Synergistic-Catalysis-Enabled Reaction of 2-Indolymethanols with Oxonium Ylides for the Construction of 3-Indolyl-3-Alkoxy Oxindole Frameworks

Article abstract of DOI:10.1002/asia.201800620

A synergistic-catalysis-enabled reaction of 2-indolymethanols with oxonium ylides has been established that makes use of a three-component reaction between 3-diazooxindoles, alcohols, and 2-indolymethanols under the cooperative catalysis of a metal complex and a Br?nsted acid. This reaction has not only provided a new approach for the construction of 3-indolyl-3-alkoxy oxindole scaffolds by utilizing the C3-electrophilicity of an indole, but it is also the first example of a nucleophilic addition of a metal-associated ylide to 2-indolylmethanols. In addition, this reaction also includes a rarely reported trapping of onium ylides with aryl electrophiles.

Full text of DOI:10.1002/asia.201800620

CHEMISTRY
AN ASIAN JOURNAL
www.chemasianj.org
Accepted Article
Title: Synergistic Catalysis-Enabled Reaction of 2-Indolymethanols
with Oxonium Ylides: Construction of 3-Indolyl-3-Alkoxy Oxindole
Framework
Authors: Chun Ma, Jia-Yu Zhou, Yi-Zhu Zhang, Yin-Chun Jiao, Guang-
Jian Mei, and Feng Shi
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To be cited as: Chem. Asian J. 10.1002/asia.201800620
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Synergistic Catalysis-Enabled Reaction of 2-Indolymethanols
with Oxonium Ylides: Construction of 3-Indolyl-3-Alkoxy Oxindole
Framework
Chun Ma, Jia-Yu Zhou, Yi-Zhu Zhang, Yinchun Jiao, Guang-Jian Mei and Feng Shi*
Abstract:
A
synergistic catalysis-enabled reaction of 2-
In previous approaches for constructing 3-indolyl-3-alkoxy
oxindole scaffolds (Scheme 1a), indoles were used as
nucleophiles and isatins were employed as electrophiles, which
underwent an aldol reaction to generate 3-indolyl-3-hydroxy
oxindoles A.[7] Then, under acidic conditions, intermediate
products A could derive into 3-indolyl-3-ethoxy oxindoles by the
reactions with ethanol (eq. 1).[8] Alternatively, under basic
conditions, intermediate products A could transform into 3-
indolyl-3-methoxy oxindoles by methylation (eq. 2).[9]
indolymethanols with oxonium ylides has been established, which
makes use of the three-component reaction of 3-diazooxindoles,
alcohols and 2-indolymethanols under the cooperative catalysis of
metal complex and Brønsted acid. This reaction has not only
provided a new approach for constructing 3-indolyl-3-alkoxy oxindole
scaffolds by utilizing the indole C3-electrophilicity, but also realized a
nucleophilic addition of metal associated ylide to 2-indolylmethanols
for the first time. In addition, this reaction has also established a
rarely reported trapping of onium ylides with aryl electrophiles.
Introduction
Indole derivatives represent one of the most important class of
heterocyclic compounds, which played important roles in
pharmaceuticals, agriculture and material science.[1] Among
indole derivatives, 3-indolyl-3-alkoxy oxindole or 3-indolyl-3-
hydroxy oxindole constitutes the core structures of many natural
products and bioactive synthetic compounds (Figure 1).[2-3] For
instance, shewanellines A is an alkaloids from deep-sea
bacterium Shewanella piezotolerans with antitumor activity.[2]
Compound I shows cytotoxic activity to U937 cell line,[3] and
compound II is a lead compound of antimicrobial agents.[4] In
addition, this class of indole derivatives serve as versatile
reactants and building blocks in organic synthesis.[5-6] Therefore,
the construction of 3-indolyl-3-alkoxy oxindole framework has
drawn great attention from the chemistry community.
Scheme 1. Approaches for constructing 3-indolyl-3-alkoxy oxindole scaffolds
In spite of the established approaches, the methods for
constructing 3-indolyl-3-alkoxy oxindole scaffolds are still
very limited. In addition, there are still some challenges in
developing new methods for constructing such scaffolds.
The first one is to develop one-step multicomponent
Figure 1. Selected bioactive compounds containing 3-indolyl-3-alkoxy (or
hydroxyl) oxindole scaffolds
reaction because
a two-step process is needed in
previous approaches. The second one is to discover new
reaction mode with wide applicability because previous
approaches utilized the well-established C3-nucleophilicity
of indoles and the substrate scope was not broad. So, it
has become an urgent task to develop one-step
multicomponent reaction with new reaction mode and wide
applicability for the construction of 3-indolyl-3-alkoxy
oxindole frameworks, which requires specific design of the
reaction.
C. Ma, J.-Y. Zhou, Y.-Z. Zhang, Dr. G.-J. Mei and Prof. Dr. F. Shi
School of Chemistry and Materials Science
Jiangsu Normal University
Xuzhou, 221116, China
Fax: (+86) 516-83403165
E-mail: fshi@jsnu.edu.cn
Dr. Y. Jiao
School of Chemistry and Chemical Engineering
Hunan University of Science and Technology
Xiangtan, 411201, China
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201xxxxxx.
In order to fulfill this task, we considered whether 3-
indolyl-3-alkoxy oxindole frameworks could be constructed
by a new approach involving a multicomponent reaction of
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indole derivatives, isatin derivatives and alcohols (Scheme
1b). This approach would utilize the indole C3-
(BH).[19] In the presence of MLn, 3-diazooxindole would
transform into metal carbene species B, which would be
attacked by alcohol to form active oxonium ylide C or D.
Meanwhile, in the presence of BH, 2-indolymethanols would
transform into delocalized cation E via dehydration. Then, the
delocalized cation E would act as an aryl electrophile to trap the
oxonium ylide C or D, leading to the generation of 3-indolyl-3-
alkoxy oxindoles.
electrophilicity, which remains
a dark side of indole
chemistry[10] and requires to be exploited.
Indolylmethanols have proven to be versatile reactants for
constructing indole-related frameworks.[5-6,11-12] Recently, we
have discovered that the C3-position of 2-indolylmethanol
displays unusual electrophilicity because it can transform into a
delocalized cation via dehydration in the presence of a Brønsted
acid (BH), which is readily to be attacked by nucleophiles (Nu) at
the C3-position (Scheme 2).[13-14] However, the nucleophiles are
confined to arenes (such as 2-naphthol and indole)[14] and
carbonyls (such as pyrazol-5-one and enolizable anhydride),[13]
and the reactions between such nucleophiles and 2-
indolylmethanols are well-established (eq. 3).[13-14] In sharp
contrast, metal associated ylide has never been employed as
nucleophiles to react with 2-indolylmethanols, which remains to
be an unexplored research area (eq. 4).
Scheme 4. Design of the reaction between 2-indolymethanols and oxonium
ylides
Herein, we report the details of our designed reaction of 2-
indolymethanols with oxonium ylides, which was enabled by a
synergistic catalysis of metal complex and Brønsted acid. This
three-component reaction of 3-diazooxindoles, alcohols and 2-
indolymethanols provided an alternative method for constructing
3-indolyl-3-alkoxy oxindole scaffolds.
