Synthesis and antitumor evaluation of analogues of the marine pyrroloiminoquinone tsitsikammamines

Article abstract of DOI:10.1016/j.ejmech.2009.10.019

Two series of analogues of the marine pyrroloiminoquinone alkaloids tsitsikammamine have been synthesized on the basis of a Michael addition between 2′-amino-1-(4-methoxyphenyl)-ethanol and two indolediones. All the compounds were evaluated in vitro for antiproliferative activity against distinct cancer cell lines.

Full text of DOI:10.1016/j.ejmech.2009.10.019

European Journal of Medicinal Chemistry 45 (2010) 343–351
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and antitumor evaluation of analogues of the marine
pyrroloiminoquinone tsitsikammamines
,
1
b,
Arnaud Rives a , Benjamin Le Calve 1, Tamara Delaine a, Laurent Legentil a, Robert Kiss b,
´
Evelyne Delfourne a
,
*
a Universite´ Paul Sabatier, UMR CNRS 5068, Laboratoire de Synthe`se et Physicochimie de Mole´cules d’Inte´rˆet Biologique, 118 route de Narbonne, 31062 Toulouse Ce´dex 9, France
b Universite´ Libre de Bruxelles, Laboratoire de Toxicologie, Institut de Pharmacie, Boulevard du Triomphe, 1050 Bruxelles, Belgium
a r t i c l e i n f o
a b s t r a c t
Article history:
Two series of analogues of the marine pyrroloiminoquinone alkaloids tsitsikammamine have been
synthesized on the basis of a Michael addition between 20-amino-1-(4-methoxyphenyl)-ethanol and two
indolediones. All the compounds were evaluated in vitro for antiproliferative activity against distinct
cancer cell lines.
Received 10 July 2009
Received in revised form
5 October 2009
Accepted 9 October 2009
Available online 14 October 2009
Ó 2009 Elsevier Masson SAS. All rights reserved.
Keywords:
Marine alkaloid
Pyrroloiminoquinone
Tsitsikammamine
Antitumor activity
1. Introduction
2. Chemistry
During the last two decades, an increasing interest has been
devoted to pyrroloiminoquinone-based alkaloids including dis-
corhabdins, prianosins or makaluvamines, issued from marine
source, due to their diverse and potent biological activities [1]. Also
belonging to this group, wakayin 1, isolated from a Fijian Clavelina
sp. Ascidian [2], and tsitsikammamine A 2 and B 3, found in the
South African latrunculid sponge Tsitsikammama favus [3], are
metabolites sharing a unique pyrrolo[4,3,2-de]pyrrolo[2,3-h]quin-
oline skeleton Fig. 1.
Many studies have been reported for the synthesis of members
of such families [4] or to design analogues of potential value as
therapeutic agents [5]. For our part, we recently proposed the first
synthetic route to tsitsikammamine A [6].
The retrosynthetic pathway investigated was based on
Michael addition between 20-amino-1-(4-methoxyphenyl)-
a
ethanol 4 and the previously described indoledione 5 [5f]. This
reaction effected in absolute ethanol gave two regioisomers 6a and
6b (57% and 19% respectively, a and b referring to the order of
elution during the purification by silica gel flash-chromatography).
The formation of the second five-membered nitrogen-ring was
achieved by direct cyclization of the hydroxy-derivatives in a tri-
fluoroacetic acid/CH2Cl2 mixture and was concomitant with the
cleavage of the Boc protective group leading to compounds 7a and
7b. MnO2 oxidation of these compounds gave the bispyrroloqui-
none derivatives 8a and 8b which were subsequently cyclized into
the corresponding iminoquinones 9a and 9b by refluxing in ethanol
and 4A molecular sieves. The overall yields of these three steps
were 16 and 22% respectively. It has to be noted that compounds 9a
and 9b could also be obtained from 7a and 7b respectively by
effecting the cyclization step prior to the MnO2 oxidation (10a and
10b being obtained as intermediates) Scheme 1.
In this paper, the complete study to prepare this alkaloid and
analogues is discussed together with the antitumor evaluation of
the different compounds both in terms of growth inhibitory activity
and mode of action.
The end of the synthesis consisted in a sequence of two steps,
i.e.: (i) removal of the tosyl group of 9a and 9b by action of 1 N
NaOH in dioxanne leading to compounds 11a and 11b (46 and 40%
yield respectively), together with secondary compounds 12a and
12b (ii) demethylation of compound 11a and 11b by BBr3 affording
* Corresponding author. Tel.: þ33 561 55 62 93; fax: þ33 561 55 60 11.
E-mail address: delfourn@chimie.ups-tlse.fr (E. Delfourne).
The two first authors contributed equally to the article.
1
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.10.019

344
A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
HO
N
O
N
O
H
N
H
H
N
N
a
9a
+
b
+
+
HN
HN
N
H
N
H
12a
N
H
N
R1
N
N
H
11a R = Me
13a R = H
H
MeO
MeO
RO
RO
O
O
1
2, R1= H
3, R1= Me
Fig. 1.
N
N
O
a
the free base of tsitsikammamine A 13b and its non natural
regioisomer 13a Scheme 2.
9b
+
N
H
N
N
H
N
H
H
As part of the synthesis of tsitsikammamine, especially focusing
on the formation of the second five-membered nitrogen ring, the
condensation step involving compounds 4 and 5 was first inves-
tigated with the unsubstituted indoledione 14 as a Michael
acceptor model. From a structure-activity point of view, the
compounds obtained in this series are of interest to check if the
iminoquinone moiety has a crucial role in the activity of pyrro-
loiminoquinone alkaloids. The previous reactional scheme begin-
ning with the condensation reaction of compounds 4 and 14 was
applied. As observed before, this step led to two regioisomers 15a
and 15b in 62 and 16% yield respectively. The cyclization of these
compounds by trifluoroacetic acid furnished derivatives 16a and
16b (38 and 58% yield) which gave by subsequent MnO2 oxidation
the pyrroloindolediones 17a and 17b in 71 and 82% yield. Removal
O
12b
11b R = Me
13b R = H
b
a- 1N NaOH, dioxanne, rt, overnight. b- BBr ,
3
CH Cl , N , 4h.
2
2
2
Scheme 2.
of the tosyl group of these compounds by action of 1 N NaOH in
dioxanne (93 and 90%) and demethylation of the resulting
compounds 18a and 18b by BBr3 gave the final derivatives 19a and
19b Scheme 3.
MeO
MeO
NHBoc
NHBoc
NHBoc
O
O
O
O
O
H
OH
N
OH
NH2
a
+
+
N
N
N
N
H
OH
Ts
Ts
Ts
4
5
O
6a
6b
MeO
b
b
MeO
NH2
MeO
NH2
NH2
NH2
O
O
O
O
O
O
H
N
H
N
c
c
N
N
N
N
H
N
N
H
Ts
Ts
Ts
Ts
O
O
8b
8a
7b
7a
MeO
c
MeO
d
d
d
d
MeO
c
MeO
N
O
N
O
H
N
H
N
N
N
O
N
N
Ts
N
N
Ts
10b
N
Ts
N
H
H
Ts
O
10a
9a
9b
MeO
MeO
a- abs EtOH, rt, 2h. b- TFA, CH Cl , rt, 4h. c- MnO , CH Cl , rt, overnight. d- abs EtOH, 4Α molecular sieve, reflux, 3h.
