Discovery of pyrrole-indoline-2-ones as aurora kinase inhibitors with a different inhibition profile

Article abstract of DOI:10.1021/jm1001869

A series of pyrrole-indolin-2-ones were synthesized, and their inhibition profile for Aurora kinases was studied. The potent compound 33 with phenylsulfonamido at the C-5 position and a carboxyethyl group at the C-3′ position selectively inhibited Aurora

Full text of DOI:10.1021/jm1001869

J. Med. Chem. 2010, 53, 5929–5941 5929
DOI: 10.1021/jm1001869
Discovery of Pyrrole-Indoline-2-ones as Aurora Kinase Inhibitors with a Different Inhibition Profile
Chao-Cheng Chiang,† Yu-Hsiang Lin,† Shu Fu Lin,† Chun-Liang Lai,† Chiawei Liu,† Win-Yin Wei, Sheng-chuan Yang,
Ru-Wen Wang, Li-Wei Teng, Shih-Hsien Chuang, Jia-Ming Chang, Ta-Tung Yuan, Ying-Shuen Lee, Paonien Chen,
Wei-Kuang Chi, Ju-Ying Yang, Hung-Jyun Huang, Chu-Bin Liao, and Jiann-Jyh Huang*
Development Center for Biotechnology, No. 101, Lane 169, Kangning Street, Xizhi City, Taipei County, Taiwan 221, R.O.C. †These authors
contributed equally to this work.
Received February 11, 2010
A series of pyrrole-indolin-2-ones were synthesized, and their inhibition profile for Aurora kinases was
studied. The potent compound 33 with phenylsulfonamido at the C-5 position and a carboxyethyl group
at the C-30 position selectively inhibited Aurora A over Aurora B with IC50 values of 12 and 156 nM,
respectively. Replacement of the carboxyl group with an amino group led to compound 47, which
retained the activity for Aurora B and lost activity for Aurora A (IC50 = 2.19 μM). Computation
modeling was used to address the different inhibition profiles of 33 and 47. Compounds 47 and 36 (the
ethyl ester analogue of 33) inhibited the proliferation of HCT-116 and HT-29 cells and suppressed levels
of the phosphorylated substrates of Aurora A and Aurora B in the Western blots.
Introduction
for the inhibition of VEGFR,a c-Kit, FLT3, PDGFR-R/β,
and CSF-1-R.16 The first compound of this type reaching the
clinic was sunitinib (Figure 1), which is approved for the treat-
ment of advanced renal cell carcinoma (RCC) and gastro-
intestinal stromal tumors (GIST). Compound 1 (SU6668)16 is
the precedent to sunitinib, originally developed as a multiple-
kinase inhibitor for VEGFR-2, PDGFR, and FGFR. In a
follow-up proteomic study, it is also found to inhibit Aurora
kinases.17 Sharing a similar indolin-2-one scaffold with the
reported Aurora B inhibitor Hesperadin,18 compound 1 inhib-
ited Aurora A with an IC50 value of 438.5 nM [determined in
house (see Figure 1)]. This finding led us to hypothesize that
Aurora kinase inhibitors could be designed on the basis of this
scaffold that would have a different inhibition profile.
In this paper, we report the synthesis of a series of new
pyrrole-indoline-2-ones of scaffold A (Figure 1), thestructure-
activity relationship of these compounds for the inhibition
of Aurora kinases, and the finding that selective inhibitors
of Aurora A and Aurora B can be designed. Sulfonamido
substituentsatthe C-5 positionof scaffoldA greatly improved
the activity for both Aurora A and Aurora B inhibition. The
carboxyethyl group at the C-30 position of the pyrrole (X =
COOH) provided selective inhibitors of Aurora A. Com-
pounds 33 and 47, differing only by a single functionality,
are selective Aurora A and Aurora B inhibitors, respectively.
Docking experiments attributed the selectivity to the affinity
of the carboxyl group for residues Arg220 and Thr217 in
Aurora A and Lys164 and Glu161 in Aurora B. Compounds
33 and 47 will serve as tools for the study of biological
functions for Aurora kinases.
Aurora kinases belong to the serine/threonine subclass of
kinases and play a critical role in the regulation of many process
that are pivotal in mitosis.1 Three isoforms of the enzymes have
been identified, namely, Aurora A, B, and C, which possess a
very conserved catalytic domain and an N-terminal domain that
varies in sequence and in length.2 Aurora A and Aurora B are
both overexpressed in solid tumors and leukemias3-6 and are
considered interesting targets for new anticancer drugs.7 How-
ever, it is not clear whether Aurora A or Aurora B is the better
target for cancer therapy.8 Compounds with different inhibition
profiles, including pan-Aurora VX-6809,10 and PHA-739358,11,12
Aurora-A-selective MLN8054,13 and Aurora-B-selective
AZD115214,15, have shown promising in vivo antitumor acti-
vity and entered clinical trials for the treatment of various cancers.
Pyrrole-indoline-2-ones were among the first structures
identified as kinase inhibitors and have been intensively studied
*To whom correspondence should be addressed. Telephone: þ886 2
2695 6933, ext. 2501. Fax: þ886 2 2695 7474. E-mail: lukehuang0226@
gmail.com.
a Abbreviations: ABL1 (ABL), c-abl oncogene 1 receptor tyrosine
kinase; AKT1 (PRKBA), ν-akt murine thymoma viral oncogene homo-
logue 1; ALK, anaplastic lympoma kinase; B-Raf, ν-raf murine sarcoma
viral oncogene homologue B1; CDC2, cell division control protein 2
homologue; CDI, 1,1-carbonyldiimidazole; cdk2, cyclin-dependent ki-
nase 2; CHK1, checkpoint kinase 1; CHK2, checkpoint kinase 2; C-Raf,
ν-raf leukemia viral oncogene 1; CSF-1-R (FMS), colony-stimulating
factor 1 receptor; EGFR, epidermal growth factor receptor; EPHA1,
EPH receptor A1; ERBB2 (HER2), V-erb-b2 erythroblastic leukemia
viral oncogene homologue 2; FGFR, fibroblast growth factor receptor;
FLT3, FMS-like tyrosine kinase 3; GIST, gastrointestinal stromal
tumors; GSK3B (GSK3 β), glycogen synthase kinase 3; IC50, half-
maximal inhibition; IGF-1R, insulin-like growth factor 1 receptor;
JAK2, Janus-activated kinase 2; c-Kit, stem cell factor receptor;
MAPK14 (p38R), mitogen-activated protein kinase 14; c-Met, hepato-
cyte growth factor receptor; PDGFR-R/β, platelet-derived growth
factor receptor R/β; PDK1, 3-phosphoinositide-dependent protein ki-
nase; PI3K, phosphoinositide 3-kinase; PLK1, polo-like kinase; pS10-
H3, histone H3 serine-10 phosphorylation; RCC, renal cell carcinoma;
TFA, trifluoroacetic acid; mTOR, mammalian target of rapamycin;
VEGFR, vascular endothelial growth factor receptor.
Results and Discussion
For the initial exploration of the structure-activity relation-
ship of pyrrole-indolin-2-ones of scaffold A as Aurora
kinase inhibitors, we first varied the substituents on the pyrrole
moiety by the synthetic methods illustrated in Schemes 1
and 2. 2-Formylpyrroles 5a-c fused with cycloalkanones as
r
2010 American Chemical Society
Published on Web 08/03/2010
pubs.acs.org/jmc

5930 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16
Chiang et al.
Table 1. Inhibition of the Kinase Activities of Aurora A and Aurora B
by Pyrrole-Indolin-2-ones 12a, 12b, 13a-d, and 14
Figure 1. Structure of sunitinib, Hesperadin, 1, and new pyrrole-
indolin-2-one (scaffold A). The enzymatic IC50 values of sunitinib
and 1 were determined in house by radiometric assay as described in
the Experimental Section.
Scheme 1. Synthesis of 2-Formylpyrroles 5a-c and 9 as the
Precursorsa
a Reagents and conditions: (i) 5-aminolevulinic acid hydrochloride,
NaOAc, H2O, 100 °C, 16 h, 75-87%; (ii) H2SO4 (catalytic), EtOH,
reflux, 12 h, >99%; (iii) CH(OMe)3, TFA, 19-21%.
a The IC50 values were averaged from two independent dose-
response curves; the variation was generally <15%. b The numbers in
parentheses are the percent inhibition values of compounds at 1.0 μM.
Scheme 2. Synthesis of Pyrrole-Indolin-2-ones 12-14 from
5a-c and 9a
4a-c, respectively, which were formylated with trimethyl-
orthoformate [CH(OMe)3] in TFA20 to give 5a-c, respec-
tively, in 19-21% yield. Application of the same methods with
2,4-pentanedione (6) as the starting material gave 2-formyl-
pyrrole 9 through intermediates 7 and 8 (Scheme 1b). Com-
pounds 5a-c were reacted with indolin-2-one 10 or 11 via aldol
condensation under basic conditions to give the corresponding
pyrrole-indolin-2-one 12 (Scheme 2). Subsequent saponifica-
tion converted 12 to 13. For the preparation of pyrrole-
indolin-2-one 14, pyrrole 9 was reacted with 11 by the afore-
mentioned methods.
In the formylation step for the synthesis, application of the
traditional Vilsmeier-Haack reaction did not provide 2-for-
mylpyrrole 5a-c and 9, possibly due to the formation of the
vinyl chloride functionality from the carbonyl group.21 The
reaction was accomplished with CH(OMe)3 in TFA, and the
resulting 2-formylpyrroles 5a-c and 9 were used directly for
the next step without optimization of the reaction conditions.
The IC50 values of pyrrole-indolin-2-ones 12-14 for the
inhibition of Aurora kinases are presented in Table 1. Com-
pounds 13a and 13b that contain the carboxyethyl group on
the pyrrole moiety were more potent than their ethyl ester
analogues 12a and 12b, respectively, for Aurora A inhibition.
The unsubstituted 40-oxo-40,50,60,70-tetrahydroindole moiety
a Reagents and conditions: (i) piperidine, EtOH, reflux, 12 h; (ii) (a)
NaOH, EtOH, (b) 3.0 N HCl.
the precursors were synthesized by the reaction of diketones
2a-c with 5-aminolevulinic acid hydrochloride in the presence
of NaOAc in H2O to provide the corresponding pyrroles 3a-c,
respectively, in 75-87% yield by Knorr pyrrole synthesis
(Scheme 1a).19 Esterification of 3a-c with EtOH produced

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16 5931
Table 2. Synthesis of 5-Substituted Pyrrole-Indolin-2-ones 15-35 and Their Inhibition of the Kinase Activities for Aurora A and Aurora B
a The IC50 values were averaged from two independent dose-response curves; the variation was generally <15%. b The numbers in parentheses are
the percent inhibition values of compounds at 1.0 μM.
in compound 13b was more potent than its analogous 60-
dimethyl-substituted 13c, seven-membered 13d, and acyclic
14. Therefore, the pyrrole moiety of 13b that originated from
5a served as the template for optimization. Selective inhibition
ofAuroraA overAuroraBwas observed on these compounds
(Table 1).
For further investigation of the structure-activity relation-
ship, a series of pyrrole-indolin-2-ones 15-35 possessing
various substituents at the C-5 position22 were synthesized
and evaluated (Table 2). In comparison with compound 13b
(R = F), the potencies of compounds 15-20 possessing a
bromo, nitro, aryl, or amido group were not improved for
Aurora A inhibition. Ethyl- and allylsulfonyl substitution
Aurora B (IC50 = 0.441 μM). For 5-indolin-1-ylsulfonyl
derivative 31, the potency was similar to that of 28 for Aurora
A with a 1.7-fold improvement for Aurora B (IC50 =
0.292 μM). For pyrrole-indolin-2-ones 32-34 bearing C-5
alkyl- or aryl-sulfonamido substituents, the activity was
also potent against Aurora A. Compound 33 was most active
against Aurora B in this series with an IC50 value of 0.156 μM
and also showed activity (IC50 = 12 nM) comparable to
that of compound 28 against Aurora A. Replacement of
the phenylsulfonamido group with a benzylsulfonamido or
2-naphthylsulfonamido group reduced the potency for both
Aurora A and Aurora B inhibition (see compounds 34 and 35
in Table 2).
gave compounds 21 and 22 with improved activity (IC50
=
Potent compounds 28, 31, and 33 (Table 2) lacked anti-
proliferative activity in HCT-116 cells (IC50 > 10 μM). The
lack of activity in the cell-based assay was hypothesized to be
from poor cell membrane permeability caused by the car-
boxylic acid group. We thus analyzed compound 36, the ethyl
ester analogue to 33, in the cell-based assay, and the com-
pound was active (see Table 3). In addition, 36 induced a
0.057 and 0.039 μM, respectively) versus benzyl- and 4-fluoro-
benzylsulfonyl derivatives 23 and 24. Sulfamoyl substitutions
greatly improved the activity of compounds 25-31, with IC50
values of <0.1 μM for Aurora A. Pyrrolidin-1-ylsulfonyl
derivative 28 was the most potent in this series with an IC50
of 7 nM for Aurora A and also showed moderate inhibition of