Scheme 2. Profile of 2-indolylmethanol-involved C3-substitutions
Among metal associated ylides, onium ylides bearing both
acidic protons and basic carbanions in vicinal proximity,
generated in situ from diazocompounds and anilines/alcohols,
have recently been recognized as active nucleophiles, which
can be trapped by electrophiles (Scheme 3).[15] So, elegant
achievements have been obtained in this research field by using
aldimines, carbonyls and activated alkenes as electrophiles (eq.
5).[15-16] However, on the contrary, the reactions between onium
ylides and aryl electrophiles are still underdeveloped (eq. 6),
which remains to be an unknown chemistry.
Results and Discussion
To testify the possibility of our design, the three-component
reaction of 2-indolymethanol 1a, 3-diazooxindole 2a and ethanol
3a was employed as a model reaction under the cooperative
catalysis of a metal complex and a Brønsted acid in chloroform
at 30 oC (Table 1). Initially, in the presence of an iridium complex
and racemic binaphthol-derived phosphoric acid (RPA), the
desired reaction indeed occurred to afford 3-indolyl-3-alkoxy
oxindole 4aaa albeit with a low yield of 28% (entry 1). Then, a
series of metal complexes were screened (see the Supporting
Information for details), which found that Rh2(OAc)4 was the best
metal catalyst (entry 2) because it could promote the reaction in
the highest yield of 45% (entry 2). Next, different solvents were
evaluated (entries 2-7), which revealed chloroform was still the
most suitable solvent in terms of the yield (entry 2 vs entries 3-7).
Subsequently, several Brønsted acids were screened (entries 8-
11), only diphenyl phosphoric acid (entry 8) and trifluoroacetic
acid (entry 10) could catalyze the reaction. Among them,
diphenyl phosphoric acid could deliver the reaction in the highest
yield of 53% (entry 8). Furthermore, slightly modulating the ratio
of the reagents led to a higher yield of 58% (entry 12). In order
to further improve the yield, other reaction parameters such as
additives, reaction temperature, reagents ratio and catalyst
loading were carefully modulated, however, no improvement
could be obtained (see the Supporting Information for details).
Scheme 3. Profile of reactions trapping onium ylides
In order to develop new approach for constructing 3-
indolyl-3-alkoxy oxindole scaffolds, and to explore the above
mentioned unknown chemistry, we designed a synergistic
catalysis-enabled reaction of 2-indolymethanols with oxonium
ylides based on the great advantages of cooperative
catalysis.[17-18] As illustrated in Scheme 4, the three-component
reaction of 3-diazooxindoles, alcohols and 2-indolymethanols
would construct 3-indolyl-3-alkoxy oxindole scaffolds under the
synergistic catalysis of metal complex (MLn) and Brønsted acid
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This is because a byproduct 5 was always generated during the
condition optimization, which was formed via proton transfer of
oxonium ylide C. So, the optimal reaction conditions were finally
chosen as what entry 12 illustrated.
entry
4
R/Ar (1)
yield (%)[b]
1
2
4aaa
4baa
4caa
4daa
4eaa
4faa
4gaa
4haa
4iaa
H/Ph (1a)
4-Cl/Ph (1b)
5-Cl/Ph (1c)
58
47
40
3
Table 1. Optimization of reaction conditions[a]
4
5-MeO/Ph (1d)
6-Cl/Ph (1e)
46
42
56
40
51
40
48
5
6
6-Br/Ph (1f)
7
6-MeO/Ph (1g)
H/p-MeC6H4 (1h)
H/p-MeOC6H4 (1i)
6-Cl/p-FC6H4 (1j)
8
9
yield
entry
Metal complex
BH
solvent
(%)[b]
28
10
4jaa
1
2
[Ir(COE)2Cl]2
Rh2(OAc)4
RPA
RPA
CHCl3
CHCl3
[a] Unless indicated otherwise, the reaction was carried out in 0.1 mmol scale
in CHCl3 (2 mL) for 12 h, and the molar ratio of 1:2a:3a was 1:2:8.5. [b]
Isolated yield.
45
34
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
3
RPA
EtOAc
4
RPA
CH3CN
trace
trace
43
5
RPA
THF
Next, the substrate scope of 3-diazooxindoles 2 was studied
by the reactions with 2-indolylmethanol 1a and alcohol 2a (Table
3). Obviously, this reaction was amenable to a wide scope of 3-
diazooxindoles 2 bearing various R substituents at different
positions of the phenyl ring (entries 1-10), which generated
structurally diversified products 4 in moderate to good yields
(41% to 78%). Specifically, C5 or C6-substituted 3-
diazooxindoles 2b-2h could be applicable to the reaction (entries
1-7). In addition, disubstituted 3-diazooxindoles 2i-2k also
served as suitable substrates (entries 8-10). Among them, 6-
acetone
6
RPA
toluene
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
7
RPA
40
8
(PhO)2PO2H
TsOH
53
9
trace
46
10
11
12[c]
CF3COOH
CF3SO3H
trace
58
(PhO)2PO2H
chloro-substituted
3-diazooxindole
2f
delivered
the
[a] Unless otherwise indicated, the reaction was carried out at the 0.1 mmol
scale in a solvent for 12 h, the molar ratio of 1a:2a:3a was 1:1.5:8.5. [b]
Isolated yield of product 4aaa. [c]The molar ratio of 1a:2a:3a was 1:2:8.5. RPA
= racemic binaphthol-derived phosphoric acid.
corresponding product 4afa in the highest yield of 78% (entry 5).
Notably, N-Boc protected 3-diazooxindole 2l could be
successfully employed to the reaction in a considerable yield of
64% (entry 11), which demonstrated that the N-H group of 3-
diazooxindoles 2 was not a necessity for carrying out the desired
three-component reaction.
After establishing the optimal reaction conditions, we carried
out the investigation on the substrate scope of the reaction.
First, the generality of 2-indolylmethanols 1 was investigated. As
shown in Table 2, this three-component reaction was applicable
to a wide range of 2-indolylmethanols 1 bearing different R/Ar
groups, offering 3-indolyl-3-alkoxy oxindoles 4 in moderate
yields. In detail, C4 to C6-substituted 2-indolylmethanols 1b-1g
regardless of their electronic nature could smoothly participate in
the reaction (entries 2-7), while the position and the electronic
nature of the substituents seemed to have no evident effect on
the yield. In addition, several phenyls groups bearing either
electron-donating or electron-withdrawing substituents could
serve as suitable Ar groups of 2-indolylmethanols 1, which took
part in the three-component reaction with moderate yields
(entries 8-10).
Table 3. Substrate scope of 3-diazooxindoles 2[a]
entry
4
R/R1 (2)
yield (%)[b]
1
2
4aba
4aca
4ada
4aea
4afa
4aga
4aha
4aia
5-F/H (2b)
5-Cl/H (2c)
47
41
64
63
78
52
40
64
48
60
3
5-Br/H (2d)
5-NO2/H (2e)
6-Cl/H (2f)
4
5
Table 2. Substrate scope of 2-indolylmethanols 1[a]
6
6-Br/H (2g)
6-Me/H (2h)
4,6-F2/H (2i)
5,6-F2/H (2j)
5,7-Me2/H (2k)
7
8
9
4aja
10
4aka
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11
4ala
H/Boc (2l)
64
[a] Unless indicated otherwise, the reaction was carried out in 0.1 mmol scale
in CHCl3 (2 mL) for 12 h, and the molar ratio of 1a:2:3a was 1:2:8.5. [b]
Isolated yield.
