Efficient synthesis of bis-indolyloxindoles from (phenylimino)indolin-2-ones and 1H-indole catalyzed by p-toluenesulfonic acid

Article abstract of DOI:10.1134/S1070363216050273

p-Toluenesulfonic acid (p-TSA) efficiently catalyzed the reaction of (phenylimino)indolin-2-ones with 1H-indole in dichloromethane at room temperature to afford 3,3-di(indolyl)indolin-2-ones in 2-3 min with high yields.

Full text of DOI:10.1134/S1070363216050273

ISSN 1070-3632, Russian Journal of General Chemistry, 2016, Vol. 86, No. 5, pp. 1144–1150. © Pleiades Publishing, Ltd., 2016.
Efficient Synthesis of Bis-indolyloxindoles
from (Phenylimino)indolin-2-ones and 1H-Indole Catalyzed
1
by p-Toluenesulfonic Acid
*
B. Suresh, G. Brahmeshwary, T. Swamy, I. Gopi, and V. Ravinder
Department of Chemistry, Kakatiya University, Warangal, 506009 India
*
e-mail: ravichemku@yahoo.co.in
Received November 19, 2015
Abstract—p-Toluenesulfonic acid (p-TSA) efficiently catalyzed the reaction of (phenylimino)indolin-2-ones
with 1H-indole in dichloromethane at room temperature to afford 3,3-di(indolyl)indolin-2-ones in 2-3 min with
high yields.
Keywords: 3,3-di(indolyl)indolin-2-ones, 1H-indole, (phenylimino)indolin-2-ones
DOI: 10.1134/S1070363216050273
INTRODUCTION
the use of p-TsOH in the synthesis of 3,3-di(indolyl)-
oxindoles from (phenylimino)indolin-2-ones.
Oxindole is a structural block of a variety of
pharmacologically and biologically active compounds
As a part of development of new synthetic methods
[13] we, herein, disclose our results on p-TsOH
[
1, 2]. 3,3-Diaryloxindoles exhibit mechanism-specific
catalyzed synthesis of 3,3-di(indolyl)oxindoles from
antibacterial, antiprotozoal, antiproliferative, and anti-
inflammatory activities [3]. These compounds have
also been used as laxatives [4] and lead compounds for
(
phenylimino)indolin-2-ones and 1H-indole.
RESULTS AND DISCUSSION
Ca C-depletion mediated inhibition of translation
2
initiation [5]. The parent compound, trisindoline, is a
natural product and has been isolated by Kabayshi and
co-workers [6]. Ru(III)-catalyzed synthesis of 3,3-di-
Initially, we have studied the reaction of 3-(phenyl-
imino)indolin-2-one (1a) with 1H-indole 2 in the
presence of 10 mol % of p-TsOH in CH Cl at room
2
2
(
indolyl)indolin-2-ones by the reaction of (phenyl-
temperature (Scheme 1). The reaction reached its
completion in 2–3 min and gave 3,3-di(1H-indol-3-yl)-
indolin-2-one (3a) (85%, see the table).
imino)indolin-2-ones and indoles was presented [7].
The use of mild acids is essential in developing
efficient methods of synthesis of 3,3-di(indolyl)oxindoles
from (phenylimino)indolin-2-ones and indoles. In some
protocols sulfonic acids have been used as catalysts
Encouraged by that result, we turned our attention
to various substituted 3-(phenylimino)indolin-2-ones.
-Methyl-3-(phenylimino)indolin-2-one (1b) reacted
smoothly with 2 to give the corresponding 3,3-di(1H-
indol-3-yl)-5-methylindolin-2-one (3b). The scope of
the reaction was exemplified with a disubstituted
compound, 5,7-dimethyl-3-(phenylimino)indolin-2-one
1c), to produce the desired product 3c. Thus, 1H-
indole was used as a representative starting material.
The reaction was performed with various substituted
phenylimino)indolin-2-ones such as 5-methoxy, 5-
fluoro, 5-chloro, 5-bromo, 6-bromo, 5-nitro derivatives
and gave the corresponding products with high yields
[8]. Some other methods have also been reported for
5
the synthesis of this class of compounds [9].
p-Toluenesulfonic acid (p-TsOH) has received
considerable attention as a nontoxic, inexpensive and
readily available catalyst for various organic reactions
that lead to the corresponding products with high
selectivity and excellent yields [10-12]. Therefore, p-
TsOH could be an effective Bronshed acid in activa-
tion of (phenylimino)indolin-2-ones and 1H-indole
under mild conditions. There have been no reports on
(
(
(
see the table). This method was further extended to N-
1
The text was submitted by the authors in English.
methyl, N-benzyl, and N-acetyl (phenylimino)indolin-
1
144