5932 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16
Table 3. Enzymatic and Cellular Activities of Compounds 33 and 36
Chiang et al.
IC50 (μM)a
compd
Aurora A
Aurora B
HCT-116
HCT-116b
>10
1.02 ( 0.12
HT-29
33
36
0.012 ( 0.001
0.084 ( 0.005
0.156 ( 0.012
0.214 ( 0.020
>10
3.74 ( 0.54
>10
3.23 ( 0.32
a The IC50 values were averaged from two independent dose-response curves. b The concentration that reduced the level of [3H]thymidine
incorporation by 50%.
Scheme 3. Preparation of Compounds 37-40 and 46-50a
a Reagents and conditions: (i) R2NH, CDI, CH2Cl2, 66-98%; (ii) CDI, CH2Cl2, HNR2, 73-96%; (iii) ethane-1,2-dithiol, BF3 OEt2, THF, 85-93%;
3
(iv) LiAlH4, THF, reflux, 60-96%; (v) DMF, POCl3, CH2Cl2, 71-97%; (vi) HgCl2, MeOH, CaCO3, 66-93%; (vii) indolin-2-ones, piperidine, EtOH,
reflux, 12 h, 45-97%.
complete suppression in phosphorylation of the substrate
of Aurora kinases, histone H3 at serine 10, which is regar-
ded as a biomarker of Aurora B inhibition in HCT-116
cells (Table 3).23 Decreased levels of phospho-Aurora A
(pThr288)12 were also observed. As an ester analogue to 33,
compound 36 might possess better cell permeabilizing ability,
thus demonstrating cellular activity in its original form or acid
form (i.e., 33) after entering the cell.
To improve the activity within the cell and to replace the
potentially labile ester group in compound 36, we synthesized
a series of amides and amine analogues of compounds 31
and 33 as illustrated in Scheme 3. The preparation of amide
analogues 37-40 was straightforward from the reaction of 31
or 33 with different amines using CDI as the coupling agent
(Scheme 3a). The preparation of amine analogues 46-50,
however, required the protection-deprotection methodo-
logy (Scheme 3b). Compound 3a was coupled with different
amines using CDI, and the obtained amide 41 was protected
by ethane-1,2-dithiol to produce compound 42. Hydride
reductionof42 provided amine43, which was then formylated
by the Vilsmeier-Haack method to give compound 44.
Removal of the dithilane protection in 44 by mercuric chloride
(HgCl2) under basic conditions gave 2-formylpyrrole 45.
After condensation with indolin-2-ones, compound 45 was
converted to pyrrole-indolin-2-ones 46-50 possessing the
amino group in the side chain. In the search for protection
methodsfor compound41, we found the useof ethyleneglycol
with an acid catalyst was not feasible because the conjugation
between the pyrrole nitrogen and carbonyl group deactivates
both functions.24 Use of ethane-1,2-dithiol as an alternative,

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16 5933
Table 4. Enzymatic and Cellular Activities of Compounds 37-40 and 46-50
a The IC50 values were averaged from two independent dose-response curves; the variation was generally <15%.
which is not reported for the protection of 4-oxo-4,5,6,7-
tetrahydroindoles, gave the corresponding product 42 in high
yields. The protection of the 4-oxo group also improved the
yield of the formylation step from 43 to 44 in comparison with
the step from 4a to 5a shown in Scheme 1.
would bind to the hinge region,25 the finding that different
equivalent residues interacted with the carboxyl group of 31
and 33 in Aurora A and Aurora B will be helpful for the
development of selective inhibitors. Targeting the pocket near
the C-5 position, however, would promote the activities for
both kinases (Table 2). Compounds 46-50 showed better
antiproliferative activity than 31 and 33 on cancer cells, and
we attributed the cellular activity to membrane-penetrating
ability as the predescribed ester 36.
In the Western blot analysis shown in Figure 2A, com-
pound 47 exhibited an apparent suppression of phosphory-
lated histone H3 at serine 10 in HCT-116 cells equivalent to
that for compound 36 (cf. Table 3). A reduction of pSer10 was
observed when cells were treated with both compounds
at a concentration of 10 μM. However, the suppression of
phospho-Aurora A (pThr288) by compound 47 was not as
significant as for compound 36. Compound 47 also demon-
strated the same cell cycle profile with Aurora kinase inhibi-
tors from literature,11,26 for the incubation of HCT-116 cells
Table 4 summarizes the activities of compounds 37-40 and
46-50 in biochemical assays and revealed their antiprolifera-
tive activities on HCT-116, HeLa, and HT-20 cells. In com-
parison with those of carboxylic acid analogues 31 and 33, the
potency of compounds 37-40 with an amido side chain
decreased significantly against Aurora A (∼10-70-fold) and
moderately against Aurora B. Surprisingly, the substantial
loss of activity for Aurora A (IC50 >2.0 μM, ∼200-fold less
potent) and retention of Aurora B inhibition were observed
for compounds 46-50 with an amino side chain. The results
indicate that the carboxyl group is important for Aurora A
inhibition but not for Aurora B and could be considered as the
change in the inhibition profile form Aurora A to Aurora B
by a single functionality variation. Because the indolin-2-one

5934 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16
Chiang et al.
Figure 2. Western blot analysis of phospho-histone H3 and phospho-Aurora A (T288) in HCT-116 cells by compounds 47 and 49. An
antibody recognizing β-actin was used as a loading control.
Table 5. Kinase Profiling of 36 and 47 by the Radiometric Method
% inhibition at 1.0 μM
kinase tested
compound 36
compound 47
ABL1 (ABL)a
AKT1 (PRKBA)a
ALKa
31
11
80
33
71
10
17
34
5
-17
9
85
12
46
58
56
56
4
CDC2b
cdk2/cyclin Ab
CHK1b
CHK2b
CSF-1-R (FMS)a
EGFRb
Figure 3. Cell cycle profile of HCT-116 cells treated with 4 μM
compound 47 for 24 h.
EGFR (T790M)b
EPHA1 (EphA1)a
ERBB2 (HER2)a
FGFR-1b
14
29
-28
77
97
47
24
30
41
4
8
with 47 for 24 h resulted in an increase of tetraploid 4 N DNA
and multinucleated octoploid (g8 N DNA) populations
(Figure 3). Because compounds 36 and 47 presented similar
enzymatic and cellular activities for Aurora B with com-
parable antiproliferative IC50 values, it is likely to refer the
antiproliferative effects of both compounds to Aurora B
inhibition. However, the inhibition of other kinases could
not be excluded because 36 and 47 shared a similar scaffold
with the multiple-kinase inhibitor sunitinib.16 To explore the
inhibition profiles of 36 and 47 against various kinases, we
first used a radiometric method to examine both compounds
against a panel of 30 kinases. The results revealed that 47 hit
the reported targets of sunitinib, including VEGFR-2, c-Kit,
FLT3, PDGFR-β, and CSF-1-R with IC50 values of <1.0 μM
while compound 36 was less active against c-Kit, PDGFR-β,
and CSF-1-R in comparison with 47 (IC50 >1.0 μM) (see
Table 5). An extensive test was conducted using 36 and 47 at
1.0 μM against a panel of 442 kinases on Ambit Biosciences
Kinomescan scanMax plateform.27 Kinases, including AXL,
DDR1, FLT3, GRK7, LCK, LOK, MAP4K3, MAP4K5,
MERTK, MUSK, PHKG1, PIP5K2C, RET, and TRK, were
found to be inhibited significantly by both compounds with a
percentage of control of <10% (see the table in the Support-
ing Information). As for compound 49 with the best anti-
proliferative activity in this series, the inhibition of pSer10 and
pT228 was inferior to that of 36 and 47 (Figure 2B). The
contribution of other targetsto the antiproliferative activityof
49 could not be ruled out.
24
-19
41
95
24
6
FLT3b
GSK3B (GSK3 β)a
IGF-1Rb
JAK2a
c-Kitb
-3
65
11
32
70
11
5
MAPK14 (p38R)a
c-Metb
32
47
24
11
1
PDGFR-βb
PDK1a
PI3K (p110R/p85R)b
PI3K (p110β/p85R)b
PLK1a
-2
-24
25
2
-20
9
mTORb
B-Rafb
-1
3
B-Raf (V600E)b
C-Rafb
-4
-7
51
-8
74
VEGFR-2b
a Conducted by Ricerca Taiwan Ltd. b Conducted in house.
C2dO groups with Glu171and Ala173 in the hinge region and
two H-bonds from the oxygen atom in sulfonamide with
Lys103 and Lys122 (Figure 4A,B). The binding was similar
to that of Hesperadin25 because they shared the same indolin-
2-one scaffold. An additional hydrogen bonding interaction
was found for the carboxyl group in 33 with Lys122, and the
interaction was absent in 47 possessing the dimethylamino
group at the same position. We rationalized that the contribu-
tion of the additional H-bond would not be important for the
activity because similar activity was observed for compounds
33 and 47 in the inhibition of Aurora B.
To determine the structural basis of compounds 33 and 47
for the different selective inhibition profiles, we used docking
simulations to model the binding modes. After energy mini-
mization, both compounds fit the ATP pocket of Aurora A
and Aurora B as shown in Figure 4. For Aurora B, com-
pounds 33 and 47 formed two H-bonds from N1-H and
The interaction of 33 and 47 with Aurora A was different
from that with Aurora B, because the N1-H group and the

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16 5935
Figure 4. Docked binding modes of compounds 33 and 47 in the ATP binding site of Aurora A and Aurora B: (A) 33 in Aurora B, (B) 47 in
Aurora B, (C) 33 in Aurora A, and (D) 47 in Aurora A. Compounds are shown as light blue or yellow sticks; hydrogen bonds are shown as
dashed gray line, and the oxygen, nitrogen, and sulfur atoms are colored red, blue, and orange, respectively.
pyrrole N-H group were responsible for hinge binding
[Glu211 and Ala213 (see Figure 4C,D)]. The carboxyl group
in 33 formed two H-bonds with Arg220 and Thr217,28 but
such interaction was not found for the dimethylamino group
atthe same position in47. ThesubstantialshiftinIC50 from 33
to 47 (12 nM to2.19μM) for Aurora A inhibitionwouldimply
the importance of H-bonds from the carboxyl group. The
poor interaction of the amino groups with Aurora A deduced
from the docking experiments also explained the similar IC50
values of compounds 46-50. As the residues equivalent to
Arg220 and Thr217, respectively, in Aurora A, Lys164 and
Glu161 in Aurora B could not form strong H-bonds with the
carboxyl group in 33. As a result, conversion of the carboxyl
to an amino group at the side chain of the pyrrole caused a
great loss of activity for Aurora A and retained that for
Aurora B, as demonstrated in compounds 33 and 47. These
results revealed the possibility of designing a single appro-
priate functionality for selective Aurora A or Aurora B
inhibitors by targeting these residues.
that the equivalent residues Arg220 and Thr217 in Aurora A
and Lys164 and Glu161 in Aurora B were responsible for the
different inhibition profile. Targeting the residues would thus
be helpful in the development of selective inhibitors for
Aurora kinases. Consistent results in the enzymatic activity
were found for compounds 47 and 36 (the ethyl ester analogue
to 33), which showed antiproliferative effects in cancer cells
and suppression of phosphorylation of substrates for Aurora
A and Aurora B at the cellular level.
Experimental Section
General Procedure. Reagents were used as purchased without
further purification. 5-Substituted indolin-2-ones were pur-
chased from commercial sources or prepared according to
literature procedures.22 Analytical thin-layer chromatography
(TLC) was performed on precoated plates (silica gel 60 F-254),
purchased from Merck Inc. Purification by gravity column
chromatography was conducted using Merck Reagents Silica
Gel 60 (particle size of 0.063-0.200 mm, 70-230 mesh ASTM).
Proton NMR spectra were recorded on a Bruker (300 MHz)
spectrometer with CDCl3 and DMSO-d6 as solvents. Multi-
plicities are abbreviated as follows: s, singlet; d, doublet; t,
triplet; q, quartet; m, multiplet; J, coupling constant (hertz).
ESI-MS spectra were recorded with an Applied Biosystems API
300 mass spectrometer. The purities of the compounds were
greater than 95% as determined by reversed-phase HPLC.
General Procedure for the Synthesis of Pyrroles 3a-c and 7. A
mixture of 5-aminolevulinic acid hydrochloride (∼0.30 mol, 1.0
equiv), diketone 2a, 2b, 2c, or 6 (1.2 equiv), and sodium acetate
(2.0 equiv) in water (125 mL) was heated at 100 °C for 16 h.
Conclusion
In conclusion, we synthesized a series of pyrrole-indolin-
2-ones and explored their inhibition profile against Aurora
kinases. Varying the substituents at the C-5 position on
scaffold A showed the same tendency for activity against
Aurora A and Aurora B. The carboxyethyl group on the
pyrrole ring was important for Aurora A inhibition but not
for Aurora B. Results of computational modeling indicated

