Rapid and efficient synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones and 2,2-Di(1H-indol-3-yl)-2H-acenaphthen-1-ones catalyzed by p-TSA

Article abstract of DOI:10.1080/00397911.2014.886330

An efficient synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones and 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones via a reaction of various isatins or acenaphthenequinone with indoles in the presence of p-methylbenzene sulfonic acid (p-TSA) in CH₂Cl₂ at room temperature is described. The advantages of this method include good reaction yield, simple workup procedure, and mild reaction condition. Copyright

Full text of DOI:10.1080/00397911.2014.886330

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Rapid and Efficient Synthesis of 3,3-
Di(1H-indol-3-yl)indolin-2-ones and 2,2-
Di(1H-indol-3-yl)-2H-acenaphthen-1-ones
Catalyzed by p-TSA
Jiangxia Yu a , Tianhua Shen a , Yan Lin a , Yongbing Zhou a &
Qingbao Song a
a College of Chemical Engineering and Material Science, Zhejiang
University of Technology , Hangzhou , China
Accepted author version posted online: 03 Apr 2014.Published
online: 09 Jun 2014.
To cite this article: Jiangxia Yu , Tianhua Shen , Yan Lin , Yongbing Zhou & Qingbao Song (2014)
Rapid and Efficient Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones and 2,2-Di(1H-indol-3-
yl)-2H-acenaphthen-1-ones Catalyzed by p-TSA, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 44:14, 2029-2036, DOI:
10.1080/00397911.2014.886330
To link to this article: http://dx.doi.org/10.1080/00397911.2014.886330
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Synthetic Communications1, 44: 2029–2036, 2014
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2014.886330
RAPID AND EFFICIENT SYNTHESIS OF
3,3-DI(1H-INDOL-3-YL)INDOLIN-2-ONES AND
2,2-DI(1H-INDOL-3-YL)-2H-ACENAPHTHEN-1-ONES
CATALYZED BY p-TSA
Jiangxia Yu, Tianhua Shen, Yan Lin, Yongbing Zhou, and
Qingbao Song
College of Chemical Engineering and Material Science, Zhejiang University
of Technology, Hangzhou, China
GRAPHICAL ABSTRACT
Abstract An efficient synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones and 2,2-di(1H-
indol-3-yl)-2H-acenaphthen-1-ones via a reaction of various isatins or acenaphthenequinone
with indoles in the presence of p-methylbenzene sulfonic acid (p-TSA) in CH2Cl2 at room
temperature is described. The advantages of this method include good reaction yield, simple
workup procedure, and mild reaction condition.
Keywords Acenaphthenequinone; 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones; 3,3-
di(1H-indol-3-yl)indolin-2-ones; indole; isatin; p-TSA
INTRODUCTION
Oxindole fragment widely exists in a variety of natural products.[1–4] Oxindoles
are known to show biological and pharmacological activities.[5–7] Particularly,
3,3-diaryloxindoles are found to possess pharmacological activities such as anti-
inflammatory, antiproliferative, antibacterial, and antiprotozoal activities.[8] The
various biological activities of oxindole derivatives have attracted the attention of
many synthetic chemists.[9,10] Therefore, considerable efforts have been made to syn-
thesize analogs of 3,3-di(indolyl)oxindole deravitivies, which were prepared by the
reaction of isatin and indoles using various catalysts. Typical catalytic approach
Received August 19, 2013.
Address correspondence to Qingbao Song, College of Chemical Engineering and Material Science,
Zhejiang University of Technology, Hangzhou, China. E-mail: qbsong@zjut.edu.cn
2029