Finally, the applicability of alcohols
3 in the three-
component reaction was investigated (Scheme 5). Apart from
ethanol 3a, this reaction could also be applicable to methanol 3b,
isopropanol 3c and butanol 3d, which afforded the
corresponding products 4 in acceptable yields.
Scheme 5. Applicability of alcohols 3
Scheme 7. Control experiments
In addition to 3-diazooxindoles 2, ethyl 4-
nitrophenyldiazoacetate 2m could also be employed as a
competent substrate in the three-component reaction under
the standard reaction conditions, which offered product
4ama in a moderate yield of 53% (Scheme 6). This result
further enlarged the applicability of the designed three-
component reaction.
Based on the control experiments, we suggested a possible
reaction pathway (Scheme 8). As exemplified by the formation of
product 4aaa, under the catalysis of RhLn, 3-diazooxindole 2a
transform into a rhodium carbene species B, which was attacked
by ethanol 3a to form active oxonium ylides C and D. The 1,2-
hydrogen transfer of oxonium ylide C led to the generation of
byproduct 5. At same time, under the catalysis of BH, 2-
indolymethanol 1a transformed into delocalized cation E via
dehydration. Then, activated by the anion of BH via forming
hydrogen-bonding and ion-paring interactions, the oxonium ylide
D performed a nucleophilic attack to the delocalized cation E,
thus affording the desired product 4aaa. In the whole process,
the synergistic catalysis of RhLn and BH enabled the proceeding
of the designed three-component reaction. Among the reaction
process, the nucleophilic attack of intermediate D to cation E
might be the rate-determining step. This is because byproduct 5
could rapidly generated in the reaction system, which means
that the formation of oxonium ylide C is very quickly. In addition,
the formation of delocalized cation E from 2-indolymethanol 1a
in the presence of an acid is also very fast, which could be
detected by TLC. So, the step of nucleophilic attack of
intermediate D to cation E is relatively slow and difficult, which
led to the moderate yield of product 4aaa.
Scheme 6. Using ethyl 4-nitrophenyldiazoacetate 2m as a substrate
The structures of all products 4 were unambiguously identified
1
by H and 13C NMR, IR and HRMS. Moreover, the structure of
product 4aaa was determined by single crystal X-ray diffraction
analysis (see the Supporting Information for details).[20]
In order to gain some insights into the reaction mechanism,
we performed some control experiments (Scheme 7). First, N-
methyl protected 2-indolylmethanol 1k was utilized as
a
substrate, which failed to perform the three-component reaction
with 3-diazooxindole 2a and ethanol 3a (eq. 7). This result
indicated that the N-H group of 2-indolylmethanols played an
important role in controlling the reactivity of the three-component
reaction. Second, we studied the formation of byproduct 5 by
reacting 3-diazooxindole 2a with ethanol 3a under the catalysis
of Rh2(OAc)4. As expected, this reaction generated byproduct 5
in a high yield (eq. 8), which implied that the formation of
byproduct 5 is a competitive side reaction of the designed three-
component reaction. At last, byproduct 5 was subject to the
reaction with 2-indolylmethanol 1a either under the mono-
catalysis of diphenyl phosphoric acid (eq. 9) or under the
cooperative catalysis of Rh2(OAc)4 and diphenyl phosphoric acid
(eq. 10). In both cases, product 4aaa could not be generated,
which indicated that byproduct 5 was not an intermediate
product toward the generation of desired products 4.
Scheme 8. Suggested reaction pathway
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In the three-component reactions, 2-indolylmethanols
1
bearing two phenyl groups are employed as substrates in all
cases. This is because the two phenyl group could stabilize the
delocalized cation E. In order to investigate the possible
substrate limitation of the reaction, we utilized 2-
indolylmethanols 1l and 1m as substrates, which have two alkyl
groups or one phenyl group instead of two phenyl groups
(Scheme 9). However, the two substrates 1l and 1m failed to
participate in the reaction, and only byproduct 5 was generated
in both cases. This result demonstrated that the two phenyl
groups in the structure of 2-indolylmethanols 1 were necessary
for performing the three-component reaction.
T (oC)
30
30
30
30
30
30
30
30
30
30
30
30
30
30
50
0
yield (%)[b]
58
ee (%)[c]
OEt
entry
1
6
N2
2 mol% Rh2(OAc)4
Et
OH
Et
10 mol% (PhO)2PO2H
6a
15
11
0
O
O
+
EtOH
+
N
N
CHCl3, 30 oC, 12h
N
H
H
2
3
6b
6c
6d
6e
6f
38
H
5
72%
3a
1l
2a
16
OEt
4
41
12
-
N2
2 mol% Rh2(OAc)4
10 mol% (PhO)2PO2H
PMP
OH
5
trace
trace
trace
trace
trace
52
O
O
+
+
EtOH
3a
N
CHCl3, 30 oC, 12h
N
N
H
H
H
6
-
5
PMP = p-MeOC6H4
2a
1m
81%
7
6g
6h
6i
-
Scheme 9. Substrate limitation
8
-
Finally, we performed a preliminary investigation on the
catalytic asymmetric version of this three-component reaction.
As shown in Table 4, we initially utilized several representative
chiral phosphoric acids (CPAs) 6a-6g bearing different
substituents on the 3,3’-position as chiral Brønsted acids to
catalyze the reaction (entries 1-7). It was found that CPAs 6a-6d
could catalyze the reaction to give product 4aaa albeit with low
enantioselectivities (entries 1-4), while CPAs 6e-6g failed to
catalyze the reaction (entries 5-7). Among them, CPA 6a
bearing two para-chlorophenyl substituents on the 3,3’-position
could promote the reaction to afford product 4aaa in 15% ee
(entry 1). So, we further screened a series of CPAs 6h-6n
bearing different substituted phenyl groups (entries 8-14).
However, most of these CPAs failed to catalyze the reaction
(entries 8-9, 12, 14). Although CPAs 6j-6k and 6m could
catalyze the reaction, the enantioselectivities were still in an
extremely low level (entry 10-11, 13). Then, in the presence of
CPA 6a, we changed the reaction temperature (entries 15-17).
9
-
10
11
12
13
14
15
16
17
6j
15
8
6k
6l
51
trace
41
-
6m
6n
6a
6a
6a
12
-
trace
42
0
19
18
-
-30
trace
[a] Unless indicated otherwise, the reaction was carried out at 0.1 mmol scale
in CHCl3 (2 mL) for 12 h, and the molar ratio of 1:2a:3a was 1:1.2:8.5. [b]
Isolated yield. [c] The ee value was determined by HPLC.
o
o
Elevating the reaction temperature from 30 C to 50 C led to a
sharp decrease of the enantioselectivity (entry 1 vs entry 15).
Conclusions
o
o
Although lowering the reaction temperature from 30 C to 0 C
could slightly improve the enantioselectivity, the yield of product
4aaa was dropped sharply (entry 1 vs entry 16). In addition,
when the reaction temperature was lowered to -30 oC, the three-
component reaction could hardly occur (entry 17). Thus, it
In summary, we have established a synergistic catalysis-
enabled reaction of 2-indolymethanols with oxonium ylides,
which makes use of the three-component reaction of 3-
diazooxindoles, alcohols and 2-indolymethanols under the
cooperative catalysis of metal complex and Brønsted acid. This
reaction has not only provided a new approach for constructing
3-indolyl-3-alkoxy oxindole scaffolds by utilizing the indole C3-
electrophilicity, but also realized a nucleophilic addition of metal
associated ylide to 2-indolylmethanols for the first time. In
addition, this reaction has also established a rarely reported
trapping of onium ylides with aryl electrophiles. This approach
will not only advance the chemistry of 2-indolylmethanols and
onium ylides, but also provide a good example of synergistic
catalysis.
seemed that it is
a
great challenge to control the
enantioselectivity of this three-component reaction.
