UV4 cells, 50 EMT6 cells,
or 600 SKOV3 cells in 50 µL medium per well. After 24 h,
drugs were added and cultures were incubated at 37 °C in a
5% CO2 incubator for 4 h. Cultures were then washed
thoroughly with fresh medium and grown for a further 4 days
(5 days for SKOV3) in 150 µL medium, and cell density was
then determined by staining with sulforhodamine B.32 The IC50
was calculated as the drug concentration providing 50%
) 8.8 Hz, 2 H, H-2′,6′), 7.61 (d, J ) 16.0 Hz, 1 H, PhCHdCH),
6.98 (d, J ) 8.8 Hz, 2 H, H-3′,5′), 6.49 (d, J ) 16.0 Hz, 1 H,
PhCHdCH), 4.09 (t, J ) 5.8 Hz, 2 H, OCH2CH2), 3.71 (s, 3 H,
OCH3), 2.62 (t, J ) 5.8 Hz, 2 H, OCH2CH2), 2.21 (s, 6 H,
N(CH3)2). Anal. (C14H19NO3) C, H, N.
The ester 21 (2.0 g, 8.0 mmol) was added to a solution of
NaOH (0.5 g) in water (6 mL) and MeOH (6 mL), and the
mixture was heated at reflux for 45 min. The solution was
diluted with water, concentrated to 10 mL, and acidified with
excess 12 N HCl. After cooling, the resulting solid was
collected, washed with cold 2 N HCl and acetone, and
recrystallized from water to give (E)-4-[2-(dimethylamino)-
ethoxy]cinnamic acid hydrochloride (22) (1.57 g, 72%): mp
1
(MeOH/EtOAc) 257-258 °C; H NMR [(CD3)2SO] δ 12.27 (br
s, 1 H, CO2H), 10.73 (br s, 1 H, NH+), 7.68 (d, J ) 8.8 Hz, 2 H,
H-2′,6′), 7.56 (d, J ) 16.0 Hz, 1 H, PhCHdCH), 7.05 (d, J )
8.8 Hz, 2 H, H-3′,5′), 6.42 (d, J ) 16.1 Hz, 1 H, PhCHdCH),

5-Amino-1-(Chloromethyl)-1,2-dihydro-3H-benz[e]indoles
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 17 3411
(13) Denny, W. A. The design of selectively activated prodrugs for
cancer chemotherapy. Curr. Pharm. Des. 1996, 2, 281-294.
(14) Patel, J . U.; Prankerd, R. J .; Sloan, K. B. A prodrug approach
to increasing the oral potency of a phenolic drug. 1. Synthesis,
characterization, and stability of an O-(imidomethyl) derivative
of 17 beta-estradiol. J . Pharm. Sci. 1994, 83, 1477-1481.
(15) Tercel, M.; Denny, W. A.; Wilson, W. R. Nitrogen and sulfur
analogues of the seco-CI alkyating agent: synthesis and cyto-
toxicity. Bioorg. Med. Chem. Lett. 1996, 6, 2735-2740.
(16) Tercel, M.; Denny, W. A. Synthesis of nitrogen and sulfur
analogues of the seco-CI alkylating agent. J . Chem. Soc., Perkin
Trans. 1 1998, 509-519.
(17) Milbank, J . B. J .; Tercel, M.; Atwell, G. J .; Wilson, W. R.; Hogg,
A.; Denny, W. A. Synthesis of 1-substituted 3-(chloromethyl)-6-
aminoindoline (6-amino-seco-CI) DNA minor groove alkylating
agents and structure-activity relationships for the cytotoxicity.
J . Med. Chem. 1999, 42, 649-658.
(18) Atwell, G. J .; Wilson, W. R.; Denny, W. A. Synthesis and
cytotoxicity of amino analogues of the potent DNA alkylating
agent seco-CBI-TMI. Bioorg. Med. Chem. Lett. 1997, 7, 1493-
1496.
(19) Atwell, G. J .; Tercel, M.; Boyd, M.; Wilson, W. R.; Denny, W. A.
Synthesis and cytotoxicity of 5-amino-1-(chloromethyl)-3-[(5,6,7-
trimethoxyindol-2-yl)carbonyl]-1,2-dihydro-3H-benz[e]indole (ami-
no-seco-CBI-TMI) and related 5-alkylamino analogues: new
DNA minor groove alkylating agents. J . Org. Chem. 1998, 63,
9414-9420.
(20) Warpehoski, M. A.; Gebhard, I.; Kelly, R. C.; Krueger, W. C.;
Li, L. H.; McGovren, J . P.; Prairie, M. D.; Wicnienski, N.;
Wierenga, W. Stereoelectronic factors influencing the biological
activity and DNA interaction of synthetic antitumor agents
modeled on CC-1065. J . Med. Chem. 1988, 31, 590-603.