2
2
2
2
2
Scheme 1.

A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
345
O
O
O
O
O
R
H
N
OH
a
+
4
+
N
N
H
N
N
R
OH
Ts
Ts
Ts
O
O
14
15b
b
15a
b
O
O
O
O
O
R
R
H
N
H
N
c
c
N
N
N
N
H
N
N
H
Ts
Ts
Ts
R
R
Ts
R
O
O
O
d
16b
17a
16a
17b
d
O
O
O
R'
R
H
N
H
N
e
e
N
H
N
H
N
H
N
H
N
H
N
H
R'
O
O
O
O
18b
19b
18a
19a
HO
MeO
R' =
R =
a- abs EtOH, rt, 2h. b- TFA, CH Cl , rt, 4h. c- MnO , CH Cl , rt, overnight.d- 1N NaOH, dioxanne,
2
2
2
2
2
rt, overnight. e- BBr , CH Cl , N , 4h.
3
2
2
2
Scheme 3.
3. Structural assignment
detailed elsewhere [10,11]. Briefly, the cell lines were incubated for
24 h in 96-microwell plates (at a concentration of 10,000 to
40,000 cells/mL culture medium depending on the cell type) to
ensure adequate plating prior to cell growth determination. The
assessment of cell population growth by means of the MTT color-
imetric assay is based on the capability of living cells to reduce the
yellow product MTT (3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyl-
tetrazolium bromide) to a blue product, formazan, by a reduction
reaction occurring in the mitochondria. The number of living cells
after 72 h of culture in the presence (or absence: control) of the
various compounds is directly proportional to the intensity of the
blue, which is quantitatively measured by spectrophotometry – in
our case using a Biorad Model 680XR (Biorad, Nazareth, Belgium) at
a 570 nM wavelength (with a reference of 630 nM). Each experi-
ment was carried out in sextuplicate.
The origin of the cell lines used in the current study and the
culture media are also fully detailed in references [10,11]. We made
use of three human cancer cell lines, i.e. the U373 glioblastoma
(GBM), the A549 non-small-cell-lung cancer (NSCLC) and the PC-3
prostate cancer cell lines. We employed these three cell lines
because they display distinct profiles of sensitivity to various cyto-
toxic and/or cytostatic compounds. Indeed, the U373 GBM cells are
resistant to apoptosis [11], but sensitive to autophagy-related cell
death [12]. The A549 NSCLC cells are resistant to apoptosis [13] and
to autophagy-related cell death [13], but sensitive to lysosomal
membrane permeabilization-related cell death [13]. The PC-3
prostate cancer cells are sensitive to apoptosis [14]. These distinct
profiles of sensitivity of the three cell lines to various types of cell
death is emphasized at best by the data obtained in the current
study. Indeed, for example, while being not active against U373 GBM
and A549 NSCLC cells, compounds 6a and 6b display significant
anti-tumoractivityagainst PC-3 prostatecancercells. The possibility
The structure assignment of each isomer in the series leading to
the natural product was effected by comparison of the spectro-
scopic data of the trifluoroacetic salt of 13b which were proven to
be identical with those reported for tsitsikammamine A (2) [3]. In
the second series (15–19a,b), the structure assignment resulted of
the comparison of 13C NMR chemical shift of the C4 carbonyl.
Previous work by Qiao et al [7]. have shown that significant
chemical shifts occurred at 1,4-benzoquinone units, for instance, in
dipyrroloquinones 20a and 20b, the 13C NMR chemical shifts of
these C4 carbonyl groups being 174 and 179.3 ppm respectively.
Furthermore, other data reported both by Lee et al. [8]. and Li et al.
[9]. indicated that the presence of substituents on pyrrole rings
have no significant influence on the chemical shift of C4. As a result
of that, the carbonyl group of compounds 19a and 19b are 174.18
and 180.39 ppm respectively Fig. 2.
4. Pharmacology
We evaluated the IC50 in vitro growth inhibitory values of the 26
compounds under study by means of the MTT colorimetric assay as
O
O
H
N
H
N
H
N
20a
20b
4
4
N
H
O
O
Fig. 2.

346
A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
thus remains that compounds 6a and 6b display their anti-tumor
activity at least partly though activation of apoptosis. In contrast,
compounds 9a, 9b,18b and 19a could exert their anti-tumor activity
through non-apoptotic cell death processes. We labelled all these
compounds as ‘‘heterogeneous’’ in terms of anti-tumor activity (see
Table 1 and its legend) and we did not include them in the structure–
activity relationship (SAR) analysis we report below. In a general
way, compounds of the series leading to the natural product and its
regioisomer (13b and 13a respectively) exhibited higher anti-
proliferative effects than compounds of the second series missing
the functional chain or without the iminoquinone moiety. In almost
all couple of products, excepted compounds 11a/11b, regioisomers
b appeared to display equal or higher in vitro antitumor activity than
the a ones, the natural product tsitsikammamine exhibiting
a greater activity than its regioisomer.
The morphological information revealed by this figure clearly
indicate that compound 8b exerts its growth inhibitory activity in
vitro (as revealed by means of the MTT colorimetric assay; Table 1)
through cytotoxic and not cytostatic effects. These effects (analyzed
at approximately the compound 8b’s IC50 growth inhibitory
concentration; see Table 1) occur very rapidly, i.e. within 2 hrs after
the addition of compound 8b into the culture medium of U373 GBM
cells as illustrated in the figure above. The type of cell death
induced by compound 8b remains to be determined and should not
relate to a rapid induction of apoptosis according to the fact that: i)
U373 GBM cells are apoptosis-resistant [11], and ii) the compound
8b-induced cytotoxic effects occur too rapidly to be able to actually
induce full apoptotic processes. We previously reported on the
synthesis of tsitsikammamines A and B aza-analogues and we have
observed that one of the final compounds partially inhibits human
topoisomerase I, whereas synthetic intermediates inhibit the
enzyme DNA cleavage activity at a concentration comparable to
that of the control drug camptothecin [5e]. A second larger series of
aza-analogues of tsitsikammamines A and B have then been
synthesized [5f] and once more some of the compounds inhibited
the topoisomerase I and/or II catalyzed relaxation of supercoiled
DNA at a concentration comparable to the drugs camptothecin and
etoposide. Altogether these data previously reported [5e,5f] and
the current ones suggest that those tsitsikammamine analogues,
such as compound 8b under the current study, that display the
highest in vitro growth inhibitory concentration on various cancer
cell types, including apoptosis-resistant ones, kills cancer cell by
Of the 26 compounds under study, compound 8b displayed IC50
in vitro growth inhibitory values in the single mM range for the three
cell lines under study (Table 1). We thus made use of computer-
assisted phase-contrast microscopy (quantitative video-
microscopy) to grossly decipher the mechanism of action of
compound 8b when exerting its anti-tumor effects in vitro. Quan-
titative videomicroscopy already made it possible to help in such
a gross deciphering of anti-tumor mode of action of various types of
compounds including cardiotonic steroids [12,13], naphthalimides
[10], alkaloids [11] and platinum derivatives [15].
We made use of the apoptosis-resistant U373 GBM cell line that
has been cultured in the absence (control) or the presence of 5 mM
of compound 8b.

A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
347
Table 1
inhibitory concentrations calculated on cancer cells and normal
cells must be >5 [14]. We made use of two human normal fibroblast
cell lines (NHDF and Wi38) whose origin and culture conditions are
fully detailed in reference [11].
