Chemospecific synthesis of 2-acetoxyindole-3-carbonitriles catalyzed by Cu(acac)2

Article abstract of DOI:10.1007/s11172-016-1509-6

A chemospecific one-pot synthesis of easily isolable 2-acetoxyindole-3-carbonitriles was described. The intermediate 2-oxindole-3-carbonitriles successfully prepared from 2-cyano diazoacetanilides without isolation were treated with acetyl chloride and tr

Full text of DOI:10.1007/s11172-016-1509-6

Russian Chemical Bulletin, International Edition, Vol. 65, No. 7, pp. 1773—1778, July, 2016
1773
Chemospecific synthesis of 2ꢀacetoxyindoleꢀ3ꢀcarbonitriles
catalyzed by Cu(acac)2*
Shanyan Mo, Jianzhuo Tu, and Jiaxi Xu
State Key Laboratory of Chemical Engineering Resource, Department of Organic Chemistry,
Faculty of Science, Beijing University of Chemical Technology,
Beijing 100029, People’s Republic of China.
Fax: +(86) 106 443 5565. Eꢀmail: jxxu@mail.buct.edu.cn
A chemospecific oneꢀpot synthesis of easily isolable 2ꢀacetoxyindoleꢀ3ꢀcarbonitriles was
described. The intermediate 2ꢀoxindoleꢀ3ꢀcarbonitriles successfully prepared from 2ꢀcyanoꢀ
diazoacetanilides without isolation were treated with acetyl chloride and triethylamine to give
2ꢀacetoxyindoleꢀ3ꢀcarbonitriles. The developed oneꢀpot approach showed broad substrate
scope.
Key words: indole, diazoacetanilide, insertion reactions, Cu(acac)2, oxindole.
The indole skeleton is one of the most significant and
valuable heterocycles due to its wide and extensive appliꢀ
cation in chemical, medicinal, and materials science.1
Therefore, the synthetic methods to access indole derivaꢀ
tives have attracted much attention. Numerous synthetic
approaches have been developed during the last decades.2,3
Among them, the intramolecular cyclization of αꢀdiꢀ
azoacetanilides through carbene insertion into the aroꢀ
matic C—H bond is one of the most efficient routes to
prepare oxindole derivatives with broad substrate scope.4
However, this reaction requires the use of the expensive
catalysts, such as dirhodium tetracarboxylates and tetraꢀ
carboxamidates, and can proceed with different chemoseꢀ
lectivities (carbene insertion into aromatic or aliphatic
C—H bonds, cyclopropanation, and even 1,3ꢀdipolar
cycloaddition).5 Thus, recent efforts have been devoted to
the improvement of chemoselectivity and application of
inexpensive catalysts.6,7
As a part of our ongoing project to develop greenꢀ
chemistry approaches involving catalysis with low cost
transition metals to synthesize heterocyclic compounds,8
we were interested in the synthesis of oxindoles from 2ꢀcyꢀ
anodiazoacetanilides. Padwa and coꢀworkers5 noted that
substituted 2ꢀoxindoles bearing the electronꢀwithdrawing
group (EWG) at the 3ꢀposition are very difficult to isolate
due to their strong polarity. The obtained products were
amorphous substances and cannot be recrystallized from
any solvents. Moreover, the attempts to purify ethyl
2ꢀoxindoleꢀ3ꢀcarboxylates by silica gel column chromaꢀ
tography resulted in their decomposition.5
To solve the isolation problem, a strategy based on
transformation of oxindoles into 2ꢀhydroxyindoles in
the presence of base and hydroxy group protecting reꢀ
agents, such as chlorosilanes and benzoyl chloride, was
developed (Scheme 1).5 Using this approach, 2ꢀtrialkylsiꢀ
lyloxyꢀ and 2ꢀbenzoyloxyindoles were prepared. Generꢀ
Scheme 1
EWG (electronꢀwithdrawing group) = CO2Et, SO2Ph, CN
1 = Me, R2 = H; R3 = (Pri)3Si (TIPS), ButMe2Si (TBDMS), PhCO
Cat is catalyst.
R
* Based on the materials of the International Congress on the Heterocyclic Chemistry "KOSTꢀ2015" (October 18—23, 2015, Moscow,
Russia).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1773—1778, July, 2016.
1066ꢀ5285/16/6507ꢀ1773 © 2016 Springer Science+Business Media, Inc.

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Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Mo et al.
Scheme 2
ally, they have very low polarity and, therefore, can be
easily isolated.
Herein, we report a chemospecific oneꢀpot synthesis
of easily isolable 2ꢀacetoxyindoleꢀ3ꢀcarbonitriles from
2ꢀcyanodiazoacetanilides.
Results and Discussion
In our previous studies on the chemospecific intramoꢀ
lecular Buchner reaction,8a we applied catalysis with inꢀ
expensive CuII complexes, for instance Cu(acac)2, to reꢀ
alize the chemospecific synthesis of 5,7ꢀbicyclic cycloꢀ
heptapyrrolones from Nꢀbenzylꢀ2ꢀcyanodiazoacetamides.
Now, we pursued to realize chemospecific synthesis of
2ꢀoxindoleꢀ3ꢀcarbonitriles from 2ꢀcyanodiazoacetanilꢀ
ides in the presence of CuII catalysts. Note that to date
the only one example was reported for the synthesis of
1ꢀmethylꢀ2ꢀoxindolineꢀ3ꢀcarbonitrile from 2ꢀcyanoꢀ2ꢀdiꢀ
azoꢀNꢀmethylacetanilide under the catalysis of dirhodꢀ
ium(II) tetra(perfluorobutyramidate).5a The aim of the
present investigation is the replacement of precious metal
salts with inexpensive Cu(acac)2 and the improvement of
reaction chemoselectivity.
