Synthesis and biological evaluation of a benz[cd]indol-2(1H)-one derivatives

Article abstract of DOI:10.14233/ajchem.2014.16729

Virtual screening of a library of 6.4 million compounds versus the structure of Xenopus Laevis' Aurora B kinase identified 1-(n-propyl)-6-[2-(carboxyl)tetrahydropyrrol-1-yl]sulfonyl-benzo[cd]indol-2(1H)-one 1 as a possible lead compound. Then, a novel series of benz[cd]indol-2(1H)-one derivatives were synthesized and evaluated as Aurora B kinase inhibitors. The structures of the synthetic compounds were confirmed by ¹H NMR, IR, mass spectrometry and elemental analysis. These compounds were evaluated by in vitro enzyme assay using spectrophotometry. Among them, compound 7e displayed potent antitumor activity against Aurora B kinase.

Full text of DOI:10.14233/ajchem.2014.16729

Asian Journal of Chemistry; Vol. 26, No. 21 (2014), 7329-7336
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2014.16729
Synthesis and Biological Evaluation of a Benz[cd]indol-2(1H)-one Derivatives
1
2
3
3
4
1,*
JING NIE , DAN-DAN DONG , YAN ZHANG , TAI-YI WANG , WEI LIU and SHOU-ZHI YI
1School of Material Science and Chemical Engineering, Tianjin University of Science and Technology, Tianjin 300457, P.R. China
2College of Pharmacy, NanKai University, Tianjin 300071, P.R. China
3College of Life Sciences, NanKai University, Tianjin 300071, P.R. China
4College of Sciences, Tianjin University of Science and Technology, Tianjin 300457, P.R. China
*Corresponding author: Fax: +86 22 65378878; Tel: +86 22 23766049; E-mail: yshzh@tust.edu.cn
Received: 20 November 2013;
Accepted: 21 March 2014;
Published online: 30 September 2014;
AJC-16131
Virtual screening of a library of 6.4 million compounds versus the structure of Xenopus Laevis' Aurora B kinase identified 1-(n-propyl)-
6-[2-(carboxyl)tetrahydropyrrol-1-yl]sulfonyl-benzo[cd]indol-2(1H)-one 1 as a possible lead compound. Then, a novel series of
benz[cd]indol-2(1H)-one derivatives were synthesized and evaluated asAurora B kinase inhibitors. The structures of the synthetic compounds
were confirmed by 1H NMR, IR, mass spectrometry and elemental analysis. These compounds were evaluated by in vitro enzyme assay
using spectrophotometry. Among them, compound 7e displayed potent antitumor activity against Aurora B kinase.
Keywords: Aurora B, Kinase inhibitor, Benz[cd]indol-2(1H)-one derivatives.
In this paper, we aim to discover inhibitors with novel
INTRODUCTION
scaffolds by virtual screening. Currently, the X-ray crystallized
Aurora kinase family of serine/threonine kinases are
crucial regulators of mitosis and cytokinesis that are constantly
overexpressed in human cancers. Among the three members
of the kinase family in humans,AuroraA,Aurora B andAurora
C, that are distinctive localized and mediate different functions
in cell division1,2.Aurora B kinase is a member of the Chromo-
somal Passenger Complex (CPC), widely expressed in the inner
centromere from early mitosis to the spindle midzone, equa-
torial cortex and midbody in late mitosis and cytokinesis, which
binds other chromosomal passenger proteins INCENP, survivin
and borealin to form a chromosomal complex3,4. Aurora B
functions associates with regulation of chromosome-micro-
tubule interactions, cohesion, spindle stability and cytokinesis5.
Given Aurora A and B pivotal roles in mitotic process, over
expression in multiple human tumor types including breast,
colourectal, prostate, ovarian, pancreas, thyroid and glioma
as well as oncogenic signaling pathways, Aurora kinase
inhibitors have emerged as promising antitumor agents6-9.
Currently, there are a few of inhibitors in phase I/II clinical
trials for cancer10. In preclinical experiments, some reports
have demonstrated that the phenotype of pan-Aurora inhibitors
is the same asAurora B selective inhibitors, namely, the clinical
reaction of pan-Aurora inhibitors will resemble compounds
which selectively inhibit Aurora B11. Therefore, Aurora B has
become a drug target in cancer treatment.
structure (3D-structure) of human Aurora B is unavailable,
the alternative structure of Xenopus Laevis (PDB ID: 2VRX,
Resolution: 1.86 Å) downloaded from the Protein Data Bank
(http://www.pdb.org) was applied since the 3D sturcture of
which was rather similar with humanAurora B (similarity more
than 98 %)12. In this study, our screening database which
consists of 6.4 million compounds were collected from the
Internet and prepared for docking and screening. Finally, 1-
(n-propyl)-6-[2-(carboxyl)tetrahydropyrrol-1-yl]sulfonyl-
benzo[cd]indol-2(1H)-one 1 was obtained as non-peptide
small-molecule inhibitor from virtual screening, which got an
highest score in the results by Schrodinger Suite 2009 (Fig. 1).
Fig. 1. Structure of the compound 1
In the early 1920s, benzo[c,d]indol-2(1H)-one derivatives
were initially developed as dyes and then were used for electro-
nic typing materials13. Many researches focused on optimizing
its structure to broaden its application. Until recently, their

7330 Nie et al.
Asian J. Chem.
excellent bioactivities have been found. As shown in Fig. 2,
Guez et al. reported that a series of 5-HT7R antagonists (a)
showed satisfactory pharmacological properties for depression
and IBS (irritable bowel syndrome)14. Liu et al.15 reported that
compound (b) showed good binding affinity for CDK2 in the
major solid tumor types including colon, breast, prostate,
ovarian carcinomas and non-small cell lung. The discovery of
new compound (c) with selective antitumor activity for
leukemia P388 cell line and lung cancer A549 cell line was
reported in 200716. It was reported by Chen et al.17 that
compound (d) was capable of blocking the mPTPB-mediated
ERK1/2 inactivation and may become a novel class of anti-
TB agents. Meanwhile, Talukdar et al.18 showed compound
(e) with moderately improved inhibitory activity against M.
tuberculosis lumazine synthase.
region of 4000-400 cm-1 with a Perkin Elmer spectrum 65 FT-
IR spectrometer using KBr pellets. Melting points were deter-
mined using an SGW-X4B digital melting point apparatus.
Elemental analysis of carbon, hydrgen and nitrogen were
obtained with a Perkin Elmer 2400 Serie II CHN elemental
analyzer.