Compound
IC50 in vitro growth inhibitory values (
m
M)
Profiles of
anti-tumor activitya
U373 GBM
A549 NSCLC
PC-3 prostate
cancer
The data we obtained clearly indicate that neither compound 8a
nor compound 8b display significant bioselective indices. Indeed,
the IC50 in vitro growth inhibitory concentrations associated with
these two compounds in three distinct human cancer cell lines
(U373, A549, PC3) are of the same magnitude when compared to
two normal human fibroblast cell lines (NHDF, Wi38). However,
altogether these data show that while compound 8b displays
similar cytotoxic effects in normal versus cancer cells, compound
8a displays much higher heterogeneity in its cytotoxic effects
towards normal and cancer cells. Thus, while it clearly appears that
compound 8b is definitively not bioselective but cytotoxic,
compound 8a seems to be associated with more or less specific
antiproliferative activity when one considers the ranges displayed
by its IC50 in vitro growth inhibitory concentrations in both normal
and cancer cell lines. Compound 8a could therefore be used as an
original pharmacophore to design novel bioselective anticancer
compounds.
6a
6b
7a
7b
8a
8b
9a
9b
10a
10b
11a
11b
12a
12b
13a
13b
15a
15b
16a
16b
17a
17b
18a
18b
19a
19b
> 100
> 100
28.3
48.5
8.5
> 100
> 100
35.7
52.4
11.2
4.1
9.7
9.5
26.1
33.7
31.3
4.2
> 100
> 100
20.5
20.5
55.7
> 100
> 100
88.8
63.7
23.0
37.3
> 100
33.7
Heterogeneous
Heterogeneous
2
2
1
1
Heterogeneous
Heterogeneous
2
1
2
3
3
2
3.2
41.4
57.4
30.5
18.3
4.1
3.1
15.4
25.9
9.7
38.1
> 100
> 100
80.6
35.2
15.6
70.2
> 100
52.4
35.4
41.3
77.6
> 100
7.8
> 100
> 100
97.8
62.2
18.1
56.4
29.2
51.9
47.2
48.2
> 100
> 100
7.6
2
2
2
Heterogeneous
2
2
2
Heterogeneous
3
Heterogeneous
Heterogeneous
3
37.5
48.2
24.6
> 100
> 100
> 100
> 100
5. Experimental section
1H and 13C NMR spectra were performed on Bruker Avance
300 or Avance 500 (cryoprobe TCI 1H{13C, 31P}) spectrometers
with the chemical shifts of the remaining protons of the deuter-
ated solvents serving as internal standards. IR spectra were
obtained on a Perkin-Elmer 883 spectrophotometer. High reso-
lution mass spectra (HRMS) were recorded on a micromass
LCT mass spectrometer. Reagents were purchased from commer-
cial sources and used as received. Chromatography was per-
37.0
> 100
74.5
> 100
a
We labelled as heterogeneous those compounds that display markedly distinct
anti-tumor activities against the three cancer cell lines under study. We did not
include these compounds in the structure-activity relationship analysis we per-
formed in the Pharmacology section. We labelled as ‘‘1’’ those compounds dis-
playing mean IC50 values < 20
compounds displaying IC50 values in the 21–100
compounds displaying IC50 values > 100 M.
mM on the three cell lines under study, as ‘‘2’’ those
m
M range, and as ‘‘3’’ those
m
formed on silica gel (15–40
indicated below.
mM) by means of the solvent systems
a yet unknown but very rapid process paralleled by topoisomerase I
and II inhibition.
5.1. 6[2-hydroxy-2-(4-methoxyphenyl)-ethylamino]-4,7-dioxo-3-
(2-tert-butyloxycarbonylaminoethyl)-1-(toluene-4-sulfonyl)-indole
(6a) and 5[2-hydroxy-2-(4-methoxyphenyl)-ethylamino]-
4,7-dioxo-3-(2-tert-butyloxycarbonylaminoethyl)-1-(toluene-4-
sulfonyl)-indole (6b)
According to the fact that compound 8b could serve as a lead to
develop novel series of anticancer compounds active against
cancers associated with dismal prognoses, such as apoptosis-
resistant cancers, we analyze its bioselectivity profile along with
the one of compound 8a. We define as bioselective a compound
that displays at least 5 fold higher inhibitory effects on cancer cell
population growth than on normal cell population growth [14]. In
other words, the ratio between the mean IC50 in vitro growth
To a solution of hydroxylamine 4 (1.6 g, 10.0 mmoL) in ethanol
(13 mL) was added dropwise a solution of quinone 5 [5f] (2.1 g, 4.73
mmoL) in ethanol (27 mL). After 4 h of stirring at room tempera-
ture, the mixture was concentrated over vacuum and the crude
product was purified by flash-chromatography (CH2Cl2/MeOH
99:1) to give the two separated isomers.
6a: dark pink solid (1.64 g, 57%), mp 92 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 610.2223, found 610.2249. 1H NMR (CDCl3) 1.39 (s,
9H); 2.37 (s, 3H); 2.85 (t, 2H, J ¼ 6.1 Hz); 3.19 (m, 2H); 3.32 (m, 2H,);
3.75 (s, 3H); 4.83 (m, 1H); 5.09 (s, 1H); 6.18 (m, 1H); 6.83 (d, 2H,
J ¼ 7.9 Hz); 7.23 (d, 2H, J ¼ 7.9 Hz); 7.27 (d, 2H, J ¼ 8.0 Hz); 7.46 (s,
1H); 7.93 (d, 2H, J ¼ 0.8 Hz). 13C NMR (CDCl3). 21.73; 26.09; 28.37
(3C); 40.01; 49.87; 55.29; 70.95; 79.32; 97.39; 114.10 (2C); 122.06;
124.46; 125.78; 127.05 (2C); 129.03 (2C); 129.41 (2C); 132.89;
133.37; 134.28; 145.73; 147.33; 156.06; 159.50; 174.97; 179.59. IR
(KBr) 3400; 3380; 1698; 1676; 1620; 1603 cmꢁ1
.
6b: dark pink solid (0.55 g, 19%), mp 88 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 610.2223, found 610.2235. 1H NMR (CDCl3) 1.36 (s,
9H); 2.34 (s, 3H); 2.87 (t, 2H, J ¼ 6.1 Hz); 3.14 (m, 2H); 3.29 (m,
2H,); 3.71 (s, 3H); 4.82 (m, 1H); 5.08 (s, 1H); 6.24 (m 1H); 6.79 (d,
2H, J ¼ 8.5 Hz); 7.23 (m, 4H); 7.58 (s, 1H); 7.89 (d, 2H, J ¼ 8.5 Hz).