Condensation of cyanoacetic acid with various secꢀ
ondary amines 1a—l using N,N´ꢀdicyclohexylcarbodiimꢀ
ide (DCC) and 4ꢀ(N,Nꢀdimethylamino)pyridine (DMAP)
as coupling reagents gave a series of cyanoacetanilides
2a—l (Scheme 2). By the reaction with triflic azide as the
diazo transfer agent, cyanoacetanilides 2a—l were conꢀ
verted into the desired starting materials, cyanodiazoacetꢀ
anilides 3a—l. We selected Nꢀbenzylꢀ2ꢀcyanoꢀ2ꢀdiazoacꢀ
etanilide (3a) as a model compound. Starting from comꢀ
pound 3a, we successfully obtained 1ꢀbenzylꢀ2ꢀoxoindoꢀ
lineꢀ3ꢀcarbonitrile (4) in 79% yield under the Cu(acac)2
catalysis. However, the product 4 was difficult to isolate
by column chromatography because of its strong polarity
even using MeOH—CHCl3 as an eluent. Next, triisoꢀ
propylsilyl chloride (TIPSCl) in the presence of triethylꢀ
amine was attempted to protect the hydroxy group generꢀ
ating 1ꢀbenzylꢀ2ꢀtriisopropylsilyloxyindoleꢀ3ꢀcarbonitrile
(5). Product 5 was easily isolated by silica gel column
chromatography but it was contaminated with TIPSCl
used in the reaction in an excess due to its very close
polarity to 5. Because the reaction was conducted in small
scale, this mixture cannot be subjected to vacuum distillaꢀ
tion, which can be regarded as an efficient purification
method for the largeꢀscale syntheses.
Reagents: i. DCC, DMAP, CH2Cl2; ii. CF3SO2N3, Et3N;
iii. Cu(acac)2, ClCH2CH2Cl; iv. 1) Cu(acac)2 (5 mol.%),
ClCH2CH2Cl, 2) AcCl, Et3N; v. (Pri)3SiCl (TIPSCl), Et3N.
Compounds
1—3 and 6
R1
R2
Yield of
6 (%)
50
44
40
63
40
30
42
a
b
c
d
e
f
g
h
i
Bn
Me
cycloꢀHex
Pr
H
H
H
H
H
H
H
H
H
CH2CH=CH2
4ꢀO2NC6H4CH2
2ꢀClC6H4CH2
3ꢀClC6H4CH2
4ꢀClC6H4CH2
Ph
41
40
52
j
H
k
l
Bn
Bn
Me
OMe
47
50
with high purity. 2,5ꢀDiacetoxyꢀ3ꢀcyanoꢀ4,6,7ꢀtrimethꢀ
ylindoles were prepared previously9 via the reaction of triꢀ
methylbenzoquinone and cyanoacetamides in the presꢀ
ence of sodium methoxide.
Next, we explored the scope of substrates 3 in the carbꢀ
ene insertion reaction (see Scheme 2). Substrates 3b—i
bearing different Nꢀalkyl groups afforded the correspondꢀ
ing 2ꢀacetoxyꢀ1ꢀalkylindoleꢀ3ꢀcarbonitriles 6b—i regardꢀ
less the Nꢀalkyl group nature (linear, branched, cyclic, or
Since the synthesis involving TIPSCl was unsuccessꢀ
ful, AcCl was selected as the protecting reagents for the
hydroxy groups of compounds 3a—l with an advantage
that the excessive AcCl can be easily removed by washings
with water. After functionalization of the C—H aromatic
bond by carbene insertion, AcCl and TEA were added
1
in situ into the reaction mixture. According to H NMR
spectral data, 2ꢀacetoxyꢀ3ꢀcyanoindole 6a was obtained

2ꢀAcetoxyindoleꢀ3ꢀcarbonitriles
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1775
2ꢀCyanoꢀNꢀmethylꢀNꢀphenylacetamide (2b). Colorless crysꢀ
tals. Yield 1.43 g (82%), m.p. 87—89 °C (cf. Ref. 11: 76—79 °C).
1H NMR, δ: 7.51—7.47 (m, 2 H); 7.45—7.41 (m, 1 H); 7.26—7.23
(m, 2 H); 3.32 (s, 3 H); 3.25 (s, 2 H). 13C NMR, δ: 161.6, 142.3,
130.4, 128.9, 127.0, 114.1, 37.8, 25.3. IR, ν/cm–1: 2259 (CN),
1668 (C=O).
2ꢀCyanoꢀNꢀcyclohexylꢀNꢀphenylacetamide (2c). Colorless
crystals. Yield 2.13 g (88%), m.p. 158—159 °C. 1H NMR,
δ: 7.50—7.46 (m, 3 H); 7.15—7.13 (m, 2 H); 4.55 (tt, 1 H,
J = 12.0 Hz, J = 3.6 Hz); 3.07 (s, 2 H); 1.86 (d, 2 H, J = 12.8 Hz);
1.75 (d, 2 H, J = 13.6 Hz); 1.58 (d, 1 H, J = 13.2 Hz); 1.39
(ddddd, 2 H, J = 13.6 Hz, J = 13.2 Hz, J = 12.8 Hz, J = 3.6 Hz,
J = 3.2 Hz); 1.05 (dddd, 2 H, J = 12.8 Hz, J = 12.8 Hz, J = 12.0 Hz,
J = 3.6 Hz); 0.91 (dtt, 1 H, J = 13.2 Hz, J = 13.2 Hz, J = 3.6 Hz).
13C NMR, δ: 161.1, 137.6, 129.9, 129.8, 129.3, 114.3, 55.4, 31.2,
26.2, 25.5, 25.1. IR, ν/cm–1: 2261 (CN), 1667 (C=O). MS (ESI),
m/z: 243.1495 [M + H]+. Calculated for C15H19N2O: 243.1492
[M + H]+.
2ꢀCyanoꢀNꢀphenylꢀNꢀpropylacetamide (2d). Colorless crysꢀ
tals. Yield 1.84 g (91%), m.p. 60—64 °C. 1H NMR, δ: 7.51—7.42
(m, 3 H); 7.23—7.21 (m, 2 H); 3.69 (t, 2 H, J = 7.6); 3.19 (s, 2 H);
1.56 (sext, 2 H, J = 7.6 Hz); 0.91 (t, 3 H, J = 7.6 Hz). 13C NMR,
δ: 161.4, 140.9, 130.3, 129.0, 127.9, 114.2, 51.5, 25.7, 20.6, 11.0.