(21) Lee, H. H.; Boyd, M.; Gravatt, G. L.; Denny, W. A. Pyrazole
analogues of the bispyrrolecarboxamide antitumour antibiotics:
synthesis, DNA binding and antitumour properties. Anti-Cancer
Drug Des. 1991, 6, 501-517.
(22) Lee, H. H.; Cain, B. F.; Denny, W. A.; Buckleton, J .; Clark, G.
R. Synthesis and characterization of masked aminopyrazolecar-
boxylic acid synthons. J . Org. Chem. 1989, 54, 428-431.
(23) Leon, P.; Garbay-J aureguiberry, C.; Barsi, M. C.; Le Pecq, J .
B.; Roques, P. B. Modulation of the antitumor activity by methyl
substitution in the series of 7H-pyridocarbazole monomers and
dimers. J . Med. Chem. 1987, 30, 2074-2080.
(24) Hoy, C. A.; Salazar, E. P.; Thompson. L. H. Rapid detection of
DNA-damaging agents using repair-deficient CHO cells. Mutat.
Res. 1984, 130, 321-332.
(25) Hoy, C. A.; Thompson, L. H.; Mooney, C. L.; Salazar, E. P.
Defective DNA cross-link removal in Chinese hamster cell
mutants hypersensitive to bifunctional alkylating agents. Cancer
Res. 1985, 45, 1737-1743.
(26) Gieseg, M. A.; Matejovic, J .; Denny, W. A. Comparison of the
patterns of DNA alkylation by phenol and amino seco-CBI-TMI
compounds: use of a PCR method for the facile preparation of
single end-labeled double stranded DNA. Anti-Cancer Drug Des.,
in press.
(27) Boger, D. L.; Bollinger, B.; J ohnson, D. S. Examination of the
role of the duocarmycin SA methoxy substituents: identification
of the minimum, fully potent DNA binding subunit. Bioorg. Med.
Chem. Lett. 1996, 6, 2207-2210.
(28) Fregeau, N. L.; Wang, Y.; Pon, R. T.; Wylie, W. A.; Lown, J . W.
Characterization of a CPI-lexitropsin conjugate-oligonucleotide
covalent complex by 1H NMR and restrained molecular dynamics
simulation. J . Am. Chem. Soc. 1995, 117, 8917-8925.
(29) Nagamura, S.; Asai, A.; Amishiro, N.; Kobayashi, E.; Gomi, K.;
Saito, H. Synthesis and antitumor activity of duocarmycin
derivatives: A-ring pyrrole compounds bearing cinnamoyl groups.
J . Med. Chem. 1997, 40, 972-979.
(30) Parmerter, S. M.; Cook, A. G.; Dixon, W. B. The synthesis of
4-nitro, 6-nitro and 7-nitroindole. J . Am. Chem. Soc. 1958, 80,
4621-4622.
(31) Boger D. L.; Yun, W.; Han, N. 1,2,9,9a-Tetrahydrocyclopropa-
[c]benz[e]indol-4-one (CBI) analogues of CC-1065 and the duo-
carmycins: synthesis and evaluation. Bioorg. Med. Chem. 1995,
3, 1429-1453.
(32) Skehan, P.; Storeng, R.; Scuderio, D.; Monks, A.; McMahon, J .;
Vistica, D.; Warren, J . T.; Bokesch, H.; Kenney, S.; Boyd, M. R.
New colorimetric cytotoxicity assay for anticancer-drug screen-
ing. J . Natl. Cancer Inst. 1990, 82, 1107-1112.
inhibition of growth relative to controls on the same multiwell
plate.
Mou se Toxicity. Compounds were formulated in DMSO/
poly(ethylene glycol) (MW 400)/water (1:4:5, v/v/v) immediately
before use. Male C3H mice (ca. 25 g) were treated ip with single
doses of compounds at 0.01 mL/g body weight, using 101/8-fold
dose increments, and were observed daily. Animals becoming
moribund during the study, and those still alive after 60 days,
were terminated and a necropsy was performed. Grossly
identifiable lesions were fixed in neutral buffered formalin,
paraffin embedded, and processed for histology with hema-
toxylin and eosin staining.
Ack n ow led gm en t. This work was supported by the
Health Research Council of New Zealand and the
Auckland Division of the Cancer Society of New Zealand,
and by contract NO1-CM 47019 from the National
Cancer Institute, USA. We thank Alan E. Lee for
performing the mouse toxicity studies and Dr. L. J . Zwi
for interpretation of the histology.