Table 4. Preliminary investigation on the catalytic asymmetric version[a]
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1261, 764, 750 cm-1; ESI FTMS exact mass calcd for
(C31H25ClN2O2+Na)+ requires m/z 515.1503, found m/z 515.1505.
3-(2-benzhydryl-5-methoxy-1H-indol-3-yl)-3-ethoxyindolin-2-one
(4daa): 46% yield (22.4 mg); white solid; m.p. 110–112 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.29 (s, 1H), 7.54 (s, 1H), 7.28 (d, J = 7.5 Hz, 1H),
7.25 – 7.17 (m, 6H), 7.13 (m, 1H), 7.05 – 6.96 (m, 6H), 6.80 (s, 1H), 6.76
– 6.69 (m, 2H), 6.10 (s, 1H), 3.66 (s, 3H), 3.50 – 3.43 (m, 1H), 3.35 –
3.26 (m, 1H), 1.14 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
(ppm): 177.4, 153.9, 142.8, 142.6, 141.3, 138.4, 130.3, 129.9, 129.2,
128.9, 128.8, 128.5, 128.2, 127.4, 126.6, 126.4, 126.3, 122.9, 111.9,
111.3, 110.3, 109.1, 102.9, 82.4, 59.9, 55.5, 48.5, 15.2; IR (KBr): 2360,
1659, 1401, 1261, 764, 750, 669 cm-1; ESI FTMS exact mass calcd for
(C32H28N2O3+Na)+ requires m/z 511.1998, found m/z 511.1997.
3-(2-benzhydryl-6-chloro-1H-indol-3-yl)-3-ethoxyindolin-2-one
(4eaa): 42% yield (20.7 mg); white solid; m.p. 103–105 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.21 (s, 1H), 7.62 (s, 1H), 7.42 – 7.31 (m, 1H),
7.25 – 7.08 (m, 9H), 7.02 – 6.86 (m, 6H), 6.71 (d, J = 7.7 Hz, 1H), 5.99 (s,
1H), 3.50 – 3.39 (m, 1H), 3.31 – 3.19 (m, 1H), 1.15 (t, J = 6.9 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ (ppm): 177.1, 142.4, 142.2, 141.1, 137.9,
135.5, 130.0, 129.1, 128.9, 128.6, 128.4, 127.6, 126.8, 126.6, 126.1,
125.7, 123.0, 122.3, 120.6, 110.6, 110.5, 109.8, 82.2, 60.1, 48.3, 15.2; IR
(KBr): 2360, 1722, 1470, 1261, 764, 749, 672 cm-1; ESI FTMS exact
mass calcd for (C31H25ClN2O2+Na)+ requires m/z 515.1503, found m/z
515.1505.
Experimental Section
General information
1H and 13C NMR spectra were measured respectively at 400 and
100 MHz, respectively. The solvent used for NMR spectroscopy
was CDCl3, using tetramethylsilane as the internal reference.
HRMS (ESI) was determined by a HRMS/MS instrument. Optical
rotation values were measured with instruments operating at λ =
589 nm, corresponding to the sodium D line at the temperatures
indicated. The X-ray source used for the single crystal X-ray
diffraction analysis of compound 4aaa was GaKα (λ = 1.34139),
and the thermal ellipsoid was drawn at the 30% probability level.
Analytical grade solvents for the column chromatography were
distilled before use. All starting materials commercially available
were used directly.
General procedure for the synthesis of products 4
Under argon atmosphere, Rh2(OAc)4 (0.002 mmol), diphenyl
phosphate (0.01 mmol) and 2-indolylmethanols
added to a dry Schlenk tube. Then, chloroform (1 mL) was added to
the reaction mixture, which was stirred at 30 oC for 5 minutes.
Subsequently, a solution of the diazo compounds
1 (0.1 mmol) were
2 (0.2 mmol) and
3-(2-benzhydryl-6-bromo-1H-indol-3-yl)-3-ethoxyindolin-2-one
alcohols (0.85 mmol) in chloroform (1 mL) was slowly added to
3
o
1
the reaction mixture, which was further stirred at 30 oC for 12 h.
Finally, the reaction mixture was directly purified through
preparative thin layer chromatography on silica gel to afford pure
(4faa): 56% yield (30.2 mg); white solid; m.p. 171–172 C; H NMR (400
MHz, CDCl3) δ (ppm): 8.26 (s, 1H), 7.63 (s, 1H), 7.40 – 7.27 (m, 2H),
7.24 – 7.14 (m, 8H), 7.08 – 7.03 (m, 1H), 6.99 – 6.91 (m, 5H), 6.72 (d, J
= 7.8 Hz, 1H), 6.01 (s, 1H), 3.49 – 3.41 (m, 1H), 3.31 – 3.23 (m, 1H),
1.15 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.2,
142.4, 142.1, 141.1, 137.9, 135.9, 130.0, 129.1, 128.9, 128.6, 128.4,
126.8, 126.6, 126.1, 126.0, 123.2, 123.0, 122.7, 115.3, 113.6, 110.5,
109.8, 82.2, 60.1, 48.3, 15.2; IR (KBr): 2359, 1720, 1469, 1261, 764, 750
cm-1; ESI FTMS exact mass calcd for (C31H25BrN2O2+Na)+ requires m/z
559.0997, found m/z 559.1000.
products
4.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxyindolin-2-one
(4aaa):
58% yield (26.7 mg); white solid; m.p. 184–185 oC; 1H NMR (400 MHz,
CDCl3) δ (ppm): 8.51 (s, 1H), 7.65 (s, 1H), 7.33 (s, 1H), 7.26 – 7.13 (m,
9H), 7.09 – 6.91 (m, 7H), 6.75 (d, J = 7.7 Hz, 1H), 6.19 (s, 1H), 3.52 –
3.41 (m, 1H), 3.34 – 3.22 (m, 1H), 1.14 (t, J = 6.9 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ (ppm): 177.6, 142.8, 142.6, 141.2, 137.6, 135.2, 129.8,
129.2, 129.0, 128.5, 128.3, 127.0, 126.6, 126.5, 126.2, 122.9, 121.6,
121.1, 119.9, 110.6, 110.4, 109.5, 82.5, 60.0, 48.4, 15.2; IR (KBr): 2359,
1722, 1470, 1261, 745, 699, 668 cm-1; ESI FTMS exact mass calcd for
(C31H26N2O2+Na)+ requires m/z 481.1892, found m/z 481.1895; The
enantiomeric excess: 15%, determined by HPLC (Daicel Chiralpak IA,
3-(2-benzhydryl-6-methoxy-1H-indol-3-yl)-3-ethoxyindolin-2-one
o
1
(4gaa): 40% yield (19.7 mg); white solid; m.p. 99–100 C; H NMR (400
MHz, CDCl3) δ (ppm): 7.90 (s, 1H), 7.49 (s, 1H), 7.31 (s, 1H), 7.24 – 7.15
(m, 8H), 7.02 – 6.93 (m, 5H), 6.70 (d, J = 7.9 Hz, 1H), 6.67 – 6.61 (m,
2H), 5.99 (s, 1H), 3.75 (s, 3H), 3.50 – 3.42 (m, 1H), 3.33 – 3.26 (m, 1H),
1.14 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.1,
156.0, 142.9, 142.6, 141.0, 135.9, 129.8, 129.1, 129.0, 128.9, 128.4,
128.3, 126.6, 126.4, 126.2, 122.9, 122.0, 121.3, 110.2, 109.8, 109.4,
94.1, 82.3, 60.0, 55.5, 48.3, 15.2; IR (KBr): 2359, 1727, 1462, 1261, 764,
750, 668 cm-1; ESI FTMS exact mass calcd for (C32H28N2O3+Na)+
requires m/z 511.1998, found m/z 511.2000.
