Synthesis and biological evaluation of novel 4-azaindolyl-indolyl-maleimides as glycogen synthase kinase-3β (GSK-3β) inhibitors

Article abstract of DOI:10.1016/j.bmc.2009.05.031

A series of novel 4-azaindolyl-indolyl-maleimides were synthesized and evaluated for their GSK-3β inhibitory activity. Most compounds exhibited high potency to GSK-3β. Among them, compound 7c was the most promising GSK-3β inhibitor. Preliminary structure-activity relationships were discussed based on the experimental data obtained and showed that different substituents on the indole ring and side chains at 1-position of indole had varying degrees of influence on the GSK-3β inhibitory potency. In a cell-based functional assay, compounds 7c and 15a significantly reduced Aβ-induced Tau hyperphosphorylation by inhibiting GSK-3β.

Full text of DOI:10.1016/j.bmc.2009.05.031

Bioorganic & Medicinal Chemistry 17 (2009) 4302–4312
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis and biological evaluation of novel 4-azaindolyl-indolyl-maleimides
as glycogen synthase kinase-3b (GSK-3b) inhibitors
a,
Qing Ye a, Guiqing Xu a,b, Dan Lv a, Zhe Cheng c, Jia Li c, , Yongzhou Hu
*
*
a ZJU-ENS Joint Laboratory of Medicinal Chemistry, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
b College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007, China
c The National Center for Drug Screening, Shanghai 201203, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 20 March 2009
Revised 8 May 2009
Accepted 12 May 2009
Available online 18 May 2009
A series of novel 4-azaindolyl-indolyl-maleimides were synthesized and evaluated for their GSK-3b
inhibitory activity. Most compounds exhibited high potency to GSK-3b. Among them, compound 7c
was the most promising GSK-3b inhibitor. Preliminary structure–activity relationships were discussed
based on the experimental data obtained and showed that different substituents on the indole ring
and side chains at 1-position of indole had varying degrees of influence on the GSK-3b inhibitory potency.
In a cell-based functional assay, compounds 7c and 15a significantly reduced Ab-induced Tau hyper-
phosphorylation by inhibiting GSK-3b.
Keywords:
4-Azaindolyl-indolyl-maleimides
Synthesis
Ó 2009 Elsevier Ltd. All rights reserved.
Biological evaluation
GSK-3b inhibitors
1. Introduction
4-azaindol-3-yl 15a–d regio-isomers and in silico molecular mod-
eling study in a homology GSK-3 protein are discussed as well.
Glycogen synthase kinase-3 (GSK-3) is a multifunctional serine/
threonine protein kinase. It was first identified in the late 1970s as
a consequence of its phosphorylation activity toward glycogen
synthase, the rate limiting enzyme of glycogen biosynthesis.1,2 To-
day, it is known that GSK-3 plays a critical role in various cellular
and physiological events.3–6 From a drug discovery standpoint,
inhibition of GSK-3 may provide therapy for several diseases such
as cancer,7 diabetes type-2,8 chronic inflammatory processes,9
stroke,10 bipolar disorders and Alzheimer’s disease.11 Accordingly,
searching for GSK-3 inhibitors is a very active area in both aca-
demic centers and pharmaceutical companies. Mammalian GSK-3
2. Results and discussion
2.1. Chemistry
The synthetic routes of 3-(4-azaindol-1-yl)-4-(indol-3-yl)-
maleimides 6a, 7a–m and 8 were diagrammed in Scheme 1. Indole
adducts 2a–e were readily synthesized from indoles 1a–e by the
method described in the literature with minor modifications.18,19
Treatment of 2a–e with benzenesulfonyl chloride (PhSO2Cl) gave
intermediates 3a–e,20 then condensation of 3a–e with 4-azaindole
in the presence of lithium diisopropylamide (LDA) in THF resulted
in desired bisindolylmaleimide analogues 4a–e,20 followed by N-
debenzenesulfonylation in the presence of tetrabutylammonium
fluoride (TBAF) afforded 5a–e,20 which were reacted with different
alkyl chlorides to yield 6a–m.21 The target compounds 7a–m were
obtained by reaction of 6a–m with ammonium acetate
(NH4OAc).22 Treatment of 5a with the same procedure as prepara-
tion of 7a yielded 8.
On the other hand, reaction of 3-indoleacetamide 12 with 13a–
c yielded 14a–c. Condensation of 14a–c with 1123 in the presence
of t-BuOK afforded 3-(4-azaindol-3-yl)-4-(indol-3-yl)-maleimides
15a–c. Compound 14d was synthesized following the method de-
scribed in the literature with minor modifications.24 Reaction of
14d with 11 followed by removal of the silyl-protecting group with
TBAF afforded compound 15d (Scheme 2).
exists as two isoforms, GSK-3a and GSK-3b, which share high
homology at their catalytic domain, but which have shown distinct
pharmacology.12,13 Staurosporine, a microbial alkaloid, was identi-
fied as a potent but nonselective GSK-3b inhibitor, based on which
various bisindolylmaleimides have also been developed as potent
GSK-3b inhibitors (Fig. 1).14–17 These facts prompted us to design
and synthesis a series of novel 4-azaindolyl-indolyl-maleimides
to find more potent and selective GSK-3b inhibitors. In this paper,
we described the synthesis of the 4-azaindolyl-indolyl-maleimides
and the evaluation of these compounds as GSK-3b inhibitors. Their
structure–activity relationship between 4-azaindol-1-yl 7a–m and
* Corresponding authors. Tel./fax: +86 571 88208460 (Y.H.).
E-mail addresses: jli@mail.shcnc.ac.cn (J. Li), huyz@zju.edu.cn (Y. Hu).
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.05.031

Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4303
Figure 1. GSK-3b inhibitors.
Scheme 1. Synthetic route to compounds 6a, 7a–m and 8. Reagents and conditions: (a) (i) ethyl magnesium bromide, Et2O, benzene; (ii) N-phenyl-3,4-dichloromaleimide,
THF, rt; (b) NaH, PhSO2Cl, THF, ꢀ30 to ꢀ20 °C; (c) 4-azaindole, LDA, THF, ꢀ20 °C; (d) TBAF, THF, rt, 2 h; (e) R1-(CH2)3-Cl, DMF, NaH, rt, then 75 °C, 6 h; (f) NH4OAc, 140 °C, 4 h.
2.2. Biological activity and molecular modeling
ferent hydrophilic side chains at N1-position of the indole ring re-
sulted in an obvious enhancement of GSK-3b inhibitory activity.
Compound 7a, with a alkyl-imidazole group at N1-position of the
indole ring, exhibited potent GSK-3b inhibitory activity with IC50
2.2.1. Enzymatic activity
The GSK-3b inhibitory potency of all target compounds was
examined. In addition, the assays of inhibitory activity toward
PKCE, IKK2, Aurora A, MEK1 and ERK1 were also conducted to
determine the selectivity of tested compounds. Staurosporine, a
well-known kinase inhibitor, was used as a reference compound
in these assays. The results are summarized in Tables 1 and 2.
As shown in Table 1, most of the tested compounds displayed
similar or more potent GSK-3b inhibitory activity in comparison
with staurosporine. Among them, compound 6a, with the hydro-
gen on the nitrogen in maleimide ring being replaced by phenyl,
had less inhibitory activity toward GSK-3b. It suggested that a
hydrogenbond donor in maleimide ring was essential for the
GSK-3b inhibitory activity.
of 0.55
lM, which was about 56-fold more potent than
8
(IC50 = 30.6
lM). In series of 3-(4-azaindol-1-yl)-4-(indol-3-yl)-
maleimides, the inhibitory activity of compounds was dependent
on the sorts of side chain at N1-position of the indole ring. Com-
pounds 7a–e, 7l and 7m containing a alkyl-imidazole group at
N1-position of the indole ring, showed more potent inhibitory
activity toward GSK-3b than those with a alkyl-dimethylamino
group at N1-position (7f–i). Otherwise, the sorts of side chain at
N1-position of the indole ring had a slight influence on the inhibi-
tory activity compared 15a with 15b and 15d in series of 3-(4-
azaindol-3-yl)-4-(indol-3-yl)-maleimides.
Comparing the inhibitory activity of 7a with 7b–e, it appeared
that different substituents on the indole ring could affect the po-
tency. Compound 7b with bromine at 5-position of the indole ring
Comparing the inhibitory activity of compound 8 with all other
target compounds except 6a, it appeared that introduction of dif-

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Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
Scheme 2. Synthetic route to compounds 15a-d. Reagents and conditions: (a) NaH, CH3I, DMF, 0–5 °C; (b) anhydrous AlCl3, ethyl oxalyl monochloride; (c) NaH, DMF, 0–5 °C,
then 70 °C, 6 h; (d) 11, t-BuOK, 0–5 °C, 1 h; (e) NaH, DMF, (3-bromopropoxy)(tert-butyl) dimethylsilane, rt; (f) (i) 11, t-BuOK, 0–5 °C 1 h; (ii) TBAF, THF, rt, 2 h.
Table 1
GSK-3b inhibitory activity of the target compounds
Compds
R
R1
n
IC50 (l
M) SEa
Staurosporine
0.20 0.0b
>73.34
6a
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
7m
8
15a
15b
15c
15d
H
Imidazol-1-yl
Imidazol-1-yl
Imidazol-1-yl
Imidazol-1-yl
Imidazol-1-yl
Dimethylamino
Dimethylamino
Dimethylamino
Dimethylamino
Piperidin-1-yl
Morpholino
3
3
3
3
3
3
3
3
3
3
3
2
4
0.55 0.01
0.48 0.01
0.14 0.01
0.95 0.20
0.31 0.11
13.58 0.23
22.46 2.30
2.26 0.02
12.44 1.12
12.45 1.08
1.79 0.07
0.26 0.01
0.85 0.01
30.6 14.95
0.76 0.01
0.66 0.16
0.90 0.02
1.14 0.07
5-OCH3
5-Br
6-Br
6-F
H
5-OCH3
6-Br
6-F
H
H
H
H
Imidazol-1-yl
Imidazol-1-yl
Morpholino
Imidazol-1-yl
Morpholino
Hydroxy
3
3
2
3
a
SE: standard error mean.
b
Lit.25 IC50 = 0.056 0.0069
lM.

Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4305
Table 2
The selectivity to tested kinases of target compounds 7c, 7l and 15aa
Kinase assay
IC50 SEb
(l
M)
Staurosporine
7c
7l
15a
GSK-3b
PKCE
IKK2
0.20 0.0
0.0015 0.0001
1.41 0.26
0.14 0.01
>40
>40
0.26 0.01
>40
>40
0.76 0.01
>40
>40
Aurora A
MEK1
ERK1
0.018 0.002
0.67 0.035
1.31 0.035
>40
>40
>40
>40
>40
>40
>40
>40
>40
a
‘>40’ means <50% inhibition at 40
SE: standard error mean.
lM of compound.
b
showed a fourfold activity increase toward GSK-3b as compared to
7a. Methoxyl at the 5-position or fluorine at 6-position of the in-
dole ring was tolerated, while bromine at 6-position led to some
loss of activity.