EFFICIENT SYNTHESIS OF BIS-INDOLYLOXINDOLES
1145
Scheme 1. Synthesis of 3,3-di(1H-indol-3-yl)indolin-2-one.
Ph
H
N
N
NH
p-TsOH (10 mol %)
O + 2
CH Cl , room temperature, 2−3 min
2
2
N
N
H
H
O
N
H
1
a
2
3a
Scheme 2. Proposed mechanism for the synthesis of 3a.
p-TsO
p-TsO
Ph
Ph
N
Ph
H
H
N
N
p-TsOH
O
O
N
O
H
N
N
H
H
N
H
1
a
1a1
2a
p-TsO
H
p-TsO
H
Ph
NH
Ph
N
H
H
N
N
H
O
O
N
N
H
H
H
p-TsO
H
H
p-TsO
NH
N
N
N
NH
p-TsOH
H
N
H
−
PhNH2
HN
O
O
O
N
N
H
H
2
a
3a
2
-ones that produced the desired products (see the
indolin-2-ones 1a to generate p-TsOH-(phenylimino)-
indolin-2-one carbenium ion (1a ), which subsequently
reacts with 2 equiv. of 1H-indole 2 to furnish the 3,3-di-
table).
1
Without catalysis by p-TsOH the reaction did not
(
1H-indol-3-yl)indolin-2-one (3a).
proceed even at reflux temperature. Lowering the
reaction temperature was detrimental to the efficiency
of this procedure. The mild reaction conditions
resulted in formation of no side products. All products
were characterized by H and C NMR and mass
spectrometry.
EXPERIMENTAL
All reagents were used without further purification
1
13
unless specified otherwise. Solvents were dried and
distilled by conventional methods. All air or moisture-
sensitive reactions were conducted under the
The reaction mechanism may be presented as follows
(
Scheme 2). Initially, p-TsOH activates (phenylimino)-
atmosphere of N or Ar in flame-dried or oven-dried
2
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 5 2016

1
146
SURESH et al.
a
p-TSA catalyzed synthesis of bis-indolyloxindoles from (phenylimino)indolin-2-ones and 1H-indole
b
Isatin-imine 1
Indole 2
Product 3
Yield, %
Ph
N
H
N
8
5
NH
NH
NH
N
H
O
O
O
N
H
O
N
H
Ph
N
H
8
0
N
N
H
N
H
O
O
N
H
Ph
N
H
8
1
N
N
H
N
H
N
H
Ph
H
82
N
N
MeO
NH
N
H
O
MeO
N
H
O
N
H
Ph
H
7
8
8
0
N
N
NH
F
N
H
O
F
N
H
O
N
H
H
Ph
N
N
NH
Cl
N
H
O
Cl
N
H
O
N
H
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 5 2016

EFFICIENT SYNTHESIS OF BIS-INDOLYLOXINDOLES
1147
Table 1. (Contd.)
Isatin-imine 1
b
Indole 2
Product 3
Yield, %
Ph
H
N
75
N
NH
Br
N
H
O
O
Br
N
H
O
N
H
Ph
H
72
N
N
NH
N
H
N
Br
H
O
Br
N
H
H
Ph
70
N
N
NH
N
H
O N
2
O
O N
2
N
H
O
N
H
Ph
H
7
8
N
N
NH
N
H
O
N
O
N
Ph
H
80
N
N
NH
N
H
O
N
O
Ph
N
Ph
Ph
H
7
2
N
N
NH
N
H
O
O
N
O
N
O
a
1
13
b
The reaction time was 2–3 min. All products were characterized by H and C NMR, IR, and mass spectroscopy. Yield of isolated product.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 5 2016