o
hexane/ isopropanol = 70/ 30, flow rate 1.0 mL/min, T = 30 C, 254 nm):
tR = 4.787 (major), tR = 8.657 (minor).
3-(2-benzhydryl-4-chloro-1H-indol-3-yl)-3-ethoxyindolin-2-one
(4baa): 47% yield (23.3 mg); white solid; m.p. 110–112 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 1H NMR (400 MHz, CDCl3) δ 8.17 (s, 1H), 7.57 (s,
1H), 7.32 – 7.26 (m, 2H), 7.26 – 7.20 (m, 3H), 7.19 – 7.14 (m, 3H), 7.07
(d, J = 8.0 Hz, 1H), 7.03 – 6.91 (m, 6H), 6.91 – 6.86 (m, 1H), 6.78 (d, J =
7.7 Hz, 1H), 6.37 (s, 1H), 3.47 – 3.39 (m, 1H), 3.31 – 3.23 (m, 1H), 1.08
(t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.4, 141.1,
140.9, 140.8, 135.2, 132.7, 132.5, 130.5, 130.3, 130.0, 128.8, 128.7,
128.6, 126.6, 126.3, 123.2, 121.9, 120.7, 120.1, 110.8, 110.2, 109.9,
82.3, 60.0, 47.4, 15.2; IR (KBr): 2360, 1722, 1469, 1260, 1232, 765, 751
cm-1; ESI FTMS exact mass calcd for (C31H25ClN2O2+Na)+ requires m/z
515.1503, found m/z 515.1501.
3-(2-benzhydryl-5-chloro-1H-indol-3-yl)-3-ethoxyindolin-2-one
(4caa): 40% yield (19.6 mg); light yellow solid; m.p. 110–111 oC; 1H NMR
(400 MHz, CDCl3) δ (ppm): 7.98 (s, 1H), 7.65 (s, 1H), 7.48 (s, 1H), 7.26 –
7.12 (m, 8H), 7.12 – 7.02 (m, 2H), 7.02 – 6.99 (m, 1H), 6.98 – 6.89 (m,
4H), 6.72 (d, J = 7.7 Hz, 1H), 5.93 (s, 1H), 3.50 – 3.41 (m, 1H), 3.32 –
3.24 (m, 1H), 1.17 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
(ppm): 176.9, 142.3, 142.1, 141.1, 138.6, 133.4, 130.1, 129.1, 128.9,
128.6, 128.5, 128.3, 126.8, 126.7, 126.1, 125.6, 123.1, 122.0, 121.1,
111.6, 110.5, 109.5, 82.2, 60.1, 48.4, 15.2; IR (KBr): 2359, 1723, 1469,
3-(2-(di-p-tolylmethyl)-1H-indol-3-yl)-3-ethoxyindolin-2-one
(4haa): 51% yield (24.9 mg); white solid; m.p. 107–108 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 7.60 (d, J = 7.8 Hz, 2H), 7.54 – 7.44 (m, 1H), 7.23
– 7.18 (m, 2H), 7.15 (d, J = 8.0 Hz, 1H), 7.08 – 7.02 (m, 3H), 6.99 – 6.92
(m, 4H), 6.89 – 6.81 (m, 4H), 6.67 (d, J = 7.9 Hz, 1H), 5.96 (s, 1H), 3.51
– 3.44 (m, 1H), 3.36 – 3.29 (m, 1H), 2.31 (s, 3H), 2.28 (s, 3H), 1.17 (t, J =
7.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 176.8, 140.9, 139.8,
139.6, 136.0, 135.9, 135.0, 129.6, 129.2, 129.1, 129.0, 128.9, 128.8,
126.2, 122.9, 121.5, 119.8, 110.6, 110.0, 109.2, 101.7, 82.2, 59.9, 47.6,
21.1, 21.0, 15.3; IR (KBr): 2359, 1513, 1470, 1275, 764, 750 cm-1; ESI
FTMS exact mass calcd for (C33H30N2O2+Na)+ requires m/z 509.2205,
found m/z 509.2198.
3-(2-(bis(4-methoxyphenyl)methyl)-1H-indol-3-yl)-3-
ethoxyindolin-2-one (4iaa): 40% yield (20.9 mg); white solid; m.p. 114–
116 oC; 1H NMR (400 MHz, CDCl3) δ (ppm): 7.57 (s, 1H), 7.52 (s, 1H),
7.44 (s, 1H), 7.25 – 7.18 (m, 2H), 7.15 (d, J = 8.0 Hz, 1H), 7.09 – 7.04 (m,
1H), 7.00 – 6.93 (m, 2H), 6.92 – 6.82 (m, 4H), 6.77 (d, J = 8.7 Hz, 2H),
6.73 – 6.64 (m, 3H), 5.90 (s, 1H), 3.78 (s, 3H), 3.75 (s, 3H), 3.51 – 3.44
(m, 1H), 3.37 – 3.30 (m, 1H), 1.17 (t, J = 7.0 Hz, 3H); 13C NMR (100 MHz,
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10.1002/asia.201800620
Chemistry - An Asian Journal
FULL PAPER
CDCl3) δ (ppm): 176.6, 158.2, 140.9, 135.0, 130.0, 129.9, 129.6, 129.2,
126.2, 122.9, 121.5, 119.8, 113.7, 113.6, 110.6, 109.9, 109.1, 82.2, 59.9,
55.2, 46.7, 15.3; IR (KBr): 2359, 1520, 1461, 1275, 764, 750 cm-1; ESI
FTMS exact mass calcd for (C33H30N2O4+Na)+ requires m/z 541.2104,
found m/z 541.2109.
3-(2-benzhydryl-1H-indol-3-yl)-6-chloro-3-ethoxyindolin-2-one
(4afa): 78% yield (38.4 mg); brown solid; m.p. 126–127 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.11 (s, 1H), 7.65 (s, 1H), 7.46 (s, 1H), 7.28 – 7.16
(m, 7H), 7.13 – 7.08 (m, 2H), 7.07 – 6.95 (m, 5H), 6.95 – 6.91 (m, 1H),
6.70 (s, 1H), 6.18 (s, 1H), 3.52 – 3.42 (m, 1H), 3.39 – 3.30 (m, 1H), 1.18
(t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.1, 142.6,
142.2, 141.9, 135.3, 135.1, 129.1, 129.0, 128.5, 128.4, 127.5, 127.1,
126.9, 126.7, 126.6, 122.9, 121.8, 121.0, 120.1, 110.8, 110.7, 108.9,
81.9, 60.1, 48.5, 15.2; IR (KBr): 2360, 1723, 1400, 1261, 748, 700 cm-1;
ESI FTMS exact mass calcd for (C31H25ClN2O2+Na)+ requires m/z
515.1503, found m/z 515.1497.