The results in Table 1 also showed that when the 3-position of
4-azaindole was attached with maleimide ring, the resulting com-
pounds 15a–d also exhibited potent inhibitory activity toward
GSK-3b. This fact indicated the attached position of 4-azaindole
with maleimide has little effect on the activity.
Figure 3. Docking of 7c to GSK-3b crystal structure.
As reported in the literature,17 staurosporine was found to be a
potent and nonselective kinase inhibitor. Although staurosporine
potently inhibits GSK-3b (IC50 = 0.2 lM), it also potently inhibits
bond interactions between the maleimide portion of 7c to Asp-
133 and Val-135 backbone carbonyl and amide hydrogen, respec-
tively. Another hydrogen-bond forms between the 3-position
nitrogen atom of imidazole of the side chain and the residue of
Asp-200. The 4-position nitrogen of azaindole is about 3.55 Å from
the carboxyl group of Ile-62 and may not form an additional hydro-
gen bond interaction with Ile-62 but may keep hydrogen bonding
with water around the catalytic site.
many kinases (e.g., PKCE, IKK2, Aurora A, MEK1 and ERK1). The
data of inhibitory activity toward PKCE, IKK2, Aurora A, MEK1
and ERK1 showed that compounds 7c, 7l and 15a displayed high
selectivity for GSK-3b over other tested kinases (see Table 2).
2.2.2. Cellular activity
Among the multiple cellular processes in which GSK-3b has
been implicated, the ability to hyperphosphorylate Tau protein
and induce neurofibrillary tangle was intensively studied. There-
fore, the cell-based assay examining Tau phosphorylation at Ser
396 represents a direct functional assay to measure the cellular
activity of GSK-3 inhibitors. Compounds 7b–d, 7l, 7m and 15a
were tested for the ability to reduce Tau phosphorylation at Ser
396 in human neuroblastoma SH-SY5Y cells. LiCl is a known inhib-
itor of GSK-3b and reduces Tau phosphorylation at Ser 396 in
SH-SY5Y cells,26 which was used as a reference compound in this
assay. As shown in Figure 2, compounds 7c and 15a significantly
reduced Ab-induced Tau hyperphosphorylation, showing the inhi-
bition of GSK-3b at the cell level, while compounds 7b, 7d, 7l and
7m exhibited no significant cellular activity.
3. Conclusion
In summary, a series of novel 4-azaindolyl-indolyl-maleimide
derivatives were prepared and tested for their biological activity.
Most synthesized compounds showed potent GSK-3b inhibitory
activities with compound 7c being the most potent one. Among
them, compounds 7c, 7l and 15a exhibited high selectivity against
PKCE, IKK2, Aurora A, MEK1 and ERK1. Further cell-based func-
tional assay revealed that 7c and 15a could significantly reduce
Ab-induced Tau hyperphosphorylation by inhibiting GSK-3b. Preli-
minary structure–activity relationships and molecular modeling
study provided further insight into interactions between the en-
zyme and its ligand. The results provided valuable information
for the design of GSK-3b inhibitors.
2.2.3. Molecular modeling
To probe the possible binding conformation and protein–ligand
interaction mode of a GSK-3b inhibitor, a molecular docking study
of the optimum compound 7c was performed using the Tripos
FLEXIDOCK program,27 based on the published GSK-3b crystal struc-
ture (1Q3D).17 Figure 3 illustrates that there are two hydrogen-
4. Experimental
4.1. Chemistry
All reactions were monitored by thin-layer chromatography
(TLC). All reagents were obtained from commercial sources and
used without further purification unless stated. Et2O, THF and ben-
zene were distilled from sodium-benzophenone. DMF was distilled
from calcium hydride. Melting points were determined with a
BÜCHI Melting Point B-450 apparatus (Büchi Labortechnik, Flawil,
Switzerland). The 1H NMR spectra were recorded in DMSO-d6 or
CDCl3 on Bruker Avance DMX 400 using TMS as an internal stan-
dard (Bruker, Billerica, MA, USA). Chemical shifts are expressed
in parts per million d. ESI-MS were obtained on an Esquire-LC-
00075 mass spectrometer (Bruker, USA). Elemental analyses were
performed by ERBA-1110 analyzer (Carlo, Italy).
Figure 2. Effects of GSK-3b inhibitors on tau phosphorylation (ser396) in SH-SY5Y.
cells.

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Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4.1.1. 3-Chloro-4-(1H-indol-3-yl)-1-phenyl-1H-pyrrole-2,5-
dione (2a)
crystalline powder, mp: 176–178 °C. 1H NMR (CDCl3, 400 MHz, d):
7.34 (t, J = 8.0 Hz, 1H), 7.41–7.43 (m, 4H), 7.49–7.53 (m, 4H), 7.60
(t, J = 8.0 Hz, 1H), 7.88 (d, J = 8.0 Hz, 1H), 7.98 (d, J = 8.0 Hz, 2H),
8.06 (d, J = 8.0 Hz, 1H), 8.31 (s, 1H). ESI-MS: m/z [M+H]+ 463. Anal.
Calcd for C24H15ClN2O4S: C, 62.27; H, 3.27; N, 6.05. Found: C, 62.41;
H, 3.43; N, 6.15.
Ethyl magnesium bromide (4.98 g, 37.5 mmol) in Et2O (15 mL)
was added dropwise to a solution of 1a (4.57 g, 39 mmol) in ben-
zene (5 mL) at room temperature over 30 min. After stirring for
30 min, the mixture was added dropwise to a solution of N-phe-
nyl-3,4-dichloromaleimide (6.05 g, 25 mmol) in THF (10 mL) over
2 h. The resulting mixture was stirred for 4 h at room temperature.
After that, it was adjusted to weak acidity with 1 M aqueous hydro-
chloric acid and extracted with ethyl acetate (3 ꢁ 100 mL). The or-
ganic phase was combined and washed with brine (3 ꢁ 300 mL),
dried over Na2SO4 and concentrated in vacuo. The residue was
recrystallized from ethyl acetate to get 5.84 g (72.4%) of 2a as a
red solid, mp: 203–204 °C. 1H NMR (DMSO-d6, 400 MHz, d):
7.19–7.26 (m, 2H), 7.45–7.54 (m, 6H), 7.97 (d, J = 8.0 Hz, 1H),
8.13 (s, 1H), 12.18 (br s, 1H).
4.1.7. 3-Chloro-4-(5-methoxy-1-benzenesulfonyl-1H-indol-3-
yl)-1-phenyl-1H-pyrrole-2,5-dione (3b)
According to the procedure used to prepare 3a, reaction of 2b
with benzenesulfonyl chloride provided 3b in 49.7% yield as a yel-
low solid, mp: 166–168 °C. 1H NMR (CDCl3, 400 MHz, d): 3.83 (s,
3H), 7.06 (dd, J = 1.6, 8.0 Hz, 1H), 7.31 (d, J = 8.0 Hz, 1H), 7.41–
7.43 (m, 3H), 7.47–7.49 (m, 4H), 7.59 (t, J = 8.0 Hz, 1H), 7.93–7.95
(m, 3H), 8.26 (s, 1H). ESI-MS: m/z [M+H]+ 493. Anal. Calcd for
C25H17ClN2O5S: C, 60.91; H, 3.48; N, 5.68. Found: C, 60.80; H,
3.33; N, 5.79.
4.1.2. 3-Chloro-4-(5-methoxy-1H-indol-3-yl)-1-phenyl-1H-
pyrrole-2,5-dione (2b)
4.1.8. 3-(5-Bromo-1-benzenesulfonyl-1H-indol-3-yl)-4-chloro-
1-phenyl-1H-pyrrole-2,5-dione (3c)
According to the procedure used to prepare 2a, reaction of 1b
with N-phenyl-3,4-dichloromaleimide provided 2b in 72.6% yield
as an orange solid, mp: 185–187 °C. 1H NMR (DMSO-d6, 400 MHz,
d): 3.78 (s, 3H), 6.90 (dd, J = 2.0, 8.4 Hz, 1H), 7.43–7.47 (m, 5H),
7.51–7.55 (m, 2H), 8.08 (d, J = 3.2 Hz, 1H), 12.10 (br s, 1H).
According to the procedure used to prepare 3a, reaction of 2c
with benzenesulfonyl chloride provided 3c in 43.5% yield as a yel-
low solid, mp: 136–138 °C. 1H NMR (CDCl3, 400 MHz, d): 7.42–7.46
(m, 3H), 7.51–7.55 (m, 5H), 7.62 (t, J = 7.6 Hz, 1H), 7.94–7.98 (m,
3H), 7.07 (d, J = 1.6 Hz, 1H), 8.32 (s, 1H). ESI-MS: m/z [M+H]+ 541.
Anal. Calcd for C24H14BrClN2O4S: C, 53.20; H, 2.60; N, 5.17. Found:
C, 53.35; H, 2.43; N, 5.49.
4.1.3. 3-(5-Bromo-1H-indol-3-yl)-4-chloro-1-phenyl-1H-
pyrrole-2,5-dione (2c)
According to the procedure used to prepare 2a, reaction of 1c
with N-phenyl-3,4-dichloromaleimide provided 2c in 63.4% yield
as a red solid, mp: 212–214 °C. 1H NMR (DMSO-d6, 400 MHz, d):
7.37 (dd, J = 2.4, 7.6 Hz, 1H), 7.44–7.47 (m, 3H), 7.51–7.53 (m,
3H), 8.15 (s, 1H), 8.20 (d, J = 3.2 Hz, 1H), 12.36 (br s, 1H).
4.1.9. 3-(6-Bromo-1-benzenesulfonyl-1H-indol-3-yl)-4-chloro-
1-phenyl-1H-pyrrole-2,5-dione (3d)
According to the procedure used to prepare 3a, reaction of 2d
with benzenesulfonyl chloride provided 3d in 44.1% yield as a yel-
low solid, mp: 218–220 °C. 1H NMR (CDCl3, 400 MHz, d): 7.41–7.55
(m, 8H), 7.65 (t, J = 7.6 Hz, 1H), 7.78 (d, J = 8.0 Hz, 1H), 7.99 (d,
J = 7.6 Hz, 2H), 8.26 (d, J = 1.2 Hz, 1H), 8.29 (s, 1H). ESI-MS: m/z
[M+H]+ 541. Anal. Calcd for C24H14BrClN2O4S: C, 53.20; H, 2.60;
N, 5.17. Found: C, 53.05; H, 2.71; N, 5.06.