IR, ν/cm–1: 2254 (CN), 1670 (C=O). MS (ESI), m/z: 203.1180
[M + H]+. Calculated for C12H15N2O: 203.1179 [M + H]+.
NꢀAllylꢀ2ꢀcyanoꢀNꢀphenylacetamide (2e).12 Colorless crysꢀ
tals. Yield 1.76 g (88%). 1H NMR, δ: 7.50—7.42 (m, 3 H); 7.21
(d, 2 H, J = 7.2 Hz); 5.85 (ddt, 1 H, J = 16.8 Hz, J = 10.0 Hz,
J = 6.4 Hz); 5.18 (d, 1 H, J = 10.0 Hz); 5.11 (d, 1 H, J = 16.8 Hz);
4.32 (d, 2 H, J = 6.4 Hz); 3.25 (s, 2 H). 13C NMR, δ: 162.0,
140.5, 131.4, 130.3, 129.3, 127.9, 119.4, 113.9, 53.0, 25.6. IR,
ν/cm–1: 2260 (CN), 1743 (C=O).
aromatic). No product of carbene insertion into the C—H
aliphatic bond was observed showing chemospecific forꢀ
mation of 2ꢀacetoxyindoleꢀ3ꢀcarbonitriles.
NꢀAllylꢀsubstituted substrate 3e produced the target
product in low yield (40%); however, even in this case
products of neither cyclopropanation nor 1,3ꢀdipolar
cycloaddition to the allyl group were observed. Substrate
3j bearing two Nꢀphenyl groups was also attempted and
the target indole product was obtained in 52% yield without
formation of the corresponding Buchner reaction product.
Substrates 3k,l bearing the electronꢀdonating methyl and
methoxy groups at the 4ꢀposition of the phenyl ring proꢀ
duced the corresponding carbonitriles 6k,l in moderate
yields. It should be noted that the unambiguous concluꢀ
sion about effect of electronic nature of the substituent on the
reaction yield cannot be drawn from the obtained results.
In summary, we have developed a practical protocol to
synthesize 2ꢀacetoxyindoleꢀ3ꢀcarbonitriles from 2ꢀcyanoꢀ
2ꢀdiazoacetanilides. The distinguished features of the deꢀ
veloped chemospecific approach are the catalysis with inꢀ
expensive Cu(acac)2, the oneꢀpot reaction, and the easiꢀ
ness of the target product isolation. The oneꢀpot reaction
sequence involved insertion of carbene into the aromatic
C—H bond, aromatization, and protection of the hydroxy
group using AcCl in the presence of TEA. The methodolꢀ
ogy showed broad substrate scope and excellent chemoꢀ
specificity.
Experimental
NꢀBenzylꢀ2ꢀcyanoꢀNꢀ(4ꢀnitrophenyl)acetamide (2f). Colorꢀ
less crystals. Yield 2.40 g (81%), m.p. 183—185 °C. 1H NMR, δ:
8.25 (d, 2 H, J = 8.8 Hz); 7.34—7.27 (m, 3 H, J = 2.7 Hz);
7.27—7.21 (m, 2 H); 7.20—7.13 (m, 2 H); 4.95 (s, 2 H); 3.28
(s, 2 H). 13C NMR, δ: 161.1, 147.6, 146.0, 135.2, 129.4, 128.9,
128.4, 125.5, 113.5, 53.8, 26.0. IR, ν/cm–1: 2261 (CN), 1677
(C=O). MS (ESI), m/z: 296.1033 [M + H]+. Calculated for
1,2ꢀDichloroethane was dried over CaCl2, refluxed over
CaH2 under nitrogen, and freshly distilled prior to use. 1H
(400 MHz) and 13C (100 MHz) NMR spectra were recorded on
a Bruker 400 spectrometer in CDCl3 relative to Me4Si (an interꢀ
nal standard). IR spectra were recorded in dichloromethane on
a Nicolet Avatar 300 FTIR spectrometer. High resolution elecꢀ
trospray ionization mass spectrometry was performed with Bruker
Apex IV LC/MSD TOF instrument. Melting points were meaꢀ
sured with a Yanaco MPꢀ500 apparatus and are uncorrected.
Silica gel GF254 plates were used for TLC; spots were visualized
with UV light or iodine vapors. Column chromatography was
performed on silica gel (200—300 mesh) using gradient elution
with petroleum ether (b.p 60—90 °C)—ethyl acetate.
C
16H14N3O3: 296.1030 [M + H]+.
Nꢀ(2ꢀChlorobenzyl)ꢀ2ꢀcyanoꢀNꢀphenylacetamide (2g). Colorꢀ
less crystals. Yield 0.97 g (34%), m.p. 103—104 °C. 1H NMR,
δ: 7.38—7.31 (m, 4 H); 7.29—7.26 (m, 1 H); 7.22—7.17 (m, 2 H);
7.07—7.03 (m, 2 H); 5.08 (s, 2 H); 3.26 (s, 2 H). 13C NMR,
δ: 161.8, 140.1, 134.0, 133.4, 130.9, 130.1, 129.5, 129.2, 128.0,
127.0, 114.0, 50.5, 25.7. IR, ν/cm–1: 2259 (CN), 1674 (C=O).
MS (ESI), m/z: 285.0795 [M + H]+. Calculated for C16H14ClN2O:
285.0789 [M + H]+.
Synthesis of 2ꢀcyanoacetanilides (general procedure).10 A soluꢀ
tion of DCC (2.27 g, 11 mmol) and DMAP (61 mg, 0.5 mmol) in
CH2Cl2 (20 mL) was added to a solution of secondary amine 1
(10 mmol) and 2ꢀcyanoacetic acid (936 mg, 11 mmol) in CH2Cl2
(10 mL) at 0 °C. The resulting solution was stirred for 1 h. Durꢀ
ing this period, a white solid (1,3ꢀdicyclohexylurea) was precipꢀ
itated, which was subsequently filtrated. The solvent was reꢀ
moved under reduced pressure. The resulting crude product was
recrystallized from EtOH to afford pure amides 2a—l.