Preparation of 1-(aliphatic group)-benzo[cd]indol-
2(1H)-one (4, 5): 1,8-Naphthalic anhydride 2 (13 g, 0.065 mol)
and hydroxylamine hydrochloride (4.6 g, 0.065 mol) were
heated under reflux in dry pyridine (75 mL) for 1 h. p-Toluene
sulfonyl chloride (27 g, 0.141 mol) was carefully added in
portions to cause controlled boiling. Reflux was continued
for a further 1 h. The mixture was poured onto water (300
mL) and the crystalline precipitate collected by filtration and
washed with 0.5 N NaOH and water to remove N-hydroxy-
naphthalimide. The crystals were stirred in refluxing water
(150 mL) and ethanol (50 mL) containing NaOH (10 g) for
2 h. After this time ethanol was removed by distillation. The
resulting mixture was cooled to room temperature, acidified
with concentrated HCl (30 mL) and the crude product allowed
to precipitate overnight. The solid was collected by filtration,
washed with water and dried at 100 °C. Recrystallization from
benzene gave 1,8-naphtholactam 3 (10 g, 91.7 %) as yellow
needles. 1-Chlorobutane or ethyl chloroacetate (0.005 mol)
was added to solution of compound 3 (0.005 mol) in DMF
(20 mL), then K2CO3 (1.38 g) and a little of KI was added, the
reaction mixture was stirred at 140 °C for 4 h. The mixture
was cooled and filtered and extract with ethyl acetate, The crude
product was separated on silica gel chromatography, eluting
with ethyl acetate-petroleum ether (1:5) to give the product.
General procedure A: Preparation of 1-(n-butyl)-6-
substituted sulfonyl-benzo[cd]indol-2(1H)-one (7a-f):
Chlorosulfonic acid (3.2 mL) was added slowly to compound
4 (5.9 mmol). The reaction mixture was stirred at 0 °C for 1 h
at room temperature for 2 h. The mixture was then poured
into ice water (20 mL) and extract with ethyl acetate (3 × 20
mL), then washed with brine, dried over anhydrous sodium
sulfate overnight. The solvent was removed under vacuum and
dried to give compound 6 as yellow solid (44 %). amines (0.84
mmol) was added to solution of compound 6 (0.56 mmol) in
THF (5 mL) and the reaction mixture was stirred at room
temperature for 12 h. THF was removed under vacuum and
the residue was purified by silica gel column chromatography,
eluting with ethyl acetate-petroleum ether (1:5) to give the
product.
Fig. 2. Structures of some reported compounds a-e
Although the benzo[c,d]indol-2(1H)-one derivatives were
widely used as protein inhibitors, their inhibition activity
againstAurora B haven't been reported. Therefore, we focused
on the modification of the 1- and 6-position of benzo[c,d]indol-
2(1H)-one (f) to design and synthesis of novel benzo[c,d]indol-
2(1H)-one derivatives. In this paper, we reported the design,
synthesis and initial biological evaluation as Aurora B kinase
inhibitors
EXPERIMENTAL
General procedure B: Preparation of 1-(n-butyl)-6-
substituted sulfonyl-benzo[cd]indol-2(1H)-one (7g-v):
Under nitrogen, amines (4.5 mmol) and diisopropylethylamine
(6 mmol) was dissolved in 5 mL dried THF, a solution of com-
pound 6 (4 mmol) in 15 mL THF was added dropwise at 0 °C.
Then the reaction mixture was stirred at room temperature
overninght. After removal of solvent and the residue was
purified by silica gel column chromatography, eluting with
ethyl acetate-petroleum ether (1:10) to give the product.
General procedure C: Preparation of 1-(n-butyl)-6-
substituted sulfonyl-benzo[cd]indol-2(1H)-one (9a-e):
Chlorosulfonic acid (3.2 mL) was added slowly to compound
5 (5.9 mmol). The reaction mixture was stirred at 0 °C for 1 h
at room temperature for 2 h. The mixture was then poured
All solvents of reagent grade were obtained from commer-
cial suppliers and were used without further purification. All
commercial reagents were of the highest purity available.
Tetrahydrofuran was distilled over sodium and benzophenone.
Pyridine was distilled over KOH. Column chromatography
was carried out on SHANGHAI SANPONT Gel (200-300
mesh). NMR spectra were recorded on a Bruker AM-400. All
NMR spectra were recorded in CDCl3, CD3OD or DMSO at
room temperature (20 °C). Chemical shifts for 1H spectra are
quoted in ppm downfield from TMS. Coupling constants are
referred to as J values. ESI mass spectra were obtained using
a Bruker ESQUIRELCTM ESI ion trap spectrometer. FT-IR
spectra were determined at room temperature (20 °C) in the

Vol. 26, No. 21 (2014)
Synthesis and Biological Evaluation of a Benz[cd]indol-2(1H)-one Derivatives 7331
into ice water (20 mL) and extract with ethyl acetate (3 × 20
mL), then washed with brine, dried over anhydrous sodium
sulfate overnight. The solvent was removed under vacuum and
dried to give compound 8 as yellow solid (44 %). Under
nitrogen, amines (4.5 mmol) and diisopropylethylamine
(6 mmol) was dissolved in 5 mL dried THF, a solution of
compound 8 (4 mmol) in 15 mL THF was added dropwise at
0 °C. Then the reaction mixture was stirred at room temperature
overninght. After removal of solvent and the residue was
purified by silica gel column chromatography, eluting with
ethyl acetate-petroleum ether (1:20) to give the product.
1-(n-Butyl)-6-(morpholin-1-yl)sulfonyl-benzo[cd]-
indol-2(1H)-one (7a): Compound 7a was prepared according
to standard procedureA by using compound 6 and morpholine,
obtained a yellow solid in 87.2 % yield. m.p. 123.1-124.9 °C.
IR (KBr, νmax, cm-1): 1705, 1626, 1496, 1344, 1160. 1H NMR
(CDCl3, 400 MHz): 8.71 (d, J = 8.4 Hz, 1H), 8.12 (dd, J = 12
Hz, 7.2 Hz, 2H), 7.84 (dd, J = 8.4 Hz, 6.8 Hz, 1H), 6.97 (d,
J = 7.2 Hz, 1H), 3.94 (t, J = 7.2 Hz, 2H), 3.73 (t, J = 4.8 Hz,
4H), 3.10 (t, J = 4.8 Hz, 4H), 1.78 (m, 2H), 1.45 (m, 2H), 0.99
(t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 375.01. Anal. (%)
Calcd. for C19H22N2O4S: C, 60.94; H, 5.92; N, 7.48. Found: C,
60.55; H, 5.81; N, 7.66.
1-(n-Butyl)-6-(piperidin-1-yl)sulfonyl-benzo[cd]indol-
2(1H)-one (7b): Compound 7b was prepared according to
standard procedure A by using compound 6 and piperidine,
obtained a yellow solid in 85.6 % yield. m.p. 111.3-112.8 °C.
IR (KBr, νmax, cm-1): 1711, 1626, 1495, 1336, 1149. 1H NMR
(CDCl3, 400 MHz): 8.72 (d, J = 8.4 Hz, 1H), 8.11 (t, J = 6.4
Hz, 2H), 7.82 (dd, J = 7.6 Hz, 8.4 Hz, 1H), 6.94 (d, J = 7.6 Hz,
1H), 3.93 (t, J = 7.2 Hz, 2H), 3.84 (d, J = 11.6 Hz, 2H), 3.39
(t, J = 11.6 Hz, 2H), 1.78 (m, 2H), 1.66 (d, J = 9.6 Hz, 2H),
1.45 (m, 2H), 1.29-1.26 (m, 4H), 0.98 (t, J = 7.2 Hz, 3H). MS
[M + H+]: m/z = 373.03. Anal. (%) Calcd. for C20H24N2O3S: C,
64.49; H, 6.49; N, 7.52. Found: C, 64.35; H, 6.36; N, 7.43.