13C NMR (CDCl3). 21.76; 25.69; 28.39 (3C); 40.53; 50.02; 55.33;
71.22; 79.32; 97.49; 114.18 (2C); 120.28; 123.51; 127.09 (2C);
128.88 (2C); 129.74 (2C); 130.09; 130.66; 133.25; 133.98; 146.07;

348
A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
147.79; 156.10; 159.65; 170.00; 184.11. IR (KBr) 3430, 3362; 1709;
1674; 1599 cmꢁ1
CH2Cl2 (32 mL). Purification of the crude product by flash-chroma-
tography (CH2Cl2/MeOH 90: 10) gave the product as an orange solid
(164 mg, 82%), mp 203 ꢀC. HRMS (ESIþ) [M þ H]þ calcd 490.1437,
found 490.1429. 1H NMR (DMSO-d6) 2.43 (s, 3H); 3.07 (m, 2H); 3.12
(m, 2H); 3.80 (s, 3H); 6.95 (d, 2H, J ¼ 8.7 Hz); 7.36 (s,1H); 7.52 (d, 2H,
J ¼ 8.4 Hz); 7.69 (d, 2H, J ¼ 8.7 Hz); 7.85 (s, 1H); 8.02 (d, 2H,
J ¼ 8.4 Hz). 13C NMR (DMSO-d6) 21.66; 23.87; 38.72; 55.63; 113.82
(2C); 121.04; 121.33; 125.57; 125.69; 126.79; 128.91 (2C); 129.42;
130.16 (2C); 130.25 (2C); 130.40; 130.69; 133.12; 134.29; 146.55;
.
5.2. 5-(2-aminoethyl)-3-(4-methoxyphenyl)-7-(toluene-4-
sulfonyl)-2,3-dihydro-1H,7H-pyrrolo[3,2-f]indole-4,8-dione (7a)
To a solution of compound 6a (600 mg, 0.99 mmoL) in dry CHCl3
(24 mL) was added dropwise TFA (15 mL). The mixture was stirred
for 2 h at room temperature and concentrated. 1 N NaOH (10 mL)
and CH2Cl2 (10 mL) were added to the residue, the organic layer
was separated and the aqueous layer was extracted with CH2Cl2
(3 ꢂ10 mL). The combined organic layers were dried over MgSO4
and concentrated in vacuum. The crude product was purified by
flash-chromatography (CH2Cl2/MeOH 90:10) to give the expected
product as a violine solid (248 mg, 51%), mp 159 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 492.1593, found 492.1591. 1H NMR (DMSO-d6) 2.39
(s, 3H); 2.98 (m, 2H); 3.13 (t, 2H, J ¼ 5.4 Hz); 3.72 (s, 3H); 3.74 (m,
1H); 4.00 (dd, 1H, J ¼ 11.4 Hz and 12.6 Hz); 4.26 (dd, 1H, J ¼ 5.4 and
11.4 Hz); 6.82 (d, 2H, J ¼ 8.7 Hz); 7.05 (d, 2H, J ¼ 8.7 Hz); 7.42 (d, 2H,
J ¼ 8.1 Hz); 7.65 (s, 1H); 7.87 (d, 2H, J ¼ 8.4 Hz). 13C NMR (DMSO-d6)
21.61; 23.73; 38.49; 44.01; 55.50; 56.36; 114.30 (2C); 115.54;
119.59; 125.33; 126.59; 128.37 (2C); 128.77 (2C); 130.06 (2C);
133.43; 134.55; 136.54; 146.15; 154.07; 158.38; 170.48; 178.45. IR
159.16; 165.85; 180.42. IR (CHCl3) 3281, 1651, 1610, 1596 cmꢁ1
.
5.6. 9-(4-methoxyphenyl)-5-toluene-4-sulfonyl)-2,3,5,7-
tetrahydro-1,5,7-triazacyclopenta[e]acenaphthylen-6-one (9a)
From 8a: a mixture of compound 8a (120 mg, 0.25 mmoL), 4 A
molecular sieves and ethanol (8 mL) was refluxed for 4 h. After
filtration and concentration of the filtrate, the crude product was
purified by flash-chromatography (CH2Cl2/MeOH 99: 1) to give the
product as a dark violine solid (46 mg, 39%). From 10a: the same
procedure was used as for compound 8a involving compound 10a
(100 mg, 0.21 mmoL), MnO2 (307 mg, 3.53 mmoL) in CH2Cl2
(15 mL). Purification of the crude product by flash-chromatography
(CH2Cl2/MeOH 99: 1) gave the product (71 mg, 72%), mp 148 ꢀC.
HRMS (ESIþ) [M þ H]þ calcd 472.1331, found 472.1331.1H NMR
(CDCl3) 2.43 (s, 3H); 2.86 (t, 2H, J ¼ 7.5 Hz); 3.90 (s, 3H); 4.15 (t, 2H,
J ¼ 7.5 Hz); 6.93 (s, 1H); 6.95 (d, 2H, J ¼ 8.7 Hz); 7.32 (d, 2H,
J ¼ 8.7 Hz); 7.45 (s, 1H); 7.55 (d, 2H, J ¼ 8.7 Hz); 8.09 (d, 2H,
J ¼ 8.7 Hz). 13C NMR (CDCl3) 21.56; 29.72; 55.36; 58.52; 113.46 (2C);
116.50; 123.91; 124.17; 126.49; 128.82; 129.03 (2C); 129.64 (2C);
129.74; 130.13 (2C); 130.91; 132.45; 134.53; 145.77; 149.48; 159.04;
(CHCl3) 3337, 3252, 1674, 1610 cmꢁ1
.
5.3. 7-(2-aminoethyl)-3-(4-methoxyphenyl)-5-(toluene-4-
sulfonyl)-2,3-dihydro-1H,5H-pyrrolo[2,3-f]indole-4,8-dione (7b)
The same procedure was used as for compound 7a involving
compound 6b (580 mg, 0.99 mmoL), dry CHCl3 (24 mL) and TFA
(15 mL). Purification by flash-chromatography (CH2Cl2/MeOH 95:
5) gave the product as a violine solid (224 mg, 48%), mp 175 ꢀC.
HRMS (ESIþ) [M þ H]þ calcd 492.1593, found 492.1584. 1H NMR
(DMSO-d6) 2.43 (s, 3H); 2.92 (m, 2H); 3.05 (m, 2H); 3.39 (dd, 1H,
J ¼ 6.3 and 12.6 Hz); 3.70 (s, 3H); 4.02 (dd, 1H, J ¼ 11.4 Hz and
12.6 Hz); 4.33 (dd, 1H, J ¼ 6.0 and 11.4 Hz); 6.81 (d, 2H, J ¼ 8.7 Hz);
7.11 (d, 2H, J ¼ 8.7 Hz); 7.51 (d, 2H, J ¼ 8.7 Hz); 7.71 (br. s, 2H); 7.89
(s, 1H); 7.99 (d, 2H, J ¼ 8.7 Hz). 13C NMR (DMSO-d6) 21.67; 23.57;
38.70; 44.10; 54.92; 55.49; 114.26 (2C); 115.51; 121.03; 127.85;
128.53 (2C); 128.88 (2C); 130.38 (2C); 131.29; 131.95; 134.02;
136.68; 146.66; 154.32; 158.34; 168.83; 177.95. IR (CHCl3) 3350,
167.80; 171.25. IR (CHCl3) 3261, 1728, 1651, 1598 cmꢁ1
.