4.1.4. 3-(6-Bromo-1H-indol-3-yl)-4-chloro-1-phenyl-1H-
pyrrole-2,5-dione (2d)
According to the procedure used to prepare 2a, reaction of 1d
with N-phenyl-3,4-dichloromaleimide provided 2d in 70.1% yield
as a red solid, mp: 205–207 °C. 1H NMR (DMSO-d6, 400 MHz, d):
7.33 (dd, J = 1.6, 8.0 Hz, 1H), 7.45–7.48 (m, 3H), 7.50–7.53 (m,
2H), 7.73 (d, J = 1.6 Hz, 1H), 7.91 (d, J = 8.0 Hz, 1H), 8.15 (d,
J = 3.2 Hz, 1H), 12.27 (br s, 1H).
4.1.10. 3-Chloro-4-(6-fluoro-1-benzenesulfonyl-1H-indol-3-yl)-
1-phenyl-1H-pyrrole-2,5-dione (3e)
According to the procedure used to prepare 3a, reaction of 2e
with benzenesulfonyl chloride provided 3e in 40.5% yield as a yel-
low solid, mp: 202–204 °C. 1H NMR (CDCl3, 400 MHz, d): 7.11 (td,
J = 8.4 Hz, 1.2 Hz, 1H), 7.42–7.45 (m, 3H), 7.53–7.55 (m, 4H), 7.65
(t, J = 8.0 Hz, 1H), 7.79 (dd, J = 2.0, 7.6 Hz, 1H), 7.88–7.90 (m, 1H),
7.98–8.00 (m, 2H), 8.31 (s, 1H). ESI-MS: m/z [M+H]+ 481. Anal.
Calcd for C24H14ClFN2O4S: C, 59.94; H, 2.93; N, 5.83. Found: C,
59.75; H, 2.83; N, 5.99.
4.1.5. 3-Chloro-4-(6-fluoro-1H-indol-3-yl)-1-phenyl-1H-
pyrrole-2,5-dione (2e)
According to the procedure used to prepare 2a, reaction of 1e
with N-phenyl-3,4-dichloromaleimide provided 2e in 66.4% yield
as a red solid, mp: 205–208 °C. 1H NMR (DMSO-d6, 400 MHz, d):
7.06 (t, J = 9.6 Hz, 1H), 7.33 (d, J = 9.6 Hz, 1H), 7.42–7.45 (m, 3H),
7.51–7.54 (m, 2H), 7.94–7.97 (m, 1H), 8.14 (d, J = 2.8 Hz, 1H),
12.22 (br s, 1H). ESI-MS: m/z [M+H]+ 341. Anal. Calcd for
C18H10ClFN2O2: C, 63.45; H, 2.96; N, 8.22. Found: C, 63.68; H,
3.03; N, 8.03.
4.1.11. 3-(1-Benzenesulfonyl-1H-indol-3-yl)-1-phenyl-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (4a)
A solution of 4-azaindole (0.71 g, 6 mmol) in THF (20 mL) was
added to a solution of LDA (6 mmol) in THF (3 mL) at ꢀ10 °C under
N2 and stirred for 30 min at this temperature. The mixture was
cooled to ꢀ20 °C and a solution of 3a (2.31 g, 5 mmol) in THF
(15 mL) was added dropwise. After addition, it was stirred at
ꢀ20 °C for 1 h, and then poured into water (300 mL), extracted
with ethyl acetate (3 ꢁ 50 mL). The organic phase was washed
with brine (3 ꢁ 150 mL), dried over Na2SO4 and concentrated in
vacuo. The residue was purified by flash column chromatography
on silica gel using dichloromethane/methanol (50:1, v/v) as eluent
to afford 1.21 g (44.5%) of 4a as an orange solid, mp: 130–132 °C.
1H NMR (CDCl3, 400 MHz, d): 6.15 (d, J = 8.0 Hz, 1H), 6.58–6.60
(m, 1H), 6.73 (t, J = 8.0 Hz, 1H), 6.97 (d, J = 4.0 Hz, 1H), 7.07 (d,
J = 8.0 Hz, 1H), 7.16 (t, J = 8.0 Hz, 1H), 7.49–7.52 (m, 7H), 7.62 (t,
J = 7.6 Hz, 1H), 7.78 (d, J = 4.0 Hz, 1H), 7.92 (d, J = 8.0 Hz, 1H),
4.1.6. 3-(1-Benzenesulfonyl-1H-indol-3-yl)-4-chloro-1-phenyl-
1H-pyrrole-2,5-dione (3a)
60% NaH (0.48 g, 12 mmol) was added portion-wise to a solu-
tion of 2a (3.22 g, 10 mmol) in THF (15 mL) at ꢀ5 to 0 °C and stir-
red for additional 30 min. Then, benzenesulfonyl chloride (2.65 g,
15 mmol) in THF (5 mL) was added dropwise to the above mixture
at ꢀ30 to ꢀ20 °C. The resulting mixture was stirred at ꢀ30 to
ꢀ20 °C for 1 h. After that it was poured into water (100 mL) and ex-
tracted with ethyl acetate (3 ꢁ 50 mL). The organic phase was
combined, washed with brine (3 ꢁ 300 mL), dried over Na2SO4
and concentrated in vacuo. The residue was purified by flash col-
umn chromatography on silica gel using petroleum ether/ethyl
acetate (6:1, v/v) as eluent to afford 2.52 g (54.4%) of 3a as a yellow

Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4307
7.96 (d, J = 8.0 Hz, 2H), 8.32 (d, J = 4.4 Hz, 1H), 8.37 (s, 1H). ESI-MS:
m/z [M+H]+ 545. Anal. Calcd for C31H20N4O4S: C, 68.37; H, 3.70; N,
10.29. Found: C, 68.55; H, 3.81; N, 10.09.
0.66 g (81.3%) of 5a as a red solid, mp: >250 °C. 1H NMR (DMSO-d6,
400 MHz, d): 6.06 (d, J = 8.0 Hz, 1H), 6.53 (t, J = 8.0 Hz, 1H), 6.90–
6.92 (m, 2H), 6.97 (t, J = 8.0 Hz, 1H), 7.38 (d, J = 8.0 Hz, 1H), 7.46–
7.49 (m, 2H), 7.54–7.57 (m, 4H), 7.89 (d, J = 3.6 Hz, 1H), 8.14 (d,
J = 3.2 Hz, 1H), 8.29 (d, J = 4.4 Hz, 1H), 12.37 (br s, 1H). ESI-MS:
m/z [M+H]+ 405. Anal. Calcd for C25H16N4O2: C, 74.25; H, 3.99; N,
13.85. Found: C, 74.45; H, 4.05; N, 13.99.
4.1.12. 3-(5-Methoxy-1-benzenesulfonyl-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(4b)
According to the procedure used to prepare 4a, reaction of 3b
with 4-azaindole provided 4b in 40.7% yield as a red solid, mp:
176–178 °C. 1H NMR (CDCl3, 400 MHz, d): 3.12 (s, 3H), 5.56 (d,
J = 2.4 Hz, 1H), 6.65–6.68 (m, 1H), 6.75 (dd, J = 1.6, 8.4 Hz, 1H),
6.97 (d, J = 3.2 Hz, 1H), 7.20 (d, J = 8.0 Hz, 1H), 7.46–7.53 (m, 7H),
7.61 (t, J = 7.6 Hz, 1H), 7.79–7.81 (m, 2H), 7.95 (d, J = 8.0 Hz, 2H),
8.37–8.39 (m, 2H). ESI-MS: m/z [M+H]+ 575. Anal. Calcd for
C32H22N4O5S: C, 66.89; H, 3.86; N, 9.75. Found: C, 66.65; H, 3.94;
N, 10.01.
4.1.17. 3-(5-Methoxy-1H-indol-3-yl)-1-phenyl-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (5b)
According to the procedure used to prepare 5a, reaction of 4b
with TBAF provided 5b in 79.5% yield as a red solid, mp: 226–
229 °C. 1H NMR (DMSO-d6, 400 MHz, d): 3.09 (s, 3H), 5.42 (d,
J = 2.0 Hz, 1H), 6.62 (dd, J = 2.0, 8.0 Hz, 1H), 7.25 (d, J = 3.6 Hz,
1H), 7.30 (d, J = 8.0 Hz, 1H), 7.51–7.55 (m, 6H), 8.21 (d, J = 3.6 Hz,
1H), 8.26 (d, J = 8.4 Hz, 1H), 8.35 (d, J = 3.2 Hz, 1H), 8.68 (d,
J = 4.8 Hz, 1H), 12.27 (br s, 1H). ESI-MS: m/z [M+H]+ 435. Anal.
Calcd for C26H18N4O3: C, 71.88; H, 4.18; N, 12.90. Found: C,
71.98; H, 4.09; N, 12.79.
4.1.13. 3-(5-Bromo-1-benzenesulfonyl-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(4c)
According to the procedure used to prepare 4a, reaction of 3c
with 4-azaindole provided 4c in 42.8% yield as a red solid, mp:
136–138 °C. 1H NMR (CDCl3, 400 MHz, d): 6.23 (d, J = 2.4 Hz, 1H),
6.58–6.60 (m, 1H), 7.02 (d, J = 8.8 Hz, 1H), 7.07 (d, J = 3.6 Hz, 1H),
7.24 (dd, J = 1.6, 8.0 Hz, 1H), 7.51–7.55 (m, 7H), 7.66 (t, J = 7.6 Hz,
1H), 7.80–7.83 (m, 2H), 7.92 (d, J = 7.6 Hz, 2H), 8.32 (s, 1H), 8.37
(dd, J = 1.2, 4.8 Hz, 1H). ESI-MS: m/z [M+H]+ 623. Anal. Calcd for
C31H19BrN4O4S: C, 59.72; H, 3.07; N, 8.99. Found: C, 59.61; H,
3.16; N, 9.11.
4.1.18. 3-(5-Bromo-1H-indol-3-yl)-1-phenyl-4-(1H-pyrrolo[3,2-
b]pyridin-1-yl)-1H-pyrrole-2,5-dione (5c)
According to the procedure used to prepare 5a, reaction of 4c
with TBAF provided 5c in 85.3% yield as a red solid, mp: 216–
218 °C. 1H NMR (DMSO-d6, 400 MHz, d): 5.93 (d, J = 2.0 Hz, 1H),
7.13 (dd, J = 2.0, 8.0 Hz, 1H), 7.28 (d, J = 3.6 Hz, 1H), 7.39 (d,
J = 8.0 Hz, 1H), 7.54–7.59 (m, 6H), 8.20 (d, J = 8.4 Hz, 1H), 8.25 (d,
J = 3.2 Hz, 1H), 8.36 (d, J = 3.6 Hz, 1H), 8.70 (d, J = 4.8 Hz, 1H),
12.58 (br s, 1H). ESI-MS: m/z [M+H]+ 483. Anal. Calcd for
C25H15BrN4O2: C, 62.13; H, 3.13; N, 11.59. Found: C, 62.35; H,
3.08; N, 11.67.