Nꢀ(3ꢀChlorobenzyl)ꢀ2ꢀcyanoꢀNꢀphenylacetamide (2h). Colorꢀ
less crystals. Yield 1.49 g (54%), m.p. 98—99 °C. 1H NMR,
δ: 7.42—7.39 (m, 3 H); 7.27—7.19 (m, 3 H); 7.08—7.07 (m, 1 H);
7.04—7.01 (m, 2 H); 4.85 (s, 2 H); 3.24 (s, 2 H). 13C NMR,
δ: 161.9, 140.3, 138.1, 134.3, 130.3, 129.8, 129.3, 128.9, 128.1,
128.0, 127.1, 113.9, 53.1, 25.7. IR, ν/cm–1: 2258 (CN), 1657
(C=O). MS (ESI), m/z: 285.0794 [M + H]+. Calculated for
C16H14ClN2O: 285.0789 [M + H]+.
NꢀBenzylꢀ2ꢀcyanoꢀNꢀphenylacetamide (2a). Colorless crysꢀ
tals. Yield 1.25 g (50%), m.p. 94—97 °C (cf. Ref. 11: 91—94 °C).
1H NMR, δ: 7.38—7.37 (m, 3 H); 7.32—7.22 (m, 3 H); 7.22—7.11
(m, 2 H); 7.07—6.91 (m, 2 H); 4.89 (s, 2 H); 3.21 (s, 2 H). 13C
NMR, δ: 161.7, 140.6, 136.1, 130.2, 129.2, 129.1, 128.5, 128.2,
127.9, 114.1, 53.7, 25.7. IR, ν/cm–1: 2259 (CN), 1664 (C=O).
Nꢀ(4ꢀChlorobenzyl)ꢀ2ꢀcyanoꢀNꢀphenylacetamide (2i). Colorꢀ
less crystals. Yield 2.05 g (72%), m.p. 131—132 °C. 1H NMR,
δ: 7.42—7.39 (m, 3 H); 7.25 (dd, 2 H, J = 7.2 Hz, J = 2.0 Hz); 7.08
(dd, 2 H, J = 7.2 Hz, J = 2.0 Hz); 7.04—7.01 (m, 2 H); 4.85 (s, 2 H);
3.24 (s, 2 H). 13C NMR, δ: 161.8, 140.3, 134.6, 133.8, 130.4,
130.3, 129.3, 128.7, 128.1, 113.9, 53.0, 25.7. IR, ν/cm–1: 2259

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Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Mo et al.
(CN), 1676 (C=O). MS (ESI), m/z: 285.0795 [M + H]+. Calcuꢀ
lated for C16H14ClN2O: 285.0789 [M + H]+.
2ꢀCyanoꢀN,Nꢀdiphenylacetamide (2j). Colorless crystals.
Yield 2.00 g (88%), m.p. 161—162 °C (cf. Ref. 12: 154—156 °C).
1H NMR, δ: 7.47—7.23 (m, 10 H); 3.41 (s, 2 H). 13C NMR,
δ: 161.6, 141.4, 130.5, 129.1, 128.4, 126.9, 125.8, 113.9, 26.7. IR,
ν/cm–1: 2260 (CN), 1676 (C=O).
NꢀBenzylꢀ2ꢀcyanoꢀNꢀ(4ꢀmethylphenyl)acetamide (2k). Colorꢀ
less crystals. Yield 2.53 g (96%), m.p. 104—106 °C. 1H NMR,
δ: 7.29—7.25 (m, 3 H); 7.19—7.15 (m, 4 H); 6.87—6.84 (m, 2 H);
4.86 (s, 2 H); 3.21 (s, 2 H); 2.35 (s, 3 H). 13C NMR, δ: 161.8,
139.3, 137.9, 136.2, 130.8, 129.0, 128.5, 127.9, 127.8, 114.1,
53.7, 25.7, 21.1 IR, ν/cm–1: 2259 (CN), 1670 (C=O). MS (ESI),
m/z: 265.1339 [M + H]+. Calculated for C17H17N2O: 265.1335
[M + H]+.
NꢀBenzylꢀ2ꢀcyanoꢀNꢀ(4ꢀmethoxyphenyl)acetamide (2l). Colorꢀ
less crystals. Yield 2.21 g (79%), m.p. 108—110 °C. 1H NMR,
δ: 7.29—7.25 (m, 3 H); 7.19—7.16 (m, 2 H); 6.90—6.84 (m, 4 H);
4.84 (s, 2 H); 3.79 (s, 3 H); 3.21 (s, 2 H). 13C NMR, δ: 162.1,
159.7, 136.2, 133.0, 129.2, 129.0, 128.5, 127.8, 115.2, 114.2,
55.4, 53.7, 25.6. IR, ν/cm–1: 2260 (CN), 1670 (C=O). MS (ESI),
m/z: 281.1287 [M + H]+. Calculated for C17H17N2O2: 281.1285
[M + H]+.
Synthesis of 2ꢀcyanoꢀ2ꢀdiazoacetanilides 3a—l (general proꢀ
cedure).13 Sodium azide (2.34 g, 36 mmol) was dissolved in
a mixture of H2O (10 mL) and CH2Cl2 (5 mL) and the resulting
solution was cooled to 0 °C in an iceꢀwater bath. To this vigorꢀ
ously stirred solution, triflic anhydride (1 mL, 6 mmol) was addꢀ
ed dropwise through a syringe over 10 min. After 2 h stirring at
0 °C, the organic phase was separated and the aqueous phase was
extracted with CH2Cl2 (5 mL). The combined organics were
washed with aqueous NaHCO3 (10 mL), dried with Na2SO4,
and immediately used on the next step. To a 0 °C solution of
amide 2a—l (5 mmol) in MeCN (10 mL), freshly prepared solution
of CF3SO2N3 in CH2Cl2 was added under nitrogen followed by
addition of TEA (758 mg, 7.5 mmol). The resulting mixture was
stirred at room temperature for 18 h and concentrated under
reduced pressure. The residue was purified by silica gel column
chromatography (gradient elution with ethyl acetate—petroleum
ether (1 : 4 → 4 : 1, v/v) to give pure products 3a—l.
NꢀBenzylꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀphenylacetamide (3a). Yellow
crystals. Yield 1.24 g (90%), m.p. 46—47 °C. 1H NMR, δ: 7.45—7.40
(m, 1 H), 7.38—7.34 (m, 2 H); 7.30—7.26 (m, 3 H); 7.21—7.19
(m, 2 H); 7.07—7.05 (m, 2 H); 4.93 (s, 2H). 13C NMR, δ: 159.3,
139.5, 136.1, 129.9, 129.7, 128.9, 128.5, 128.0, 127.9, 107.0,
54.9. IR, ν/cm–1: 2215 (CN), 2121 (CN2), 1638 (C=O). MS
(ESI), m/z: 277.1092 [M + H]+. Calculated for C16H13N4O:
277.1084 [M + H]+.
2ꢀCyanoꢀ2ꢀdiazoꢀNꢀmethylꢀNꢀphenylacetamide (3b).5a Yelꢀ
low oil. Yield 0.90 g (90%). 1H NMR, δ: 7.48—7.44 (m, 3 H);
7.29—7.24 (m, 2 H); 3.37 (s, 3 H). 13C NMR, δ: 159.2, 141.2,
130.1, 129.5, 127.7, 107.2, 39.1. IR, ν/cm–1: 2180 (CN), 2135
(CN2), 1729 (C=O).
2ꢀCyanoꢀNꢀcyclohexylꢀ2ꢀdiazoꢀNꢀphenylacetamide (3c).
Yellow oil. Yield 1.07 g (80%). 1H NMR, δ: 7.52 (t, 1 H, J = 7.6 Hz);
7.44 (dd, 2 H, J = 8.0 Hz, J = 7.6 Hz); 7.17 (d, 2 H, J = 8.0 Hz);
4.55 (tt, 1 H, J = 12.0 Hz, J = 3.6 Hz); 1.87 (d, 2 H, J = 12.4 Hz);
1.77 (d, 2 H, J = 13.6 Hz); 1.59 (d, 1 H, J = 12.8 Hz); 1.39
(ddddd, 2 H, J = 13.6 Hz, J = 13.2 Hz, J = 12.8 Hz, J = 3.6 Hz,
J = 3.2 Hz); 1.15 (dddd, 2 H, J = 12.8 Hz, J = 12.4 Hz, J = 12.0 Hz,
J = 3.6 Hz); 0.93 (dtt, 1 H, J = 13.2 Hz, J = 12.8 Hz, J = 3.6 Hz).
13C NMR, δ: 158.6, 136.3, 131.2, 130.2, 129.4, 107.0, 56.7, 31.3,
25.7, 25.1. IR, ν/cm–1: 2213 (CN), 2125 (CN2), 1724 (C=O).
MS (ESI), m/z: 269.1399 [M + H]+. Calculated for C15H17N4O:
269.1397 [M + H]+.
2ꢀCyanoꢀ2ꢀdiazoꢀNꢀphenylꢀNꢀpropylacetamide (3d). Yellow
oil. Yield 1.02 g (90%). 1H NMR, δ: 7.48—7.43 (m, 3 H); 7.26—7.21
(m, 2 H); 3.72 (t, 2 H, J = 7.6 Hz); 1.59 (sext, 2 H, J = 7.6 Hz);
0.92 (t, 3 H, J = 7.6 Hz). 13C NMR, δ: 158.9, 139.7, 130.0,
129.6, 128.7, 107.2, 52.8, 20.8, 11.0. IR, ν/cm–1: 2216 (CN),
2125 (CN2), 1729 (C=O). MS (ESI), m/z: 229.1083 [M + H]+.
Calculated for C12H13N4O: 229.1084 [M + H]+.
NꢀAllylꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀphenylacetamide (3e). Yellow oil.
Yield 0.7 g (62%). 1H NMR, δ: 7.54—7.38 (m, 3 H); 7.26—7.22
(m, 2 H); 5.93—5.83 (m, 1 H); 5.19 (d, 1 H, J = 10.4 Hz); 5.14
(d, 1 H, J = 18.4 Hz); 4.35 (d, 2 H, J = 4.8 Hz). 13C NMR,
δ: 159.0, 139.7, 131.8, 129.9, 129.7, 128.7, 119.1, 107.1, 54.1. IR,
ν/cm–1: 2232 (CN), 2123 (CN2), 1701 (C=O). MS (ESI), m/z:
227.0922 [M + H]+. Calculated for C12H11N4O: 227.0927
[M + H]+.
2ꢀCyanoꢀ2ꢀdiazoꢀNꢀ(4ꢀnitrobenzyl)ꢀNꢀphenylacetamide (3f).
Yellow crystals. Yield 1.44 g (90%), m.p. 132—134 °C. 1H NMR,
δ: 8.16 (d, 2 H, J = 8.7 Hz); 7.47—7.39 (m, 5 H); 7.08 (d, 2 H,
J = 8.7 Hz); 5.02 (s, 2 H). 13C NMR, δ: 159.8, 147.6,
143.3, 139.2, 130.2, 130.1, 129.7, 128.6, 123.8, 106.7, 54.2.
IR, ν/cm–1: 2217 (CN), 2123 (CN2), 1638 (C=O). MS (ESI),
m/z: 322.0937 [M + H]+. Calculated for C16H12N5O3: 322.0935
[M + H]+.
Nꢀ(2ꢀChlorobenzyl)ꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀphenylacetamide
(3g). Yellow oil. Yield 1.41 g (91%). 1H NMR, δ: 7.43—7.28
(m, 5 H); 7.24—7.19 (m, 2 H); 7.11—7.09 (m, 2 H); 5.12 (s, 2 H).
13C NMR, δ: 159.5, 139.2, 133.8, 133.5, 130.4, 129.8, 129.8,
129.6, 129.2, 128.8, 127.0, 107.0, 51.7. IR, ν/cm–1: 2215 (CN),
2122 (CN2), 1734 (C=O). MS (ESI), m/z: 311.0691 [M + H]+.
Calculated for C16H12ClN4O: 311.0694 [M + H]+.