5936 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16
Chiang et al.
The solution was cooled to room temperature, and the resultant
precipitate was filtered, washed with water (2 ꢀ 200 mL), and
dried under vacuum to give the desired pyrrole 3a, 3b, 3c, or 7,
respectively, as a yellow solid in 75-87% yield.
3-(4-Oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic acid (3a).
Yield: 87%. 1H NMR (DMSO-d6): δ 11.02 (s, 1 H), 6.46 (s, 1 H),
2.77 (t, J = 7.7Hz, 2 H), 2.70(t, J = 6.0 Hz, 2 H), 2.42-2.48 (m, 2
H), 2.27 (t, J = 6.2 Hz, 2 H), 1.94-2.00 (m, 2 H). ESI-MS: m/z
208.0 (M þ H)þ.
10.22 (s, 1 H), 9.73 (s, 1 H), 4.07 (q, J = 7.2 Hz, 2 H), 3.29 (t, J =
7.1 Hz, 2 H), 2.71-2.77 (m, 4 H), 2.38 (s, 2 H), 1.20 (t, J = 7.1
Hz, 3 H), 1.12 (s, 6 H). ESI-MS: m/z 292.0 (M þ H)þ.
Ethyl 3-(2-Formyl-4-oxo-1,4,5,6,7,8-hexahydrocyclohepta-
1
[b]pyrrol-3-yl)propanoate (5c). Yield: 19%. H NMR (CDCl3):
δ 10.21 (brs, 1 H), 9.71 (s, 1 H), 4.08 (q, J = 7.2 Hz, 2 H), 3.29 (t,
J = 7.4 Hz, 2 H), 3.04 (t, J = 7.4 Hz, 2 H), 2.63-2.70 (m, 4 H),
1.88-1.95 (m, 4 H), 1.20 (t, J = 7.2 Hz, 3 H). ESI-MS: m/z 278.0
(M þ H)þ.
Ethyl 3-(4-Acetyl-2-formyl-5-methyl-1H-pyrrol-3-yl)propano-
ate (9). Yield: 21%. 1H NMR (CDCl3): δ 10.25 (s, 1 H), 9.71 (s,
1 H), 4.08 (q, J = 7.1 Hz, 2 H), 3.31 (t, J = 7.2 Hz, 2 H), 2.67 (t,
J = 7.2 Hz, 2 H), 2.62 (s, 3 H), 2.47 (s, 3 H), 1.21 (q, J = 7.1 Hz,
3 H). ESI-MS: m/z 252.0 (M þ H)þ.
3-(6,6-Dimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propa-
noic acid (3b). Yield: 76%. 1H NMR (DMSO-d6): δ 10.99 (s, 1 H),
6.47 (s, 1 H), 2.74-2.81 (m, 2 H), 2.59 (s, 2 H), 2.43-2.48 (m,
2 H), 2.18 (s, 2 H), 1.02 (s, 6 H). ESI-MS: m/z 236.0 (M þ H)þ.
3-(4-Oxo-1,4,5,6,7,8-hexahydrocyclohepta[b]pyrrol-3-yl)propa-
noic acid (3c). Yield: 75%. 1H NMR (DMSO-d6): δ 8.27 (s, 1 H),
6.42 (s, 1 H), 3.04 (t, J = 7.2 Hz, 2 H), 2.80-2.88 (m, 2 H), 2.57-
2.65 (m, 4 H), 1.80-1.90 (m, 4 H). ESI-MS: m/z 222.0 (M þ H)þ.
3-(4-Acetyl-5-methyl-1H-pyrrol-3-yl)propanoic acid (7). Yield:
85%. 1H NMR (DMSO-d6):δ 11.96 (brs, 1 H), 10.95 (s, 1 H), 6.39
(s, 1 H), 2.80(t, J = 7.7Hz, 2 H), 2.37-2.45 (m, 5H), 2.30 (s, 3 H).
ESI-MS: m/z 196.0 (M þ H)þ.
General Procedure for the Synthesis of Pyrroles 41a-c. Com-
pound 3a (∼5.0 g, 1.0 equiv) was suspended in CH2Cl2 (100 mL)
and supplemented with CDI (1.2 equiv). The reaction mixture
was stirred at room temperature for 3.0 h. To the solution was
added dimethylamine, diethylamine, or pyrrolidine (2.0 equiv),
and the solution was stirred at room temperature for 12 h. The
solution was diluted with CH2Cl2 (200 mL) and washed with
0.1 N HCl (50 mL), saturated Na2CO3 (50 mL), and brine
(50 mL). The organic layer was dried over anhydrous MgSO4(s)
and concentrated under reduced pressure to provide the desired
41a-c as white solids in 73-96% yield.
General Procedure for the Synthesis of Esters 4a-c and 8.
Pyrrole 3a, 3b, 3c, or 7 (∼0.25 mol, 1.0 equiv) in ethanol was
added with sulfuric acid (1.0 mL). The reaction mixture was
heated at reflux for 12 h. The solution was concentrated under
reduced pressure, and the resultant solids were washed with
water (2 ꢀ 200 mL). The solids were dried under vacuum to give
the desired ester 4a, 4b, 4c, or 8, respectively, as a yellow solid
in >99% yield.
N,N-Dimethyl-3-(4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)-
1
propanamide (41a). Yield: 73%. H NMR (CDCl3): δ 9.32 (s,
1 H), 6.45 (d, J = 1.8 Hz, 1 H), 3.11 (s, 3 H), 2.91-2.98 (m, 5 H),
2.77 (t, J = 6.2 Hz, 2 H), 2.68-2.72 (m, 2 H), 2.41-2.46 (m, 2
H), 2.06-2.13 (m, 2 H). ESI-MS: m/z 235.0 (M þ H)þ.
Ethyl 3-(4-Oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoate
(4a). 1H NMR (DMSO-d6): δ 11.03 (s, 1 H), 6.47 (s, 1 H), 4.03
(q, J = 7.1 Hz, 2 H), 2.77-2.83 (m, 2 H), 2.70 (t, J = 6.2 Hz, 2
H), 2.50-2.53 (m, 2 H), 2.24-2.31 (m, 2 H), 1.93-2.01 (m, 2 H),
1.16 (t, J = 7.1 Hz, 3 H). ESI-MS: m/z 236.0 (M þ H)þ.
Ethyl 3-(6,6-Dimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-
yl)propanoate (4b). 1H NMR (DMSO-d6): δ 11.00 (s, 1 H),
6.47 (s, 1 H), 4.02 (q, J = 7.1 Hz, 2 H), 2.79 (t, J = 7.7 Hz,
2 H), 2.58 (s, 2 H), 2.53 (t, J = 7.7 Hz, 2 H), 2.17 (s, 2 H), 1.15 (t,
J = 7.1 Hz, 3 H), 1.00 (s, 6 H). ESI-MS: m/z 264.0 (M þ H)þ.
Ethyl 3-(4-Oxo-1,4,5,6,7,8-hexahydrocyclohepta[b]pyrrol-3-
N,N-Diethyl-3-(4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propana-
mide (41b). Yield: 96%. 1H NMR (CDCl3): δ 8.34 (s, 1 H), 6.52 (s,
1 H), 3.35-3.49 (m, 4 H), 2.97-3.02 (m, 2 H), 2.78 (t, J = 6.2 Hz,
2 H), 2.69-2.75 (m, 2 H), 2.43-2.48 (m, 2 H), 2.09-2.16 (m, 2 H),
1.08-1.20 (m, 6 H). ESI-MS: m/z 263.0 (M þ H)þ.
3-[3-Oxo-3-(pyrrolidin-1-yl)propyl]-6,7-dihydro-1H-indol-
4(5H)-one (41c). Yield: 92%. 1H NMR (CDCl3): δ 8.59 (s, 1 H),
6.49 (s, 1 H), 3.50 (t, J = 6.9 Hz, 2 H), 3.44 (t, J = 6.9 Hz, 2 H),
2.95-3.02 (m, 2 H), 2.77 (t, J = 6.2 Hz, 2 H), 2.60-2.65 (m,
2 H), 2.42-2.47 (m, 2 H), 2.07-2.15 (m, 2 H), 1.88-1.95 (m,
2 H), 1.79-1.86 (m, 2 H). ESI-MS: m/z 261.0 (M þ H)þ.
General Procedure for the Synthesis of Protected Pyrroles
42a-c. To a MeOH solution (50 mL) containing compounds
41a-c (∼3.0 g, 1.0 equiv) and ethane-1,2-dithiol (2.0 equiv) was
1
yl)propanoate (4c). H NMR (CDCl3): δ 8.29 (s, 1 H), 6.41 (s,
1 H), 4.10 (q, J = 7.2 Hz, 2 H), 3.01 (t, J = 7.4 Hz, 2 H),
2.86-2.92 (m, 2 H), 2.59-2.69 (m, 4 H), 1.82-1.91 (m, 4 H),
1.22 (t, J = 7.2 Hz, 3 H). ESI-MS: m/z 250.0 (M þ H)þ.
Ethyl 3-(4-Acetyl-5-methyl-1H-pyrrol-3-yl)propanoate (8). 1H
NMR (DMSO-d6): δ 8.30 (s, 1 H), 6.39 (s, 1 H), 4.11 (q, J = 7.1
Hz, 2 H), 3.02 (t, J = 7.5 Hz, 2 H), 2.60 (t, J = 7.5 Hz, 2 H), 2.50
(s, 3 H), 2.43 (s, 3 H), 1.23 (t, J = 7.1 Hz, 3 H). ESI-MS: m/z
224.0 (M þ H)þ.
added BF3 OEt2 (0.50 equiv). The reaction mixture was stirred
3
at room temperature for 12 h. The solution was mixed with
water (100 mL), and the resultant precipitate was filtered and
dried under vacuum to provide the desired 42a-c as yellow
solids in 85-93% yield.
N,N-Dimethyl-3-(10,50,60,70-tetrahydrospiro[[1,3]dithiolane-
2,40-indole]-30-yl)propanamide (42a). Yield: 93%. 1H NMR
(CDCl3): δ 7.63 (s, 1 H), 6.46 (s, 1 H), 3.45-3.53 (m, 2 H), 3.33-
3.40 (m, 2 H), 3.07-3.13 (m, 2 H), 3.00 (s, 3 H), 2.96 (s, 3 H),
2.69-2.75 (m, 2 H), 2.54 (t, J = 6.2 Hz, 2 H), 2.30-2.34 (m,
2 H), 1.99-1.92 (m, 2 H). ESI-MS: m/z 311.0 (M þ H)þ.
N,N-Diethyl-3-(10,50,60,70-tetrahydrospiro[[1,3]dithiolane-
2,40-indole]-30-yl)propanamide (42b). Yield: 92%. 1H NMR
(CDCl3): δ 7.60 (s, 1 H), 6.45 (s, 1 H), 3.46-3.53 (m, 2 H), 3.28-
3.42 (m, 6 H), 3.09-3.14 (m, 2 H), 2.68-2.74 (m, 2 H), 2.54 (t,
J = 6.2 Hz, 2 H), 2.30-2.35 (m, 2 H), 1.93-1.99 (m, 2 H),
1.10-1.15 (m, 6 H). ESI-MS: m/z 339.0 (M þ H)þ.
General Procedure for the Synthesis of 2-Formylpyrroles 5a-c
and 9. To a trifluoroacetic acid solution (50 mL) containing
compound 4a, 4b, 4c, or 8 (∼10 g, 1.0 equiv) was added trimethyl
orthoformate (3.0 equiv) at 0 °C. The reaction mixture was
stirred at 0 °C for 30 min, warmed to room temperature, and
stirred at room temperature for 2.0 h. To the solution were
added ethyl acetate (250 mL), water (200 mL), and NaOH (18 g).
The organic layer was collected and washed with saturated
aqueous NaHCO3 (200 mL), dried over MgSO4(s), and con-
centrated under reduced pressure. The oily residue was purified
by gravity column chromatography (50% EtOAc in hexanes) to
give 2-formylpyrrole 5a, 5b, 5c, and 9, respectively, as a yellow
solid in 19-21% yield.
1-(Pyrrolidin-1-yl)-3-(10,50,60,70-tetrahydrospiro[[1,3]dithiolane-
2,40-indole]-30-yl)propan-1-one (42c). Yield: 85%. 1H NMR
(CDCl3): δ 7.61 (s, 1 H), 6.46 (s, 1 H), 3.45-3.55 (m, 4 H), 3.31-
3.43 (m, 4 H), 3.07-3.16 (m, 2 H), 2.65-2.70 (m, 2 H), 2.50-2.56
(m, 2 H), 2.31-2.34 (m, 2 H), 1.78-2.01 (m, 6 H). ESI-MS: m/z
337.0 (M þ H)þ.
Ethyl 3-(2-Formyl-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)-
1
propanoate (5a). Yield: 21%. H NMR (DMSO-d6): δ 9.75 (s,
1 H), 4.08 (q, J = 7.1 Hz, 2 H), 3.28 (t, J = 7.1 Hz, 2 H), 2.87 (t,
J = 6.2 Hz, 2 H), 2.74 (t, J = 7.1 Hz, 2 H), 2.50 (t, J = 6.2 Hz,
2 H), 2.11-2.20 (m, 2 H), 1.20 (t, J = 7.1 Hz, 3 H). ESI-MS: m/z
264.0 (M þ H)þ.
General Procedure for the Synthesis of Amines 43a-c. To a
THF solution (200 mL) containing protected pyrroles 42a-c
(∼5.0 g, 1.0 equiv) was added LiAlH4 (4.0 equiv) at 0 °C.
Ethyl 3-(2-Formyl-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydro-1H-
indol-3-yl)propanoate (5b). Yield: 20%. 1H NMR (DMSO-d6): δ