4.1.14. 3-(6-Bromo-1-benzenesulfonyl-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(4d)
4.1.19. 3-(6-Bromo-1H-indol-3-yl)-1-phenyl-4-(1H-pyrrolo[3,2-
b]pyridin-1-yl)-1H-pyrrole-2,5-dione (5d)
According to the procedure used to prepare 4a, reaction of 3d
with 4-azaindole provided 4d in 34.8% yield as a red solid, mp:
160–163 °C. 1H NMR (CDCl3, 400 MHz, d): 6.03 (d, J = 8.4 Hz, 1H),
6.64–6.66 (m, 1H), 6.89 (dd, J = 2.0, 8.4 Hz, 1H), 7.00 (d, J = 3.6 Hz,
1H), 7.08 (d, J = 8.4 Hz, 1H), 7.44–7.50 (m, 3H), 7.54–7.58 (m,
4H), 7.67 (t, J = 8.0 Hz, 1H), 7.77 (d, J = 3.6 Hz, 1H), 7.96 (d,
J = 7.6 Hz, 2H), 8.12 (d, J = 2.0 Hz, 1H), 8.32 (s, 1H); 8.38 (d,
J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 623. Anal. Calcd for
C31H19BrN4O4S: C, 59.72; H, 3.07; N, 8.99. Found: C, 59.94; H,
3.13; N, 9.21.
According to the procedure used to prepare 5a, reaction of 4d
with TBAF provided 5d in 76.6% yield as a red solid, mp: 185–
188 °C. 1H NMR (DMSO-d6, 400 MHz, d): 5.95 (d, J = 8.0 Hz, 1H),
6.77 (dd, J = 1.6, 8.0 Hz, 1H), 7.21 (d, J = 3.6 Hz, 1H), 7.54–7.58 (m,
6H), 7.63 (d, J = 1.6 Hz, 1H), 8.21–8.23 (m, 2H), 8.30 (d, J = 3.6 Hz,
1H), 8.68 (d, J = 4.8 Hz, 1H), 12.42 (br s, 1H). ESI-MS: m/z [M+H]+
483. Anal. Calcd for C25H15BrN4O2: C, 62.13; H, 3.13; N, 11.59.
Found: C, 62.27; H, 3.21; N, 11.85.
4.1.20. 3-(6-Fluoro-1H-indol-3-yl)-1-phenyl-4-(1H-pyrrolo[3,2-
b]pyridin-1-yl)-1H-pyrrole-2,5-dione (5e)
4.1.15. 3-(6-Fluoro-1-benzenesulfonyl-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(4e)
According to the procedure used to prepare 5a, reaction of 4e
with TBAF provided 5e in 81.8% yield as a red solid, mp: 215–
218 °C. 1H NMR (DMSO-d6, 400 MHz, d): 5.95–5.98 (m, 1H), 6.52
(dd, J = 1.6, 8.8 Hz, 1H), 7.22–7.24 (m, 2H), 7.53–7.57 (m, 6H),
8.21–8.23 (m, 2H), 8.33 (d, J = 3.6 Hz, 1H), 8.67 (d, J = 5.2 Hz, 1H),
12.47 (br s, 1H). ESI-MS: m/z [M+H]+ 423. Anal. Calcd for
C25H15FN4O2: C, 71.08; H, 3.58; N, 13.26. Found: C, 71.36; H,
3.41; N, 13.55.
According to the procedure used to prepare 4a, reaction of 3e
with 4-azaindole provided 4e in 44.2% yield as a red solid, mp:
104–107 °C. 1H NMR (CDCl3, 400 MHz, d): 6.10–6.12 (m, 1H),
6.52 (td, J = 2.0, 8.8 Hz, 1H), 6.61–6.63 (m, 1H), 7.01 (d, J = 3.2 Hz,
1H), 7.08 (d, J = 8.4 Hz, 1H), 7.54–7.58 (m, 7H), 7.66–7.68 (m,
2H), 7.79 (d, J = 3.2 Hz, 1H), 7.96 (d, J = 8.0 Hz, 2H), 8.34 (s, 1H),
8.36 (d, J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 563. Anal. Calcd for
C31H19FN4O4S: C, 66.18; H, 3.40; N, 9.96. Found: C, 66.42; H,
3.33; N, 9.69.
4.1.21. 3-(1-(3-(1H-Imidazol-1-yl)propyl)-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(6a)
4.1.16. 3-(1H-Indol-3-yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-
1-yl)-1H-pyrrole-2,5-dione (5a)
60% NaH (12.8 mg, 0.32 mmol) was added portion-wise to a
solution of 5a (121 mg, 0.3 mmol) in DMF (25 mL) at room temper-
ature. After stirring for 30 min, 1-(3-chloropropyl)-1H-imidazole
(65 mg, 0.45 mmol) was added and the mixture was then headed
to 75 °C for 6 h. After that, the mixture was poured into water
(500 mL) and extracted with ethyl acetate (3 ꢁ 100 mL). The or-
ganic phase was combined, washed with brine (3 ꢁ 300 mL), dried
over Na2SO4 and concentrated in vacuo. The residue was purified
by flash column chromatography on silica gel using dichlorometh-
A mixture of TBAF (1.57 g, 6 mmol) and 4a (1.09 g, 2 mmol) in
THF (20 mL) was stirred at room temperature for 2 h. The reaction
mixture was then poured into water (200 mL) and extracted with
ethyl acetate (3 ꢁ 100 mL). The organic phase was washed with
brine (3 ꢁ 300 mL), dried over Na2SO4 and concentrated in vacuo.
The residue was purified by flash column chromatography on silica
gel using dichloromethane/methanol (30:1, v/v) as eluent to afford

4308
Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
ane/methanol/triethylamine (90:30:1, v/v/v) as eluent to afford
64 mg (41.7%) of 6a as a red solid, mp: 126–128 °C. 1H NMR (CDCl3,
400 MHz, d): 2.39–2.41 (m, 2H), 3.94 (t, J = 6.8 Hz, 2H), 4.17 (t,
J = 6.8 Hz, 2H), 6.17 (d, J = 8.0 Hz, 1H), 6.69 (t, J = 8.0 Hz, 1H),
6.82–6.84 (m, 1H), 6.95 (br s, 1H), 6.98 (d, J = 3.6 Hz, 1H), 7.14–
7.17 (m, 3H), 7.30 (d, J = 8.0 Hz, 1H), 7.41–7.42 (m, 1H), 7.51–
7.55 (m, 5H), 7.74 (d, J = 3.6 Hz, 1H), 7.98 (s, 1H), 8.39 (d,
J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 513. Anal. Calcd for
C31H24N6O2: C, 72.64; H, 4.72; N, 16.40. Found: C, 72.36; H,4.49;
N, 16.25.
4.1.26. 3-(1-(3-(Dimethylamino)propyl)-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(6f)
According to the procedure used to prepare 6a, reaction of 5a
with 3-chloro-N,N-dimethylpropan-1-amine provided 6f in 49.0%
yield as a red solid, mp: 150–152 °C. 1H NMR (CDCl3, 400 MHz,
d): 2.04–2.06 (m, 2H), 2.26–2.32 (m, 8H), 4.30 (t, J = 6.8 Hz, 2H),
6.14 (d, J = 8.0 Hz, 1H), 6.67 (t, J = 8.0 Hz, 1H), 6.82–6.84 (m, 1H),
6.98 (d, J = 3.6 Hz, 1H), 7.08 (t, J = 8.0 Hz, 1H), 7.31–7.33 (m, 2H),
7.42–7.43 (m, 1H), 7.53–7.56 (m, 4H), 7.74 (d, J = 3.6 Hz, 1H),
8.09 (s, 1H), 8.39 (dd, J = 1.2, 4.0 Hz, 1H). ESI-MS: m/z [M+H]+
490. Anal. Calcd for C30H27N5O2: C, 73.60; H, 5.56; N, 14.31. Found:
C, 73.54; H,5.63; N, 14.48.
4.1.22. 3-(5-Methoxy-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-
3-yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-
2,5-dione (6b)
According to the procedure used to prepare 6a, reaction of 5b
with 1-(3-chloropropyl)-1H-imidazole provided 6b in 33.2% yield
as a red solid, mp: 56–58 °C. 1H NMR (CDCl3, 400 MHz, d): 2.41–
2.42 (m, 2H), 3.06 (s, 3H), 4.01 (t, J = 6.4 Hz, 2H), 4.18 (t,
J = 6.4 Hz, 2H), 5.56 (d, J = 1.6 Hz, 1H), 6.69 (dd, J = 1.6, 8.4 Hz,
1H), 6.87–6.90 (m, 1H), 6.95 (d, J = 3.6 Hz, 2H), 7.04 (d, J = 8.4 Hz,
1H), 7.13 (br s, 1H), 7.41 (m, 2H), 7.50–7.54 (m, 4H), 7.73 (d,
J = 3.6 Hz, 1H), 7.88 (br s, 1H), 8.01 (s, 1H), 8.40 (d, J = 4.4 Hz,
1H). ESI-MS: m/z [M+H]+ 543. Anal. Calcd for C32H26N6O3: C,
70.84; H, 4.83; N, 15.49. Found: C, 70.59; H, 4.68; N, 15.58.
4.1.27. 3-(5-Methoxy-1-(3-(dimethylamino)propyl)-1H-indol-
3-yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-
2,5-dione (6g)
According to the procedure used to prepare 6a, reaction of 5b
with 3-chloro-N,N-dimethylpropan-1-amine provided 6g in 41.7%
yield as a red solid, mp: 178–180 °C. 1H NMR (CDCl3, 400 MHz,
d): 2.01–2.03 (m, 2H), 2.23–2.27 (m, 8H), 3.06 (s, 3H), 4.25 (t,
J = 6.8 Hz, 2H), 5.55 (d, J = 2.0 Hz, 1H), 6.66 (dd, J = 2.0, 8.0 Hz,
1H), 6.88–6.89 (m, 1H), 6.94 (d, J = 3.6 Hz, 1H), 7.18 (d, J = 8.0 Hz,
1H), 7.40–7.42 (m, 2H), 7.50–7.53 (m, 4H), 7.73 (d, J = 3.6 Hz,
1H), 8.11 (s, 1H), 8.42 (d, J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 520.
Anal. Calcd for C31H29N5O3: C, 71.66; H, 5.63; N, 13.48. Found: C,
71.47; H,5.44; N, 13.62.
4.1.23. 3-(5-Bromo-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-3-
yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-
dione (6c)
According to the procedure used to prepare 6a, reaction of 5c
with 1-(3-chloropropyl)-1H-imidazole provided 6c in 31.3% yield
as a red solid, mp: 135–137 °C. 1H NMR (CDCl3, 400 MHz, d):
2.35–2.37 (m, 2H), 3.92 (t, J = 6.8 Hz, 2H), 4.12 (t, J = 6.8 Hz, 2H),
6.24 (d, J = 2.0 Hz, 1H), 6.79–6.82 (m, 1H), 6.92 (br s, 1H), 6.99 (d,
J = 8.0 Hz, 1H), 7.06 (d, J = 3.6 Hz, 1H), 7.14 (br s, 1H), 7.17–7.21
(m, 2H), 7.42–7.45 (m, 1H), 7.52–7.56 (m, 5H), 7.74 (d, J = 3.6 Hz,
1H), 7.88 (s, 1H), 8.41 (d, J = 3.6 Hz, 1H). ESI-MS: m/z [M+H]+ 591.