Nꢀ(3ꢀChlorobenzyl)ꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀphenylacetamide
(3h). Yellow oil. Yield 1.13 g (73%). 1H NMR, δ: 7.47—7.37 (m,
3 H); 7.27—7.19 (m, 3 H); 7.08—7.06 (m, 3 H); 4.89 (s, 2 H).
13C NMR, δ: 159.4, 139.3, 138.1, 134.4, 130.0, 129.8, 129.8,
128.9, 128.8, 128.1, 127.0, 106.9, 54.3. IR, ν/cm–1: 2213 (CN),
2123 (CN2), 1767 (C=O). MS (ESI), m/z: 311.0696 [M + H]+.
Calculated for C16H12ClN4O: 311.0694 [M + H]+.
Nꢀ(4ꢀChlorobenzyl)ꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀphenylacetamide
(3i). Yellow crystals. Yield 1.46 g (94%), m.p. 67—68 °C. 1H NMR,
δ: 7.47—7.42 (m, 1 H); 7.41—7.36 (m, 2 H); 7.27—7.24 (m, 2 H);
7.16—7.13 (m, 2 H); 7.07—7.04 (m, 2 H); 4.89 (s, 2 H). 13C NMR,
δ: 159.4, 139.3, 134.6, 133.9, 130.4, 130.0, 129.8, 128.9, 128.7,
106.9, 54.2. IR, ν/cm–1: 2213 (CN), 2121 (CN2), 1763 (C=O).
MS (ESI), m/z: 311.0700 [M + H]+. Calculated for C16H12ClN4O:
311.0694 [M + H]+.
2ꢀCyanoꢀ2ꢀdiazoꢀN,Nꢀdiphenylacetamide (3j). Yellow crysꢀ
tals. Yield 1.20 g (92%), m.p. 96—99 °C. 1H NMR, δ: 7.43—7.38
(m, 4 H); 7.36—7.33 (m, 2 H); 7.28—7.25 (m, 4 H). 13C NMR,
δ: 159.8, 141.3, 129.7, 128.1, 127.4, 106.9. IR, ν/cm–1: 2218
(CN), 2129 (CN2), 1735 (C=O). MS (ESI), m/z: 263.0925
[M + H]+. Calculated for C15H11N4O: 263.0927 [M + H]+.
NꢀBenzylꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀ(4ꢀmethylphenyl)acetamide
(3k). Yellow crystals. Yield 1.00 g (69%), m.p. 95—96 °C. 1H NMR,
δ: 7.29—7.25 (m, 3 H); 7.21—7.19 (m, 2 H); 7.15 (d, 2 H,
J = 8.0 Hz); 6.92 (d, 2 H, J = 8.0 Hz); 4.89 (s, 2 H); 2.37 (s, 3 H).
13C NMR, δ: 159.4, 140.0, 136.8, 136.2, 130.4, 128.9, 128.6,
128.5, 127.8, 107.2, 54.9, 21.2. IR, ν/cm–1: 2213 (CN), 2124

2ꢀAcetoxyindoleꢀ3ꢀcarbonitriles
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1777
(CN2), 1724 (C=O). MS (ESI), m/z: 291.1244 [M + H]+. Calꢀ
culated for C17H15N4O: 291.1240 [M + H]+.
(d, 1 H, J = 12.8 Hz); 1.42 (ddddd, 2 H, J = 13.2 Hz, J = 13.2 Hz,
J = 12.8 Hz, J = 3.6 Hz, J = 3.2 Hz); 1.30 (dtt, 1 H, J = 13.2 Hz,
J = 12.8 Hz, J = 3.8 Hz). 13C NMR, δ: 166.4, 147.1, 130.7,
125.5, 123.0, 122.1, 119.6, 114.1, 111.8, 76.1, 56.1, 31.2, 26.1,
25.3, 20.5. IR, ν/cm–1: 2217 (CN), 1797 (C=O). MS (ESI), m/z:
305.1264 [M + H]+. Calculated for C17H18N2NaO2: 305.1260
[M + H]+.
3ꢀCyanoꢀ1ꢀpropylꢀ1Hꢀindolꢀ2ꢀyl acetate (6d). Colorless oil.
Yield 150 mg (63%). 1H NMR, δ: 7.68—7.66 (m, 1 H); 7.33—7.25
(m, 3 H); 3.97 (t, 2 H, J = 7.2 Hz); 2.46 (s, 3 H); 1.80 (sext, 2 H,
J = 7.2 Hz); 0.92 (t, 3 H, J = 7.2 Hz). 13C NMR, δ: 166.1, 147.2,
131.3, 125.2, 123.4, 122.4, 119.4, 114.1, 110.3, 75.5, 44.6, 22.6,
20.3, 11.2. IR, ν/cm–1: 2219 (CN), 1797 (C=O). MS (ESI), m/z:
265.0946 [M + H]+. Calculated for C14H14N2NaO2: 265.0947
[M + H]+.
1ꢀAllylꢀ3ꢀcyanoꢀ1Hꢀindolꢀ2ꢀyl acetate (6e). Colorless oil.
Yield 96 mg (40%). 1H NMR, δ: 7.70—7.68 (m, 1 H); 7.30—7.26
(m, 3 H); 5.87 (ddt, 1 H, J = 17.2 Hz, J = 10.2 Hz, J = 5.2 Hz);
5.23 (d, 1 H, J = 10.2 Hz); 5.08 (d, 1 H, J = 17.2 Hz); 4.63 (d, 2 H,
J = 5.2 Hz); 2.44 (s, 3 H). 13C NMR, δ: 166.1, 147.1, 131.4,
131.0, 125.1, 123.6, 122.6, 119.5, 118.2, 113.9, 110.5, 76.1, 45.2,
20.3. IR, ν/cm–1: 2219 (CN), 1798 (C=O). MS (ESI), m/z:
263.0793 [M + H]+. Calculated for C14H12N2NaO2: 263.0791
[M + H]+.