5.7. 7-(4-methoxyphenyl)-5-toluene-4-sulfonyl)-2,3,5,9-
tetrahydro-1,5,9-triazacyclopenta[e]acenaphthylen-6-one (9b)
From 8b: the same procedure was used as for compound 9a
involving compound 8b (200 mg, 0.41 mmoL), 4 A molecular sieves
and ethanol (14 mL). Purification of the crude product by flash-
chromatography (CH2Cl2/MeOH 98: 2) gave the product as a brown
solid (108 mg, 56%). From 10b: the same procedure was used as for
compound 8a involving compound 10b (100 mg, 0.21 mmoL),
MnO2 (307 mg, 3.53 mmoL) in CH2Cl2 (15 mL). Purification of the
crude product by flash-chromatography (CH2Cl2/MeOH 98: 2) gave
the product (87 mg, 88%), mp 158 ꢀC. HRMS (ESIþ) [M þ H]þ calcd
472.1331, found 472.1378. 1H NMR (CDCl3) 2.44 (s, 3H); 2.78 (t, 2H,
J ¼ 7.5 Hz); 3.86 (s, 3H); 4.20 (t, 2H, J ¼ 7.5 Hz); 6.93 (d, 2H, J ¼ 8.7);
7.09 (d, 2H, J ¼ 2.7 Hz); 7.36 (d, 2H, J ¼ 8.4 Hz); 7.51 (s, 1H); 7.77 (d,
2H, J ¼ 8.7 Hz); 8.09 (d,1H, J ¼ 8.4 Hz). 13C NMR (CDCl3) 17.74; 21.76;
49.80; 55.29; 113.48 (2C); 118.94; 122.63; 124.55; 125.16; 125.94;
126.81; 128.21; 128.66 (2C); 129.07; 129.70 (2C); 129.94 (2C);
133.05; 134.93; 145.67; 153.14; 158.92, 165.98. IR (CHCl3) 3279,
3228, 1672, 1610 cmꢁ1
.
5.4. 3-(2-aminoethyl)-5-(4-methoxyphenyl)-1-toluene-4-
sulfonyl)-1H,7H-pyrrolo[3,2-f]indole-4,8-dione (8a)
A suspension of compound 7a (200 mg, 0.41 mmoL), MnO2
(600 mg (6.90 mmoL) in CH2Cl2 (32 mL) was stirred at room
temperature overnight. After filtration and concentration of the
filtrate, the crude product was purified by flash-chromatography
(CH2Cl2/MeOH 90: 10) to give the product as an orange solid (160 mg,
80%), mp 180 ꢀC. HRMS (ESIþ) [M þ H]þ calcd 490.1437, found
490.1416.1H NMR (DMSO-d6) 2.39 (s, 3H); 3.06 (m, 2H); 3.18 (m, 2H);
3.80 (s, 3H); 6.95 (d, 2H, J ¼ 8.7 Hz); 7.33 (s, 1H); 7.48 (dd, 2H, J ¼ 8.4
and 2.4 Hz); 7.51 (d, 2H, J ¼ 8.7 Hz); 7.81 (s, 1H); 7.95 (d, 2H,
J ¼ 8.4 Hz). 13C NMR (DMSO-d6) 21.62; 23.75; 38.58; 55.64; 113.92
(2C); 120.79; 120.63; 125.47; 125.98 (2C); 126.87; 128.07; 128.48
(2C); 128.71; 128.92; 129.99 (2C); 130.20; 133.08; 134.56; 146.33;
1712, 1650, 1613, 1598 cmꢁ1
.
5.8. 7-(4-methoxyphenyl)-5-(toluene-4-sulfonyl)-2,3,5,7,8,9-
hexahydro-1,5,9-triazacyclopenta[e]acenaphtylen-6-one (10a)
The same procedure was used as for compound 9a involving
compound 7a (200 mg, 0.41 mmoL), 4 A molecular sieve and
ethanol (14 mL). Purification of the crude product by flash-
chromatography (CH2Cl2/MeOH 98: 2) gave the product as a dark
blue solid (84 mg, 43%), mp 129 ꢀC. HRMS (ESIþ) [M þ H]þ calcd
474.1488, found 472.1460. 1H NMR (CDCl3) 2.39 (s, 3H); 2.81 (t, 2H,
J ¼ 7.5 Hz); 3.63 (dd, 1H, J ¼ 10.8 and 4.8 Hz); 3.78 (s, 3H); 4.08 (t,
2H, J ¼ 7.5 Hz); 4.14 (m, 1H); 4.38 (dd, 1H, J ¼ 4.8 and 11.4 Hz); 6.79
(d, 2H, J ¼ 8.7 Hz); 7.15 (d, 2H, J ¼ 8.4 Hz); 7.24 (d, 1H, J ¼ 8.7 Hz);
159.13; 172.13; 174.41. IR (CHCl3) 3368, 1676, 1631, 1608 cmꢁ1
.
5.5. 3-(2-aminoethyl)-7-(4-methoxyphenyl)-1-toluene-4-
sulfonyl)-1H,5H-pyrrolo[2,3-f]indole-4,8-dione (8b)
The same procedure was used as for compound 8a involving
compound 7b (200 mg, 0.41 mmoL), MnO2 (600 mg, 6.90 mmoL) in

A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
349
7.29 (s, 1H); 8.00 (d, 2H, J ¼ 8.4 Hz). 13C NMR (CDCl3) 18.06; 21.71;
44.65; 50.11; 55.28; 56.57; 113.92 (2C); 116.09; 119.64; 122.55;
122.79; 125.92; 128.12 (2C); 128.67 (2C); 129.53 (2C);135.05;
136.09; 145.31; 151.82; 153.6; 158.27; 171.65. IR (CHCl3) 1673,
133.10; 161.89; 161.89; 164.60; 167.00. IR (KBr) 3442,
1679, 1630 cmꢁ1
.
12b: orange solid (2.7 mg, 8%), mp > 260 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 316.1086, found 316.1086. 1H NMR (DMSO-d6) 3.83
(s, 3H); 7.00 (d, 2H, J ¼ 9.0 Hz); 7.38 (d, 1H, J ¼ 3 Hz); 7.68 (d, 1H,
J ¼ 6 Hz); 8.07 (s, 1H); 8.09 (d, 2H, J ¼ 9 Hz); 8.34 (d, 1H, J ¼ 6 Hz);
12.53 (br.s, 1H); 14.25 (br.s, 1H). 13C NMR (DMSO-d6) 55.54; 113.67;
113.74; 114.69; 121.00; 122.22; 123.55; 123.82; 123.86; 124.87;
127.61; 130.31(2C); 135.39; 140.93; 140.92; 146.81; 158.45; 164.81.
1609, 1596 cmꢁ1
.
5.9. 9-(4-methoxyphenyl)-5-(toluene-4-sulfonyl)-2,3,5,7,8,9-
hexahydro-1,5,7-triazacyclopenta[e]acenaphtylen-6-one (10b)
The same procedure was used as for compound 9a involving
compound 7b (100 mg, 0.21 mmoL), 4 A molecular sieves and
ethanol (7 mL). Purification of the crude product by flash-chro-
matography (CH2Cl2/MeOH 98: 2) gave the product as a dark blue
solid (50 mg, 50%), mp 135 ꢀC. HRMS (ESIþ) [M þ H]þ calcd
474.1488, found 474.1502. 1H NMR (CDCl3) 2.28 (s, 3H); 2.68 (t, 2H,
J ¼ 7.0 Hz); 3.51 (dd, 1H, J ¼ 4.8 and 10.5 Hz); 3.67 (s, 3H); 3.93-4.05
(m, 1H); 4.05 (t, 2H, J ¼ 7.0 Hz); 4.29 (dd, 1H, J ¼ 3.9 and 10.5 Hz);
6.68 (d, 2H, J ¼ 8.7 Hz); 7.06 (d, 2H, J ¼ 8.7 Hz); 7.17 (s, 1H); 7.21 (d,
2H, J ¼ 8.7 Hz); 7.89 (d, 2H, J ¼ 8.7 Hz). 13C NMR (DMSO-d6) 21.67;
22.54; 44.11; 55.35; 55.49; 56.31; 114.25 (2C); 115.51; 121.03;
127.82; 128.53 (2C); 128.89 (2C); 130.37 (2C); 131.30; 131.94;
134.02; 136.67; 146.68; 154.32; 158.34; 168.82; 177.95. IR (CHCl3)
IR (KBr) 3415, 3250, 1718, 1648, 1609 cmꢁ1
.