Anal. Calcd for C31H23BrN6O2: C, 62.95; H, 3.92; N, 14.21. Found:
C, 62.76; H, 3.69; N, 14.25.
4.1.28. 3-(6-Bromo-1-(3-(dimethylamino)propyl)-1H-indol-3-
yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-
dione (6h)
According to the procedure used to prepare 6a, reaction of 5d
with 3-chloro-N,N-dimethylpropan-1-amine provided 6h in 44.0%
yield as a red solid, mp: 82–84 °C. 1H NMR (CDCl3, 400 MHz, d):
1.97–1.99 (m, 2H), 2.21–2.26 (m, 8H), 4.23 (t, J = 6.8 Hz, 2H), 5.98
(d, J = 8.0 Hz, 1H), 6.75 (d, J = 8.0 Hz, 1H), 6.81–6.82 (m, 1H), 6.97
(d, J = 3.6 Hz, 1H), 7.23 (d, J = 8.0 Hz, 1H), 7.41–7.43 (m, 1H),
7.52–7.56 (m, 5H), 7.71 (d, J = 3.6 Hz, 1H), 8.00 (s, 1H), 8.41 (d,
J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 568. Anal. Calcd for
C30H26BrN5O2: C, 63.39; H, 4.61; N, 12.32. Found: C, 63.51; H,
4.46; N, 12.51.
4.1.24. 3-(6-Bromo-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-3-
yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-
dione (6d)
According to the procedure used to prepare 6a, reaction of 5d
with 1-(3-chloropropyl)-1H-imidazole provided 6d in 35.2% yield
as a red solid, mp: 120–122 °C. 1H NMR (CDCl3, 400 MHz, d):
2.38–2.40 (m, 2H), 3.95 (t, J = 6.4 Hz, 2H), 4.12 (t, J = 6.8 Hz, 2H),
6.02 (d, J = 8.4 Hz, 1H), 6.79–6.84 (m, 2H), 6.97–7.01 (m, 2H),
7.16 (br s, 1H), 7.23 (d, J = 8.0 Hz, 1H), 7.32 (br s, 1H), 7.42–7.45
(m, 1H), 7.51–7.54 (m, 5H), 7.73 (d, J = 3.2 Hz, 1H), 7.90 (s, 1H),
8.41 (d, J = 3.6 Hz, 1H). ESI-MS: m/z [M+H]+ 591. Anal. Calcd for
C31H23BrN6O2: C, 62.95; H, 3.92; N, 14.21. Found: C, 62.99;
H,3.88; N, 14.45.
4.1.29. 3-(6-Fluoro-1-(3-(dimethylamino)propyl)-1H-indol-3-
yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-
dione (6i)
According to the procedure used to prepare 6a, reaction of 5e
with 3-chloro-N,N-dimethylpropan-1-amine provided 6i in 35.0%
yield as a red solid, mp: 128–130 °C. 1H NMR (CDCl3, 400 MHz,
d): 2.14–2.26 (m, 2H), 2.44 (s, 6H), 2.52 (t, J = 6.8 Hz, 2H), 4.29 (t,
J = 6.8 Hz, 2H), 6.04–6.05 (m, 1H), 6.41 (t, J = 9.2 Hz, 1H), 6.81–
6.83 (m, 1H), 6.99–7.01 (m, 2H), 7.24 (d, J = 6.4 Hz, 1H), 7.41–
7.42 (m, 1H), 7.49–7.52 (m, 4H), 7.72 (d, J = 3.6 Hz, 1H), 8.04 (s,
1H); 8.38 (d, J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 508. Anal. Calcd
for C30H26FN5O2: C, 70.99; H, 5.16; N, 13.80. Found: C, 70.71; H,
5.32; N, 13.53.
4.1.25. 3-(6-Fluoro-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-3-
yl)-1-phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-
dione (6e)
According to the procedure used to prepare 6a, reaction of 5e
with 1-(3-chloropropyl)-1H-imidazole provided 6e in 37.5% yield
as a red solid, mp: 90–92 °C. 1H NMR (CDCl3, 400 MHz, d): 2.38–
2.40 (m, 2H), 3.97 (t, J = 6.4 Hz, 2H), 4.12 (t, J = 6.8 Hz, 2H), 6.06–
6.09 (m, 1H), 6.46 (td, J = 9.2, 1.6 Hz 1H), 6.81–6.86 (m, 2H), 6.95
(br s, 1H), 6.99 (d, J = 3.2 Hz, 1H), 7.14 (br s, 1H), 7.28 (d,
J = 8.0 Hz 1H), 7.40–7.44 (m, 1H), 7.51–7.54 (m, 4H), 7.65 (br s,
1H), 7.74 (d, J = 3.6 Hz, 1H); 7.93 (s, 1H); 8.40 (d, J = 4.4 Hz, 1H).
ESI-MS: m/z [M+H]+ 531. Anal. Calcd for C31H23FN6O2: C, 70.18;
H, 4.37; N, 15.84. Found: C, 70.26; H,4.56; N, 15.57.
4.1.30. 3-(1-(3-(Piperidin-1-yl)propyl)-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H -pyrrole-2,5-dione
(6j)
According to the procedure used to prepare 6a, reaction of 5a
with 1-(3-chloropropyl)piperidine provided 6j in 47.2% yield as a
red solid, mp: 78–80 °C. 1H NMR (CDCl3, 400 MHz, d): 1.43–1.46
(m, 2H), 1.60–1.63 (m, 4H), 2.03–2.06 (m, 2H), 2.28 (t, J = 6.4 Hz,
2H), 2.33–2.37 (m, 4H), 4.28 (t, J = 7.2 Hz, 2H), 6.13 (d, J = 8.0 Hz,
1H), 6.65 (t, J = 8.0 Hz, 1H), 6.79–6.82 (m, 1H), 6.98 (d, J = 3.2 Hz,
1H), 7.07 (t, J = 8.0 Hz, 1H), 7.27–7.30 (m, 2H), 7.40–7.44 (m, 1H),

Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4309
7.51–7.54 (m, 4H), 7.73 (d, J = 3.2 Hz, 1H), 8.08 (s, 1H), 8.38 (dd,
J = 1.6, 4.0 Hz, 1H). ESI-MS: m/z [M+H]+ 530. Anal. Calcd for
C33H31N5O2: C, 74.84; H, 5.90; N, 13.22. Found: C, 74.65; H, 5.71;
N, 13.47.
4.1.35. 3-(5-Methoxy-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-
3-yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(7b)
According to the procedure used to prepare 7a, reaction of 6b
with ammonium acetate provided 7b in 82.3% yield as a red solid,
mp: >250 °C. 1H NMR (DMSO-d6, 400 MHz, d): 2.23–2.24 (m, 2H),
2.95 (s, 3H), 3.98 (t, J = 7.2 Hz, 2H), 4.20 (t, J = 6.8 Hz, 2H), 5.43
(d, J = 1.6 Hz, 1H), 6.55 (dd, J = 1.6, 8.4 Hz, 1H), 6.79 (d, J = 3.2 Hz,
1H), 6.86–6.88 (m, 1H,), 6.93 (br s, 1H), 7.12 (br s, 1H), 7.19 (d,
J = 8.4 Hz, 1H), 7.40 (d, J = 8.0 Hz, 1H), 7.60 (br s, 1H), 7.74 (d,
J = 2.4 Hz, 1H), 8.04 (s, 1H), 8.28 (d, J = 4.0 Hz, 1H), 11.21 (br s,
1H). ESI-MS: m/z [M+H]+ 467. Anal. Calcd for C26H22N6O3: C,
66.94; H, 4.75; N, 18.02. Found: C, 66.71; H, 4.63; N, 18.15.
4.1.31. 3-(1-(3-Morpholinopropyl)-1H-indol-3-yl)-1-phenyl-4-
(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (6k)
According to the procedure used to prepare 6a, reaction of 5a
with 4-(3-chloropropyl)morpholine provided 6k in 53.0% yield as
a red solid, mp: 109–111 °C. 1H NMR (CDCl3, 400 MHz, d): 2.03–
2.07 (m, 2H), 2.29 (t, J = 6.4 Hz, 2H), 2.40–2.44 (m, 4H), 3.73–
3.77 (m, 4H), 4.32 (t, J = 6.8 Hz, 2H), 6.13 (d, J = 8.0 Hz, 1H), 6.65
(t, J = 8.0 Hz, 1H), 6.80–6.83 (m, 1H), 6.98 (d, J = 3.6 Hz, 1H),
7.07 (t, J = 8.0 Hz, 1H), 7.28–7.32 (m, 2H), 7.40–7.43 (m, 1H),
7.49–7.53 (m, 4H), 7.73 (d, J = 3.6 Hz, 1H,), 8.09 (s, 1H), 8.39
(dd, J = 1.6, 4.0 Hz, 1H). ESI-MS: m/z [M+H]+ 532. Anal. Calcd for
C32H29N5O3: C, 72.30; H, 5.50; N, 13.17. Found: C, 72.53; H,
5.64; N, 13.41.
4.1.36. 3-(5-Bromo-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-3-
yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7c)
According to the procedure used to prepare 7a, reaction of 6c
with ammonium acetate provided 7c in 80.5% yield as a red solid,
mp: >250 °C. 1H NMR (DMSO-d6, 400 MHz, d): 2.22–2.24 (m, 2H),
3.93 (t, J = 6.8 Hz, 2H), 4.25 (t, J = 7.2 Hz, 2H), 6.08 (d, J = 2.4 Hz
1H), 6.81–6.84 (m, 1H), 6.90–6.91 (m, 2H), 7.12 (dd, J = 2.4,
8.4 Hz, 1H), 7.19 (br s, 1H), 7.30 (d, J = 7.6 Hz, 1H), 7.37 (d,
J = 8.4 Hz, 1H), 7.61 (br s, 1H), 7.85 (d, J = 2.4 Hz, 1H), 8.06 (s,
1H), 8.26 (d, J=4.4 Hz, 1H), 11.34 (br s, 1H). ESI-MS: m/z [M+H]+
515. Anal. Calcd for C25H19BrN6O2: C, 58.26; H, 3.72; N, 16.31.
Found: C, 58.14; H, 3.82; N, 16.47.
4.1.32. 3-(1-(2-(1H-Imidazol-1-yl)ethyl)-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(6l)
According to the procedure used to prepare 6a, reaction of 5a
with 1-(2-chloroethyl)-1H-imidazole provided 6l in 36.0% yield
as a red solid, mp: 115–117 °C. 1H NMR (CDCl3, 400 MHz, d):
4.41 (t, J = 6.4 Hz, 2H), 4.52 (t, J = 6.4 Hz, 2H), 6.08 (d, J = 8.0 Hz,
1H), 6.67 (t, J = 7.6 Hz, 1H), 6.76 (br s, 1H), 6.91–6.94 (m, 1H),
7.02–7.06 (m, 4H), 7.17 (d, J = 8.4 Hz, 1H), 7.27 (d, J = 8.0 Hz, 1H),
7.38–7.42 (m, 1H), 7.47–7.53 (m, 4H), 7.58 (s, 1H), 7.78 (d,
J = 4.0 Hz, 1H), 8.39 (d, J = 4.0 Hz, 1H). ESI-MS: m/z [M+H]+ 499.