3-(2-(bis(4-fluorophenyl)methyl)-6-chloro-1H-indol-3-yl)-3-
ethoxyindolin-2-one (4jaa): 48% yield (25.3 mg); white solid; m.p. 100–
102 oC; 1H NMR (400 MHz, CDCl3) δ (ppm): 8.20 (s, 1H), 7.57 (s, 1H),
7.29 – 7.25 (m, 1H), 7.20 (d, J = 7.3 Hz, 1H), 7.17 – 7.16 (m, 1H), 7.13 (s,
1H), 7.02 – 6.98 (m, 1H), 6.97 – 6.85 (m, 9H), 6.75 (d, J = 7.8 Hz, 1H),
6.14 (s, 1H), 3.47 – 3.38 (m, 1H), 3.30 – 3.22 (m, 1H), 1.11 (t, J = 6.9 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.2, 162.9, 160.4, 160.3,
141.0, 138.2, 137.8, 135.5, 130.5 (d, J = 7.8 Hz), 130.3 (d, J = 7.8 Hz),
130.2, 128.5, 127.9, 126.1, 125.4, 123.2, 122.1, 120.8, 115.5 (d, J = 16.1
Hz), 115.3 (d, J = 16.1 Hz), 110.5 (d, J = 29.0 Hz), 110.0, 82.1, 60.1,
46.9, 15.2; IR (KBr): 2359, 1723, 1505, 1276, 764, 751, 669 cm-1; ESI
FTMS exact mass calcd for (C31H23ClF2N2O2+Na)+ requires m/z
551.1314, found m/z 551.1320.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-5-fluoroindolin-2-one
(4aba): 47% yield (22.5 mg); white solid; m.p. 126–127 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.20 (s, 1H), 7.65 (s, 1H), 7.53 – 7.27 (m, 2H),
7.25 – 7.15 (m, 6H), 7.10 – 7.06 (m, 1H), 7.04 (d, J = 7.1 Hz, 2H), 7.01 –
6.93 (m, 3H), 6.92 – 6.87 (m, 1H), 6.86 – 6.81 (m, 1H), 6.67 – 6.59 (m,
1H), 6.22 (s, 1H), 3.52 – 3.44 (m, 1H), 3.35 – 3.27 (m, 1H), 1.16 (t, J =
6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.2, 160.5, 142.5 (d,
J = 53.0 Hz), 136.7, 135.1, 130.9, 129.01, 129.0, 128.5, 128.4, 126.7,
121.8, 120.7, 120.1, 116.2 (d, J = 23.7 Hz), 113.8 (d, J = 24.4 Hz), 110.8,
108.9, 82.6, 60.1, 48.5, 15.2; IR (KBr): 2360, 1722, 1401, 1276, 764, 750,
669 cm-1; ESI FTMS exact mass calcd for (C31H25FN2O2+Na)+ requires
m/z 449.1798, found m/z 449.1791.
3-(2-benzhydryl-1H-indol-3-yl)-5-chloro-3-ethoxyindolin-2-one
(4aca): 41% yield (20.0 mg); white solid; m.p. 128–129 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.17 (s, 1H), 7.65 (s, 1H), 7.54 – 7.27 (m, 2H),
7.25 – 7.13 (m, 7H), 7.10 – 7.06 (m, 1H), 7.03 (d, J = 7.1 Hz, 3H), 7.01 –
6.91 (m, 3H), 6.63 (d, J = 8.3 Hz, 1H), 6.20 (s, 1H), 3.51 – 3.43 (m, 1H),
3.35 – 3.27 (m, 1H), 1.17 (t, J = 6.9 Hz, 3H).; 13C NMR (100 MHz, CDCl3)
δ (ppm): 176.9, 142.7, 142.1, 139.2, 135.0, 130.9, 129.7, 129.1, 129.0,
128.5, 128.4, 126.7, 126.3, 121.8, 120.7, 120.1, 111.2, 110.8, 108.7,
82.4, 60.2, 48.6, 15.2; IR (KBr): 2360, 1725, 1265, 744, 669 cm-1; ESI
FTMS exact mass calcd for (C31H25ClN2O2+Na)+ requires m/z 515.1503,
found m/z 515.1501.
3-(2-benzhydryl-1H-indol-3-yl)-5-bromo-3-ethoxyindolin-2-one
(4ada): 64% yield (34.1 mg); white solid; m.p. 188–190 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.71 (s, 1H), 7.71 (s, 1H), 7.39 (s, 1H), 7.34 – 7.31
(m, 1H), 7.28 – 7.25 (m, 2H), 7.25 – 7.21 (m, 4H), 7.21 – 7.14 (m, 2H),
7.14 – 7.09 (m, 1H), 7.09 – 7.01 (m, 4H), 7.01 – 6.96 (m, 1H), 6.62 (d, J
= 8.3 Hz, 1H), 6.25 (s, 1H), 3.53 – 3.44 (m, 1H), 3.37 – 3.27 (m, 1H),
1.20 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.2,
142.7, 142.1, 139.9, 135.0, 132.6, 131.3, 129.2, 129.1, 129.0, 128.6,
128.5, 126.8, 121.8, 120.7, 120.2, 115.8, 111.8, 110.8, 108.7, 82.5, 60.2,
48.6, 15.2; IR (KBr): 2360, 1717, 1457, 1187, 764, 743, 669 cm-1; ESI
FTMS exact mass calcd for (C31H25BrN2O2+H)+ requires m/z 559.0997,
found m/z 559.1005.