1
148
SURESH et al.
8.0 Hz), 7.35–7.00 m (2H), 6.85–6.81 m (6H), 2.30 m
glassware with magnetic stirring. IR spectra (KBr
discs) were recorded on a Bruker Vector 22 FT-IR
spectrophotometer. H and C NMR spectra were
1
3
(3H, –CH ), 2.16 m (3H, –CH ). C NMR spectrum,
3
3
1
13
δ, ppm: 179.3, 137.3, 137.1, 134.2, 130.1, 129.3,
125.5, 124.1, 122.5, 121.1, 120.7, 118.5, 118.2, 114.7,
111.6, 52.9, 20.8, 18.6. MS (ESI, MeOH): m/z 392
measured in DMSO-d (500 and 125 MHz) with TMS
6
as the internal standard on a Bruker AV 300 or 500 MHz
NMR spectrometers. Mass spectra were measured on a
Bruker Micro-TOF-Q mass spectrometer using elec-
trospray ionization (ESI) technique. Column chromato-
graphy was carried out using silica gel (60–120 or
+
[M + H] .
3
,3-Di(1H-indol-3-yl)-5-methoxylindolin-2-one
–1
(
3
3d). White solid, mp 288–290°C. IR spectrum, ν, cm :
1
364, 3048, 1689, 1487, 1148, 1015, 858, 742. H NMR
spectrum, δ, ppm: 10.95 s (2H, NH), 10.42 s (1H, NH),
.35 d (2H, J = 8.0 Hz), 7.22 d (2H, J = 8.1 Hz), 7.02–
7.02 m (2H), 6.92–6.90 m (1H), 6.88 s (2H), 6.84–6.81
1
00–200 mesh) packed in glass columns. Distilled
ethyl acetate and petroleum ether were used as eluents.
7
General synthesis of 3,3-di(1H-indol-3-yl)indolin-
-ones (3a–3l). To the mixture of (phenylimino)indolin-
-ones (1a) (1 mmol) and 1H-indole 2 (2 mmol) in
1
3
2
2
m (4H), 3.61 m (3H, OCH ). C NMR spectrum, δ,
3
ppm: 178.4, 154.5, 136.7, 135.9, 134.6, 125.3, 124.4,
anhydrous CH Cl (10 mL) was added p-TsOH
120.9, 120.6, 118.1, 114.2, 112.1, 112.1, 115.7, 109.9,
2
2
+
(
10 mol %) in a 50 mL flask and stirred at room
55.4, 53.2 (OCH ). MS (ESI, MeOH): m/z 394 [M + H] .
3
temperature for 2–3 min. Upon completion of the
process the reaction mixture was diluted, washed with
water (3 × 15 mL) and extracted with ethyl acetate.
The combined organic layers were concentrated to
afford the crude mixture which was purified by
hexane/AcOEt flash chromatography to give the pure
product 3a (0.30 g, 80%).
3
,3-Di(1H-indol-3-yl)-5-fluoroindolin-2-one (3e).
–1
White solid, mp 239–240°C. IR spectrum, ν, cm :
436, 3316, 1696, 1481, 1104, 861, 734. H NMR
spectrum, δ, ppm: 10.95 s (2H, NH), 10.62 s (1H, NH),
.34 d (2H, J = 8.1 Hz), 7.22 d (2H, J = 8.0 Hz), 7.05–
. 21 m (5H), 6.91 s (2H), 6.84 t (2H, J = 7.5 Hz). C
NMR spectrum, δ, ppm: 178.7, 157.9, 137.6, 136.8,
1
3
7
7
13
1
1
36.4, 125.6, 124.5, 121.2, 120.4, 118.2, 114.1, 113.4,
3
,3-Di(1H-indol-3-yl)indolin-2-one (3a). White
–
1
12.2, 111.6, 110.4, 53.0. MS (ESI, MeOH): m/z 382
solid, mp 317–319°C. IR spectrum, ν, cm : 3429,
+
1
[
M + H] .
3
326, 3040, p1709, 1613, 1471, 1106, 930, 736. H
NMR spectrum, δ, ppm: 10.82 s (2H, NH), 10.50 s
1H, NH), 7.43 d (2H, J = 8.1 Hz), 7.33–7.28 m (4H),
.01 m (3H, J = 8.0 Hz), 6.96 t (1H, J = 7.5 Hz), 6.71 s
2H), 6.80 t (2H, J = 7.5 Hz). C NMR spectrum, δ,
ppm: 178.7, 141.3, 136.9, 134.6, 127.8, 125.7, 124.9,
3
,3-Di(1H-indol-3-yl)-5-chloroindolin-2-one (3f).
–
1
(
7
(
White solid, mp 290–291°C. IR spectrum, ν, cm :
1
3440, 3362, 3037, 1699, 1476, 1105, 817, 736. H NMR
1
3
spectrum, δ, ppm: 10.35 s (1H, NH), 10.25 s (2H, NH),
7
7
.39 d (2H, J = 8.1 Hz), 7.31 d (1H, J = 8.3Hz), 7.19–
1
5
24.2, 121.4, 120.9, 120.7, 118.2, 114.3, 111.6, 109.5,
2.5. MS (ESI, MeOH): m/z 364 [M + H] .
.21 m (3H), 7.05–7.01 m (3H), 6.89 s (2H), 6.84 t
+
1
3
(
2H, J = 7.5 Hz). C NMR spectrum, δ, ppm: 178.3,
1
1
40.3, 136.9, 136.6, 127.8, 125.5, 125.4, 124.6, 124.4,
3
,3-Di(1H-indol-3-yl)-5-methylindolin-2-one (3b).
–
1
21.0, 120.5, 118.4, 113.5, 111.7, 111.1, 52.8. MS
White solid, mp 306–307°C. IR spectrum, ν, cm :
375 (NH), 3325 (NH), 3041, 1704, 1489, 1100, 809,
36. H NMR spectrum, δ, ppm: 10.93 s (2H, NH),
0.50 s (1H, NH), 7.35 d (2H, J = 8.1 Hz), 7.24 d (2H,
J = 7.9 Hz), 7.05–7.00 (4H, m), 6.90–6.88 m (1H),
.85 s (2H), 6.83–6.80 m (2H), 2.19 m (3H, –CH ). C
NMR spectrum, δ, ppm: 178.5, 138.6, 136.8, 134.5,
30.0, 128.2, 125.8, 125.5, 124.5, 121.0, 120.8, 118.0,
14.5, 111.2, 109.1, 52.7, 20.1 (–CH ). MS (ESI,
+
(
ESI, MeOH): m/z 398 [M + H] .
3
7
1
1
3
,3-Di(1H-indol-3-yl)-5-bromoindolin-2-one (3g).
–
1
White solid, mp 304–306°C. IR spectrum, ν, cm :
355 (NH), 3123 (NH), 3075, 1693, 1615, 1475, 745.
3
1
3
1
6
3
H NMR spectrum, δ, ppm:
2H, NH), 7.47 s (3H), 7.32 d (1H, J = 2 Hz), 7.26 d
2H, J = 8 Hz), 7.05 t (2H, J = 8 Hz), 6.99 d (1H, J =
10.14 s (1H, NH), 10.03 s
(
(
1
1
1
3
3
8 Hz), 6.91–6.87 m (2H), 6.86–6.82 m (2H). C NMR
spectrum, δ, ppm: 178.2, 140.7, 136.9, 130.6, 127.2,
+
MeOH): m/z 378 [M + H] .
1
25.3, 124.32, 121.0, 120.7, 120.4, 118.3, 113.5, 113.1,
3
,3-Di(1H-indol-3-yl)-5,7-dimethylindolin-2-one
+
–1
111.4, 111.5, 52.8. MS (ESI, MeOH): m/z 444 [M + H] .
(
3c). White solid, mp 296–297°C. IR spectrum, ν, cm :
457 (NH), 3337 (NH), 1680, 1456, 1101, 850, 742.
H NMR spectrum, δ, ppm: 10.92 s (2H, NH), 10.51 s
1H, NH), 7.35 d (2H, J = 8.2 Hz), 7.24 d (2H, J =
3
3,3-Di(1H-indol-3-yl)-6-bromoindolin-2-one (3h).
1
–1
White solid, mp 309–311°C. IR spectrum, ν, cm :
3405 (NH), 3110 (NH), 3030, 1710, 1608, 1452, 1115,
(
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 5 2016