Anal. Calcd for C30H22N6O2: C, 72.28; H, 4.45; N, 16.86. Found: C,
72.41; H, 4.55; N, 16.59.
4.1.37. 3-(6-Bromo-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-3-
yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7d)
According to the procedure used to prepare 7a, reaction of 6d
with ammonium acetate provided 7d in 83.7% yield as a red solid,
mp: 104–106 °C. 1H NMR (DMSO-d6, 400 MHz, d): 2.23–2.25 (m,
2H), 3.95 (t, J = 7.2 Hz, 2H), 4.26 (t, J = 6.8 Hz, 2H), 5.98 (d,
J = 8.4 Hz, 1H), 6.69 (dd, J = 2.0, 8.0 Hz, 1H), 6.82–6.84 (m, 1H),
6.87 (d, J = 3.6 Hz, 1H), 6.92 (br s, 1H), 7.21 (br s, 1H), 7.30 (d,
J = 8.4 Hz, 1H), 7.64 (br s, 1H), 7.70 (d, J = 2.0 Hz, 1H), 7.85 (d,
J = 3.6 Hz, 1H), 8.01 (s, 1H), 8.25 (d, J = 3.6 Hz, 1H), 11.36 (br s,
1H). ESI-MS: m/z [M+H]+ 515. Anal. Calcd for C25H19BrN6O2: C,
58.26; H, 3.72; N, 16.31. Found: C, 58.39; H, 3.70; N, 16.24.
4.1.33. 3-(1-(4-(1H-Imidazol-1-yl)butyl)-1H-indol-3-yl)-1-
phenyl-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione
(6m)
According to the procedure used to prepare 6a, reaction of 5a
with 1-(4-chlorobutyl)-1H-imidazole provided 6m in 36.9% yield
as a red solid, mp: 81–83 °C. 1H NMR (CDCl3, 400 MHz, d): 1.80–
1.83 (m, 2H), 1.87–1.89 (m, 2H), 3.91 (t, J = 6.4 Hz, 2H), 4.19 (t,
J = 6.8 Hz, 2H), 6.18 (d, J = 8.0 Hz, 1H), 6.69 (t, J = 7.6 Hz, 1H),
6.80–6.86 (m, 2H), 6.99 (br s, 1H), 7.09 (t, J = 8.0 Hz, 2H), 7.22 (d,
J = 8.0 Hz, 1H), 7.30 (d, J = 8.0 Hz, 1H), 7.40–7.44 (m, 1H), 7.49–
7.53 (m, 5H), 7.72 (d, J = 3.6 Hz, 1H), 7.98 (s, 1H), 8.40 (br s, 1H).
ESI-MS: m/z [M+H]+ 527. Anal. Calcd for C32H26N6O2: C, 72.99; H,
4.98; N, 15.96. Found: C, 72.76; H, 4.86; N, 16.13.
4.1.38. 3-(6-Fluoro-1-(3-(1H-imidazol-1-yl)propyl)-1H-indol-3-
yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5- dione (7e)
According to the procedure used to prepare 7a, reaction of 6e
with ammonium acetate provided 7e in 84.1% yield as a red solid,
mp: >250 °C. 1H NMR (DMSO-d6, 400 MHz, d): 2.22–2.24 (m, 2H),
3.95 (t, J = 6.8 Hz, 2H), 4.22 (t, J = 6.8 Hz, 2H), 5.99–6.03 (m, 1H),
6.42 (td, J = 9.2, 2.4 Hz, 1H), 6.80–6.83 (m, 1H), 6.85 (d, J = 3.2 Hz,
1H), 6.92 (br s, 1H), 7.21 (br s, 1H), 7.28–7.32 (m, 2H), 7.63 (br s,
1H), 7.84 (d, J = 3.6 Hz, 1H), 8.01 (s, 1H), 8.24 (dd, J = 2.4, 4.4 Hz,
1H), 11.34 (br s, 1H). ESI-MS: m/z [M+H]+ 455. Anal. Calcd for
C25H19FN6O2: C, 66.07; H, 4.21; N, 18.49. Found: C, 66.00; H,
4.09; N, 18.23.
4.1.34. 3-(1-(3-(1H-Imidazol-1-yl)propyl)-1H-indol-3-yl)-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7a)
Compound 6a (28 mg, 0.055 mmol) was heated with ammo-
nium acetate (1.16 g, 15 mmol) for 4 h at 140 °C. The mixture
was cooled, poured into water (100 mL), adjusted to weak alkalin-
ity with Na2CO3 and extracted with ethyl acetate (3 ꢁ 50 mL). The
organic layer was washed with brine (3 ꢁ 150 mL), dried over
Na2SO4 and concentrated in vacuo. The residue was purified by
preparative thin layer chromatography using dichloromethane/
methanol/triethylamine (90:30:1, v/v/v) as eluent to afford 20 mg
4.1.39. 3-(1-(3-(Dimethylamino)propyl)-1H-indol-3-yl)-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7f)
According to the procedure used to prepare 7a, reaction of 6f
with ammonium acetate provided 7f in 90.6% yield as a red solid,
mp: 124–126 °C. 1H NMR (CDCl3, 400 MHz, d): 2.16–2.20 (m, 2H),
2.33 (s, 6H), 2.41 (t, J = 6.8 Hz, 2H), 4.30 (t, J = 7.2 Hz, 2H), 6.04
(d, J = 8.0 Hz, 1H), 6.62 (t, J = 8.0 Hz, 1H), 6.82–6.83 (m, 1H), 6.97
(d, J = 3.6 Hz, 1H), 7.06 (t, J = 8.0 Hz, 1H), 7.28 (d, J = 8.0 Hz, 2H),
7.67 (d, J = 3.6 Hz, 1H), 8.28 (s, 1H), 8.37 (dd, J = 1.6, 4.8 Hz, 1H),
10.84 (br s, 1H). ESI-MS: m/z [M+H]+ 414. Anal. Calcd for
C24H23N5O2: C, 69.72; H, 5.61; N, 16.94. Found: C, 69.83; H, 5.58;
N, 16.67.
(83.3%) of 7a as
a red solid, mp: 152–154 °C. 1H NMR
(CDCl3 + DMSO-d6, 400 MHz, d): 2.48–2.50 (m, 2H), 4.27 (t,
J = 6.4 Hz, 2H), 4.32 (t, J = 6.4 Hz, 2H), 6.01 (d, J = 8.0 Hz, 1H), 6.59
(t, J = 8.0 Hz, 1H), 6.89–6.90 (m, 2H), 7.03 (t, J = 8.0 Hz, 1H), 7.35–
7.37 (m, 3H), 7.61 (d, J = 8.0 Hz, 1H), 7.76 (d, J = 3.6 Hz, 1H), 7.99
(s, 1H), 8.33 (d, J = 4.4 Hz, 1H), 8.97 (br s, 1H), 11.12 (br s, 1H).
ESI-MS: m/z [M+H]+ 437. Anal. Calcd for C25H20N6O2: C, 68.80; H,
4.62; N, 19.25. Found: C, 68.72; H, 4.58; N, 19.17.

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Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4.1.40. 3-(5-Methoxy-1-(3-(dimethylamino)propyl)-1H-indol-3-
yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7g)
According to the procedure used to prepare 7a, reaction of 6g
with ammonium acetate provided 7g in 77.6% yield as a red solid,
mp: 194–196 °C. 1H NMR (CDCl3 + DMSO-d6, 400 MHz, d): 2.06–
2.08 (m, 2H), 2.33–2.37 (m, 8H), 3.01 (s, 3H), 4.28 (t, J = 6.8 Hz,
2H), 5.46 (d, J = 2.0 Hz, 1H), 6.61 (dd, J = 2.0, 8.0 Hz, 1H), 6.87–
6.88 (m, 2H), 7.19 (d, J = 8.0 Hz, 1H), 7.35 (d, J = 8.4 Hz, 1H), 7.67
(d, J = 3.6 Hz, 1H), 8.06 (s, 1H), 8.37 (d, J = 4.4 Hz, 1H), 10.95 (br s,
1H). ESI-MS: m/z [M+H]+ 444. Anal. Calcd for C25H25N5O3: C,
67.70; H, 5.68; N, 15.79. Found: C, 67.63; H, 5.54; N, 15.88.
mp: 108–110 °C. 1H NMR (DMSO-d6, 400 MHz, d): 4.42 (t,
J = 6.4 Hz, 2H), 4.67 (t, J = 6.4 Hz, 2H), 5.92 (d, J = 8.0 Hz, 1H), 6.48
(t, J = 7.6 Hz, 1H), 6.86 (br s, 1H), 6.88–6.91 (m, 2H), 6.95 (t,
J = 7.6 Hz, 1H), 7.07 (br s, 1H), 7.16 (d, J = 8.4 Hz, 1H), 7.24 (br s,
1H), 7.41 (d, J = 7.6 Hz, 1H), 7.82 (s, 1H), 7.89 (d, J = 3.2 Hz, 1H),
8.25 (d, J = 3.6 Hz, 1H), 11.30 (br s, 1H). ESI-MS: m/z [M+H]+ 423.
Anal. Calcd for C24H18N6O2: C, 68.24; H, 4.29; N, 19.89. Found: C,
68.13; H, 4.34; N, 19.72.