5.12. 7-(4-hydroxyphenyl)-2,3,5,9-tetrahydro-1,5,9-
triazacyclopenta[e]acenaphtylen-6-one (13a)
To a suspension of compound 11a (5 mg, 0.016 mmoL) in CH2Cl2
(2 mL) at 0 ꢀC and under nitrogen atmosphere, was added dropwise
a 1 M solution of BBr3 in CH2Cl2 (0.2 mL). The mixture was stirred
for 4 h and a saturated NaHCO3 solution (2 mL) was added. After
concentration over vacuum, the crude product was purified by
flash-chromatography (CH2Cl2/MeOH 90:10) to give the product as
a dark red solid (2.9 mg, 60%), mp >260 ꢀC. HRMS (ESIþ) [M þ H]þ
calcd 304.1086, found 304.1064. 1H NMR (DMSO-d6) 2.73 (t, 2H,
J ¼ 8.1 Hz); 4.05 (t, 2H, J ¼ 8.1 Hz); 6.72 (d, 2H, J ¼ 8.7 Hz); 6.82 (s,
1H); 6.95 (s, 1H); 7.47 (d, 2H, J ¼ 8.7 Hz); 7.6 (br.s, 1H); 7.7 (br.s, 1H);
11.81 (br.s,1H). 13C NMR (DMSO-d6) 31.15; 49.05; 114.83 (2C); 115.4;
116.13; 119.85; 120.66; 120.93; 125.57; 126.41; 129.46; 130.36 (2C);
134.26; 150.57; 156.71; 174.49. IR (KBr) 3408, 3148, 1640,
3266, 1714, 1660, 1599 cmꢁ1
.
5.10. 7-(4-methoxyphenyl)-2,3,5,9-tetrahydro-1,5,9-
triazacyclopenta[e]acenaphtylen-6-one (11a) and 7-(4-
methoxyphenyl)-5,9-dihydro-1,5,9-triazacyclopenta
[e]acenaphtylen-6-one (12a)
1599 cmꢁ1
.
A mixture of compound 9a (20 mg, 0.042 mmoL) in 1 N NaOH
(2 mL) and dioxanne (2 mL) was stirred at room temperature
overnight. After concentration, the crude product was purified by
flash-chromatography (CH2Cl2/MeOH 90:10) to give the expected
product 11a and a side-product 12a
5.13. 9-(4-hydroxyphenyl)-2,3,5,7-tetrahydro-1,5,7-
triazacyclopenta[e]acenaphtylen-6-one (13b)
The same procedure was used as for compound 13a involving
compound 11b (5 mg, 0.016 mmoL), CH2Cl2 (2 mL) and 1 M solu-
tion of BBr3 in CH2Cl2 (0.2 mL). Purification of the crude product by
flash-chromatography (CH2Cl2/MeOH 90:10) gave the product as
a dark red solid (3 mg, 62%), mp > 260 ꢀC. HRMS (ESIþ) [M þ H]þ
calcd 304.1086, found 304.1130. 1H NMR (DMSO-d6) 2.71 (t, 2H,
J ¼ 7.8 Hz); 3.97 (t, 2H, J ¼ 7.8 Hz); 6.74 (d, 2H, J ¼ 8.7 Hz); 6.96 (d,
1H, J ¼ 2.1 Hz); 7.16 (d, 1H, J ¼ 3.0 Hz); 7.69 (d, 2H, J ¼ 8.7 Hz); 12.15
(br.s, 1H); 12.44 (br.s, 1H). 13C NMR (DMSO-d6) 29.46; 49.07; 115.08
(2C); 118.13; 121.84; 122.17; 123.52; 125.09; 125.28; 125.53; 130.16
(2C); 133.83; 154.95; 156.72; 167.99; 172.45. IR (KBr) 3442, 1679,
11a: orange solid (5.3 mg, 40%), mp 128 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 318.1243, found 318.1281. 1H NMR (DMSO-d6) 2.76
(t, 2H, J ¼ 7.8 Hz); 3.79 (s, 3H); 4.07 (t, 2H, J ¼ 7.8 Hz); 6.86 (s, 1H);
6.91 (d, 2H, J ¼ 8.7 Hz); 7.06 (s, 1H); 7.61 (d, 2H, J ¼ 8.7 Hz). 13C NMR
(DMSO-d6) 18.88; 55.52; 55.91; 113.43 (2C); 114.35; 116.25; 119.85;
123.42; 126.76; 127.13; 130.31 (2C); 131.87; 150.51; 158.47; 163.30;
167.48; 174.38. IR (KBr) 3392, 1640 cmꢁ1
.
12a: orange solid (1.3 mg, 10%), mp > 260 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 316.1086, found 316.1115. 1H NMR (DMSO-d6) 3.80
(s, 3H); 6.92 (d, 2H, J ¼ 8.7 Hz); 7.20 (s, 1H); 7.66 (d, 1H, J ¼ 6 Hz);
7.69 (d, 2H, J ¼ 8.7 Hz); 7.90 (s, 1H); 8.32 (d, 1H, J ¼ 6 Hz). 13C NMR
(DMSO-d6) 55.55; 113.37 (2C); 115.07; 120.18; 122.02; 122.28;
122.67; 123.22; 126.23; 127.55,130.37; 130.68 (2C); 134.50; 140.79;
1630 cmꢁ1
.
5.14. 5-[2-Hydroxy-2-(4-methoxy-phenyl)-ethylamino]-1-
(toluene-4-sulfonyl)-1H-indole-4,7-dione (15a) and 6-[2-Hydroxy-
2-(4-methoxy-phenyl)-ethylamino]-1-(toluene-4-sulfonyl)-1H-
indole-4,7-dione (15b)
142.17; 158.36; 171.49. IR (KBr) 3452, 1635 cmꢁ1
.
5.11. 9-(4-methoxyphenyl)-2,3,5,7-tetrahydro-1,5,7-
triazacyclopenta[e]acenaphtylen-6-one (11b) and 9-(4-
methoxyphenyl)-5,7-dihydro-1,5,7-triazacyclopenta
[e]acenaphtylen-6-one (12b)
The same procedure was used as for compound 6a and 6b
involving the hydroxylamine 4 (1.3 g, 7.78 mmoL), ethanol (23 mL)
and a solution of quinone 14 (1.2 g, 3.99 mmoL) in ethanol (12 mL).
Purification of the crude product by flash-chromatography (CH2Cl2/
MeOH 99:1) gave the two separated isomers.