EFFICIENT SYNTHESIS OF BIS-INDOLYLOXINDOLES
1149
1
7
1
44. H NMR spectrum, δ, ppm: 11.00 s (2H, NH);
108.46, 52.17, 23.05. MS (ESI, MeOH): m/z 406
[M + H] .
+
0.74 s (1H, NH), 7.36 d (2H, J = 8.0 Hz), 7.20 d (2H,
J = 8.0 Hz), 7.10–7.16 m (3H), 7.02 t (2H, J = 7.6 Hz),
1
3
6
.84 d (2H, J = 2.4 Hz), 6.81 t (2H, J = 7.6 Hz). C
CONCLUSIONS
NMR spectrum, δ, ppm: 178.4, 143.1, 136.7, 133.9,
1
1
26.8, 125.5, 124.4, 124.1, 121.0, 120.8, 120.2, 118.6,
Here is presented a simple and efficient method of
synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones from
(phenylimino)indolin-2-ones with p-TSA catalysis.
This method offers such advantages as low cost, short
reaction time, high yield, and mild reaction conditions.
13.7, 112.5, 111.8, 52.2. MS (ESI, MeOH): m/z 444
+
[
M + H] .
3
,3-Di(1H-indol-3-yl)-5-nitroindolin-2-one (3i).
–
1
Yellow solid, mp 281–282°C. IR spectrum, ν, cm :
366, 3112, 1710, 1697, 1626, 1470, 1335, 735 cm .
H NMR spectrum, δ, ppm: 11.33 s (1H, NH), 11.09 s
2H, NH), 8.25 d (1H, J = 8.7 Hz), 7.90 (1H, s), 7.39 d
2H, J = 8.1 Hz), 7.20–7.22 m (3H), 7.04 t (2H, J =
–
1
3
ACKNOWLEDGMENTS
1
(
(
7
The authors thankful to DST-SERB and UGC New
Delhi for financial assistance.
1
3
.8 Hz), 6.96 s (2H), 6.83 t (2H, J = 7.3 Hz). C NMR
REFERENCES
spectrum, δ, ppm: 179.0, 147.5, 142.5, 137.9, 136.1,
1
1
26.2, 125.6, 125.4, 122.1, 121.2, 119.4, 119.4, 113.6,
12.7, 110.2, 52.4. MS (ESI, MeOH): m/z 409 [M + H] .
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1
Poradosu, E., Gilon, C., and Levitzki, A., J. Med.
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White solid, mp 277–279°C. IR spectrum, ν, cm :
360 (NH), 3118 (NH), 3047, 2950, 1695, 1670, 1611,
472, 734. H NMR spectrum, δ, ppm: 10.17 s (2H,
NH), 7.56 d (2H, J = 8 Hz), 7.35–7.31 m (2H), 7.24 d
2H, J = 8 Hz), 7.12–7.15 m (1H), 7.05–7.00 m (3H),
.91 t (2H, J = 7.6 Hz), 6.83 t (2H, J = 7.4 Hz), 3.32 m
3Hs, N–CH3). C NMR spectrum, δ, ppm:
42.69, 136.95, 133.69, 127.88, 125.62, 124.55, 124.29,
3
1
1
(
6
(
1
1
5
(
d) Klumpp, D.A., Yeung, K.Y., Prakash, G.K., and
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noff, B.E., Org. Lett., 2000, vol. 2, p. 89. DOI: 10.1021/
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10.1002/jps.2600720330. (c) Marti, C. and Carreira, E.M.,
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1
3