NꢀBenzylꢀ2ꢀcyanoꢀ2ꢀdiazoꢀNꢀ(4ꢀmethylphenyl)acetamide
(3l). Yellow oil. Yield 1.47 g (96%). 1H NMR, δ: 7.29—7.27 (m, 3 H);
7.20—7.18 (m, 2 H); 6.95—6.91 (m, 2 H); 6.85—6.82 (m, 2 H);
4.87 (s, 2 H); 3.80 (s, 3 H). 13C NMR, δ: 160.6, 159.6, 136.1,
132.0, 130.2, 129.0, 128.5, 127.9, 114.9, 107.1, 55.5, 54.9. IR,
ν/cm–1: 2217 (CN), 2123 (CN2), 1637 (C=O). MS (ESI), m/z:
307.1195 [M + H]+. Calculated for C17H15N4O2: 307.1190
[M + H]+.
1ꢀBenzylꢀ2ꢀoxoindolineꢀ3ꢀcarbonitrile (4). A solution of
2ꢀcyanodiazoacetamide 3 (276 mg, 1 mmol) in 1,2ꢀdichloroꢀ
ethane (5 mL) was added dropwise via syringe over 40 min to
a refluxing solution of Cu(acac)2 (13 mg, 0.05 mmol) in 1,2ꢀdichloꢀ
roethane (5 mL) under nitrogen. The reaction course was moniꢀ
tored by TLC. After complete consumption of the starting mateꢀ
rial, the reaction mixture was concentrated under reduced presꢀ
sure. Product 4 was purified by silica gel column chromatoꢀ
graphy (successive elution with the ethyl acetate—petroleum ether
gradient (1 : 1 → 100 : 0, v/v) and methanol). Colorless crystals.
Yield 0.196 g (79%), m.p. 97—98 °C. 1H NMR, δ: 7.45—7.43
(m, 1 H); 7.36—7.25 (m, 6 H); 7.15—7.11 (m, 1 H); 6.81—6.79
(m, 1 H); 4.96 (d, 1 H, J = 7.4 Hz); 4.89 (d, 1 H, J = 7.4 Hz);
4.63 (s, 1 H). 13C NMR, δ: 167.2, 142.9, 134.5, 130.3, 129.0,
128.1, 127.4, 124.9, 123.8, 120.1, 113.9, 110.2, 44.7, 36.6. IR,
ν/cm–1: 2203 (CN), 1726 (C=O). MS (ESI), m/z: 271.0852
[M + H]+. Calculated for C16H12N2NaO: 271.0842 [M + H]+.
Synthesis of compounds 6 (general procedure). A solution of
2ꢀcyanoacetamide 3 (1 mmol) in 1,2ꢀdichloroethane (5 mL) was
added dropwise via syringe over 40 min to a refluxing solution of
Cu(acac)2 (13 mg, 0.05 mmol) in 1,2ꢀdichloroethane (5 mL)
under nitrogen. The reaction course was monitored by TLC.
After complete consumption of the starting material, the reꢀ
action mixture was cooled to 0 °C and treated with triethylamine
(121 mg, 1.2 mmol) and then a solution of AcCl (94 mg,
1.2 mmol) in 1,2ꢀdichloroethane (5 mL) was added dropwise via
syringe over 30 min. After 1 h, the solution was concentrated
under reduced pressure and the residue was purified by silica gel
column chromatography (elution with ethyl acetate—petroleum
ether (1 : 9 → 1 : 1, v/v) to afford pure products 6.
3ꢀCyanoꢀ1ꢀ(4ꢀnitrobenzyl)ꢀ1Hꢀindolꢀ2ꢀyl acetate (6f). Colorꢀ
1
less crystals. Yield 134 mg (40%), m.p. 188—192 °C. H NMR,
δ: 8.16 (d, 2 H, J = 8.4 Hz); 7.72 (d, 1 H, J = 7.6 Hz); 7.33—7.25
(m, 4 H); 7.13 (d, 1 H, J = 7.6 Hz); 5.33 (s, 2 H); 2.40 (s, 3 H).
13C NMR, δ: 166.0, 147.7, 147.1, 142.0, 131.2, 127.2, 125.2,
124.3, 124.2, 123.1, 119.8, 113.5, 110.3, 71.7, 45.7, 20.2. IR,
ν/cm–1: 2203 (CN), 1727 (C=O). MS (ESI), m/z: 336.0985
[M + H]+. Calculated for C18H14N3O4: 336.0979 [M + H]+.
1ꢀ(2ꢀChlorobenzyl)ꢀ3ꢀcyanoꢀ1Hꢀindolꢀ2ꢀyl acetate (6g).
Colorless oil. Yield 130 mg (40%). 1H NMR, δ: 7.73 (d, 1 H,
J = 7.2 Hz); 7.43 (d, 1 H, J = 7.9 Hz); 7.32—7.29 (m, 1 H);
7.27—7.22 (m, 2 H); 7.19 (d, 1 H, J = 7.7 Hz); 7.12 (t, 1 H,
J = 7.7 Hz); 6.65 (d, 1 H, J = 7.7 Hz); 5.33 (s, 2 H); 2.37 (s, 3 H).
13C NMR, δ: 166.0, 147.4, 132.4, 132.2, 131.5, 129.7, 129.4,
127.5, 127.5, 125.2, 124.0, 122.9, 119.7, 113.7, 110.5, 76.7, 43.9,
20.2 IR, ν/cm–1: 2222 (CN), 1801 (C=O). MS (ESI), m/z:
325.0732 [M + H]+. Calculated for C18H14ClN2O2: 325.0738
[M + H]+.
1ꢀBenzylꢀ3ꢀcyanoꢀ1Hꢀindolꢀ2ꢀyl acetate (6a). Colorless crysꢀ
tals. Yield 148 mg (51%), m.p. 143—144 °C. 1H NMR, δ: 7.69
(d, 1 H, J = 7.6 Hz); 7.33—7.21 (m, 6 H); 7.10 (d, 2 H, J = 6.8 Hz);
5.21 (s, 2 H); 2.35 (s, 3 H). 13C NMR, δ: 165.9, 147.3, 134.9,
131.5, 129.0, 128.2, 126.5, 125.2, 123.7, 122.7, 119.5, 113.9,
110.7, 76.3, 46.5, 20.2. IR, ν/cm–1: 2221 (CN), 1784 (C=O).
MS (ESI), m/z: 291.1130 [M + H]+. Calculated for C18H15N2O2:
291.1128 [M + H]+.