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16 5937
The reaction mixture was warmed to room temperature and
stirred for 12 h. The solution was mixed with 15% NaOH, and
the insoluble white solids were filtered off. The filtrate was
concentrated under reduced pressure to give the desired 43a-c
as a yellow liquid in 60-96% yield.
4-Oxo-3-[3-(pyrrolidin-1-yl)propyl]-4,5,6,7-tetrahydro-1H-in-
dole-2-carbaldehyde (45c). Yield: 70%. 1H NMR (CDCl3): δ
9.69 (s, 1 H), 3.06-3.10 (m, 2 H), 2.84-2.90 (m, 2 H), 2.40-2.52
(m, 8 H), 2.12-2.20 (m, 2 H), 1.84-1.92 (m, 2 H), 1.72-1.80 (m,
4 H). ESI-MS: m/z 275.0 (M þ H)þ.
N,N-Dimethyl-3-(10,50,60,70-tetrahydrospiro[[1,3]dithiolane-
2,40-indole]-30-yl)propan-1-amine (43a). Yield: 95%. 1H NMR
(CDCl3): δ 7.67 (s, 1 H), 6.44 (s, 1 H), 3.42-3.51 (m, 2 H), 3.33-
3.40 (m, 2 H), 2.73-2.79 (m, 2 H), 2.54 (t, J = 6.1 Hz, 2 H),
2.30-2.45 (m, 4 H), 2.25 (s, 6 H), 1.92-1.99 (m, 2 H), 1.82-1.90
(m, 2 H). ESI-MS: m/z 297.0 (M þ H)þ.
General Procedure for the Synthesis of Pyrrole-Indoline-2-
ones 12-14, 15-36, and 46-50. A mixture of 2-formylpyrrole
5a, 5b, 5c, 9, 45a, 45b, or 45c (∼0.50 mmol, 1.0 equiv) and the
corresponding indolin-2-one (1.0 equiv) was mixed with EtOH
(5.0 mL) and piperidine (0.1 mL). The reaction mixture was
heated at reflux for 12 h. The resultant precipitate was filtered
and washed with EtOH to provide the corresponding pyrrole-
indoline-2-one in ethyl ester form. The compound was sus-
pended in MeOH and mixed with aqueous NaOH (3.0 equiv).
The solution was heated at reflux until all the solids were
dissolved. The solution was mixed with 3 N HCl, and the
resultant precipitant was filtered, washed with MeOH, and dried
in a vacuum oven at 50 °C to provide the desired pyrrole-
indoline-2-one in acid form.
N,N-Diethyl-3-(10,50,60,70-tetrahydrospiro[[1,3]dithiolane-2,40-
indole]-30-yl)propan-1-amine (43b). Yield: 96%. 1H NMR
(CDCl3): δ 7.59 (s, 1 H), 6.44 (s, 1 H), 3.45-3.48 (m, 2 H),
3.36-3.40 (m, 2 H), 2.72-2.77 (m, 2 H), 2.50-2.58 (m, 8 H),
2.31-2.35 (m, 2 H), 1.94-1.98 (m, 2 H), 1.82-1.86 (m, 2 H),
1.04 (t, J = 7.2 Hz, 6 H). ESI-MS: m/z 325.0 (M þ H)þ.
30-[3-(Pyrrolidin-1-yl)propyl]-10,50,60,70-tetrahydrospiro[[1,3]-
1
dithiolane-2,40-indole] (43c). Yield: 60%. H NMR (CDCl3): δ
7.58 (s, 1 H), 6.45 (s, 1 H), 3.42-3.51 (m, 2 H), 3.31-3.41 (m,
2 H), 2.75-2.82 (m, 2 H), 2.50-2.57 (m, 8 H), 2.27-2.36 (m, 2 H),
1.87-2.00 (m, 4 H), 1.75-1.82 (m, 4 H). ESI-MS: m/z 323.0
(M þ H)þ.
(Z)-Ethyl 3-{4-Oxo-2-[(2-oxoindolin-3-ylidene)methyl]-4,5,6,7-
tetrahydro-1H-indol-3-yl}propanoate (12a). Yield: 84%. 1H NMR
(CDCl3): δ 13.49 (s, 1 H), 7.93 (s, 1 H), 7.61 (s, 1 H), 7.59 (d, J =
7.6 Hz, 1 H), 7.19 (dd, J = 7.6, 7.6 Hz, 1 H), 7.09 (dd, J = 7.6, 7.6
Hz, 1 H), 6.89 (d, J = 7.6 Hz, 1 H), 4.06 (q, J = 7.1 Hz, 2 H), 3.27
(t, J = 7.1 Hz, 2 H), 2.91 (t, J = 6.1 Hz, 2 H), 2.74 (t, J = 7.2 Hz, 2
H), 2.52 (t, J = 6.1 Hz, 2 H), 2.13-2.20 (m, 2 H), 1.18 (t, J = 7.1
Hz, 3 H). ESI-MS: m/z 379.0 (M þ H)þ.
General Procedure for the Synthesis of the Protected 2-For-
mylpyrroles 44a-c. POCl3 (2.0 equiv) was slowly added to DMF
(50 mL) at 0 °C, and the resultant solution was stirred for 30 min.
Amines 43a-c (∼15 g, 1.0 equiv) was dissolved in 30 mL of
DMF and added to the solution. The reaction mixture was
heated at 120 °C for 60 min. The solution was cooled to room
temperature, and 10 N NaOH was added until the pH reached
10. The solution was mixed with water, and the resultant solids
were boiled in hot water, filtered, and dried under vacuum to
provide the desired 44a-c as yellow solids in 66-96% yield.
30-[3-(Dimethylamino)propyl]-10,50,60,70-tetrahydrospiro[[1,3]-
dithiolane-2,40-indole]-20-carbaldehyde (44a). Yield: 97%. 1H
NMR (CDCl3): δ 9.55 (s, 1 H), 3.45-3.53 (m, 2 H), 3.35-3.43
(m, 2 H), 3.00-3.05 (m, 2 H), 2.61 (t, J = 6.2 Hz, 2 H), 2.37 (t,
J = 7.3 Hz, 2 H), 2.27-2.32 (m, 2 H), 2.24 (s, 6 H), 1.91-2.00
(m, 4 H). ESI-MS: m/z 325.0 (M þ H)þ.
(Z)-Ethyl 3-{2-[(5-Fluoro-2-oxoindolin-3-ylidene)methyl]-4-oxo-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoate (12b). Yield: 89%.
1H NMR (CDCl3): δ 13.49 (s, 1 H, NH), 7.73 (s, 1 H, NH), 7.59
(s, 1 H), 7.30 (dd, J = 8.5, 2.2 Hz, 1 H), 6.89 (dt, J = 2.3, 9.0 Hz,
1 H), 6.81 (dd, J = 8.4, 4.2 Hz, 1 H), 4.07 (q, J = 7.1 Hz, 2 H), 3.27
(t, J = 7.0 Hz, 2 H), 2.92 (t, J = 6.2 Hz, 2 H), 2.74 (t, J = 7.1 Hz,
2 H), 2.52 (t, J = 6.2 Hz, 2 H), 2.14-2.21 (m, 2 H), 1.19 (t, J = 7.1
Hz, 3 H). ESI-MS: m/z 397.0 (M þ H)þ.
(Z)-3-{4-Oxo-2-[(2-oxoindolin-3-ylidene)methyl]-4,5,6,7-tetra-
hydro-1H-indol-3-yl}propanoic Acid (13a). Yield: 72%. 1H NMR
(DMSO-d6):δ13.76 (s, 1 H), 11.01 (s, 1 H), 7.76-7.78 (m, 2 H), 7.17
(t, J = 7.5 Hz, 1 H), 7.01 (t, J = 7.5 Hz, 1 H), 6.90 (d, J = 7.7 Hz,
1 H), 3.15 (t, J = 7.4 Hz, 2 H), 2.91 (t, J = 6.0 Hz, 2 H), 2.38-2.43
(m, 2 H), 2.20-2.09 (m, 2 H).29 ESI-MS: m/z 351.0 (M þ H)þ.
(Z)-3-{2-[(5-Fluoro-2-oxoindolin-3-ylidene)methyl]-4-oxo-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (13b). Yield:
30-[3-(Diethylamino)propyl]-10,50,60,70-tetrahydrospiro[[1,3]-
1
dithiolane-2,40-indole]-20-carbaldehyde (44b). Yield: 92%. H
NMR (CDCl3): δ 9.57 (s, 1 H), 9.07 (s, 1 H), 3.46-3.54 (m,
2 H), 3.37-3.45 (m, 2 H), 2.98-3.05 (m, 2 H), 2.56-2.70 (m,
8 H), 2.27-2.34 (m, 2 H), 1.93-2.03 (m, 4 H), 1.09 (t, J = 7.1
Hz, 6 H). ESI-MS: m/z 353.0 (M þ H)þ.
1
79%. H NMR (DMSO-d6): δ 13.79 (s, 1 H), 11.01 (s, 1 H),
7.83 (s, 1 H), 7.75 (dd, J = 9.2, 2.4 Hz, 1 H), 6.97 (dt, J = 9.4, 2.5
Hz, 1 H), 6.86 (dd, J = 8.4, 4.4 Hz, 1 H), 3.17 (t, J = 7.5 Hz, 2 H),
2.91 (t, J = 6.0 Hz, 2 H), 2.38-2.44 (m, 2 H), 2.02-2.09 (m, 2 H).
ESI-MS: m/z 369.0 (M þ H)þ.
30-[3-(Pyrrolidin-1-yl)propyl]-10,50,60,70-tetrahydrospiro[[1,3]-
dithiolane-2,40-indole]-20-carbaldehyde (44c). Yield: 71%. 1H
NMR (CDCl3): δ 9.54 (s, 1 H), 3.44-3.51 (m, 2 H), 3.34-
3.42 (m, 2 H), 3.01-3.07 (m, 2 H), 2.61 (t, J = 6.3 Hz, 2 H),
2.48-2.55 (m, 6 H), 2.27-2.31 (m, 2 H), 1.91-2.03 (m, 4 H),
1.72-1.80 (m, 4 H). ESI-MS: m/z 351.0 (M þ H)þ.
(Z)-3-{2-[(5-Fluoro-2-oxoindolin-3-ylidene)methyl]-6,6-dimethyl-
4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (13c). Yield:
84%. 1H NMR (CDCl3): δ 13.78 (s, 1 H), 11.01 (s, 1 H), 7.81 (s,
1 H), 7.74 (dd, J = 9.2, 2.4 Hz, 1 H), 6.97 (dt, J = 9.4, 2.5 Hz, 1 H),
6.86 (dd, J = 8.4, 4.5 Hz, 1 H), 3.17 (t, J = 7.5 Hz, 2 H), 2.81 (s,
2 H), 2.31 (s, 2 H), 1.04 (s, 6 H). ESI-MS: m/z 397.0 (M þ H)þ.
(Z)-3-{2-[(5-Fluoro-2-oxoindolin-3-ylidene)methyl]-4-oxo-
1,4,5,6,7,8-hexahydrocyclohepta[b]pyrrol-3-yl}propanoic Acid (13d).
Yield: 76%. 1H NMR (DMSO-d6): δ 13.86 (s, 1 H), 10.99 (s, 1 H),
7.81 (s, 1 H), 7.73 (dd, J = 9.2, 2.4 Hz, 1 H), 6.97 (dt, J = 9.4, 2.4
Hz, 1 H), 6.86 (dd, J = 8.4, 4.5 Hz, 1 H), 3.17 (t, J = 7.6 Hz, 2 H),
2.99-3.05 (m, 2 H), 2.59-2.65 (m, 2 H), 2.44 (t, J = 7.6 Hz, 2 H),
1.74-1.90 (m, 4 H). ESI-MS: m/z 383.0 (M þ H)þ.
General Procedure for the Synthesis of the 2-Formylpyrroles
45a-c. Compounds 44a-c (1.0 equiv) in a solution of 80%
CH3CN and 20% H2O were mixed with HgCl2 (2.2 equiv) and
CaCO3 (2.2 equiv). The reaction mixture was heated at reflux for
12 h. The solution was filtered through Celite, and the cake was
washed with CH2Cl2. The filtrate was washed with aqueous
NH4Cl solution (5.0 M), water, and brine. The organic layer was
dried over Na2SO4 and concentrated under reduced pressure to
provide the desired 45a-c as solids in 66-93% yield.
3-[3-(Dimethylamino)propyl]-4-oxo-4,5,6,7-tetrahydro-1H-in-
dole-2-carbaldehyde (45a). Yield: 66%. 1H NMR (CDCl3): δ
9.84 (s, 1 H), 3.08-3.14 (m, 2 H), 2.80-2.86 (m, 2 H), 2.48-2.52
(m, 2 H), 2.24-2.34 (m, 4 H), 2.20 (s, 6 H), 1.78-1.85 (m, 2 H).
ESI-MS: m/z 249.0 (M þ H)þ.
(Z)-3-{4-Acetyl-2-[(5-fluoro-2-oxoindolin-3-ylidene)methyl]-
5-methyl-1H-pyrrol-3-yl}propanoic Acid (14). Yield: 58%. 1H
NMR (DMSO-d6): δ 13.92 (s, 1 H), 10.99 (s, 1 H), 7.80 (s, 1
H), 7.74 (d, J = 9.2, 2.3 Hz, 1 H), 6.97 (dt, J = 9.3, 2.5 Hz, 1 H),
6.87 (dd, J = 8.4, 4.5 Hz, 1 H), 3.20 (t, J = 7.5 Hz, 2 H), 2.61 (s, 3
H), 2.41-2.47 (m, 5 H). ESI-MS: m/z 357.0 (M þ H)þ.
3-[3-(Diethylamino)propyl]-4-oxo-4,5,6,7-tetrahydro-1H-indole-
2-carbaldehyde (45b). Yield: 93%. 1H NMR (CDCl3): δ 9.82 (s, 1
H), 3.06-3.12 (m, 2 H), 2.84-2.88 (m, 2 H), 2.68-2.74 (m, 2 H),
2.40-2.66 (m, 6 H), 2.16-2.22 (m, 2 H), 1.77-1.83 (m, 2 H), 1.02
(t, J = 7.1 Hz, 6 H). ESI-MS: m/z 277.0 (M þ H)þ.
(Z)-3-{2-[(5-Bromo-2-oxoindolin-3-ylidene)methyl]-4-oxo-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (15). Yield:
1
71%. H NMR (DMSO-d6): δ 13.74 (s, 1 H), 11.12 (s, 1 H),