4.1.46. 3-(1-(4-(1H-Imidazol-1-yl)butyl)-1H-indol-3-yl)-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7m)
According to the procedure used to prepare 7a, reaction of 6m
with ammonium acetate provided 7m in 81.0% yield as a red solid,
mp: 94–96 °C. 1H NMR (DMSO-d6, 400 MHz, d): 1.66–1.70 (m, 4H),
3.96 (t, J = 6.8 Hz, 2H), 4.30 (t, J = 6.8 Hz, 2H), 6.01 (d, J = 8.0 Hz,
1H), 6.52 (t, J = 7.6 Hz, 1H), 6.73–6.76 (m, 1H), 6.84–6.87 (m, 2H),
6.97 (t, J = 8.0 Hz, 1H), 7.11 (br s, 1H), 7.26 (d, J = 8.4 Hz, 1H),
7.43 (d, J = 8.4 Hz, 1H), 7.59 (br s, 1H), 7.83 (d, J = 3.6 Hz, 1H),
8.09 (s, 1H), 8.23 (d, J = 3.6 Hz, 1H), 11.25 (br s, 1H). ESI-MS: m/z
[M+H]+ 451. Anal. Calcd for C26H22N6O2: C, 69.32; H, 4.92; N,
18.66. Found. C, 69.19; H, 4.94; N, 18.51.
4.1.41. 3-(6-Bromo-1-(3-(dimethylamino)propyl)-1H-indol-3-
yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7h)
According to the procedure used to prepare 7a, reaction of 6h
with ammonium acetate provided 7h in 83.6% yield as a red solid,
mp: 212–214 °C. 1H NMR (CDCl3 + DMSO-d6, 400 MHz, d): 2.38–
2.40 (m, 2H), 2.84 (s, 6H), 3.14 (t, J = 6.8 Hz, 2H), 4.43 (t,
J = 6.4 Hz, 2H), 5.84 (d, J = 8.0 Hz, 1H), 6.68 (d, J = 8.0 Hz, 1H),
7.04 (d, J = 3.6 Hz, 1H), 7.12–7.13 (m, 1H), 7.58–7.60 (m, 2H),
7.86 (d, J = 3.6 Hz, 1H), 8.15 (s, 1H), 8.41 (d, J = 4.4 Hz, 1H), 11.90
(br s, 1H). ESI-MS: m/z [M+H]+ 492. Anal. Calcd for C24H22BrN5O2:
C, 58.55; H, 4.50; N, 14.22. Found: C, 58.48; H, 4.46; N, 14.08.
4.1.47. 3-(1H-Indol-3-yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-
pyrrole-2,5-dione (8)
4.1.42. 3-(6-Fluoro-1-(3-(dimethylamino)propyl)-1H-indol-3-
yl)-4-(1H-pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7i)
According to the procedure used to prepare 7a, reaction of 6i with
ammonium acetate provided 7i in 87.5% yield as a red solid, mp:
215–217 °C. 1H NMR (CDCl3 + DMSO-d6, 400 MHz, d): 1.90–1.92
(m, 2H), 2.30–2.35 (m, 8H), 4.28 (t, J = 6.4 Hz, 2H), 5.99–6.00 (m,
1H), 6.42 (dd, J = 1.6, 8.4 Hz, 1H), 6.82–6.83 (m, 1H), 6.88 (d,
J = 3.6 Hz, 1H), 7.27 (d, J = 8.4 Hz, 1H), 7.38 (dd, J = 1.6, 8.4 Hz, 1H),
7.85 (d, J = 3.6 Hz, 1H), 8.05 (s, 1H), 8.27 (d, J = 4.4 Hz, 1H), 11.32
(br s, 1H). ESI-MS: m/z [M+H]+ 432. Anal. Calcd for C24H22FN5O2: C,
66.81; H, 5.14; N, 16.23. Found: C, 66.97; H, 5.01; N, 16.05.
According to the procedure used to prepare 7a, reaction of 5a
with ammonium acetate provided 8 in 85.1% yield as a red solid,
mp: 188–190 °C. 1H NMR (DMSO-d6, 400 MHz, d): 5.95 (d,
J = 7.6 Hz, 1H), 6.47 (t, J = 7.6 Hz, 1H), 6.86–6.94 (m, 3H), 7.30–
7.33 (m, 2H), 7.84 (br s, 1H), 8.06 (br s, 1H), 8.24 (d, J = 2.0 Hz,
1H), 11.29 (br s, 1H), 12.00 (br s, 1H). ESI-MS: m/z [M+H]+ 329.
Anal. Calcd for C19H12N4O2: C, 69.51; H, 3.68; N, 17.06. Found: C,
69.44; H, 3.54; N, 17.22.
4.1.48. 1-Methyl-1H-pyrrolo[3,2-b]pyridine (1-methyl-4-
azaindole, 10)
60% NaH (0.88 g, 22 mmol) was added fractionally to a solution
of 4-azaindole (2.36 g, 20 mmol) in DMF (20 mL) at 0ꢂ5 °C. After
stirring for 30 min, iodomethane (3.4 g, 24 mmol) was added drop-
wise. After addition, the reaction mixture was stirred at 0–5 °C for
30 min and then 1 h at room temperature. After that, it was poured
into water (300 mL) and extracted with dichloromethane
(3 ꢁ 50 mL). The organic phase was combined and washed with
brine (3 ꢁ 150 mL), dried over Na2SO4 and concentrated in vacuo.
The residue was purified by flash column chromatography on silica
gel using petroleum ether/ethyl acetate (4:1, v/v) as eluent to af-
ford 2.23 g (84.5%) of 10 as a colorless oil. 1H NMR (CDCl3,
400 MHz, d): 3.78 (s, 3H), 6.68 (br s, 1H), 7.09–7.12 (m, 1H), 7.23
(br s, 1H), 7.59 (d, J = 8.0 Hz, 1H), 8.45 (d, J = 4.4 Hz, 1H).
4.1.43. 3-(1-(3-(Piperidin-1-yl)propyl)-1H-indol-3-yl)-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7j)
According to the procedure used to prepare 7a, reaction of 6j with
ammonium acetate provided 7j in 83.7% yield as a red solid, mp:
132–135 °C. 1H NMR (CDCl3, 400 MHz, d): 1.47–1.50 (m, 2H),
1.67–1.69 (m, 4H), 2.10–2.14 (m, 2H), 2.35 (t, J = 6.8 Hz, 2H), 2.45–
2.48 (m, 4H), 4.29 (t, J = 6.8 Hz, 2H), 6.06 (d, J = 8.0 Hz, 1H), 8.02 (t,
J = 8.0 Hz, 1H), 6.80–6.83 (m, 1H), 6.95 (d, J = 3.6 Hz, 1H), 7.05 (t,
J = 8.0 Hz, 1H), 7.23 (d, J = 8.0 Hz, 1H), 7.30 (d, J = 8.0 Hz, 1H), 7.65
(d, J = 3.6 Hz, 1H), 8.08 (s, 1H), 8.38 (dd, J = 1.2, 4.0 Hz, 1H), 11.23
(br s, 1H). ESI-MS: m/z [M+H]+ 454. Anal. Calcd for C27H27N5O2: C,
71.50; H, 6.00; N, 15.44. Found: C, 71.39; H, 6.03; N, 15.31.
4.1.44. 3-(1-(3-Morpholinopropyl)-1H-indol-3-yl)-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7k)
According to the procedure used to prepare 7a, reaction of 6k
with ammonium acetate provided 7k in 78.0% yield as a red solid,
mp: 125–127 °C. 1H NMR (DMSO-d6, 400 MHz, d): 1.91–1.96 (m,
2H), 2.21–2.25 (m, 6H), 3.60–3.64 (m, 4H), 4.34 (t, J = 6.8 Hz, 2H),
6.10 (d, J = 8.0 Hz, 1H), 6.52 (t, J = 8.0 Hz, 1H), 6.81–6.83 (m, 1H),
6.87 (d, J = 3.6 Hz, 1H), 6.99 (t, J = 8.0 Hz, 1H), 7.30 (d, J = 8.0 Hz,
1H), 7.47 (d, J = 8.4 Hz, 1H), 7.85 (d, J = 3.6 Hz, 1H), 8.12 (s, 1H),
8.25 (dd, J = 1.2, 4.0 Hz, 1H), 11.31 (br s, 1H). ESI-MS: m/z [M+H]+
456. Anal. Calcd for C26H25N5O3: C, 68.56; H, 5.53; N, 15.37. Found:
C, 68.48; H, 5.56; N, 15.22.
4.1.49. Ethyl 2-(1-methyl-1H-pyrrolo[3,2-b]pyridin-3-yl)-2-
oxoacetate (11)
Anhydrous aluminum trichloride (12.16 g, 91.2 mmol) was
added to a solution of 1-methyl-4-azaindole (2.23 g, 16.9 mmol)
in dichloromethane (150 mL) and stirred for 1 h at room tempera-
ture. Ethyl oxalyl monochloride (5.50 g, 45.6 mmol) was added
dropwise and the resulting mixture was stirred at room tempera-
ture for 6 h. After that, the supernate was abandoned and 20%
ammonium acetate aqueous (0–5 °C) was added to the reaction
mixture. The mixture was stirred sufficiently and extracted with
dichloromethane (3 ꢁ 100 mL). The organic phase was combined
and washed with brine (100 mL), dried over Na2SO4 and concen-
trated in vacuo. The residue was recrystallized with ethyl acetate
to afford 1.68 g (42.9%) of 11 as a white crystal, mp: 144–147 °C.
1H NMR (CDCl3, 400 MHz, d): 1.41 (t, J = 7.2 Hz, 3H), 3.00 (s, 3H),
4.42 (q, J = 7.2 Hz, 2H), 7.22–7.26 (m, 1H), 7.66 (d, J = 8.4 Hz, 1H),
8.36 (s, 1H), 8.69 (d, J = 4.4 Hz, 1H). ESI-MS: m/z [M+H]+ 233. Anal.
4.1.45. 3-(1-(2-(1H-Imidazol-1-yl)ethyl)-1H-indol-3-yl)-4-(1H-
pyrrolo[3,2-b]pyridin-1-yl)-1H-pyrrole-2,5-dione (7l)
According to the procedure used to prepare 7a, reaction of 6l
with ammonium acetate provided 7l in 82.0% yield as a red solid,

Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
4311
Calcd for C12H12N2O3: C, 62.06; H, 5.21; N, 12.06. Found: C, 62.31;
4.1.54. 3-(1-Methyl-1H-pyrrolo[3,2-b]pyridin-3-yl)-4-(1-(3-
H, 5.41; N, 12.23.
morpholinopropyl)-1H-indol-3-yl)-1H-pyrrole-2,5-dione (15a)
A solution of t-BuOK (100 mg, 0.9 mmol) in THF was added
dropwise to a solution of 11 (91 mg, 0.39 mmol) and 14a (90 mg,
0.3 mmol) in THF (20 mL) at 0–5 °C. After stirring for 1 h, the mix-
ture was poured into 10% ammonium chloride aqueous (100 mL)
and extracted with ethyl acetate (3 ꢁ 50 mL). The organic phase
was combined and washed with brine (3 ꢁ 150 mL), dried over
Na2SO4 and concentrated in vacuo. The residue was purified by
flash column chromatography on silica gel using ethyl acetate/
methanol/triethylanine (150:3:1, v/v/v) as eluent to afford
15.8 mg (11.2%) of 15a as a red solid, mp: 134–136 °C. 1H NMR
(CDCl3, 400 MHz, d): 2.02–2.05 (m, 2H), 2.28 (t, J = 6.8 Hz, 2H),
2.43–2.47 (m, 4H), 3.72–3.76 (m, 4H), 3.90 (s, 3H), 4.29 (t,
J = 6.8 Hz, 2H), 6.52–6.56 (m, 2H), 6.95–6.98 (m, 2H), 7.30 (d,
J = 8.0 Hz, 1H), 7.59 (d, J = 8.0 Hz, 1H), 7.76 (s, 1H), 8.01–8.04 (m,
2H), 10.35 (br s, 1H). ESI-MS: m/z [M+H]+ 470. Anal. Calcd for
C27H27N5O3: C, 69.07; H, 5.80; N, 14.92. Found: C, 69.14; H, 5.84;
N, 14.82.