1-(n-Butyl)-6-(4-methylpiperidin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7c): Compound 7c was prepared
according to standard procedure A by using compound 6 and
4-methyl piperidine, obtained a yellow solid in 88.1 % yield.
m.p. 96.1-97.4 °C. IR (KBr, νmax, cm-1): 1702, 1627, 1495,
1336, 1151. 1H NMR (CDCl3, 400 MHz): 8.73 (d, J = 8.4 Hz,
1H), 8.11 (t, J = 7.2 Hz, 2H), 7.82 (dd, J = 8.4 Hz, 7.2 Hz,
1H), 6.94 (d, J = 7.6 Hz, 1H), 3.93 (t, J = 7.2 Hz, 2H), 3.10 (t,
J = 5.6 Hz, 4H), 1.78 (m, 2H), 1.62 (m, 4H), 1.48-1.38 (m,
3H), 1.29 (d, J = 6.4 Hz, 3H), 0.99 (t, J = 7.2 Hz, 3H). MS [M
+ H+]: m/z = 387.06, Anal. (%) Calcd. for C21H26N2O3S: C,
65.26; H, 6.78; N, 7.25. Found: C, 64.88; H, 6.64; N, 7.17.
1-(n-Butyl)-6-(2-methylpiperidin-1-yl)sulfonyl-benzo[cd]-
indol-2(1H)-one (7d): Compound 7d was prepared according
to standard procedure A by using compound 6 and 2-methyl-
1-(n-Butyl)-6-(3,5-dimethylpiperidin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7e): Compound 7e was prepared
according to standard procedure A by using compound 6 and
3,5-dimethylpiperidine, obtained a yellow solid in 83.3 %
yield. m.p. 134.5-135.2 °C. IR (KBr, νmax, cm-1): 1702, 1628,
1496, 1340, 1154. 1H NMR (CDCl3, 400 MHz): 8.71 (d, J =
8.4 Hz, 1H), 8.14 (dd, J = 7.6 Hz, 4.8 Hz, 2H), 7.86 (dd, J =
7.2 Hz, 1H), 6.95 (d, J = 7.6 Hz, 1H), 3.93 (t, J = 7.2 Hz, 2H),
3.81 (d, J = 8.0 Hz, 2H), 1.86 (t, J = 11.2 Hz, 2H), 1.82-1.69
(m, 5H), 1.45 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H), 0.83 (d, J =
6.4 Hz, 6H), 0.48 (q, J = 12 Hz, 1H). MS [M + H+]: m/z =
401.08. Anal. (%) Calcd. for C22H28N2O3S: C, 65.97; H, 7.05;
N, 6.99. Found: C, 66.19 H, 6.88; N, 6.58.
1-(n-Butyl)-6-(tetrahydropyrrole-1-yl)sulfonyl-benzo-
[cd]indol-2(1H)-one (7f): Compound 7f was prepared
according to standard procedure A by using compound 6 and
tetrahydropyrrole, obtained a yellow solid in 82.5 % yield.
m.p. 76.6-78.5 °C. IR (KBr, νmax, cm-1): 1716, 1627, 1496,
1333, 1150. 1H NMR (CDCl3, 400 MHz): 8.79 (d, J = 8.4 Hz,
1H), 8.15 (d, J = 7.6 Hz, 1H), 8.12 (d, J = 7.2 Hz, 1H), 7.83
(dd, J = 8.4 Hz, 7.2 Hz, 1H), 6.95 (d, J = 7.6 Hz, 1H), 3.93 (t,
J = 7.2 Hz, 2H), 3.32 (t, J = 6.8 Hz, 4H), 1.79 (m, 2H), 1.45
(m, 2H), 0.98 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 359.02.
Anal. (%) Calcd. for C19H22N2O3S: C, 63.66; H, 6.19; N, 7.82.
Found: C, 63.55; H, 6.08; N, 7.71.
1-(n-Butyl)-6-(N-phenylpiperazin-1-yl)sulfonyl-benzo-
[cd]indol-2(1H)-one (7g): Compound 7g was prepared
according to standard procedure B by using compound 6 and
1-phenylpiperazine, obtained a yellow solid in 78.5 % yield.
m.p. 111.8-112.9 °C. IR (KBr, νmax, cm-1): 1709, 1628, 1599,
1495, 1347, 1157. 1H NMR (CDCl3, 400 MHz): 8.72 (d, J =
8.4 Hz, 1H), 8.16 (dd, J = 6.8 Hz, 1.2 Hz, 2H), 7.87 (dd, J =
8.4 Hz, 7.2 Hz, 1H), 7.29 (t, J = 8.0 Hz, 2H), 7.04-6.96 (m,
3H), 3.94 (t, J = 7.2 Hz, 2H), 3.41 (s, 4H), 3.31 (s, 4H), 1.76
(m, 2H), 1.44 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H). MS [M + H+]:
m/z = 450.08. Anal. (%) Calcd. for C25H27N3O3S: C, 66.79; H,
6.05; N, 9.35. Found: C, 66.37; H, 5.96; N, 9.01.
1-(n-Butyl)-6-[4-(4-fluorophenyl)piperazin-1-yl]-
sulfonyl-benzo[cd]indol-2(1H)-one (7h): Compound 7h was
prepared according to standard procedure B by using compound
6 and 1-(4-fluorophenyl)piperazine, obtained a yellow solid
in 75.7 % yield. m.p. 143.5-144.6 °C. IR (KBr, νmax, cm-1):
1
1709, 1628, 1509, 1495, 1348, 1156. H NMR (CDCl3, 400
MHz): 8.74 (d, J = 8.4 Hz, 1H), 8.13 (dd, J = 7.2 Hz, 2.8 Hz,
2H), 7.85 (dd, J = 8.4 Hz, 7.2 Hz, 1H), 6.98-6.92 (m, 3H),
6.84 (s, 2H), 3.94 (t, J = 7.2 Hz, 2H), 3.30 (s, 4H), 3.18 (s,
4H), 1.78 (m, 2H), 1.44 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H). MS
[M + H+]: m/z = 468.12. Anal. (%) Calcd. for C25H26FN3O3S:
C, 64.22; H, 5.60; N, 8.99. Found: C, 64.13; H, 5.25; N, 8.69.