5938 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16
Chiang et al.
8.08 (d, J = 1.7 Hz, 1 H), 7.88 (s, 1 H), 7.31 (dd, J = 8.2, 1.7
Hz, 1 H), 6.84 (d, J = 8.3 Hz, 1 H), 3.19 (t, J = 7.5 Hz, 2 H),
2.92 (t, J = 6.0 Hz, 2 H), 2.38-2.44 (m, 2 H), 1.99-2.11 (m, 2
H). ESI-MS: m/z 429.0 (M þ H)þ.
(s, 1 H), 7.40 (dd, J = 8.2, 1.7 Hz, 1 H), 7.19-7.26 (m, 2 H), 7.14
(t, J = 8.8 Hz, 2 H), 7.01 (d, J = 8.2 Hz, 1 H), 4.63 (s, 2 H), 3.21
(t, J = 6.0 Hz, 2 H), 2.94 (t, J = 6.0 Hz, 2 H), 2.51-2.56 (m, 2 H),
2.39-2.46 (m, 2 H), 2.02-2.12 (m, 2 H). ESI-MS: m/z 523.0
(M þ H)þ.
(Z)-3-{2-[(5-Nitro-2-oxoindolin-3-ylidene)methyl]-4-oxo-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (16). Yield:
(Z)-3-{4-Oxo-2-[(2-oxo-5-sulfamoylindolin-3-ylidene)methyl]-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (25). Yield:
1
73%. H NMR (DMSO-d6): δ 13.52 (s, 1 H), 12.07 (brs, 1 H),
1
75%. H NMR (DMSO-d6): δ 13.67 (s, 1 H), 11.36 (brs, 1 H),
11.57 (s, 1 H), 8.73 (d, J = 2.3 Hz, 1 H), 8.04 (dd, J = 8.6, 2.3 Hz,
1 H), 8.02 (s, 1 H), 7.00 (d, J = 8.6 Hz, 1 H), 3.18 (t, J = 7.6 Hz,
2 H), 2.89 (t, J = 6.1 Hz, 2 H), 2.36-2.41 (m, 2 H), 1.98-2.09 (m,
2 H). ESI-MS: m/z 396.0 (M þ H)þ.
8.21 (d, J = 1.4 Hz, 1 H), 7.86 (s, 1 H), 7.65 (dd, J = 8.1, 1.5 Hz,
1 H), 7.21 (s, 2 H), 7.02 (d, J = 8.2 Hz, 1 H), 3.16 (t, J = 7.4 Hz,
2 H), 2.91 (t, J = 6.0 Hz, 2 H), 2.52-2.55 (m, 2 H), 2.37-2.43 (m,
2 H), 2.00-2.09 (m, 2 H). ESI-MS: m/z 430.0 (M þ H)þ.
(Z)-3-(2-{[5-(N-Methylsulfamoyl)-2-oxoindolin-3-ylidene]-
methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(26). Yield: 86%. 1H NMR (DMSO-d6): δ 13.71 (s, 1 H), 12.08
(brs, 1 H), 11.42 (s, 1 H), 8.20 (d, J = 1.4 Hz, 1 H), 7.94 (s, 1 H),
7.60 (dd, J = 8.2, 1.7 Hz, 1 H), 7.25 (q, J = 5.0 Hz, 1 H), 7.07 (d,
J = 8.2 Hz, 1 H), 3.19 (t, J = 7.5 Hz, 2 H), 2.93 (t, J = 6.1 Hz,
2 H), 2.51-2.56 (m, 2 H), 2.40-2.44 (d, J = 5.0 Hz, 5 H),
2.02-2.10 (m, 2 H). ESI-MS: m/z 444.0 (M þ H)þ.
(Z)-3-(2-{[5-(4-Hydroxy-3-methoxyphenyl)-2-oxoindolin-3-
ylidene]methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic
1
Acid (17). Yield: 72%. H NMR (DMSO-d6): δ 13.73 (s, 1 H),
11.01 (s, 1 H), 8.08 (s, 1 H), 8.02 (s, 1 H), 7.38 (d, J = 8.0 Hz, 1 H),
7.23 (s, 1 H), 7.21 (s, 1 H), 7.09 (dd, J = 9.0, 1.5 Hz, 1 H), 6.91 (d,
J = 8.8 Hz, 1 H), 6.84 (d, J = 8.2 Hz, 1 H), 3.86 (s, 3 H), 3.13 (t,
J = 7.2 Hz, 2 H), 2.89 (t, J = 6.0 Hz, 2 H), 2.35-2.42 (m, 2 H),
2.13-2.23 (m, 2 H), 2.00-2.08 (m, 2 H). ESI-MS: m/z 473.0
(M þ H)þ.
(Z)-3-(2-{[5-(3,4-Dimethoxyphenyl)-2-oxoindolin-3-ylidene]-
methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(18). Yield: 77%. 1H NMR (DMSO-d6): δ 13.70 (s, 1 H), 11.03
(s, 1 H), 7.93-8.10 (m, 2 H), 7.40 (d, J = 7.4 Hz, 1 H), 7.25 (s,
1 H), 7.21 (d, J = 7.0 Hz, 1 H), 7.00 (d, J = 7.4 Hz, 1 H), 6.92 (d,
J = 7.3 Hz, 1 H), 3.85 (s, 3 H), 3.78 (s, 3 H), 3.10-3.19 (m, 2 H),
2.84-2.95 (m, 2 H), 2.32-2.43 (m, 2 H), 2.20-2.32 (m, 2 H),
1.91-2.11 (m, 2 H). ESI-MS: m/z 487.0 (M þ H)þ.
(Z)-3-(2-{[5-(N,N-Dimethylsulfamoyl)-2-oxoindolin-3-ylidene]-
methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(27). Yield: 87%. 1H NMR (DMSO-d6): δ 13.73 (s, 1 H),
12.04 (s, 1 H), 11.45 (s, 1 H), 8.21 (s, 1 H), 8.02 (s, 1 H), 7.55
(d, J = 8.2 Hz, 1 H), 7.10 (d, J = 8.2 Hz, 1 H), 3.22 (t, J = 7.3
Hz, 2 H), 2.93 (t, J = 6.0 Hz, 2 H), 2.62 (s, 6 H), 2.52-2.56 (m,
2 H), 2.42 (t, J = 7.3 Hz, 2 H), 2.02-2.11 (m, 2 H). ESI-MS: m/z
458.0 (M þ H)þ.
(Z)-3-(4-Oxo-2-{[2-oxo-5-(pyrrolidin-1-ylsulfonyl)indolin-3-
ylidene]methyl}-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(28). Yield: 61%. 1H NMR (DMSO-d6): δ 13.73 (s, 1 H), 11.44 (s,
1 H), 8.26 (d, J = 1.5 Hz, 1 H), 8.03 (s, 1 H), 7.61 (d, J = 9.8 Hz,
1 H), 7.08 (d, J = 8.2 Hz, 1 H), 3.22 (t, J = 7.4 Hz, 2 H), 3.13-
3.18(m, 4 H), 2.93(t, J = 6.1Hz, 2 H), 2.51-2.55 (m, 2 H), 2.38-
2.45 (m, 2 H), 1.99-2.10 (m, 2 H), 1.62-1.68 (m, 4 H). ESI-MS:
m/z 484.0 (M þ H)þ.
(Z)-3-{2-[(5-Acetamido-2-oxoindolin-3-ylidene)methyl]-4-oxo-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (19). Yield:
1
56%. H NMR (DMSO-d6): δ 13.79 (s, 1 H), 12.08 (s, 1 H),
10.94 (s, 1 H), 9.84 (s, 1 H), 7.77 (d, J = 1.7 Hz, 1 H), 7.60 (s,
1 H), 7.39 (dd, J = 8.3, 1.7 Hz, 1 H), 6.82 (d, J = 8.3 Hz, 1 H),
3.10 (t, J = 7.3 Hz, 2 H), 2.91 (t, J = 6.1 Hz, 2 H), 2.52-2.56
(m, 2 H), 2.37-2.44 (m, 2 H), 2.04-2.09 (m, 2 H), 2.02 (s, 3 H).
ESI-MS: m/z 408.0 (M þ H)þ.
(Z)-3-(4-Oxo-2-{[2-oxo-5-(piperidin-1-ylsulfonyl)indolin-3-
ylidene]methyl}-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(29). Yield: 89%. 1H NMR (DMSO-d6): δ 13.73 (s, 1 H), 11.45 (s,
1 H), 8.18 (s, 1 H), 8.01 (s, 1 H), 7.53 (d, J = 8.2 Hz, 1 H), 7.09 (d,
J = 8.2 Hz, 1 H), 3.22 (t, J = 7.4 Hz, 2 H), 2.85-2.95 (m, 6 H),
2.39-2.44 (m, 2 H), 2.02-2.10 (m, 2 H), 1.50-1.59 (m, 4 H),
1.31-1.39 (m, 2 H). ESI-MS: m/z 498.0 (M þ H)þ.
(Z)-3-{2-[(5-Benzamido-2-oxoindolin-3-ylidene)methyl]-4-oxo-
4,5,6,7-tetrahydro-1H-indol-3-yl}propanoic Acid (20). Yield:
1
70%. H NMR (DMSO-d6): δ 13.81 (s, 1 H), 12.09 (s, 1 H),
11.01 (s, 1 H), 10.20 (s, 1 H), 7.94-8.05 (m, 3 H), 7.67 (s, 1 H),
7.48-7.61 (m, 4 H), 6.89 (d, J = 8.3 Hz, 1 H), 3.12 (t, J = 7.4
Hz, 2 H), 2.92 (t, J = 6.0 Hz, 2 H), 2.38-2.45 (m, 2 H),
2.01-2.10 (m, 2 H). ESI-MS: m/z 470.0 (M þ H)þ.
(Z)-3-(2-{[5-(Morpholinosulfonyl)-2-oxoindolin-3-ylidene]-
methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(30). Yield: 72%. 1H NMR (DMSO-d6): δ 13.71 (s, 1 H), 11.49
(s, 1 H), 8.19 (d, J = 1.3 Hz, 1 H), 8.01 (s, 1 H), 7.54 (dd, J = 8.2,
1.5 Hz, 1 H), 7.11 (d, J = 8.2 Hz, 1 H), 3.59-3.69 (m, 4 H),
3.15-3.26 (m, 2 H), 2.93 (t, J = 6.0 Hz, 2 H), 2.86-2.90 (m, 4
H), 2.52-2.55 (m, 2 H), 2.38-2.44 (m, 2 H), 2.02-2.09 (m, 2 H).
ESI-MS: m/z 500.0 (M þ H)þ.
(Z)-3-(2-{[5-(Ethylsulfonyl)-2-oxoindolin-3-ylidene]methyl}-4-
oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid (21). Yield:
50%. 1H NMR (DMSO-d6): δ 13.69 (s, 1 H), 11.49 (s, 1 H), 8.35
(s, 1 H), 8.01 (s, 1 H), 7.67 (d, J = 8.2 Hz, 1 H), 7.10 (d, J = 8.2
Hz, 1 H), 3.19-3.30(m, 4 H), 2.93(t, J = 6.0 Hz, 2 H), 2.38-2.45
(m, 2 H), 2.01-2.10 (m, 2 H), 1.13 (t, J = 7.3 Hz, 3 H). ESI-MS:
m/z 443.0 (M þ H)þ.
(Z)-3-(2-{[5-(Allylsulfonyl)-2-oxoindolin-3-ylidene]methyl}-4-
oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid (22). Yield:
71%. 1H NMR (DMSO-d6): δ 13.67 (s, 1 H), 11.48 (s, 1 H), 8.32
(s, 1 H), 7.99 (s, 1 H), 7.63 (dd, J = 8.2, 1.6 Hz, 1 H), 7.08 (d, J =
8.2 Hz, 1 H), 5.67-5.77 (m, 1 H), 5.32 (d, J = 10.0 Hz, 1 H), 5.24
(d, J = 17.0 Hz, 1 H), 4.08 (d, J = 7.2 Hz, 2 H), 3.21 (t, J = 7.5
Hz, 2 H), 2.93 (t, J = 6.0 Hz, 2 H), 2.52-2.55 (m, 2 H), 2.38-2.45
(m, 2 H), 2.02-2.10 (m, 2 H). ESI-MS: m/z 455.0 (M þ H)þ.
(Z)-3-(2-{[5-(Benzylsulfonyl)-2-oxoindolin-3-ylidene]methyl}-
4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid (23). Yield:
44%. 1H NMR (DMSO-d6): δ 13.66 (s, 1 H), 11.49 (brs, 1 H), 8.18
(s, 1 H), 7.91 (s, 1 H), 7.43 (dd, J = 8.1, 1.8 Hz, 1 H), 7.27-7.30 (m,
3 H), 7.17-7.22 (m, 2 H), 7.00 (d, J = 8.1 Hz, 1 H), 4.61 (s, 2 H),
3.20 (t, J = 7.6 Hz, 2 H), 2.94 (t, J = 6.1 Hz, 2 H), 2.51-2.57 (m,
2 H), 2.39-2.45 (m, 2 H), 2.03-2.10 (m, 2 H). ESI-MS: m/z 505.0
(M þ H)þ.
(Z)-3-(2-{[5-(Indolin-1-ylsulfonyl)-2-oxoindolin-3-ylidene]-
methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(31). Yield: 85%. 1H NMR (DMSO-d6): δ 13.60 (s, 1 H), 12.13
(brs, 1 H), 11.42 (s, 1 H), 8.27 (d, J = 1.5 Hz, 1 H), 7.93 (s, 1 H),
7.53-7.60 (m, 2 H), 7.20 (t, J = 7.7 Hz, 1 H), 7.13 (d, J = 7.3
Hz, 1 H), 6.91-7.02 (m, 2 H), 3.92 (t, J = 8.3 Hz, 2 H), 3.24 (t,
J = 7.5 Hz, 2 H), 2.85-2.95 (m, 4 H), 2.51-2.54 (m, 2 H),
2.38-2.45 (m, 2 H), 2.00-2.10 (m, 2 H). ESI-MS: m/z 532.0
(M þ H)þ.
(Z)-3-(2-{[5-(Ethylsulfonamido)-2-oxoindolin-3-ylidene]methyl}-
4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid (32). Yield:
62%. 1H NMR (DMSO-d6): δ 13.79 (s, 1 H), 11.03 (s, 1 H), 9.44 (s,
1 H), 7.68 (s, 1 H), 7.55 (s, 1 H), 7.06 (d, J = 8.5 Hz, 1 H), 6.87 (d,
J = 8.5 Hz, 1 H), 3.00-3.16 (m, 4 H), 2.90-2.94 (m, 2 H),
2.38-2.46 (m, 2 H), 2.02-2.10 (m, 2 H), 1.46 (t, J = 7.2 Hz, 3 H).
ESI-MS: m/z 458.0 (M þ H)þ.
(Z)-3-(2-{[5-(4-Fluorobenzylsulfonyl)-2-oxoindolin-3-ylidene]-
methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid
(24). Yield: 77%. 1H NMR (DMSO-d6): δ 13.67 (s, 1 H),
12.11 (s, 1 H), 11.49 (s, 1 H), 8.22 (d, J = 1.4 Hz, 1 H), 7.94
(Z)-3-(4-Oxo-2-{[2-oxo-5-(phenylsulfonamido)indolin-3-ylidene]-
methyl}-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic Acid (33).
Yield: 47%. 1H NMR (DMSO-d6): δ 13.72 (s, 1 H), 10.93