4.1.50. 2-(1-(3-Morpholinopropyl)-1H-indol-3-yl)acetamide
(14a)
60% NaH (0.8 g, 20 mmol) was added fractionally to a solution
of 2-(1H-indol-3-yl)acetamide (12) (3.48 g, 20 mmol) in DMF
(20 mL) at 0–5 °C. After stirring for 30 min, 4-(3-chloropropyl)mor-
pholine (13a) (4.90 g, 30 mmol) was added. Then the mixture was
warmed to 70 °C and reacted for 6 h. After that, the reaction mix-
ture was cooled, poured into water (300 mL) and extracted with
ethyl acetate (3 ꢁ 50 mL). The organic phase was combined,
washed with brine (3 ꢁ 150 mL), dried over Na2SO4 and concen-
trated in vacuo. The residue was purified by flash column chroma-
tography on silica gel using dichloromethane/methanol/
triethylamine (180:3:1, v/v/v) as eluent to afford 2.51 g (41.7%)
of 14a as
a
white solid, mp: 115–117 °C. 1H NMR (CDCl3,
400 MHz, d): 1.96–2.00 (m, 2H), 2.16 (t, J = 6.4 Hz, 2H), 2.36–2.40
(m, 4H), 3.69–3.73 (m, 6H), 4.19 (t, J = 6.8 Hz, 2H), 5.62–5.64 (m,
2H), 7.06 (s, 1H), 7.11 (t, J = 8.0 Hz, 1H), 7.22 (t, J = 8.0 Hz, 1H),
7.37 (d, J = 8.0 Hz, 1H), 7.56 (d, J = 8.0 Hz, 1H). ESI-MS: m/z
[M+H]+ 302. Anal. Calcd for C17H23N3O2: C, 67.75; H, 7.69; N,
13.94. Found: C, 67.63; H, 7.48; N, 14.13.
4.1.55. 3-(1-(3-(1H-Imidazol-1-yl)propyl)-1H-indol-3-yl)-4-(1-
methyl-1H-pyrrolo[3,2-b]pyridin-3-yl)-1H-pyrrole-2,5-dione
(15b)
According to the procedure used to prepare 15a, reaction of 11
with 14b provided 15b in 13.2% yield as a red solid, mp: 94–96 °C.
1H NMR (DMSO-d6, 400 MHz, d): 2.42–2.46 (m, 2H), 3.90 (s, 3H),
3.97 (t, J = 6.8 Hz, 2H), 4.18 (t, J = 6.4 Hz, 2H), 6.56 (t, J = 8.0 Hz,
1H), 6.66 (d, J = 8.0 Hz, 1H), 6.92–6.99 (m, 2H), 7.07–7.16 (m,
3H), 7.46 (br s, 1H), 7.63 (d, J = 8.0 Hz, 1H), 7.79 (s, 1H), 7.83 (br
s, 1H), 7.91 (br s, 1H), 10.24 (br s, 1H). ESI-MS: m/z [M+H]+ 451.
Anal. Calcd for C26H22N6O2: C, 69.32; H, 4.92; N, 18.66. Found: C,
69.21; H, 4.96; N, 18.81.
4.1.51. 2-(1-(3-(1H-Imidazol-1-yl)propyl)-1H-indol-3-yl)
acetamide (14b)
According to the procedure used to prepare 14a, reaction of 2-
(1H-indol-3-yl)acetamide (12) with 1-(3-chloropropyl)-1H-imid-
azole (13b) afforded 14b in 39.2% yield as
a white solid,
mp:156–158 °C. 1H NMR (CDCl3, 400 MHz, d): 2.33–2.39 (m, 2H),
3.69 (s, 2H), 3.91 (t, J = 6.4 Hz, 2H), 4.09 (t, J = 7.2 Hz, 2H), 5.74–
5.78 (m, 2H), 6.89 (br s, 1H), 6.98 (br s, 1H), 7.07 (s, 1H), 7.16 (t,
J = 8.0 Hz, 1H), 7.21–7.27 (m, 2H), 7.40 (br s, 1H), 7.59 (d,
J = 7.6 Hz, 1H). ESI-MS: m/z [M+H]+ 283. Anal. Calcd for
C16H18N4O: C, 68.06; H, 6.43; N, 19.84. Found: C, 68.19; H, 6.51;
N, 19.63.
4.1.56. 3-(1-Methyl-1H-pyrrolo[3,2-b]pyridin-3-yl)-4-(1-(2-
morpholinoethyl)-1H-indol-3-yl)-1H-pyrrole-2,5-dione (15c)
According to the procedure used to prepare 15a, reaction of 11
with 14c provided 15c in 9.3% yield as a red solid, mp: 103–105 °C.
1H NMR (CDCl3 + DMSO-d6, 400 MHz, d): 2.33–2.37 (m, 4H), 2.43 (t,
J = 6.4 Hz, 2H), 3.52–3.56 (m, 4H), 3.75 (s, 3H), 4.12 (t, J = 6.8 Hz,
2H), 6.40 (t, J = 8.0 Hz, 1H), 6.49 (t, J = 8.0 Hz, 1H), 6.80–6.85 (m,
2H), 7.21 (d, J = 8.0 Hz, 1H), 7.45 (d, J = 8.0 Hz, 1H), 7.61 (s, 1H),
7.81–7.85 (m, 2H), 10.19 (br s, 1H). ESI-MS: m/z [M+H]+ 456. Anal.
Calcd for C26H25N5O3: C, 68.56; H, 5.53; N, 15.37. Found: C, 68.21;
H, 5.81; N, 15.65.
4.1.52. 2-(1-(2-Morpholinoethyl)-1H-indol-3-yl)acetamide
(14c)
According to the procedure used to prepare 14a, reaction of 2-
(1H-indol-3-yl)acetamide (12) with 4-(2-chloroethyl)morpholine
(13c) afforded 14c in 50.9% yield as a white solid, mp: 73–75 °C.
1H NMR (CDCl3, 400 MHz, d): 2.48–2.52 (m, 4H), 2.75 (t,
J = 6.4 Hz, 2H), 3.68–3.73 (m, 6H), 4.24 (t, J = 6.4 Hz, 2H), 5.50 (br
s, 1H), 5.65 (br s, 1H), 7.12–7.16 (m, 2H), 7.26 (d, J = 8.0 Hz, 1H),
7.35 (d, J = 8.0 Hz, 1H), 7.57 (d, J = 8.0 Hz, 1H). ESI-MS: m/z
[M+H]+ 288. Anal. Calcd for C16H21N3O2: C, 66.88; H, 7.37; N,
14.62. Found: C, 67.03; H, 7.48; N, 14.46.
4.1.57. 3-(1-(3-Hydroxypropyl)-1H-indol-3-yl)-4-(1-methyl-1H-
pyrrolo[3,2-b]pyridin-3-yl)-1H-pyrrole-2,5-dione (15d)
A solution of potassium t-BuOK (100 mg, 0.9 mmol) in THF was
added dropwise to a solution of 11 (91 mg, 0.39 mmol) and 14d
(104 mg, 0.3 mmol) in THF (20 mL) at 0–5 °C. After stirring for
1 h, the mixture was poured into 10% ammonium chloride aqueous
(100 mL) and extracted with ethyl acetate (3 ꢁ 50 mL). The organic
phase was combined and washed with brine (3 ꢁ 150 mL), dried
over Na2SO4 and concentrated in vacuo. The residue was solved
with THF (10 mL), and then TBAF (0.3 mmol) was added. After stir-
ring for 1 h at room temperature, the mixture was poured into
water (100 mL) and extracted with ethyl acetate (3 ꢁ 50 mL). The
organic phase was combined and washed with brine
(3 ꢁ 150 mL), dried over Na2SO4 and concentrated in vacuo. The
residue was purified by flash column chromatography on silica
gel using dichloromethane/methanol (30:1, v/v) as eluent to afford
14 mg (11.7%) of 15d as a red solid, mp: 226–228 °C. 1H NMR
(CDCl3 + DMSO-d6, 400 MHz, d): 2.02–2.06 (m, 2H), 3.55–3.58 (m,
2H), 3.89 (s, 3H), 4.11 (t, J = 6.4 Hz, 1H), 4.29 (t, J = 6.8 Hz, 2H),
6.56 (t, J = 8.0 Hz, 1H), 6.66 (t, J = 8.0 Hz, 1H), 6.95–6.70 (m, 2H),
7.32 (d, J = 8.0 Hz, 1H), 7.63 (d, J = 8.0 Hz, 1H), 7.74 (s, 1H), 7.90
4.1.53. 2-(1-(3-Propoxy) (tert-butyl)dimethylsilanyl)-1H-indol-
3-yl)acetamide (14d)
60% NaH (0.8 g, 20 mmol) was added fractionally to a solution
of 2-(1H-indol-3-yl)acetamide (3.48 g, 20 mmol) in DMF (20 mL)
at 0–5 °C. After stirring for 30 min, (3-bromopropoxy) (tert-
butyl)dimethylsilane (7.6 g, 30 mmol) was added and reacted for
2 h at room temperature. After that, the reaction mixture was
poured into water (300 mL) and extracted with ethyl acetate
(3 ꢁ 50 mL). The organic phase was combined and washed with
brine (3 ꢁ 150 mL), dried over Na2SO4 and concentrated in vacuo.
The residue was purified by flash column chromatography on silica
gel using petroleum ether/ethyl acetate (4:1, v/v) as eluent to af-
ford 4.76 g (68.7%) of 14d as a white solid, mp: 62–64 °C. 1H
NMR (CDCl3, 400 MHz, d): 0.06 (s, 6H), 0.92 (s, 9H), 1.98–2.03 (m,
2H), 3.57 (t, J = 6.4 Hz, 2H), 4.24 (t, J = 6.8 Hz, 2H), 5.64 (br s, 2H),
7.07 (s, 1H), 7.14 (t, J = 7.6 Hz, 1H), 7.25 (t, J = 7.6 Hz, 1H), 7.38
(d, J = 8.0 Hz, 1H), 7.57 (d, J = 8.0 Hz, 1H).

4312
Q. Ye et al. / Bioorg. Med. Chem. 17 (2009) 4302–4312
(br s, 1H), 8.01 (d, J = 4.0 Hz, 1H), 10.45 (s, 1H). ESI-MS: m/z [M+H]+
401. Anal. Calcd for C23H20N4O3: C, 68.99; H, 5.03; N, 13.99. Found:
C, 68.87; H, 5.08; N, 13.89.
References and notes
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4.2.3. PKCE, IKK2, Aurora A, MEK1 and ERK1 assays
The recombinant PKCE and IKK2 were expressed in Bac-to-Bac
baculovirus system, and recombinant Auroa a, MEK1 and ERK1 were
expressed in Escherichia coli system. All these kinase assays were
carried out by using the Invitrogen Z0-LYTETM Kinase Assay kits.