2030
J. YU ET AL.
to construct this class of compounds involve 3-indolylation of isatins by ionic
liquids,[11,12] FeCl3,[13] TfOH,[9] ceric ammonium nitrate (CAN),[14] Bi(OTf)3,[15]
silica–sulfuric acid,[16] I2,[17,18] Cu(OTf)2,[19] KAl(SO4)2,[20,21] RuCl3 ꢀ H2O,[22]
b-cyclo-dextrin,[23] dodecylsulfonic acid,[24] aminocatalysis,[25] H6P2W18O62,[26] and
montmorillonite KSF.[27] However, there are some drawbacks such as toxicity,[17,18]
expensive catalysts,[15,19,22] complex purification procedures,[13] and so forth in some
of these reactions. Therefore, development of new benign protocols that use simple
operating conditions is of much importance.
Recently, para-toluenesulfonic acid (p-TSA) has received considerable
attention as an nontoxic, inexpensive, and readily available catalyst for various
organic reactions, affording the corresponding products with good selectivity and
in excellent yields.[28–30] Hence it is considered as a practical catalyst in a number
of reactions.
Considering these reports and as a part of our research program, which aims
to develop an efficient methodology for the preparation of 3,3-di(1H-indol-
3-yl)indolin-2-ones and 2,2-di-(1H-indol-3-yl)-2H-acenaphthen-1-ones, we investi-
gated a reaction of various isatins or acenaphthenequinone with indoles to afford
a series of oxindole derivatives catalyzed by p-TSA with excellent yields.
RESULTS AND DISCUSSION
In our initial research, we carried out the reaction of isatin 1a with indole 2a
catalyzed by various catalysts using different solvents (Scheme 1). The results are
listed in Table 1. When the reaction was catalyzed by L-proline, the product
could be achieved with poor yields (Table 1, entry 1). It was found that when the
reaction was carried out using catalysts such as NH4OAc, AcOH, and Cu(OAc)2,
we just got trace amounts of product (Table 1, entries 2–4). To improve reaction
yield, we also tried other catalysts such as Cu(OTf)2, Bi(OTf)3, and BF3 ꢀ Et2O,
and the product could be achieved with moderate yields (Table 1, entries 5–7).
However, when the reaction was catalyzed by p-TSA, the product could be isolated
with good yield (Table 1, entry 8). To further improve reaction yield, efforts were
made to optimize the reaction parameters including the loading of catalyst and
solvents (Table 1, entries 9–13). To our satisfaction, the reaction in the presence
of p-TSA (10 mol%) in CH2Cl2 at room temperature proceeded rapidly, which
afforded the desired product in 92% yield (Table 1, entry 10). The products were
characterized by elemental analysis, mass spectrometry (MS), 1H NMR, 13C
NMR, and infrared (IR) spectra.
Scheme 1. Model reaction.

SYNTHESIS OF DI-INDOLIN-2-ONES USING p-TSA
Table 1. Effect of catalyst and solvent on the synthesis of 3aa
2031
Entry
Solvent
Catalyst (mol %)
Temp (ꢁC)b
Time (min)
Yield (%)c
1
2
H2O
L-proline (20)
NH4OAc (20)
AcOH (20)
80
rt
600
600
600
600
120
25
64
Trace
Trace
Trace
73
CH2Cl2
CH2Cl2
CH3CN
CH2Cl2
CH2Cl2
CH2Cl2
EtOH
3
rt
Reflux
4
Cu(OAc)2 (20)
Cu(OTf)2 (20)
Bi(OTf)3 (20)
BF3 ꢀ Et2O (20)
p-TSA (20)
5
rt
6
rt
85
83
7
rt
Reflux
30
25
8
88
91
9
CH2Cl2
CH2Cl2
CH2Cl2
CH3CN
H2O
p-TSA (20)
p-TSA (10)
rt
rt
rt
rt
rt
15
20
10
11
12
13
92
85
p-TSA (5)
p-TSA (10)
p-TSA (10)
25
120
240
70
67
aReaction conditions: isatin 1a (1 mmol), indole 2a (2 mmol), solvent (5 mL).
br.t. ¼ room temperature.
cIsolated yields.
Encouraged by this initial result, we went on to apply this protocol to a wide
range of isatin and indole derivatives (Scheme 2). The results are summarized in
Table 2. As shown in Table 2, both the electron-donating and the electron-
withdrawing substitutions on the phenyl ring of isatins was effective for the reaction,
providing the products with good to excellent yields under the optimized conditions.
Though the approach presented here need longer reaction time in some cases, experi-
mental simplicity, low-cost and commercially available catalyst, and excellent yields
of products rendered this method competitive compared to existing procedures.
To further clarify the generality of this reaction, acenaphthenequinone with
indole derivatives were investigated under the same reaction conditions (Scheme 3).
The results are summarized in Table 3. It was seen that a variety of indoles were
effective for this reaction and afforded the corresponding products with good yields.
The proposed mechanism for the synthesis of 3,3-di(1H-indol-3-yl)indolin-2-
one 3a is described in Scheme 4. First, this reaction probably proceeds through
the electrophilic activation of carbonyl group of isatin 1a as well as addition of
indole 2a to the carbonyl group of isatin, which gives the intermediate 4. Subsequent
proton transformation and dehydration affords the intermediate 6, followed by the
addition of the second molecule of indole 2a to give the product 3a.
Scheme 2. Preparation of product 3a–3p.