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16 5939
(s, 1 H), 7.73 (d, J = 7.3 Hz, 2 H), 7.46-7.63 (m, 4 H), 7.38 (s,
1 H), 6.77 (d, J = 8.2 Hz, 1 H), 6.70 (d, J = 8.2 Hz, 1 H),
3.08-3.15 (m, 2 H), 2.85-2.94 (m, 2 H), 2.52-2.55 (m, 2 H),
2.35-2.42 (m, 2 H), 1.99-2.06 (m, 2 H). ESI-MS: m/z 506.0
(M þ H)þ.
CH2Cl2 (20 mL) and mixed with CDI (1.2 equiv). The reaction
mixture was stirred at room temperature for 3.0 h. To the
solution was added pyrrolidine, morpholine, or methylamine
(2.0 equiv), and the mixture was stirred at room temperature for
12 h. The solution was diluted with CH2Cl2 (200 mL) and
washed with 0.1 N HCl (50 mL), saturated Na2CO3 (50 mL),
and brine (50 mL). The organic layer was dried over anhydrous
MgSO4(s) and concentrated under reduced pressure to provide
the desired 37-40 as yellow solids in 66-98% yield.
(Z)-3-(4-Oxo-2-{[2-oxo-5-(phenylmethylsulfonamido)indolin-
3-ylidene]methyl}-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic
Acid (34). Yield: 56%. 1H NMR (DMSO-d6): δ 13.81 (s, 1 H),
12.11 (s, 1 H), 11.05 (s, 1 H), 9.55 (s, 1 H), 7.66 (s, 1 H), 7.50 (d,
J = 1.2 Hz, 1 H), 7.28-7.41 (m, 6 H), 7.04 (dd, J = 8.3, 1.6 Hz,
1 H), 6.88 (d, J = 8.3 Hz, 1 H), 4.41 (s, 2 H), 3.15 (t, J = 7.4 Hz,
2 H), 2.94 (t, J = 5.9 Hz, 2 H), 2.39-2.45 (m, 2 H), 2.05-2.11
(m, 2 H). ESI-MS: m/z 520.0 (M þ H)þ.
(Z)-N-[2-Oxo-3-({4-oxo-3-[3-oxo-3-(pyrrolidin-1-yl)propyl]-
4,5,6,7-tetrahydro-1H-indol-2-yl}methylene)indolin-5-yl]benzene-
sulfonamide (37). Yield: 66%. 1H NMR (DMSO-d6): δ 13.73 (s,
1 H), 10.96 (s, 1 H), 9.93 (s, 1 H), 7.73 (d, J = 7.3 Hz, 2 H), 7.50-
7.62 (m, 4 H), 7.42 (d, J = 1.5 Hz, 1 H), 6.70-6.77 (m, 2 H),
3.22-3.31 (m, 4 H), 3.13 (t, J = 7.4 Hz, 2 H), 2.90 (t, J = 6.0 Hz,
2 H), 2.39-2.43 (m, 2 H), 2.01-2.09 (m, 2 H), 1.78-1.85 (m,
2 H), 1.68-1.74 (m, 2 H). ESI-MS: m/z 559.0 (M þ H)þ.
(Z)-N-(3-{[3-(3-Morpholino-3-oxopropyl)-4-oxo-4,5,6,7-tetra-
hydro-1H-indol-2-yl]methylene}-2-oxoindolin-5-yl)benzenesulfona-
(Z)-3-(2-{[5-(Naphthalene-2-sulfonamido)-2-oxoindolin-3-
ylidene]methyl}-4-oxo-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoic
1
Acid (35). Yield: 77%. H NMR (DMSO-d6): δ 13.73 (s, 1 H),
12.09 (brs, 1 H), 10.94 (s, 1 H), 10.04 (s, 1 H), 8.37 (s, 1 H), 8.10 (d,
J = 8.7 Hz, 2 H), 8.00 (d, J = 8.1 Hz, 1 H), 7.79 (dd, J = 8.6, 1.4
Hz, 1 H), 7.54-7.71 (m, 3 H), 7.50 (d, J = 1.1 Hz, 1 H), 6.76 (dd,
J = 8.3, 1.5 Hz, 1 H), 6.68 (d, J = 8.3Hz, 1 H), 3.10 (t, J =7.3Hz,
2 H), 2.89 (t, J = 5.8 Hz, 2 H), 2.32-2.44 (m, 2 H), 1.95-2.08 (m,
2 H). ESI-MS: m/z 556.0 (M þ H)þ.
1
mide (38). Yield: 66%. H NMR (DMSO-d6): δ 13.75 (s, 1 H),
10.97 (s, 1 H), 9.93 (s, 1 H), 7.73 (d, J = 7.4 Hz, 2 H), 7.57-7.61
(m, 1 H), 7.51-7.56 (m, 3 H), 7.42 (s, 1 H), 6.71-6.79 (m, 2 H),
3.39-3.50 (m, 8 H), 3.14 (t, J = 7.4 Hz, 2 H), 2.91 (t, J = 5.8 Hz,
2 H), 2.58 (t, J = 7.4 Hz, 2 H), 2.38-2.44 (m, 2 H), 2.01-2.09 (m,
2 H). ESI-MS: m/z 575.0 (M þ H)þ.
(Z)-Ethyl 3-(4-Oxo-2-{[2-oxo-5-(phenylsulfonamido)indolin-
3-ylidene]methyl}-4,5,6,7-tetrahydro-1H-indol-3-yl)propanoate
(36). Yield: 80%. 1H NMR (DMSO-d6): δ 13.74 (s, 1 H), 10.98
(s, 1 H), 7.72 (d, J = 7.5 Hz, 2 H), 7.50-7.62 (m, 4 H), 7.45 (s,
1 H), 6.71-6.77 (m, 2 H), 3.99 (q, J = 7.1 Hz, 2 H), 3.15 (t, J =
7.1 Hz, 2 H), 2.90 (t, J = 6.0 Hz, 2 H), 2.62 (t, J = 7.2 Hz, 2 H),
2.38-2.43 (m, 2 H), 2.02-2.07 (m, 2 H), 1.09 (t, J = 7.1 Hz,
3 H). ESI-MS: m/z 534.0 (M þ H)þ.
(Z)-N-Methyl-3-(4-oxo-2-{[2-oxo-5-(phenylsulfonamido)-
indolin-3-ylidene]methyl}-4,5,6,7-tetrahydro-1H-indol-3-yl)-
propanamide (39). Yield: 69%. 1H NMR (DMSO-d6): δ 13.71
(s, 1 H), 10.96 (s, 1 H), 9.95 (s, 1 H), 7.69-7.73 (m, 3 H),
7.49-7.63 (m, 4 H), 7.45 (d, J = 1.4 Hz, 1 H), 6.70-6.77 (m,
2 H), 3.14 (t, J = 7.1 Hz, 2 H), 2.90 (t, J = 6.0 Hz, 2 H),
2.31-2.41 (m, 5 H), 2.02-2.08 (m, 2 H). ESI-MS: m/z 519.0
(M þ H)þ.
(Z)-N-[2-Oxo-3-({4-oxo-3-[3-(pyrrolidin-1-yl)propyl]-4,5,6,7-
tetrahydro-1H-indol-2-yl}methylene)indolin-5-yl]benzenesulfona-
mide (46). Yield: 45%. 1H NMR (DMSO-d6): δ 13.71 (s, 1 H),
10.96 (s, 1 H), 7.70 (d, J = 7.5 Hz, 2 H), 7.49-7.60 (m, 4 H), 7.37
(s, 1 H), 6.69-6.75 (m, 2 H), 2.97 (t, J = 6.8 Hz, 2 H), 2.91 (t, J =
6.0 Hz, 2 H), 2.33-2.43 (m, 6 H), 2.30 (t, J = 6.6 Hz, 2 H),
2.01-2.08 (m, 2 H), 1.63-1.74 (m, 6 H). ESI-MS: m/z 545.0
(M þ H)þ.
(Z)-5-(Indolin-1-ylsulfonyl)-3-{[3-(3-morpholino-3-oxopropyl)-
4-oxo-4,5,6,7-tetrahydro-1H-indol-2-yl]methylene}indolin-2-one
(40). Yield: 98%. 1H NMR (DMSO-d6): δ 13.63 (s, 1 H), 11.39
(s, 1 H), 8.27 (s, 1 H), 7.92 (s, 1 H), 7.59 (dd, J = 8.2, 1.4 Hz, 1 H),
7.53 (d, J = 8.1 Hz, 1 H), 7.19 (t, J = 7.8 Hz, 1 H), 7.13 (d, J =
7.3 Hz, 1 H), 6.99 (d, J = 8.1 Hz, 1 H), 6.94 (t, J = 7.5 Hz, 1 H),
3.94 (t, J = 8.4 Hz, 2 H), 3.38-3.50 (m, 8 H), 3.20-3.28 (m, 2
H), 2.85-2.96 (m, 4 H), 2.55-2.60 (m, 2 H), 2.40-2.44 (m, 2 H),
2.02-2.08 (m, 2 H). ESI-MS: m/z 601.0 (M þ H)þ.
(Z)-N-[3-({3-[3-(Dimethylamino)propyl]-4-oxo-4,5,6,7-tetra-
hydro-1H-indol-2-yl}methylene)-2-oxoindolin-5-yl]benzene-
sulfonamide (47). Yield: 96%. 1H NMR (DMSO-d6): δ 13.68
(s, 1 H), 10.95 (s, 1 H), 7.63-7.76 (m, 3 H), 7.48-7.60 (m,
4 H), 7.31 (s, 1 H), 6.80 (d, J = 8.3 Hz, 1 H), 6.73 (d, J = 8.3
Hz, 1 H), 2.87-2.97 (m, 4 H), 2.35-2.42 (m, 2 H), 1.99-2.13
(m, 10 H), 1.63-1.71 (m, 2 H). ESI-MS: m/z 519.0 (M þ H)þ.
(Z)-N-[3-({3-[3-(Diethylamino)propyl]-4-oxo-4,5,6,7-tetrahy-
dro-1H-indol-2-yl}methylene)-2-oxoindolin-5-yl]benzenesulfona-
mide (48). Yield: 78%. 1H NMR (DMSO-d6): δ 13.73 (s, 1 H),
10.96 (s, 1 H), 7.69 (d, J = 7.5 Hz, 2 H), 7.48-7.62 (m, 5 H), 7.38
(s, 1 H), 6.70-6.76 (m, 2 H), 2.89-2.94 (m, 4 H), 2.33-2.46 (m, 8
H), 1.99-2.09 (m, 2 H), 1.63-1.71 (m, 2 H), 0.92 (t, J = 7.1 Hz,
6 H). ESI-MS: m/z 547.0 (M þ H)þ.
Aurora Assays. Inhibition of kinase activity by the test com-
pound was measured by quantifying the amount of 33P incorpo-
rated into the substrate in the presence of a test compound.
Standard assay conditions utilized 1 ng of recombinant Aurora
A or Aurora B kinase (Upstate Biotechnology), 2 μg of peptide
substrate (tetra-LRRLSLG, synthesized by Genesis Biotech
Inc.), 10 μM ATP (for Aurora A) or 40 μM ATP (for Aurora
B), 0.2 μCi of [33P]ATP (specific activity of 3000 Ci/mmol,
PerkinElmer), 8 mM MOPS-NaOH (pH 7.0), and 1 mM EDTA
in a total volume of 25 μL. Reaction mixtures were incubated at
30 °C for 30 min and reactions stopped by addition of 3%
phosphoric acid; mixtures were harvested onto a 96-well GF/B
UniFilter (PerkinElmer) using a unifilter harvester (PerkinElmer)
and counted with a TopCount microplate scintillation counter
(PerkinElmer). The IC50 values of inhibitors were determined
after assays were conducted at 3-fold serially diluted concentra-
tions of each compound in duplicate. The results were analyzed
using linear regression software (GraphPad Prism version 4,
GraphPad Software Inc., San Diego, CA).
(Z)-3-({3-[3-(Dimethylamino)propyl]-4-oxo-4,5,6,7-tetrahydro-
1H-indol-2-yl}methylene)-5-(indolin-1-ylsulfonyl)indolin-2-one (49).
Yield: 97%. 1H NMR (DMSO-d6): δ 13.55 (s, 1 H), 8.13 (s, 1 H),
7.92 (s, 1 H), 7.53-7.62 (m, 2 H), 7.19 (t, J = 7.7 Hz, 1 H), 7.14 (d,
J = 7.2 Hz, 1 H), 6.92-7.04 (m, 2 H), 3.91 (t, J = 8.3 Hz, 2 H),
3.02-3.06 (m, 2 H), 2.86-2.96 (m, 4 H), 2.38-2.43 (m, 2 H),
2.00-2.20 (m, 10 H), 1.65-1.70 (m, 2 H). ESI-MS: m/z 545.0
(M þ H)þ.
(Z)-3-({3-[3-(Diethylamino)propyl]-4-oxo-4,5,6,7-tetrahydro-
1H-indol-2-yl}methylene)-5-(indolin-1-ylsulfonyl)indolin-2-one
(50). Yield: 91%. 1H NMR (DMSO-d6): δ 13.63 (s, 1 H), 8.21
(s, 1 H), 7.87 (s, 1 H), 7.52-7.61 (m, 2 H), 7.10-7.23 (m, 2 H),
6.89-7.03 (m, 2 H), 3.85-3.97 (m, 2 H), 2.99-3.07 (m, 2 H),
2.83-2.96 (m, 4 H), 2.33-2.43 (m, 8 H), 2.01-2.10 (m, 2 H),
1.66-1.71 (m, 2 H), 0.94 (t, J = 7.1 Hz, 6 H). ESI-MS: m/z
573.0 (M þ H)þ.
Cell Proliferation Assay. The antiproliferative activity of the
compounds with respect to three human cancer cell lines (HCT-
116, HeLa, and HT-29) was measured using the CellTiter96 assay
kit (Promega) following the manufacturer’s instructions. In brief,
the cells were maintained in DMEM containing 10% FCS and
incubated at 37 °C in a 5% CO2 atmosphere. Cells were plated at
a density of 2000 cells/well on a 96-well plate for 24 h, then treated
with different concentrations of the compounds, and incubated
for an additional 72 h. At the end of the incubation, CellTiter 96
General Procedure for the Synthesis of Pyrrole-Indolin-2-ones
37-40. Compound 31 or 33 (∼1.0 g, 1.0 equiv) was suspended in