Refer en ces
(1) Reynolds, V. L.; McGovren, J . P.; Hurley, L. H. The chemistry,
mechanism of action, and biological properties of CC-1065, a
potent antitumor antibiotic J . Antibiot. 1986, 34, 319-334.
(2) Yasuzawa, T.; Muroi, K.; Ichimura, M.; Takahashi, I.; Ogawa,
T.; Takahashi, K.; Sano, H.; Saitoh, Y. Duocarmycins, potent
antitumor antibiotics produced by Streptomyces sp. structures
and chemistry. Chem. Pharm. Bull. 1995, 43, 378-391.
(3) Kobayashi, E.; Okamoto, A.; Asada, M.; Okabe, M.; Nagamura,
S.; Asai, A.; Saito, H.; Gomi, K.; Hirata, T. Characteristics of
antitumor activity of KW-2189, a novel water-soluble derivative
of duocarmycin, against murine and human tumors. Cancer Res.
1994, 54, 2404-2410.
(4) D’Incalci, M.; Sessa, C. DNA minor groove binding ligands: a
new class of anticancer drugs. Exp. Opin. Invest. Drugs 1997,
6, 875-884.
(5) Boger, D. L.; J ohnson, D. S. CC-1065 and the duocarmycins:
understanding their biological function through mechanistic
studies. Angew. Chem., Int. Ed. Engl. 1996, 35, 1438-1474.
(6) Boger, D. L.; Hertzog, D. L.; Bollinger, B.; J ohnson, D. S.; Cai,
H.; Goldberg, J .; Turnbull, P. Duocarmycin SA shortened,
simplified and extended agents: a systematic examination of
the role of the DNA binding subunit. J . Am. Chem. Soc. 1997,
119, 4977-4986.
(7) Boger, D. L.; Yun, W. CBI-TMI: synthesis and evaluation of a
key analogue of the duocarmycins. Validation of
a direct
relationship between chemical solvolytic stability and cytotoxic
potency and confirmation of the structural features responsible
for distinguishing behaviour of the enantiomeric pairs of agents.
J . Am. Chem. Soc. 1994, 116, 7996-8006.
(8) Boger, D. L.; Ishizaki, T.; Kitos, P. A.; Suntornwat, O. Synthesis
of N-(tert-butyloxycarbonyl)-CBI, CBI, CBI-CDPI1 and CBI-
CDPI2: enhanced functional analogues of CC-1065 incorporating
the 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CBI) left-
hand subunit. J . Org. Chem. 1990, 55, 5823-5832.
(9) Boger, D. L.; J ohnson. D. S.; Yun, W. (+)- and ent-(-)-duocar-
mycin SA and ent-(-)-N-BOC-DSA DNA alkylating properties.
Alkylation site models ther accommodate the offset AT-rich
adenine N3 alkylation selectivity of the enantiomeric agents. J .
Am. Chem. Soc. 1994, 116, 1635-1656.
(10) (a) Foster, B. J .; LoRusso, P. M.; Poplin, E.; Zalupski, M.;
Valdivieso, M.; Wozniak, A.; Flaherty, L.; Kasunic, D. A.;
Earhart, R. H.; Baker, L. H. Phase I trial of adozelesin using
the treatment schedule of daily ×5 every 3 weeks. Invest. New
Drugs. 1996, 13, 321-326. (b) Burris, H. A.; Dieras, V. C.; Tunca,
M.; Earhart, R. H.; Eckardt, J . R.; Rodriguez, G. I.; Shaffer, D.
S.; Fields, S. M.; Campbell, E.; Schaaf, L.; Kasunic, D.; Von Hoff,
D. D. Phase I study with the DNA sequence-specific agent
adozelesin. Anti-Cancer Drugs 1997, 8, 588-596.
(11) Li, L. H.; DeKoning, T. F.; Kelly, R. C.; Krueger, W. C.;
McGovren, J . P.; Padbury, G. E.; Petzold, G. L.; Wallace, T. L.;
Ouding, R. J .; Prairie, M. D.; Gebhard, I. Cytotoxicity and
antitumor activity of carzelesin, a prodrug cyclopropylpyrroloin-
dole analogue. Cancer Res. 1992, 52, 4904-4913.
(12) Ogasawara, H.; Nishio, K.; Takeda, Y.; Ohmori, T.; Kubota, N.;
Funayama, Y.; Ohira, T.; Kuraishi, Y.; Isogai, Y.; Saijo, N. A
novel antitumor antibiotic, KW-2189 is activated by carboxyl
esterase and induces DNA strand breaks in human small cell
lung cancer cells. J pn. J . Cancer Res. 1994, 85, 418-425.
J M990136B