1-(n-Butyl)-6-[4-(2-fluorophenyl)piperazin-1-yl]-
sulfonyl-benzo[cd]indol-2(1H)-one (7i): Compound 7i was
prepared according to standard procedure B by using compound
6 and 1-(2-fluorophenyl)piperazine, obtained a yellow solid
in 73.5 % yield. m.p. 168.4-168.9 °C. IR (KBr, νmax, cm-1):
1718, 1626, 1492, 1348, 1155. 1H NMR (CDCl3, 400 MHz):
8.75 (d, J = 8.4 Hz, 1H), 8.13 (d, J = 6.8 Hz, 2H), 7.85 (dd, J
= 6.8 Hz, 8 Hz, 1H), 7.06-6.97 (m, 5H), 3.95 (t, J = 7.2 Hz,
2H), 3.36 (s, 4H), 3.20 (s, 4H), 1.79 (m, 2H), 1.46 (m, 2H),
0.99 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 468.03. Anal.
piperidine, obtained a yellow oil in 87.4 % yield. IR (KBr, νmax
,
cm-1): 1715, 1630, 1494, 1321, 1143. H NMR (CDCl3, 400
MHz): 8.57 (d, J = 8.4 Hz, 1H), 8.17 (d, J = 7.6 Hz, 1H), 8.09 (d,
J = 7.2 Hz, 1H), 7.82 (dd, J = 8.4 Hz, 7.2 Hz, 1H), 6.90 (d, J = 7.6
Hz, 1H), 4.32 (m, 1H), 3.92 (t, J = 7.2 Hz, 2H), 3.70 (dt, J = 13.6 Hz,
3.2 Hz, 1H), 3.05 (td, J = 13.2 Hz, 2.4 Hz, 1H), 1.77 (m, 2H), 1.60-
1.24 (m, 8H), 1.15 (d, J = 6.8 Hz, 3H), 0.09 (t, J = 7.6 Hz, 3H).
MS [M + H+]: m/z = 387.06. Anal. (%) Calcd. for C21H26N2O3S:
C, 65.26; H, 6.78; N, 7.25. Found: C, 65.0; H, 6.42; N, 7.21.
1

7332 Nie et al.
Asian J. Chem.
1
(%) Calcd. for C25H26N3O3SF: C, 64.22; H, 5.60; N, 8.99.
Found: C, 64.43; H, 6.70; N, 9.14.
1156. H NMR (DMSO-d6, 400 MHz): 8.66 (d, J = 8.4 Hz,
1H), 8.39 (t, J = 6.0 Hz, 1H), 8.14 (d, J = 7.2 Hz, 1H), 8.05 (d,
J = 7.6 Hz, 1H), 7.92 (dd, J = 8.0 Hz, 7.2 Hz, 1H), 7.28-7.25
(m, 2H), 6.13 (t, J = 2.4 Hz, 1H), 5.99 (d, J = 3.2 Hz, 1H),
4.04 (d, J = 6.0 Hz, 2H), 3.91 (t, J = 7.2 Hz, 2H), 1.69 (m,
2H), 1.34 (m, 2H), 0.92 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z
= 385.01.Anal. (%) Calcd. for C20H20N2O4S: C, 62.48; H, 5.24;
N, 7.29. Found: C, 62.37; H, 5.03; N, 7.18.
1-(n-Butyl)-6-(3-fluoroanilin-1-yl)sulfonyl-benzo[cd]-
indol-2(1H)-one (7o): Compound 7o was prepared according
to standard procedure B by using compound 6 and 3-fluoro-
aniline, obtained a yellow solid in 74.9 % yield. m.p. 159.6-
160.9 °C, IR (KBr, νmax, cm-1): 3160, 1691, 1629, 1493, 1340,
1159. 1H NMR (CDCl3, 400 MHz): 8.55 (d, J = 8.4 Hz, 1H),
8.16 (d, J = 7.6 Hz, 1H), 8.10 (d, J = 7.2 Hz, 1H), 7.83 (dd, J =
8.4 Hz, 7.2 Hz, 1H), 7.12 (m, 1H), 6.85-6.71 (m, 5H), 3.89 (t,
J = 7.2 Hz, 2H), 1.74 (m, 2H), 1.39 (m, 2H), 0.98 (t, J = 7.2
Hz, 3H). MS [M + H+]: m/z = 399.07. Anal. (%) Calcd. for
C21H19FN2O3S: C, 63.30; H, 4.81; N, 7.03. Found: C, 63.09;
H, 4.54; N, 6.92.
1-(n-Butyl)-6-(4-fluoroanilin-1-yl)sulfonyl-benzo[cd]-
indol-2(1H)-one (7p): Compound 7p was prepared according
to standard procedure B by using compound 6 and 4-fluoro-
aniline, obtained a yellow solid in 73.7 % yield. m.p. 166.7-
168.2 °C. IR (KBr, νmax, cm-1): 3121, 1684, 1630, 1509, 1495,
1334, 1153. 1H NMR (CDCl3, 400 MHz): 8.48 (d, J = 8.4 Hz,
1H), 8.10 (d, J = 6.8 Hz, 1H), 8.03 (d, J = 7.6 Hz, 1H), 7.79 (t,
J = 7.6 Hz, 1H), 6.95-6.82 (m, 5H), 6.45 (s, 1H), 3.89 (t, J =
7.2 Hz, 2H), 1.74 (m, 2H), 1.35 (m, 2H), 0.97 (t, J = 7.2 Hz,
3H). MS [M + H+]: m/z = 399.00. Anal. (%) Calcd. for
C21H19N2O3SF: C, 63.30; H, 4.81; N, 7.03. Found: C, 63.59;
H, 4.90; N, 7.31.
1-(n-Butyl)-6-(4-anisidin-1-yl)sulfonyl-benzo[cd]indol-
2(1H)-one (7q): Compound 7q was prepared according to
standard procedure B by using compound 6 and p-anisidine,
obtained a yellow solid in 73.4 % yield. m.p. 229.7-230 °C.
IR (KBr, νmax, cm-1): 3139, 1684, 1630, 1511, 1496, 1335,
1151. 1H NMR (DMSO-d6, 400 MHz): 10.14 (s, 1H), 8.64 (d,
J = 8.4 Hz, 1H), 8.13 (d, J = 7.2 Hz, 1H), 8.02 (d, J = 7.6 Hz,
1H), 7.92 (dd, J = 8.4 Hz, 7.2 Hz, 1H), 7.23 (d, J = 7.6 Hz,
1H), 6.91 (d, J = 8.8 Hz, 2H), 6.73 (d, J = 8.8 Hz, 2H), 3.86
(t, J = 7.2 Hz, 2H), 3.62 (s, 3H), 1.65 (m, 2H), 1.31 (m, 2H),
0.89 (t, J = 7.6 Hz, 3H). MS [M + H+]: m/z = 411.02. Anal.
(%) Calcd. For C22H22N2O4S: C, 64.37; H, 5.40; N, 6.82. Found:
C, 64.16; H, 5.29; N, 6.71.