The same procedure was used as for compound 11a involving
compound 9b (50 mg, 0.106 mmoL),1 N NaOH (5 mL) and dioxanne
(5 mL). Purification of the crude product by flash-chromatography
(CH2Cl2/MeOH 98: 2) gave:
11b: orange solid (16 mg, 46%), mp 140 ꢀC. HRMS (ESIþ)
[M þ H]þ calcd 318.1243, found 318.1210, found 318.1210. 1H NMR
(DMSO-d6) 2.69 (t, 2H, J ¼ 7.8 Hz); 3.79 (s, 3H); 3.99 (t, 2H,
J ¼ 7.8 Hz); 6.91 (d, 2H, J ¼ 8.7 Hz); 6.95 (d, 1H, J ¼ 2.4 Hz); 7.22 (d,
1H, J ¼ 2.7 Hz); 7.87 (d, 2H, J ¼ 8.7 Hz); 12.08 (br.s, 1H); 12.39 (br.s,
1H). 13C NMR (DMSO-d6) 28.18; 51.93; 55.58; 113.46 (2C); 119.70;
120.93; 122.28; 126.07; 126.10; 126.92; 128.00(2C); 128.79; 132.83;
15a: dark pink solid (0.33 g, 18%), mp 100 ꢀC. HRMS (ESIþ)
[M þ Na]þ calcd 489.1096, found 489.1085. 1H NMR (CDCl3) 2.36 (s,
3H); 3.20 (m, 2H); 3.74 (s, 3H); 4.80 (dd, 1H, J ¼ 7.2 and 9.0 Hz); 5.13
(s, 1H); 6.02 (t, 1H, J ¼ 4.5 Hz); 6.60 (d, 1H, J ¼ 3.3 Hz); 6.83 (d, 2H,
J ¼ 8.7 Hz); 7.21 (d, 2H, J ¼ 8.7 Hz); 7.26 (d, 2H, J ¼ 8.4 Hz); 7.61 (d,
1H, J ¼ 3.3 Hz); 7.94 (d, 2H, J ¼ 8.4 Hz). 13C NMR (CDCl3) 21.75;
49.84; 55.30; 71.05; 97.62; 107.23; 114.14 (2C); 126.86; 127.07 (2C);
127.80; 129.11 (2C); 129.47 (2C); 132.48; 133.28; 134.16; 145.91;
147.18; 159.55; 175.11; 178.60. IR (KBr) 3364, 1681, 1597 cmꢁ1
.

350
A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
15b: dark pink solid (1.23 g, 66%), mp 128 ꢀC. HRMS (ESIþ)
5.18. 5-(4-Methoxy-phenyl)-1-(toluene-4-sulfonyl)-1H,7H-
pyrrolo[3,2-f]indole-4,8-dione (17b)
[M þ Na]þ calcd 489.1096, found 489.1105. 1H NMR (CDCl3) 2.45 (s,
3H); 3.29 (t, 2H, J ¼ 6.6 Hz); 3.83 (s, 3H); 4.88 (t,1H, J ¼ 6.3 Hz); 5.33
(s, 1H); 6.23 (t, 1H, J ¼ 7.2 Hz); 6.73 (d, 1H, J ¼ 3.0 Hz); 6.91 (d, 2H,
J ¼ 8.7 Hz); 7.30 (d, 2H, J ¼ 8.7 Hz); 7.36 (d, 2H, J ¼ 8.4 Hz); 7.81 (d,
1H, J ¼ 3.0 Hz); 8.01 (d, 2H, J ¼ 8.4 Hz). 13C NMR (CDCl3) 21.79;
49.96; 55.36; 71.41; 97.01; 108.56; 114.28 (2C); 126.95; 127.07 (2C);
128.94 (2C); 129.78 (2C); 131.24; 133.00; 133.94; 134.31; 146.20;
148.11; 159.79; 170.05; 181.43. IR (KBr) 3430, 3360, 1701, 1674,
The same procedure was used as for compound 8a involving
compound 16b (400 mg, 0.90 mmoL), MnO2 (600 mg,
6.90 mmoL) in CH2Cl2 (32 mL). Purification of the crude product
by flash-chromatography (CH2Cl2) gave the product as an orange
solid (330 mg, 82%), mp 236 ꢀC. HRMS (ESIþ) [M þ H]þ calcd
447.1015, found 447.1030. 1H NMR (CDCl3) 2.45 (s, 3H); 3.86
(s, 3H); 6.80 (d, 1H, J ¼ 3.3 Hz); 6.95 (d, 2H, J ¼ 8.4 Hz); 7.01
(d, 1H, J ¼ 3.0 Hz); 7.37 (d, 2H, J ¼ 8.4 Hz); 7.65 (d, 2H, J ¼ 8.4 Hz);
7.76 (d, 1H, J ¼ 3.0 Hz); 8.04 (d, 2H, J ¼ 8.4 Hz). 13C NMR (CDCl3)
21.78; 55.32; 109.12; 113.61 (2C); 114.09; 123.02; 124.76; 127.83;
128.82 (2C); 128.95; 129.63; 129.71 (2C); 129.79 (2C); 133.48;
134.25; 134.82; 146.10; 159.36; 166.35; 178.53. IR (KBr) 3255,
1598 cmꢁ1
.
5.15. 3-(4-Methoxy-phenyl)-5-(toluene-4-sulfonyl)-2,3-dihydro-
1H,5H-pyrrolo[2,3-f]indole-4,8-dione (16a)
To a solution of compound 15a (170 mg, 0.36 mmoL) in CH2Cl2
(6 mL) was added dropwise TFA (6 mL). The mixture was stirred
overnight at room temperature and concentrated. 1 N NaOH (5 mL)
and CH2Cl2 (5 mL) were added to the residue, the organic layer was
separated and the aqueous layer was extracted with CH2Cl2
(3 ꢂ 5 mL). The combined organic layers were dried over MgSO4
and concentrated over vacuum. The crude product was purified by
flash-chromatography (CH2Cl2/MeOH 98:2) to give the expected
product as a violine solid (61 mg, 38%), mp 122 ꢀC. HRMS (ESIþ)
[M þ Na]þ calcd 471.0991, found 471.1010. 1H NMR (CDCl3) 2.43 (s,
3H); 3.63 (dd, 1H, J ¼ 11.1 and 5.4 Hz); 3.81 (s, 3H); 4.09 (t, 1H,
J ¼ 11.4 Hz); 4.46 (dd, 1H, J ¼ 5.4 and 11.7 Hz); 6.65 (d, 1H,
J ¼ 3.3 Hz); 6.82 (d, 2H, J ¼ 8.7 Hz); 7.14 (d, 2H, J ¼ 8.7 Hz); 7.28 (d,
2H, J ¼ 8.4 Hz); 7.65 (d, 1H, J ¼ 3.3 Hz); 7.97 (d, 2H, J ¼ 8.4 Hz). 13C
NMR (CDCl3) 21.75; 44.86; 55.30; 56.05; 106.88; 114.03 (2C);
114.17; 126.97; 127.65; 128.10 (2C); 129.04 (2C); 129.43 (2C);
129.98; 134.27; 135.06; 145.68; 152.36; 158.46; 171.65; 177.29. IR
1650, 1610 cmꢁ1
.