3-(2-benzhydryl-1H-indol-3-yl)-6-bromo-3-ethoxyindolin-2-one
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1
(4aga): 52% yield (27.8 mg); pink solid; m.p. 134–136 C; H NMR (400
MHz, CDCl3) δ (ppm): 8.71 (s, 1H), 7.66 (s, 1H), 7.41 (s, 1H), 7.24 – 7.14
(m, 7H), 7.09 – 7.04 (m, 2H), 7.04 – 7.00 (m, 3H), 6.99 – 6.93 (m, 3H),
6.84 (s, 1H), 6.18 (s, 1H), 3.49 – 3.41 (m, 1H), 3.34 – 3.26 (m, 1H), 1.16
(t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.5, 142.6,
142.2, 137.5, 135.1, 129.1, 128.9, 128.5, 128.4, 127.9, 127.3, 126.9,
126.7, 126.6, 125.8, 123.3, 121.8, 120.9, 120.1, 113.8, 110.8, 108.8,
82.1, 60.1, 48.6, 15.2; IR (KBr): 2359, 1727, 1401, 1275, 764, 750, 701
cm-1; ESI FTMS exact mass calcd for (C31H25BrN2O2+Na)+ requires m/z
559.0997, found m/z 559.0999.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-6-methylindolin-2-one
(4aha): 40% yield (19.0 mg); white solid; m.p. 108–109 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 7.95 (s, 1H), 7.61 (s, 1H), 7.47 – 7.27 (m, 2H),
7.23 – 7.17 (m, 5H), 7.15 (d, J = 8.0 Hz, 2H), 7.07 – 7.05 (m, 1H), 7.04 –
6.98 (m, 4H), 6.96 – 6.91 (m, 1H), 6.76 (d, J = 7.5 Hz, 1H), 6.54 (s, 1H),
6.18 (s, 1H), 3.48 – 3.39 (m, 1H), 3.34 – 3.22 (m, 1H), 2.33 (s, 3H), 1.13
(t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.5, 142.9,
142.6, 141.2, 140.1, 135.2, 129.2, 128.9, 128.6, 128.4, 128.2, 126.5,
126.4, 126.0, 125.9, 123.5, 121.6, 119.8, 111.0, 110.6, 109.7, 82.3, 59.9,
48.4, 21.8, 15.2; IR (KBr): 2359, 1722, 1454, 1275, 764, 750, 669 cm-1;
ESI FTMS exact mass calcd for (C32H28N2O2+Na)+ requires m/z
495.2049, found m/z 495.2050.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-4,6-difluoroindolin-2-
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1
one (4aia): 64% yield (31.6 mg); white solid; m.p. 115–117 C; H NMR
(400 MHz, CDCl3) δ (ppm): 8.88 (s, 1H), 7.68 (s, 1H), 7.40 (s, 1H), 7.28 –
7.23 (m, 3H), 7.23 – 7.18 (m, 3H), 7.16 – 7.06 (m, 4H), 7.03 – 6.95 (m,
3H), 6.46 – 6.39 (m, 1H), 6.32 (d, J = 7.9 Hz, 1H), 6.20 (s, 1H), 3.48 –
3.35 (m, 2H), 1.16 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
(ppm): 177.3, 161.3, 158.7, 143.8, 142.5, 142.3, 137.4, 135.1, 129.2,
128.8, 128.6, 128.3, 126.8, 126.6, 121.8, 120.8, 120.1, 110.7, 107.5,
98.3, 95.7 (d, J = 27.3 Hz). 81.6, 60.6, 48.6, 15.1; IR (KBr): 2359, 1732,
1455, 1274, 764, 750, 705 cm-1; ESI FTMS exact mass calcd for
(C31H24F2N2O2+Na)+ requires m/z 517.1704, found m/z 517.1705.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-5,6-difluoroindolin-2-
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1
one (4aja): 48% yield (23.8 mg); white solid; m.p. 207–208 C; H NMR
(400 MHz, CDCl3) δ (ppm): 8.45 (s, 1H), 7.69 (s, 1H), 7.41 (s, 1H), 7.30
(d, J = 6.9 Hz, 1H), 7.28 – 7.19 (m, 6H), 7.14 – 7.09 (m, 1H), 7.07 (d, J =
7.1 Hz, 2H), 7.04 – 6.95 (m, 3H), 6.94 – 6.86 (m, 1H), 6.57 – 6.48 (m,
1H), 6.23 (s, 1H), 3.52 – 3.44 (m, 1H), 3.39 – 3.29 (m, 1H), 1.20 (t, J =
6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.4, 142.3 (d, J =
60.4 Hz), 135.0, 129.1, 129.0, 128.6, 128.5, 128.4, 126.8, 126.7, 126.6,
121.9, 120.5, 120.4, 120.2, 115.4 (d, J = 20.4 Hz), 110.9, 108.6, 100.3 (d,
J = 22.5 Hz), 82.2, 60.1, 48.6, 15.2; IR (KBr): 2360, 1728, 1463, 1275,
764, 750 cm-1; ESI FTMS exact mass calcd for (C31H24F2N2O2+Na)+
requires m/z 517.1704, found m/z 517.1716.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-5-nitroindolin-2-one
(4aea): 63% yield (31.7 mg); white solid; m.p. 210–211 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 8.33 (s, 1H), 8.15 – 8.09 (m, 1H), 8.02 – 7.94 (m,
1H), 7.67 (s, 1H), 7.50 – 7.42 (m, 1H), 7.31 – 7.27 (m, 2H), 7.26 – 7.22
(m, 1H), 7.20 (d, J = 8.1 Hz, 1H), 7.18 – 7.13 (m, 3H), 7.13 – 7.08 (m,
1H), 7.07 – 6.97 (m, 3H), 6.97 – 6.86 (m, 2H), 6.76 (d, J = 8.6 Hz, 1H),
6.11 (s, 1H), 3.54 – 3.46 (m, 1H), 3.41 – 3.32 (m, 1H), 1.19 (t, J = 6.9 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 176.9, 146.1, 143.8, 142.3,
141.7, 135.0, 130.4, 128.9, 128.7, 128.6, 127.0, 126.9, 126.5, 122.1,
121.9, 120.5, 111.0, 109.9, 107.6, 81.7, 60.4, 48.7, 29.7, 15.2; IR (KBr):
2359, 1732, 1455, 1275, 764, 750 cm-1; ESI FTMS exact mass calcd for
(C31H25N3O4+H)+ requires m/z 526.1743, found m/z 526.1741.
3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-5,7-dimethylindolin-2-
one (4aka): 60% yield (29.2 mg); white solid; m.p. 152–153 oC; 1H NMR
(400 MHz, CDCl3) δ (ppm): 8.10 (s, 1H), 7.57 (s, 2H), 7.23 – 7.13 (m, 7H),
7.09 – 7.05 (m, 1H), 7.01 – 6.91 (m, 5H), 6.85 (d, J = 8.8 Hz, 2H), 5.96 (s,
1H), 3.51 – 3.43 (m, 1H), 3.38 – 3.29 (m, 1H), 2.18 (s, 3H), 2.07 (s, 3H),
1.18 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.4,
142.8, 142.5, 137.3, 135.2, 132.3, 131.6, 129.1, 128.9, 128.5, 128.4,
128.3, 127.3, 126.6, 126.5, 124.1, 121.6, 119.9, 119.0, 110.5, 109.9,
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82.9, 59.9, 48.2, 21.0, 16.1, 15.3; IR (KBr): 2360, 1715, 1400, 1275, 764,
750 cm-1; ESI FTMS exact mass calcd for (C33H30N2O2+Na)+ requires
m/z 509.2205, found m/z 509.2201.
1H), 7.31 – 7.26 (m, 1H), 7.20 – 7.06 (m, 1H), 6.92 (d, J = 7.8 Hz, 1H),
4.98 (s, 1H), 3.91 – 3.80 (m, 1H), 3.79 – 3.65 (m, 1H), 1.31 (t, J = 7.0 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.6, 141.5, 129.9, 125.7,
125.5, 122.9, 110.5, 76.3, 64.3, 15.4. ESI FTMS exact mass calcd for
(C10H11NO2+Na)+ requires m/z 200.0687, found m/z 200.0691.
tert-butyl 3-(2-benzhydryl-1H-indol-3-yl)-3-ethoxy-2-oxoindoline-
1-carboxylate (4ala): 64% yield (35.8 mg); white solid; m.p. 120–121 oC;
1H NMR (400 MHz, CDCl3) δ (ppm): 7.74 (d, J = 8.2 Hz, 1H), 7.62 (s, 1H),
7.39 (d, J = 7.4 Hz, 1H), 7.37 – 7.33 (m, 1H), 7.26 – 7.20 (m, 3H), 7.20 –
7.15 (m, 5H), 7.15 – 7.06 (m, 2H), 7.03 – 6.99 (m, 1H), 6.97 – 6.93 (m,
2H), 6.92 – 6.89 (m, 2H), 5.86 (s, 1H), 3.47 – 3.40 (m, 1H), 3.34 – 3.27
(m, 1H), 1.59 (s, 9H), 1.14 (t, J = 6.9 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ (ppm): 173.3, 148.9, 142.5, 142.2, 140.3, 137.5, 135.1, 130.1,
129.1, 128.8, 128.5, 128.3, 127.5, 127.2, 126.7, 126.6, 125.7, 124.7,
121.8, 121.7, 120.1, 115.4, 110.6, 109.7, 84.2, 81.8, 60.2, 48.2, 28.1,
15.2; IR (KBr): 2360, 1728, 1463, 1276, 764, ,751, 669 cm-1; ESI FTMS
exact mass calcd for (C36H34N2O4+Na)+ requires m/z 581.2417, found
m/z 581.2416.