1-(n-Butyl)-6-(4-(4-methylphenyl)piperazin-1-yl)-
sulfonyl-benzo[cd]indol-2(1H)-one (7j): Compound 7j was
prepared according to standard procedure B by using comp-
ound 6 and 1-(4-methylphenyl)piperazine, obtained a yellow
solid in 79.3 % yield. m.p. 145.3-145.9 °C. IR (KBr, νmax
,
cm-1): 1709, 1628, 1495, 1347, 1157. H NMR (CDCl3, 400
MHz): 8.67 (d, J = 8.4 Hz, 1H), 8.13 (d, J = 7.2 Hz, 2H), 7.85
(dd, J = 8.4 Hz, 7.2 Hz, 1H), 7.15 (m, 4H), 6.96 (d, J = 7.6 Hz,
1H), 3.94 (t, J = 7.2 Hz, 2H), 3.56 (s, 4H), 3.36 (s, 4H), 1.78
(m, 2H), 1.45 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H). MS [M + H+]:
m/z = 464.29. Anal. (%) Calcd. for C26H29N3O3S: C, 67.36; H,
6.31; N, 9.06. Found: C, 67.25; H, 6.20; N, 8.95.
1
1-(n-Butyl)-6-(4-(4-ethylformate)piperidin-1-yl)-
sulfonyl-benzo[cd]indol-2(1H)-one (7k): Compound 7k was
prepared according to standard procedure B by using comp-
ound 6 and ethyl 4-piperidinecarboxylate, obtained a yellow
solid in 76.9 % yield. m.p. 131.4-132.6 °C, IR (KBr, νmax
,
cm-1): 1730, 1715, 1628, 1494, 1337, 1149. 1H NMR (CDCl3,
400 MHz): 8.69 (d, J = 8.4 Hz, 1H), 8.11 (dd, J = 7.2 Hz, 4.8
Hz, 2H), 7.83 (dd, J = 8.4 Hz, 7.2 Hz, 1H), 6.94 (d, J = 7.6 Hz,
1H), 4.08 (q, J = 7.2 Hz, 2H), 3.93 (t, J = 7.2 Hz, 2H), 3.73
(m, 2H), 2.64 (td, J = 2.8 Hz, 12.0 Hz, 2H), 2.25 (m, 1H), 1.97
(m, 2H), 1.83-1.74 (m, 4H), 1.45 (m, 2H), 1.19 (t, J = 7.2 Hz,
3H), 0.99 (t, J = 7.6 Hz, 3H). MS [M + H+]: m/z = 445.09.
Anal. (%) Calcd. for C23H28N2O5S: C, 62.14; H, 6.35; N, 6.30.
Found: C, 61.99; H, 6.07; N, 6.11.
1-(n-Butyl)-6-(4-(3-trifluoromethylphenyl)piperazin-
1-yl)sulfonyl-benzo[cd]indol-2(1H)-one (7l). Compound 7l
was prepared according to standard procedure B by using
compound 6 and N-(3-trifluoromethylphenyl)piperazine,
obtained a yellow solid in 72.3 % yield. m.p. 103.1-104.5 °C.
IR (KBr, νmax, cm-1): 1709, 1628, 1495, 1359, 1158. 1H NMR
(CDCl3, 400 MHz): 8.71 (d, J = 8.8 Hz, 1H), 8.14 (dd, J = 7.6
Hz, 4.4 Hz, 2H), 7.86 (t, J = 7.6 Hz, 1H), 7.38 (m, 1H), 7.21-
7.16 (t, J = 7.2 Hz, 3H), 6.97 (d, J = 7.6 Hz, 1H), 3.94 (t, J =
7.2 Hz, 1H), 3.40 (s, 4H), 3.34 (s, 4H), 1.78 (t, J = 7.2 Hz,
2H), 1.46 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/
z = 518.36. Anal. (%) Calcd. for C26H26N3O3SF3: C, 60.34; H,
5.06; N, 8.12. Found: C, 60.11; H, 4.95; N, 8.08.
1-(n-Butyl)-6-(phenylethylamin-1-yl)sulfonyl-benzo-
[cd]indol-2(1H)-one (7m): Compound 7m was prepared
according to standard procedure B by using compound 6 and
phenylethylamine, obtained a yellow solid in 78.9 % yield.
m.p. 120.0-121.4 °C. IR (KBr, νmax, cm-1): 3185, 1687, 1627,
1496, 1330, 1151. 1H NMR (DMSO-d6, 400 MHz): 8.63 (d, J
= 8.4 Hz, 1H), 8.14 (d, J = 7.2 Hz, 1H), 8.05 (d, J = 7.6 Hz,
1H), 7.93-7.90 (m, 2H), 7.26 (d, J = 7.6 Hz, 1H), 7.11-7 (m,
5H), 3.90 (t, J = 7.2 Hz, 2H), 3.03 (dd, J = 7.2 Hz, 13.6 Hz,
2H), 2.61 (t, J = 7.2 Hz, 2H), 1.69 (m, 2H), 1.34 (m, 2H), 0.91
(t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 409.24. Anal. (%)
Calcd. For C23H24N2O3S: C, 67.62; H, 5.92; N, 6.86. Found:
C, 67.41; H, 5.80; N, 6.77.
1-(n-Butyl)-6-(4-methylbenzylamin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7r): Compound 7r was prepared
according to standard procedure B by using compound 6 and
4-methylbenzylamine, obtained a yellow solid in 75.2 %
yield. m.p. 147.5-148.0 °C. IR (KBr, νmax, cm-1): 3292, 1714,
1688, 1493, 1331, 1140. 1H NMR (CDCl3, 400 MHz): 8.63
(d, J = 8.4 Hz, 1H), 8.20 (d, J = 7.6 Hz, 1H), 8.14 (d, J = 7.2
Hz, 1H), 7.85 (dd, J = 8.4 Hz, 7.2 Hz, 1H), 6.98 (dd, J = 10.8
Hz, 8.4 Hz, 4H), 6.91 (d, J = 7.6 Hz, 1H), 4.71 (t, J = 6.0 Hz,
1H), 4.11 (d, J = 6.0 Hz, 2H), 3.95 (t, J = 7.2 Hz, 2H), 2.27
(s, 3H), 1.80 (m, 2H), 1.47 (m, 2H), 1.01 (t, J = 7.2 Hz, 3H).
MS [M + H+]: m/z = 409.10. Anal. (%) Calcd. for
C23H24N2O3S: C, 67.62; H, 5.92; N, 6.86. Found: C, 67.31;
H, 5.82; N, 6.55.