5.19. 3-(4-Methoxy-phenyl)-1H,5H-pyrrolo[2,3-f]indole-4,
8-dione (18a)
The same procedure was used as for compound 11a involving
compound 17a (100 mg, 0.22 mmoL), 1 N NaOH (2 mL) and diox-
anne (2 mL). Purification of the crude product by flash-chroma-
tography (CH2Cl2/MeOH 98: 2) gave the product as an orange solid
(60 mg, 93%), mp > 260 ꢀC. HRMS (ESIþ) [M þ Na]þ calcd 315.0746,
found 315.0762. 1H NMR (DMSO-d6) 3.80 (s, 3H); 6.49 (d, 1H,
J ¼ 2.4 Hz); 6.95 (d, 2H, J ¼ 8.7 Hz); 7.07 (d, 1H, J ¼ 2.7 Hz); 7.24 (s,
1H); 7.75 (d, 2H, J ¼ 8.7 Hz); 12.51 (br.s, 2H). 13C NMR (DMSO-d6)
55.57; 107.36; 113.74 (2C); 120.78; 124.44; 125.25; 125.40; 126.26;
126.47; 130.06 (2C);134.50; 135.31; 158.87; 174.56; 174.83. IR (KBr)
3435, 3196, 1634 cmꢁ1
.
(KBr) 3397, 1681, 1609 cmꢁ1
.
5.20. 3-(4-Methoxy-phenyl)-1H,7H-pyrrolo[3,2-f]indole-4,
5.16. 3-(4-Methoxy-phenyl)-7-(toluene-4-sulfonyl)-2,3-dihydro-
8-dione (18b)
1H,7H-pyrrolo[3,2-f]indole-4,8-dione (16b)
The same procedure was used as for compound 11a involving
compound 17b (180 mg, 0.41 mmoL), 1 N NaOH (5 mL) and diox-
anne (5 mL). Purification of the crude product by flash-chroma-
tography (CH2Cl2/MeOH 98: 2) gave the product as an orange solid
(108 mg, 90%), mp > 260 ꢀC. HRMS (ESIþ) [M þ H]þ calcd 293.0926,
found 293.0955. 1H NMR (DMSO-d6) 3.77 (s, 3H); 6.45 (d, 1H,
J ¼ 2.7 Hz); 6.91 (d, 2H, J ¼ 8.7 Hz); 7.10 (d, 1H, J ¼ 2.7 Hz); 7.23 (s,
1H); 7.68 (d, 2H, J ¼ 8.7 Hz); 12.58 (br.s, 2H). 13C NMR (DMSO-d6)
55.57; 108.59; 113.70 (2C); 122.09; 124.50; 126.14; 126.19; 126.76;
128.85; 130.19 (2C); 131.51; 133.85; 158.92; 168.65; 180.65. IR (KBr)
The same procedure was used as for compound 16a involving
compound 15b (150 mg, 0.31 mmoL), CH2Cl2 (5 mL) and TFA
(5 mL). Purification of the crude product by flash-chromatography
(CH2Cl2/MeOH 98:2) gave the product as a violine solid (80 mg,
58%), mp 140 ꢀC. HRMS (ESIþ) [M þ H]þ calcd 449.1171, found
449.1175. 1H NMR (CDCl3) 2.44 (s, 3H); 3.63 (dd, 1H, J ¼ 11.1 and
6.0 Hz); 3.74 (s, 3H); 4.08 (t, 1H, J ¼ 11.7 Hz); 4.47 (dd, 1H, J ¼ 6.0
and 12.0 Hz); 6.62 (d, 1H, J ¼ 3.0 Hz); 6.79 (d, 2H, J ¼ 8.4 Hz); 7.16 (d,
2H, J ¼ 8.4 Hz); 7.35 (d, 2H, J ¼ 8.1 Hz); 7.73 (d, 1H, J ¼ 3.0 Hz); 8.01
(d, 2H, J ¼ 8.1 Hz). 13C NMR (CDCl3) 21.80; 44.75; 55.23; 55.94;
108.79; 114.09 (2C); 116.71; 126.48; 127.44; 128.14 (2C); 128.97
(2C); 129.79 (2C); 130.80; 134.06; 135.13; 135.81; 146.33; 158.63;
3377, 3225, 1636 cmꢁ1
.
5.21. 3-(4-Hydroxy-phenyl)-1H,5H-pyrrolo[2,3-f]indole-4,
8-dione (19a)
168.94; 177.59. IR (KBr) 3376, 1672, 1611 cmꢁ1
.
5.17. 7-(4-Methoxy-phenyl)-1-(toluene-4-sulfonyl)-1H,5H-
pyrrolo[2,3-f]indole-4,8-dione (17a)
The same procedure was used as for compound 13a involving
compound 18a (100 mg, 0.34 mmoL), and 1 M solution of BBr3 in
CH2Cl2 (20 mL). Purification of the crude product by flash-chro-
matography (CH2Cl2/MeOH 90:10) gave the product as a dark red
solid (61 mg, 65%), mp >260 ꢀC. HRMS (ESIþ) [M þ H]þ calcd
279.0770, found 279.0764. 1H NMR (DMSO-d6). 13C NMR (DMSO-d6)
114.51; 115.14 (2C); 115.77; 121.36; 122.79; 123.63; 125.06; 130.36;
130.99 (2C); 131.65; 133.22; 156.29; 170.45; 174.18. IR (KBr) 3410,
The same procedure was used as for compound 8a involving
compound 16a (200 mg, 0.45 mmoL), MnO2 (300 mg, 3.45 mmoL)
in CH2Cl2 (16 mL). Purification of the crude product by flash-chro-
matography (CH2Cl2) gave the product as an orange solid (143 mg,
71%), mp 199 ꢀC. HRMS (ESIþ) [M þ H]þ calcd 447.1015, found
447.1049. 1H NMR (CDCl3) 2.45 (s, 3H); 3.91 (s, 3H); 6.76 (d, 1H,
J ¼ 3.3 Hz); 6.97 (d, 2H, J ¼ 9.0 Hz); 7.02 (d, 1H, J ¼ 2.7 Hz); 7.35 (d,
2H, J ¼ 8.4 Hz); 7.58 (d, 2H, J ¼ 9.0 Hz); 7.77 (d, 1H, J ¼ 3.3 Hz); 8.07
(d, 2H, J ¼ 8.4 Hz). 13C NMR (CDCl3) 21.78; 55.35; 107.26;
113.58(2C); 121.41; 123.21; 124.83; 128.16; 129.06; 129.24; 129.50
(2C); 129.90 (2C); 130.55 (2C); 132.42; 132.95; 134.25; 145.80;
3180, 1640 cmꢁ1
.
5.22. 3-(4-Hydroxy-phenyl)-1H,7H-pyrrolo[3,2-f]indole-4,
8-dione (19b)
The same procedure was used as for compound 13a involving
compound 18b (50 mg, 0.17 mmoL), and 1 M solution of BBr3 in CH2Cl2
159.26; 171.81; 173.51. IR (KBr) 3378, 1741, 1677, 1626 cmꢁ1
.

A. Rives et al. / European Journal of Medicinal Chemistry 45 (2010) 343–351
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(10 mL). Purification of the crude product by flash-chromatography
(CH2Cl2/MeOH 90:10) gave the product as a dark red solid (30 mg,
63%), mp >260 ꢀC. HRMS (ESIþ) [M þ H]þ calcd 279.0770, found
279.0729. 1H NMR (DMSO-d6) 6.59 (d, 2H, J ¼ 8.4 Hz); 7.07 (d, 1H,
J ¼ 2.7 Hz); 7.37 (d, 1H, J ¼ 2.7 Hz); 7.38 (d, 2H, J ¼ 8.4 Hz), 12.51 (br. s,
1H); 12.54 (br. s, 1H). 13C NMR (DMSO-d6) 114.98 (2C); 115.07; 117.90;
122.88; 124.47; 124.66; 127.11; 127.38; 130.19 (2C); 131.97; 132.87;
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