Acknowledgements
We are grateful for financial support from National Natural
Science Foundation of China (21772069), Natural Science
Foundation of Jiangsu Province (BK20160003) and Six Kinds of
Talents Project of Jiangsu Province (SWYY-025).
Keywords: Synergistic catalysis • Indolymethanol • Oxonium
3-(2-benzhydryl-1H-indol-3-yl)-3-methoxyindolin-2-one (4aab):
50% yield (22.4 mg); white solid; m.p. 101–102 oC; 1H NMR (400 MHz,
CDCl3) δ (ppm): 7.96 (s, 1H), 7.66 (s, 1H), 7.37 (s, 1H), 7.26 – 7.21 (m,
3H), 7.21 – 7.14 (m, 6H), 7.10 – 7.05 (m, 1H), 7.04 – 6.98 (m, 4H), 6.98 –
6.93 (m, 2H), 6.73 (d, J = 7.8 Hz, 1H), 6.09 (s, 1H), 3.23 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ (ppm): 176.7, 142.7, 142.3, 141.2, 137.5,
135.1, 129.9, 129.1, 128.9, 128.5, 128.4, 127.2, 126.7, 126.6, 126.4,
122.9, 121.7, 121.1, 120.0, 110.7, 110.3, 109.0, 82.7, 52.2, 48.4; IR
(KBr): 2359, 1728, 1402, 1275, 764, 749, 704 cm-1; ESI FTMS exact
mass calcd for (C30H24N2O2+Na)+ requires m/z 467.1736, found m/z
467.1737.
ylide • Oxindole • Cooperative catalysis
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3-(2-benzhydryl-1H-indol-3-yl)-3-isopropoxyindolin-2-one
(4aac): 46% yield (21.8 mg); white solid; m.p. 92–93 oC; 1H NMR (400
MHz, CDCl3) δ (ppm): 7.82 (s, 1H), 7.60 (s, 1H), 7.26 – 7.15 (m, 9H),
7.13 (d, J = 8.1 Hz, 1H), 7.06 – 6.88 (m, 7H), 6.75 (d, J = 7.6 Hz, 1H),
6.20 (s, 1H), 3.57 – 3.49 (m, 1H), 1.27 (d, J = 6.2 Hz, 3H), 0.87 (d, J =
6.1 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.9, 143.1, 142.8,
141.0, 135.1, 129.8, 129.7, 129.2, 129.0, 128.5, 128.2, 126.8, 126.6,
126.4, 122.8, 121.5, 119.7, 110.6, 110.2, 82.3, 68.5, 48.5, 24.3, 23.5; IR
(KBr): 2360, 1720, 1401, 1192, 743, 699 cm-1; ESI FTMS exact mass
calcd for (C32H28N2O2+Na)+ requires m/z 495.2049, found m/z 495.2043.
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(4aad):
45% yield (21.9 mg); white solid; m.p. 111–113 oC; 1H NMR (400 MHz,
CDCl3) δ (ppm): 8.07 (s, 1H), 7.64 (s, 1H), 7.26 – 7.18 (m, 8H), 7.17 –
7.12 (m, 2H), 7.11 – 7.03 (m, 3H), 7.03 – 6.97 (m, 3H), 6.95 – 6.88 (m,
1H), 6.76 (d, J = 7.8 Hz, 1H), 6.26 (s, 1H), 3.44 – 3.37 (m, 1H), 3.21 –
3.13 (m, 1H), 1.50 – 1.43 (m, 2H), 1.23 – 1.14 (m, 2H), 0.77 (t, J = 7.4 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 177.3, 142.9, 142.8, 141.2,
137.7, 135.2, 129.8, 129.2, 129.0, 128.9, 128.5, 128.2, 126.9, 126.6,
126.4, 126.3, 122.9, 121.5, 120.9, 119.8, 110.6, 110.2, 109.6, 82.4, 64.1,
48.4, 31.9, 19.3, 13.9; IR (KBr): 2360, 1722, 1401, 1275, 764, 750, 699
cm-1; ESI FTMS exact mass calcd for (C33H30N2O2+Na)+ requires m/z
509.2205, found m/z 509.2202.
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2-(2-benzhydryl-1H-indol-3-yl)-2-ethoxy-2-(4-
nitrophenyl)acetate (4ama): 53% yield (28.5 mg); yellow solid; m.p. 60–
61 oC; 1H NMR (400 MHz, CDCl3) δ (ppm): 7.95 – 7.89 (m, 2H), 7.84 (s,
1H), 7.82 – 7.77 (m, 2H), 7.31 – 7.26 (m, 1H), 7.26 – 7.22 (m, 3H), 7.22 –
7.20 (m, 3H), 7.17 (d, J = 8.2 Hz, 1H), 7.15 – 7.10 (m, 1H), 7.02 – 6.90
(m, 5H), 5.71 (s, 1H), 4.26 – 4.14 (m, 1H), 4.12 – 4.03 (m, 1H), 3.48 –
3.40 (m, 1H), 3.25 – 3.17 (m, 1H), 1.14 (t, J = 7.0 Hz, 3H), 1.06 (t, J = 7.1
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm): 171.4, 148.5, 147.2, 142.0,
141.5, 138.9, 135.1, 129.3, 128.8, 128.7, 128.6, 128.5, 127.5, 126.9,
126.8, 122.5, 121.9, 120.7, 120.1, 111.1, 111.0, 83.0, 61.9, 61.1, 48.2,
15.3, 13.7; IR (KBr): 2359, 1728, 1463, 1275, 764, 750 cm-1; ESI FTMS
exact mass calcd for (C33H30N2O5+Na)+ requires m/z 557.2053, found
m/z 557.2056.
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Cambridge
Crystallographic
Data
Centre
via
http://www.ccdc.cam.ac.uk/data_request/cif.
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Entry for the Table of Contents
FULL PAPER
Chun Ma, Jia-Yu Zhou, Yi-Zhu Zhang,
Yinchun Jiao, Guang-Jian Mei and Feng
Shi*
Page No. – Page No.
Synergistic Catalysis-Enabled
Reaction of 2-Indolymethanols with
Oxonium Ylides: Construction of 3-
Indolyl-3-Alkoxy Oxindole Framework
A synergistic catalysis-enabled reaction of 2-indolymethanols with oxonium ylides
has been established, which makes use of the three-component reaction of 3-
diazooxindoles, alcohols and 2-indolymethanols under the cooperative catalysis of
metal complex and Brønsted acid.
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