1-(n-Butyl)-6-(furfurylamin-1-yl)sulfonyl-benzo[cd]-
indol-2(1H)-one (7n): Compound 7n was prepared according
to standard procedure B by using compound 6 and furfuryl-
amine, obtained a yellow solid in 77.6 % yield. m.p. 111.4-
112.9 °C. IR (KBr, νmax, cm-1): 3153, 1682, 1628, 1496, 1330,

Vol. 26, No. 21 (2014)
Synthesis and Biological Evaluation of a Benz[cd]indol-2(1H)-one Derivatives 7333
1-(n-Butyl)-6-(4-fluorobenzylamin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7s): Compound 7s was prepared
according to standard procedure B by using compound 6 and
4-fluorobenzylamine, obtained a yellow solid in 78.6 % yield.
m.p. 136.5-136.9 °C. IR (KBr, νmax, cm-1): 3283, 1694, 1628,
1494, 1332, 1152. 1H NMR (CDCl3, 400 MHz): 8.62 (d, J =
8.4 Hz, 1H), 8.13 (t, J = 7.2 Hz, 2H), 7.84 (t, J = 7.2 Hz, 1H),
7.06 (dd, J = 8.4 Hz, 5.2 Hz, 2H), 6.88-6.83 (m, 3H), 4.79
(t, J = 6.0 Hz, 1H), 4.12 (d, J = 6.0 Hz, 2H), 3.93 (t, J = 7.2 Hz,
2H), 1.78 (m, 2H), 1.44 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H). MS
[M + H+]: m/z = 413.02. Anal. (%) Calcd. for C22H21N2O3SF:
C, 64.06; H, 5.13; N, 6.79. Found: C, 63.88; H, 4.97; N, 6.43.
1-(n-Butyl)-6-(4-methoxybenzylamin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7t): Compound 7t was prepared
according to standard procedure B by using compound 6 and
4-methoxybenzylamine, obtained a yellow solid in 79.3 %
yield. m.p. 100.1-101.6 °C. IR (KBr, νmax, cm-1): 3239, 1717,
(t, J = 7.6 Hz, 1H), 6.84 (d, J = 7.6 Hz, 1H), 4.68 (s, 2H), 4.34
(m, 1H), 4.26 (q, J = 6.8 Hz, 2H), 3.69 (d, J = 12.8 Hz, 1H), 3.08
(t, J = 12.8 Hz, 1H), 1.33-1.26 (m, 9H), 1.15 (d, J = 6.8 Hz, 3H).
MS [M + H+]: m/z = 417.46. Anal. (%) Calcd. for C21H24N2O5S:
C, 60.56; H, 5.81; N, 6.73. Found: C, 60.45; H, 5.70; N, 6.62.
1-(Ethyl-1-acetate)-6-(morpholin-1-yl)sulfonyl-benzo-
[cd]indol-2(1H)-one (9b): Compound 9b was prepared accor-
ding to standard procedure C by using compound 8 and mor-
pholine, obtained a yellow solid in 92.7 % yield. m.p. 123.1-
131.9 °C. IR (KBr, νmax, cm-1): 1748, 1720, 1628, 1498, 1344,
1213, 1157. 1H NMR (CDCl3, 400 MHz): 8.75 (d, J = 8.4 Hz,
1H), 8.18 (d, J = 7.2 Hz, 1H), 8.11 (d, J = 7.6 Hz, 1H), 7.88 (t,
J = 7.6 Hz, 1H), 6.91 (d, J = 7.6 Hz, 1H), 4.70 (s, 2H), 4.27 (q,
J = 7.2 Hz, 2H), 3.73 (t, J = 4.8 Hz, 4H), 3.10 (t, J = 4.8 Hz,
4H), 1.31 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 405.21.
Anal. (%) Calcd. for C19H20N2O6S: C, 56.42; H, 4.98; N, 6.93.
Found: C, 56.21; H, 4.77; N, 6.82.
1
1627, 1492, 1251, 1143. H NMR (CDCl3, 400 MHz): 8.61
1-(Ethyl-1-acetate)-6-(4-methoxyanilin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (9c): Compound 9c was prepared
according to standard procedure C by using compound 8 and
4-methoxyaniline, obtained a yellow solid in 90.6 % yield.
m.p. 101.3-102.5 °C. IR (KBr, νmax, cm-1): 3178, 1746, 1696,
(d, J = 8.0 Hz, 1H), 8.17 (d, J = 7.6 Hz, 1H), 8.12 (d, J = 7.2
Hz, 1H), 7.85 (dd, J = 8.4 Hz, 7.2 Hz, 1H), 6.98 (d, J = 7.6 Hz,
2H), 6.89 (d, J = 7.6 Hz, 1H), 6.68 (d, J = 8.4 Hz, 2H), 4.71
(t, J = 6.0 Hz, 1H), 4.07 (d, J = 6.0 Hz, 2H), 3.93 (t, J = 7.2
Hz, 2H), 3.72 (s, 3H), 1.78 (m, 2H), 1.45 (m, 2H), 0.99 (t, J =
7.2 Hz, 3H). MS [M + H+]: m/z = 425.04. Anal. (%) Calcd. for
C23H24N2O4S: C, 65.07; H, 5.70; N, 6.60. Found: C, 64.96; H,
5.59; N, 6.49.
1-(n-Butyl)-6-(3-fluorobenzylamin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7u): Compound 7u was prepared
according to standard procedure B by using compound 6 and
3-fluorobenzylamine, obtained a yellow solid in 82.7 % yield.
m.p. 113.2-114.8 °C. IR (KBr, νmax, cm-1): 3230, 1692, 1629,
1495, 1323, 1151. 1H NMR (CDCl3, 400 MHz): 8.61 (d, J =
8.4 Hz, 1H), 8.16 (d, J = 7.2 Hz, 1H), 8.12 (d, J = 6.8 Hz, 1H),
7.84 (d, J = 8.4 Hz, 7.2 Hz, 1H), 7.12-7.09 (m, 1H), 6.89-6.82
(m, 3H), 6.77 (d, J = 9.6 Hz, 1H), 4.85 (t, J = 6.4 Hz, 1H),
4.15 (d, J = 6.4 Hz, 2H), 3.93 (t, J = 7.2 Hz, 2H), 1.77 (m,
2H), 1.43 (m, 2H), 0.99 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z
= 413.02. Anal. (%) Calcd. for C22H21FN2O3S: C, 64.06; H,
5.13; N, 6.79. Found: C, 63.95; H, 5.02; N, 6.88.
1-(n-Butyl)-6-(2-fluorobenzylamin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (7v): Compound 7v was prepared
according to standard procedure B by using compound 6 and
2-fluorobenzylamine, obtained a yellow solid in 83.4 % yield.
m.p. 149.0-149.9 °C. IR (KBr, νmax, cm-1): 3270, 1690, 1629,
1495, 1332, 1151. 1H NMR (CDCl3, 400 MHz): 8.57 (d, J =
8.4 Hz, 1H), 8.15 (d, J = 7.6 Hz, 1H), 8.10 (d, J = 6.8 Hz, 1H),
7.83 (dd, J = 7.2 Hz, 8.4 Hz, 1H), 7.05 (m, 2H), 6.86-6.83 (m,
2H), 6.73 (dd, J = 8.4 Hz, 10.4 Hz, 1H), 4.98 (t, J = 6.4 Hz,
1H), 4.25 (d, J = 6.4 Hz, 2H), 3.93 (t, J = 7.2 Hz, 2H), 1.79
(m, 2H), 1.46 (m, 2H), 1.02 (t, J = 7.2 Hz, 3H). MS [M + H+]:
m/z = 412.98. Anal. (%) Calcd. for C22H21FN2O3S: C, 64.06;
H, 5.13; N, 6.79. Found: C, 63.78; H, 5.43; N, 6.87.