2032
J. YU ET AL.
Table 2. Synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones derivativesa
Entry
Product
R1
R2
R3
R4
Time (min)
Yieldb (%)
1
2
3a
3b
3c
3d
3e
3f
H
5-F
H
H
H
H
H
H
20
50
35
150
25
90
120
20
15
20
10
15
50
45
15
20
92 (95c)
88 (82d)
85
3
7-CF3
6-Cl
H
H
H
4
H
H
H
82
5
5-OMe
5-NO2
5-Cl
H
H
H
90
6
H
H
H
84 (86c)
86 (88f)
93 (90e)
95
7
3g
3h
3i
H
H
H
8
5-CH3
5,7-(CH3)2
H
H
H
H
9
H
H
H
10
11
12
13
14
15
16
3j
H
H
OCH3
OCH3
H
87 (95d)
94
95 (91c)
89 (93d)
86
3k
3l
5-CH3
1-CH3
H
H
H
H
CH3
H
3m
3n
3o
3p
H
Cl
H
5-I
5-OCH3
5-CH3
CH3
H
H
H
CH3
OCH3
H
94
88 (89e)
H
aReaction conditions: isatin 1 (1 mmol), indole 2 (2 mmol), p-TSA (10 mol %), CH2Cl2 (5 mL), rt.
bIsolated yields.
c, d, e, fYields of reported literature.[26,13,16,27]
Scheme 3. Preparation of product 5a–5e.
Table 3. Synthesis of 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones derivativesa
Entry
Product
R1
R2
R3
Time (min)
Yieldb (%)
1
2
3
4
5
5a
5b
5c
5d
5e
H
H
H
H
H
Cl
80
110
150
60
89 (88c)
86
92 (90c)
90 (87c)
83 (86c)
H
H
OCH3
H
H
CH3
CH3
H
H
120
aReaction conditions: acenaphthenequinone 4 (1 mmol), indole 2 (2 mmol), p-TSA (10 mol %), CH2Cl2
(5 mL), rt.
bIsolated yields.
cYields of reported literature.[31]
CONCLUSION
In summary, we have reported a very simple and efficient method for
the synthesis of oxindole derivatives from the three-molecule reaction of isatins or
acenaphthenequinone with indoles catalyzed by p-TSA in CH2Cl2 at room

SYNTHESIS OF DI-INDOLIN-2-ONES USING p-TSA
2033
Scheme 4. Proposed mechanism for synthesis of oxindole 3a.
temperature. The products were obtained rapidly in excellent yields without further
purifications.
EXPERIMENTAL
All of the reagents were purchased from Aldrich and used without further
1
purifications. H NMR spectra and 13C NMR spectra were recorded on a Bruker
Advance III 500-MHz spectrometer and used dimethylsulfoxide (DMSO-d6;
1
500 MHz for H or 125 MHz for 13C, respectively) as solvent. Chemical shifts of
1H and 13C NMR spectra were expressed in d values (ppm) downfield from Tetra-
methylsilane (TMS). Mass spectra were carried out on a Varian 1200 instrument.
Microanalyses were taken on a Variox elemental analyzer. Infrared (IR) spectra were
obtained on a Tensor 27 spectrometer. Melting points were recorded on microscope
(SGW X-4) melting-point apparatus. The reaction was monitored by thin-layer
chromatography (TLC).
General Procedure for Preparation of 3,3-Di(1H-indol-3-yl)indolin-2-
one 3a
A mixture of the isatin 1a (1 mmol), indole 2a (2 mmol), p-TSA (10 mol%), and
CH2Cl2 (10 mL) was added to a 50-mL flask and stirred at room temperature until
the completion (monitored by TLC). Then the solid was filtered and washed with
CH2Cl2 (5 mL) and ethanol (5 mL) in turn, affording excellent yields of the product,
which was recrystallized from ethanol to produce pure crystalline products. The
1
products were identified by elemental analysis, MS, H NMR, 13C NMR, and IR
spectra.

2034
J. YU ET AL.
Spectroscopic and Characterization Data of 3a
3,3-Di(1H-indol-3-yl)indolin-2-one (3a). Yield: 92%; white solid; mp 318–
320 ꢁC (lit.[26] 312–314 ꢁC); IR (KBr, cmꢂ1): 3428, 3324, 1707, 1613, 1468, 1106,
1
932, 736; H NMR (500 MHz, DMSO-d6) d 10.96 (s, 2H, NH), 10.60 (s, 1H, NH),
7.36 (d, J ¼ 8.1 Hz, 2H), 7.24 (m, 4H), 7.01 (d, J ¼ 8.0 Hz, 3H), 6.93 (t, J ¼ 7.5 Hz,
1H), 6.86 (s, 2H), 6.80 (t, J ¼ 7.5 Hz, 2H); 13C NMR (125 MHz, DMSO-d6): d
178.7, 141.3, 136.9, 134.6, 127.8, 125.7, 124.9, 124.2, 121.4, 120.9, 120.7, 118.2,
114.3, 111.6, 109.5, 52.5; MS (EI, 70 ev): m=z 363 (Mþ, 91). Anal. calcd. for
C24H17N3O: C, 79.32; H, 4.72; N, 11.56. Found: C, 79.40; H, 4.70; N, 11.60%.
FUNDING
We gratefully acknowledge financial support from the Foundation of Natural
Science of Zhejiang Province (No. LY12B02016).
SUPPLEMENTAL MATERIAL
Full experimental details, elemental analysis, 1H NMR, 13C NMR, MS, and IR
spectra are available online. Supplemental data for this article can be accessed on the
publisher’s website.
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