5940 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16
Chiang et al.
Aqueous One Solution Reagent (Promega) was added and
incubated for an additional 4.0 h. Cell viability was determined
by measuring the absorbance at 490 nm using an EMax micro-
plate reader (Molecular Devices). Data were processed and
analyzed using GraphPad Prism version 4.
Cell Cycle Analysis by Flow Cytometry (FACS). Drug-treated
HCT-116 cells were harvested by trypsinization, washed in PBS,
resuspended in ice-cold 70% ethanol, and stored at -20 °C
overnight. Cells were then washed twice with PBS, resuspended
in PBS containing 2 μg/mL RNase A and 5 μg/mL propidium
iodide, and stained for 30 min. DNA content was analyzed by
FACSan (Becton Dickinson) using CellQuest.
Western Blot Analysis. The effect of Aurora inhibitors on
cellular protein phosphorylation was evaluated by Western blot
analysis on G2/M synchronized cells. Cells were treated with
200 ng/mL nocodazole for 17 h and further treated with various
concentrations of the Aurora inhibitors for an additional 3.0 h.
Drug-treated cells were then harvested and washed twice with
PBS, and the cell pellets were boiled in 2ꢀ SDS sample buffer
and subjected to SDS-PAGE and immunoblotting analysis.
The rabbit antibodies against pT288 Aurora A (Cell Signaling),
Aurora A (Cell Signaling), pS10-H3 (Upstate), and histone H3
(Millipore), mouse antibody against β-actin (Chemicon), and
horseradish peroxidase-conjugated secondary antibodies (Cell
Signaling) were used.
(7) For the reviews of Aurora kinases as the target for anticancer
drugs, see: (a) Keen, N.; Taylor, S. Aurora-kinase inhibitors as
anticancer agents. Nat. Rev. Cancer 2004, 4, 927–936. (b) Andrews,
P. D. Aurora kinases: Shining lights on the therapeutic horizon.
Oncogene 2005, 24, 5005–5015. (c) Jackson, J. R.; Patrick, D. R.;
Dar, M. M.; Huang, P. S. Targeted anti-mitotic therapies: Can we
improve on tubulin agents? Nat. Rev. Cancer 2007, 7, 107–117.
(d) Giet, R.; Petretti, C.; Prigent, C. Aurora kinases, aneuploidy and
cancer, a coincidence or a real link. Trends Cell Biol. 2005, 15, 241–250.
(8) Gautschi, O.; Heighway, J.; Mack, P. C.; Purnell, P. R.; Lara, P. N.,
Jr.; Gandara, D. R. Aurora kinases as anticancer drug targets. Clin.
Cancer Res. 2008, 14, 1639–1648.
(9) Cheetham, G. M. T.; Charlton, P. A.; Golec, J. M. C.; Pollard, J. R.
Structural basis for potent inhibition of the Aurora kinases and a
T315I multi-drug resistant mutant form of Abl kinase by VX-680.
Cancer Lett. 2007, 251, 323–329.
(10) Harrington, E. A.; Bebbington, D.; Moore, J.; Rasmussen, R. K.;
Ajose-Adeogun, A. O.; Nakayama, T.; Graham, J. A.; Demur, C.;
Hercend, T.; Diu-Hercend, A.; Su, M.; Golec, J. M. C.; Miller,
K. M. VX-680, a potent and selective small-molecule inhibitor of
the Aurora kinases, suppresses tumor growth in vivo. Nat. Med.
2004, 10, 262–267.
(11) Fancelli, D.; Moll, J.; Varasi, M.; Bravo, R.; Artico, R.; Berta, D.;
Bindi, S.; Cameron, A.; Candiani, I.; Cappella, P.; Carpinelli, P.;
Croci, W.; Forte, B.; Giorgini, M. L.; Klapwijk, J.; Marsiglio, A.;
Pesenti, E.; Rocchetti, M.; Roletto, F.; Severino, D.; Soncini,
C.; Storici, P.; Tonani, R.; Zugnoni, P.; Vianello, P. 1,4,5,6-
Tetrahydropyrrolo[3,4-c]pyrazoles: Identification of a potent Aur-
ora kinase inhibitor with a favorable antitumor kinase inhibition
profile. J. Med. Chem. 2006, 49, 7247–7251.
(12) Carpinelli, P.; Ceruti, R.; Giorgini, M. L.; Cappella, P.; Gianellini,
L.; Croci, V.; Degrassi, A.; Texido, G.; Rocchetti, M.; Vianello, P.;
Rusconi, L.; Storici, P.; Zugnoni, P.; Arrigoni, C.; Soncini, C.; Alli,
C.; Patton, V.; Marsiglio, A.; Ballinari, D.; Pesenti, E.; Fancelli, D.;
Moll, J. PHA-739358, a potent inhibitor of Aurora kinases with a
selective target inhibition profile relevant to cancer. Mol. Cancer
Ther. 2007, 6, 3158–3168.
(13) Manfredi, M. G.; Ecsedy, J. A.; Meetze, K. A.; Balani, S. K.;
Burenkova, O.; Chen, W.; Galvin, K. M.; Hoar, K. M.; Huck, J. J.;
LeRoy, P. J.; Ray, E. T.; Sells, T. B.; Stringer, B.; Stroud, S. G.;
Vos, T. J.; Weatherhead, G. S.; Wysong, D. R.; Zhang, M.; Bolen,
J. B.; Claiborne, C. F. Antitumor activity of MLN8054, an orally
active small-molecule inhibitor of Aurora A kinase. Proc. Natl.
Acad. Sci. U.S.A. 2007, 104, 4106–4111.
(14) Mortlock, A. A.; Foote, K. M.; Heron, N. M.; Jung, F. H.;
Pasquet, G.; Lohmann, J.-J. M.; Warin, N.; Renaud, F.; De Savi,
C.; Roberts, N. J.; Johnson, T.; Dousson, C. B.; Hill, G. B.;
Perkins, D.; Hatter, G.; Wilkinson, R. W.; Wedge, S. R.; Heaton,
S. P.; Odedra, R.; Keen, N. J.; Crafter, C.; Brown, E.; Thompson,
K.; Brightwell, S.; Khatri, L.; Brady, M. C.; Kearney, S.; McKillop,
D.; Rhead, S.; Parry, T.; Green, S. Discovery, synthesis, and in vivo
activity of a new class of pyrazoloquinazolines as selective inhibi-
tors of Aurora B kinase. J. Med. Chem. 2007, 50, 2213–2224.
(15) Wilkinson, R. W.; Odedra, R.; Heaton, S. P.; Wedge, S. R.; Keen,
N. J.; Crafter, C.; Foster, J. R.; Brady, M. C.; Bigley, A.; Brown, E.;
Byth, K. F.; Barrass, N. C.; Mundt, K. E.; Foote, K. M.; Heron,
N. M.; Jung, F. H.; Mortlock, A. A.; Boyle, F. T.; Green, S.
AZD1152, a selective inhibitor of Aurora B kinase, inhibits human
tumor xenograft growth by inducing apoptosis. Clin. Cancer Res.
2007, 13, 3682–3688.
Computational Method. The three-dimensional structures of
Aurora A and Aurora B complexes with an inhibitor 1,4,5,6-
tetrahydropyrrolo[3,4-c]pyrazole bicycle and Hesperadin were
obtained from the Protein Data Bank (entries 2BMC and
2BFY, respectively).25,26 Hydrogen atoms were added, and water
molecules cocrystallized with the protein were removed from the
original structure using Accelrys Discovery Studio 2.5 (Accelrys,
Inc.). The modified crystal structures of Aurora A and Aurora B
were docked by a genetic algorithm-based program (GOLD)
using ASP scoring (CCDC Software Limited, Cambridge, U.K.).
The genetic algorithm was executed at the default settings, and
˚
the active site radius is 10 A from inhibitor complexes for the
docking study. Two hundred genetic algorithm (GA) runs were
performed for docking of compounds 33 and 47. GOLD was run
to save up to best docking solutions for each ligands. The results
were visually analyzed using PyMOL (http://www.pymol.org/).
Acknowledgment. We are grateful to the Ministry of Eco-
nomic Affairs of the Republic of China for financial support.
Supporting Information Available: Kinase profiling data of 36
and 47. This material is available free of charge via the Internet
at http://pubs.acs.org.
References
(16) Krug, M.; Hilgeroth, A. Recent advances in the development of
multi-kinase inhibitors. Mini Rev. Med. Chem. 2008, 8, 1312–1327.
(17) Godl, K.; Gruss, O. J.; Eickhoff, J.; Wissing, J.; Blencke, S.; Weber,
(1) Fu, J.; Bian, M.; Jiang, Q.; Zhang, C. Roles of Aurora kinases in
mitosis and tumorigenesis. Mol. Cancer Res. 2007, 5, 1–10.
(2) Carmena, M.; Earnshaw, W. C. The cellular geography of aurora
kinases. Nat. Rev. Mol. Cell Biol. 2003, 4, 842–854.
(3) Sen, S.; Zhou, H.; White, R. A. A putative serine/threonine kinase
encoding gene BTAK on chromosome 20q13 is amplified and
overexpressed in human breast cancer cell lines. Oncogene 1997,
14, 2195–2200.
ꢀ
M.; Degen, H.; Brehmer, D.; Orfi, L.; Horvath, Z.; Keri, G.;
Muller, S.; Cotten, M.; Ullrich, A.; Daub, H. Proteomic character-
ꢀ
€
ization of the angiogenesis inhibitor SU6668 reveals multiple
impacts on cellular kinase signaling. Cancer Res. 2005, 65, 6919–
6926.
(18) Hauf, S.; Cole, R. W.; LaTerra, S.; Zimmer, C.; Schnapp, G.;
Walter, R.; Heckel, A.; van Meel, J.; Rieder, C. L.; Peters, J.-M.
The small molecule Hesperadin reveals a role for Aurora B in
correcting kinetochore-microtubule attachment and in maintaining
the spindle assembly checkpoint. J. Cell Biol. 2003, 161, 281–294.
(19) Gribble, G. W. Knorr and Paal-Knorr pyrrole syntheses. In Name
Reaction in Heterocyclic Chemistry; Li, J.-J., Ed.; John Wiley & Sons,
Inc.: Hoboken, NJ, 2005; Chapter 2.2.
(20) (a) Smith, K. M.; Pandey, R. K. Cyclization of terminally sub-
stituted a,c-biladiene salts to give meso-substituted porphyrins.
J. Chem. Soc., Perkin Trans. 1 1987, 1229–1236. (b) Taber, D. F.;
Nakajima, K. Unsymmetrical ozonolysis of a Diels-Alder adduct:
Practical preparation of a key intermediate for heme total synthesis.
J. Org. Chem. 2001, 66, 2515–2517.
(4) Bischoff, J. R.; Anderson, L.; Zhu, Y.; Mossie, K.; Ng, L.; Souza,
B.; Schryver, B.; Flanagan, P.; Clairvoyant, F.; Ginther, C.; Chan,
C. S.; Novotny, M.; Slamon, D. J.; Plowman, G. D. A homologue
of Drosophila Aurora kinase is oncogenic and amplified in human
colorectal cancers. EMBO J. 1998, 17, 3052–3065.
(5) Katayama, H.; Ota, T.; Jisaki, F.; Ueda, Y.; Tanaka, T.; Odashi-
ma, S.; Suzuki, F.; Terada, Y.; Tatsuka, M. Mitotic kinase expres-
sion and colorectal cancer progression. J. Natl. Cancer Inst. 1999,
91, 1160–1162.
(6) Kamada, K.; Yamada, Y.; Hirao, T.; Fujimoto, H.; Takahama, Y.;
Ueno, M.; Takayama, T.; Naito, A.; Hirao, S.; Nakajima, Y.
Amplification/overexpression of Aurora-A in human gastric car-
cinoma: Potential role in differentiated type gastric carcinogenesis.
Oncol. Rep. 2004, 12, 593–599.