1
1632, 1512, 1496, 1339, 1152. H NMR (DMSO-d6, 400
MHz): 10.16 (s, 1H), 8.69 (d, J = 8.4 Hz, 1H), 8.20 (d, J = 7.2
Hz, 1H), 8.03 (d, J = 7.6 Hz, 1H), 7.96 (dd, J = 8.4 Hz, 7.6 Hz,
1H), 7.25 (d, J = 7.6 Hz, 1H), 6.91 (d, J = 8.8 Hz, 2H), 6.73
(d, J = 8.8 Hz, 2H), 4.79 (s, 2H), 4.16 (q, J = 7.2 Hz, 2H), 3.62
(s, 3H), 1.20 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 441.00.
Anal. (%) Calcd. for C22H20N2O6S: C, 59.99; H, 4.58; N, 6.36.
Found: C, 59.76; H, 4.47; N, 6.15.
1-(Ethyl-1-acetate)-6-(furfurylamin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (9d): Compound 9d was prepared
according to standard procedure C by using compound 8 and
furfuryl amine, obtained a yellow solid in 88.9 % yield. m.p.
103.7-104.9 °C. IR (KBr, νmax, cm-1): 3253, 1749, 1727, 1631,
1
1495, 1322, 1214, 1148. H NMR (CDCl3, 400 MHz): 8.62
(d, J = 8.4 Hz, 1H), 8.15 (dd, J = 7.2 Hz, 4.8 Hz, 2H), 7.86 (t,
J = 7.2 Hz, 1H), 7.01 (s, 1H), 6.83 (d, J = 7.2 Hz, 1H), 6.06 (d,
J = 2.8 Hz, 1H), 5.93 (d, J = 2.8 Hz, 1H), 4.86 (t, J = 6.4 Hz,
1H), 4.69 (s, 2H), 4.26 (q, J = 7.2 Hz, 2H), 4.19 (d, J = 6.4 Hz,
2H), 1.30 (t, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 414.99.
Anal. (%) Calcd. for C20H18N2O6S: C, 57.96; H, 4.38; N, 6.76.
Found: C, 58.05; H, 4.67; N, 6.98.
1-(Ethyl-1-acetate)-6-(4-(4-ethylformate)piperidin-1-
yl)sulfonyl-benzo[cd]indol-2(1H)-one (9e): Compound 9e
was prepared according to standard procedure C by using
compound 8 and 4-piperidinecarboxylate, obtained a yellow
solid in 86.9 % yield. m.p. 128.3-129.7 °C. IR (KBr, νmax
,
cm-1): 1749, 1725, 1630, 1498, 1336, 1219, 1148. H NMR
(CD3OD, 400 MHz): 8.81 (d, J = 8.4 Hz, 1H), 8.19 (dd, J =
7.6 Hz, 2H), 7.98 (t, J = 7.6 Hz, 1H), 7.22 (d, J = 7.6 Hz, 1H),
4.82 (s, 2H), 4.27 (q, J = 7.2 Hz, 2H), 4.08 (q, J = 7.2 Hz, 2H),
3.76 (d, J = 12 Hz, 2H), 2.63 (t, J = 10.4 Hz, 2H), 2.33 (m,
1H), 1.95 (d, J = 10.4 Hz, 2H), 1.69 (m, 2H), 1.31 (t, J = 7.2
Hz, 3H), 1.19 (d, J = 7.2 Hz, 3H). MS [M + H+]: m/z = 475.08.
Anal. (%) Calcd. for C23H26N2O7S: C, 58.22; H, 5.52; N, 5.90.
Found: C, 58.34; H, 5.41; N, 6.13.
1
1-(Ethyl-1-acetate)-6-(2-methylpiperidin-1-yl)sulfonyl-
benzo[cd]indol-2(1H)-one (9a): Compound 9a was prepared
according to standard procedure C by using compound 8 and
2-methylpiperazine, obtained a yellow solid in 87.9 % yield.
m.p. 99.3-100.2 °C. IR (KBr, νmax, cm-1): 1748, 1716, 1633,
1
1494, 1307, 1203, 1140. H NMR (CDCl3, 400 MHz): 8.62
Preparation of active Aurora B: Recombinant human
Aurora B was produced according to a procedure published
(d, J = 8.4 Hz, 1H), 8.19 (dd, J = 11.2 Hz, 7.6 Hz, 2H), 7.85

7334 Nie et al.
Asian J. Chem.
previously with minor modification19. Briefly, Aurora B was
expressed and processed in Transetta (DE3) cells harboring a
pET-28a plasmid that contained the cloned human Aurora B
cDNA. Fermentation was performed at 37 °C for 4-5 h in 800 mL
LB media containing 100 µg/mL Kanamycin until the OD600
reached 0.8-2. Then, the culture was transferred to 16 °C and
protein expression was induced for 16 h with 1 mM isopropyl-
β-D-1-thiogalactopyranoside (IPTG). Harvested cells were
resuspended in lysis buffer containing HEPES 25 mM, NaCl
1 M, MgCl2 10 mM, imidazole 5 mM, glycerol 10 %, pH 7.5
and homogenized with a JN-3000 PLUS low temperature ultra-
high pressure cell disrupter (JNBIO, Guangzhou). The lysate
was centrifuged at 15,000 rpm for 25 min at 4 °C to remove
cell debris. The supernatant was then loaded twice onto a
Nickle-NTA agarose column pre-equilibrated with lysis buffer.
The Aurora B was eluted with 50 and 500 mM imidazole in
the above buffer respectively. Fractions containing Aurora B
were pooled and concentrated with a Millipore Ultrafree
filtration device and then the Aurora B was exchanged into a
buffer of HEPES 25 mM, NaCl 1M, MgCl2 10 mM, glycerol
10 %, pH 7.5 . The concentrated Aurora B was loaded onto a
Superdex 75 10/300 (GE Healthcare) equilibrated with above
buffer. Fractions containing Aurora B were pooled and
concentrated. TheAurora B obtained with this method showed
39 kD on 12 % SDS-PAGE and aliquots stored at -80 °C.
Aurora B inhibition assay: The test procedure to assess
the inhibition of recombinantAurora B activity of selected com-
pounds was adapted from previously reported procedures20.
The reaction carried out in 100 µL system including HEPES
pH 7.5, 60 mM NaCl, 10 mM MgCl2, 0.3 mM NADH, 1 mM
phosphoenolpyruvate (PEP), 1.5 U lactate dehydrogenase
(LDH) (Sigma, USA), 1.5 U pyruvate kinase (PK) (Sigma),
1.2 µM Aurora B, 83 µM histones H3 substrate peptide and
0.2 mM ATP in the presence of 1 µL DMSO or 1 µL inhibitor
in DMSO. The procedure was briefly described below. At 30
°C, the Aurora B, NADH, PEP, LDH, PK and histones H3
were incubated with inhibitors in 96-well plates for 5 min.