176.95,
22.07, 120.91, 120.71, 118.26, 114.05, 111.55, 108.46,
2.17, 26.17 (NCH ). MS (ESI, MeOH): m/z 378
M + H] .
3
+
[
2
3,3-Di(1H-indol-3-yl)-1-benzylindolin-2-one (3k).
–
1
White solid, mp 198–200°C. IR spectrum, ν, cm :
410, 3120, 1702, 1472, 734. H NMR spectrum, δ,
ppm: 9.81 s (2H), 7.35–7.37 m (4H), 7.24–7.33 m
5H), 7.10–7.13 m (3H), 6.98–7.03 m (3H), 6.87 s
2H), 6.74 t (2H, J = 7.2 Hz), 5.01 s (2H, CH2).
NMR spectrum, δ, ppm: 177.93, 142.57, 137.78,
37.41, 134.63, 129.44, 128.75, 128.47, 128.37, 126.44,
25.65, 125.26, 125.10, 123.12, 121.94, 121.66, 119.18,
1
3
(
(
1
3
1
0.1002/ejoc.200300050.
C
3
4
5
. Popp, F.D., J. Heterocycl. Chem., 1984, vol. 21,
p. 1367. DOI: 10.1002/jhet.5570210523.
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Harbinski, F., Christ, W.J., Aktas, H., and Halperin, J.A.,
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jm0499716.
1
1
1
19.18, 119.18, 114.83, 112.54, 110.21, 53.12, 43.84.
MS (ESI, MeOH): m/z 454 [M + H] .
+
3
,3-Di(1H-indol-3-yl)-N-acetylindolin-2-one (3l).
–
1
White solid, mp 310–312°C. IR spectrum, ν, cm :
3
1
420 (NH), 3323 (NH), 3052, 1747, 1720, 1460, 1371,
349, 1299, 1267, 1245, 1170, 764, 750, 748. H NMR
6
. Kobayashi, M., Aoki, S., Gato, K., Matsunami, K.,
Kurosu, M., and Kitagawa, I., Chem. Pharm. Bull.,
1994, vol. 42, p. 2449. DOI: 10.1248/CPB.42.2449.
1
spectrum, δ, ppm: 11.05 s (2H, NH), 7.38–6.86 m
1
3
(
14H), 2.06 m (3H, CH ). C NMR spectrum, δ, ppm:
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