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 16 5941
ꢁ
(21) Remers, W. A.; Weiss, M. J. Synthesis of indoles from 4-oxo-
4,5,6,7-tetrahydroindoles. III. Introduction of substitutents by
electrophilic substitution. J. Org. Chem. 1971, 36, 1241–1247.
(22) For the preparation of 5-subsituted indolin-2-ones as the starting
materials to pyrrole-indolin-2-one 15-35, see: (a) Sun, L.; Tran,
N.; Tang, F.; App, H.; Hirth, P.; McMahon, G.; Tang, C. Synthesis
and biological evaluations of 3-substituted indolin-2-ones: A novel
class of tyrosine kinase inhibitors that exhibit selectivity toward
particular receptor tyrosine kinases. J. Med. Chem. 1998, 41, 2588–
2603. (b) Sun, L.; Tran, N.; Liang, C.; Tang, F.; Rice, A.; Schreck, R.;
Waltz, K.; Shawver, L. K.; McMahon, G.; Tang, C. Design, synthesis,
and evaluations of substituted 3-[(3- or 4-carboxyethylpyrrol-2-yl)methyl-
idenyl]indolin-2-ones as inhibitors of VEGF, FGF, and PDGF receptor
tyrosine kinases. J. Med. Chem. 1999, 42, 5120–5130. (c) Guan, H.;
Laird, A. D.; Blake, R. A.; Tang, C.; Liang, C. Design and synthesis of
aminopropyl tetrahydroindole-based indolin-2-ones as selective and
potent inhibitors of Src and Yes tyrosine kinase. Bioorg. Med. Chem.
Lett. 2004, 14, 187–190.
M. L.; Mantegani, S.; Marsiglio, A.; Meroni, M.; Moll, J.; Pittala,
V.; Roletto, F.; Severino, D.; Soncini, C.; Storici, P.; Tonani,
R.; Varasi, M.; Vulpetti, A.; Vianello, P. Potent and selec-
tive Aurora inhibitors identified by the expansion of a novel
scaffold for protein kinase inhibition. J. Med. Chem. 2005, 48,
3080–3084.
(27) Fabian, M. A.; Biggs, W. H., III; Treiber, D. K.; Atteridge, C. E.;
Azimioara, M. D.; Benedetti, M. G.; Carter, T. A.; Ciceri, P.;
Edeen, P. T.; Floyd, M.; Ford, J. M.; Galvin, M.; Gerlack, J. L.;
Grotzfeld, R. M.; Herrgard, S.; Insko, D. E.; Insko, M. A.; Lai,
A. G.; Lelias, J.-M.; Mehta, S. A.; Milanov, Z. V.; Velasco, A. M.;
Wodicka, L. M.; Patel, H. K.; Zarrinkar, P. P.; Lockhart, D. J. A
small molecule-kinase interaction map for clinical kinase inhibi-
tors. Nat. Biotechnol. 2005, 23, 329–336.
(28) Several publications also mention the interaction of Thr217 in
Aurora A with inhibitors. See: (a) Myrianthopoulos, V.; Magiatis,
P.; Ferandin, Y.; Skaltsounis, A.-L.; Meijer, L.; Mikros, E. An
integrated computational approach to the phenomenon of potent
and selective inhibition of Aurora kinases B and C by a series of
7-substituted indirubins. J. Med. Chem. 2007, 50, 4027–4037.
(b) Coumar, M. S.; Leou, J.-S.; Shukla, P.; Wu, J.-S.; Dixit, A. K.;
Lin, W.-H.; Chang, C.-Y.; Lien, T.-W.; Tan, U.-K.; Chen, C.-H.; Hsu, J.
T.-A.; Chao, Y.-S.; Wu, S.-Y.; Hsieh, H.-P. Structure-based drug design
of novel Aurora kinase A inhibitors: Structural basis for potency and
specificity. J. Med. Chem. 2009, 52, 1050–1062. (c) Aliagas-Martin, I.;
Burdick, D.; Corson, L.; Dotson, J.; Drummond, J.; Fields, C.; Huang,
O. W.; Hunsaker, T.; Kleinheinz, T.; Krueger, E.; Liang, J.; Moffat, J.;
Phillips, G.; Pulk, R.; Rawson, T. E.; Ultsch, M.; Walker, L.; Wiesmann,
C.; Zhang, B.; Zhu, B.-Y.; Cochran, A. G. A class of 2,4-bisanilinopyr-
imidine Aurora A inhibitors with unusually high selectivity against
Aurora B. J. Med. Chem. 2009, 52, 3300–3307.
(23) Crosio, C.; Fimia, G. M.; Loury, R.; Kimura, M.; Okano, Y.;
Zhou, H.; Sen, S.; Allis, C. D.; Sassone-Corsi, P. Mitotic phos-
phorylation of histone H3: Spatio-temporal regulation by mam-
malian Aurora kinases. Mol. Cell. Biol. 2002, 22, 874–885.
~
(24) Masaguer, C. F.; Casariego, I.; Ravina, E. Conformationally
restricted butyrophenones with mixed dopaminergic (D2) and sero-
toninergic (5-HT2A) affinities. Synthesis of 5-aminoethyl- and
6-aminomethyl-4-oxotetrahydroindoles as potent atypical anti-
psychotics. Chem. Pharm. Bull. 1999, 47, 621–632.
(25) Sessa, F.; Mapelli, M.; Ciferri, C.; Tarricone, C.; Areces, L. B.;
Schneider, T. R.; Stukenberg, P. T.; Musacchio, A. Mechanism of
Aurora B activation by INCENP and inhibition by Hesperadin.
Mol. Cell 2005, 18, 379–391.
(26) Fancelli, D.; Berta, D.; Bindi, S.; Cameron, A.; Cappella, P.;
(29) In some of the compounds, one CH2 peak was not reported for its
Carpinelli, P.; Catana, C.; Forte, B.; Giordano, P.; Giorgini,
overlapping with the DMSO peak at ∼2.50 ppm.