Once added the substrateATP, the reaction was started.As the
absorptivity of NADH at 340 nm, with the reaction, NADH
continuously transformed into NAD+. Absorbance at 340 nm
was continuously recorded for 10 min. Inhibition ratio was
determined from the slope of the early linear part of the curve
obtained by plotting decrements in absorbance at 340 nm with
time (dB/dt). For IC50 determination, about 15 concentrations
of inhibitor were freshly prepared by 2 fold gradient dilution
with 95 % DMSO.After got the different initial rate according
to this method, we used the GraphPad Prism 5 software to
calculate the IC50 value of different inhibitors.
Scheme-I:Synthetic routes of compounds 4 and 5; Reagents and conditions:
i. a) H2N-OH, dry pyridine, reflux, 1 h; b) p-toluene sulfonyl-
chloride, reflux, 1 h; c) water, ethanol, NaOH, reflux, 2 h. ii.
chlorobutane, DMF, 140 °C, 4 h; iii. ethyl chloroacetate, DMF,
140 °C, 4 h.
A general approach to the preparation of derivatives 7a-v
were shown in Scheme-II, chlorosulfonic acid was added to
the compound 4 drop-wise at 0 °C and stirring for 1 h, then at
room temperature for 2 h to provide intermediate 6 in modest
yield, there is a reaction with sulfonylation of the 6-position
of benz(cd)indol-2(1H)-one18. Then 6 underwent different
reaction conditions to give all the compounds 7a-v.
Scheme-II: Synthetic routes of compounds 7a-v, Reagents and contions:
(i) HSO3Cl, 1 h, rt, 2 h; (ii) THF, rt, 12 h
The synthesis of derivatives 9a-e was described in Scheme-
III. The compound 8 was obtained according to the method
of synthesis of compound 6. Under nitrogen atmosphere,
simply mixing compound 8 with amines in THF at room
temperature provided the required compounds 9a-e in quan-
titative yield. The structures of all these final products have
been demonstrated by mass spectrometry (MS), infrared (IR),
1H NMR and elemental analysis.
1H NMR spectrum of compound 7a was recorded in
CDCl3, Its 1H NMR spectrum showed the signals of the aromatic
protons corresponding to two phenyl groups in the range δ
6.97-8.71 ppm. Signals of the morpholine group in compound
7a were found in the regions of 3.73 and 3.10 ppm. The n-butyl
substitute gave rise to one triplet at 3.94 ppm for the N-CH2,
two multiplets at 1.45 ppm and 1.78 ppm for CH2 and one
triplet at 0.99 ppm for the CH3. The IR spectra of 7a showed
absorption bands in the region of 3055, 2854, 1705, 1626,
1496, 1344 and 1160 cm-1. Characteristic frequencies of the
sulfonyl group were observed at 1344 and 1160 cm-1. The
strong absorptions at 1705 cm-1 were due to the presence of
the carbonyl group.
Biological evaluation: In the present study, benzo[c,d]-
indol-2(1H)-one was confirmed as the scaffold compound, a
series of novel derivatives have been synthesized to evaluate
their potential biological activities as Aurora B inhibitors.
Inhibition of recombinant humanAurora B by benzo[c,d]indol-
2(1H)-one derivatives 7 and 9 was assessed using an enzyme-
RESULTS AND DISCUSSION
The typical preparation of the benz(cd)indol-2(1H)-one
derivatives was shown in Scheme-I. Firstly, compounds 3 was
synthesized by a published method21. Briefly, the synthesis of
compounds 3 was carried out from desymmetrization of com-
mercially available 1, 8-naphthalic anhydride 2 via a Beckmann
rearrangement. Then, compound 3 was reacted at 140 °C for
4 h with chlorobutane or ethyl chloroacetate, respectively, in
presence of K2CO3 and KI as catalyst to give intermediates 4
and 5.

Vol. 26, No. 21 (2014)
Synthesis and Biological Evaluation of a Benz[cd]indol-2(1H)-one Derivatives 7335
57.9
26.3
25.8
7f
7g
7h
Scheme-III: Synthetic routes of compounds 9a-e, Reagents and contions:
(i) HSO3Cl, rt, 2 h; (ii) THF, rt, overninght
27.8
25.7
15.7
7i
7j
coupled continuous spectrophotometric assay22. The Aurora
Kinase Inhibitor II (CAS:331770-21-9) 10 was used as the
positive control, which is aATP-competitive inhibitor ofAurora
B with IC50 values of 756 nM (Fig. 3). The inhibitors synthe-
sized were examined for their ability to inhibit the activity of
recombinant human effector Aurora B. The results were
summarized in Tables 1 and 2.
7k
24.9
10.7
65.2
7l
7m
7n
Fig. 3. Structure of the positive control
All 1-(n-butyl)-benzo[cd]indol-2(1H)-ones 7 were assessed
for enzymatic activity against Aurora B kinase as shown in
Table-1. Variation of the benzo[c,d]indol-2(1H)-one in 6-
position revealed that substitution at this position could not
increase in inhibitory potency, but provided only poor Aurora
34.7
7o
35.3
32.6
7p
7q
TABLE-1
INHIBITORY ACTIVITY OF COMPOUNDS 7
AGAINST AURORA B KINASE
46.8
34.3
32.2
7r
7s
7t
Compound
R1
IC50a or Inhibition ratio
(%) in 50 mM
99.1; 756 nM
10
7a
45.3
10.8
49.6
7b
7c
35.2
34.6
7u
7v
7d
7e
47.3
87.3; 143.28 µM
aIC50 value of compounds was tested when its inhibition ratio
exceeded 80 %

7336 Nie et al.
Asian J. Chem.
TABLE-2
of 1- and 6-position to synthesis of novel benzo[c,d]indol-
2(1H)-one derivatives had a poor potency for inhibiting human
Aurora B kinase in vitro. In this research, benzo[c,d]indol-
2(1H)-one derivative 1 was not synthesized and tested inhibi-
tory activity against recombinant human Aurora B kinase.
According to experimental result above, presence of carboxyl
group in compound 1 may be necessary. Thus, our further
work is paid more attention to optimize the structures of benzo-
[c,d]indol-2(1H)-one derivative 1 retaining carboxyl group.
Meanwhile, we will carry out to modify the NH group of
benzo[c,d]indol-2(1H)-one to improve potency and selectivity
in vitro against human Aurora B kinase.
INHIBITORY ACTIVITY OF COMPOUNDS 9
AGAINST AURORA B KINASE
Inhibition ratio
(0.5 mM) (%)
Compound
R2
ACKNOWLEDGEMENTS
99.1
10
Supported by Tianjin SME Technology Innovation Fund
(10ZCKFSY08300, 11ZXCXSY03500)
9a
25.3
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40.8
43.6
9b
9c
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Conclusion
In summary, we have completed the synthesis and in vitro
evaluation of a series of benzo[c,d]indol-2(1H)-one derivatives.
The biological activity results suggest that the modification