1ꢀ(3ꢀChlorobenzyl)ꢀ3ꢀcyanoꢀ1Hꢀindolꢀ2ꢀyl acetate (6h).
Colorless oil. Yield 133 mg (41%). 1H NMR, δ: 7.77—7.68
(m, 1 H); 7.31—7.18 (m, 6 H); 6.95 (d, 1 H, J = 7.2 Hz); 5.18
(s, 2 H); 2.38 (s, 3 H). 13C NMR, δ: 165.9, 147.2, 136.9, 135.0,
131.4, 130.4, 128.5, 126.7, 125.2, 124.6, 124.0, 122.9, 119.7,
113.7, 110.5, 77.2, 45.9, 20.2. IR, ν/cm–1: 2210 (CN), 1738
(C=O). MS (ESI), m/z: 325.0739 [M + H]+. Calculated for
3ꢀCyanoꢀ1ꢀmethylꢀ1Hꢀindolꢀ2ꢀyl acetate (6b). Colorless
1
crystals. Yield 94 mg (44%), m.p. 61—63 °C. H NMR, δ: 7.66
C
18H14ClN2O2: 325.0738 [M + H]+.
(d, 1 H, J = 7.2 Hz); 7.34—7.26 (m, 3 H); 3.59 (s, 3 H); 2.47 (s, 3 H).
13C NMR, δ: 166.4, 147.5, 132.0, 125.0, 123.5, 122.6, 119.4,
114.0, 110.0, 75.4, 28.9, 20.2. IR, ν/cm–1: 2206 (CN), 1729
(C=O). MS (ESI), m/z: 237.0633 [M + H]+. Calculated for
1ꢀ(4ꢀChlorobenzyl)ꢀ3ꢀcyanoꢀ1Hꢀindolꢀ2ꢀyl acetate (6i). Colorꢀ
1
less crystals. Yield 136 mg (42%), m.p. 143—146 °C. H NMR,
δ: 7.70 (dd, 1 H, J = 6.9 Hz, J = 1.2 Hz), 7.31—7.23 (m, 4 H);
7.16 (dd, 1 H, J = 7.2 Hz, J = 1.2 Hz); 7.04 (d, 2 H, J = 8.4 Hz);
5.18 (s, 2 H); 2.38 (s, 3 H). 13C NMR, δ: 166.0, 147.2, 134.1,
133.4, 131.4, 129.2, 127.8, 125.2, 123.9, 122.9, 119.7, 113.7,
110.5, 76.6, 45.8, 20.2. IR, ν/cm–1: 2222 (CN), 1800 (C=O).
MS (ESI), m/z: 325.0731 [M + H]+. Calculated for C18H14ClN2O2:
325.0738 [M + H]+.
C
12H10N2NaO2: 237.0634 [M + H]+.
3ꢀCyanoꢀ1ꢀcyclohexylꢀ1Hꢀindolꢀ2ꢀyl acetate (6c). Colorless
crystals. Yield 113 mg (40%), m.p. 77—81 °C. 1H NMR, δ:
7.69—7.65 (m, 1 H); 7.52—7.47 (dd, 1 H, J = 6.4 Hz, J = 2.6 Hz);
7.30—7.23 (dd, 2 H, J = 5.9 Hz, J = 2.5 Hz); 4.11 (tt, 1 H,
J = 12.4 Hz, J = 3.8 Hz); 2.48 (s, 3 H); 2.08 (dddd, 2 H, J = 12.8 Hz,
J = 12.4 Hz, J = 12.0 Hz, J = 3.6 Hz); 2.00—1.89 (m, 4 H); 1.81
3ꢀCyanoꢀ1ꢀphenylꢀ1Hꢀindolꢀ2ꢀyl acetate (6j). Yellow crysꢀ
1
tals. Yield 144 mg (52%), m.p. 125—128 °C. H NMR, δ: 7.74

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Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Mo et al.
(d, 1 H, J = 7.6 Hz); 7.59—7.52 (m, 3 H); 7.38—7.36 (m, 2 H);
7.32 (td, 1 H, J = 7.6 Hz, J = 1.2 Hz); 7.27 (td, 1 H, J = 7.6 Hz,
J = 1.2 Hz); 7.19 (d, 1 H, J = 8.0 Hz); 2.21 (s, 3 H). 13C NMR,
δ: 166.4, 147.1, 133.7, 132.8, 129.8, 129.3, 127.0, 124.9, 124.1,
123.1, 119.5, 113.6, 111.1, 77.4, 20.0. IR, ν/cm–1: 2220 (CN),
1794 (C=O). MS (ESI), m/z: 299.0792 [M + H]+. Calculated for
2. (a) M. Platon, R. Amardeil, L. Djakovitch, J.ꢀC. Hierso,
Chem. Soc. Rev., 2012, 41, 3929; (b) M. Shiri, Chem. Rev.,
2012, 112, 3508; (c) K. Krueger, A. Tillack, M. Beller, Adv.
Synth. Catal., 2008, 350, 2153.
3. Y. H. Jang, S. W. Youn, Org. Lett., 2014, 16, 3720 (and the
references therein).
4. (a) T. L. Guo, F. Huang, L. K. Yu, Z. K. Yu, Tetrahedron
Lett., 2015, 56, 296; (b) J. H. J. Song, J. T. Reeves, D. R.
Fandrick, Z. L. Tan, N. K. Yee, C. H. Senanayake, ARKIVOC,
2010, Part (i), 390.
5. (a) S. Miah, A. M. Z. Slawin, C. J. Moody, S. M. Sheehan,
J. P. Marino, Jr., M. A. Semones, A. Padwa, I. C. Richards,
Tetrahedron, 1996, 52, 2489; (b) D. S. Brown, M. C. Elliott,
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J. Org. Chem., 1994, 59, 2447.
C
17H12N2NaO2: 299.0791 [M + H]+.
1ꢀBenzylꢀ3ꢀcyanoꢀ5ꢀmethylꢀ1Hꢀindolꢀ2ꢀyl acetate (6k).
Colorless crystals. Yield 143 mg (47%), m.p. 107—111 °C.
1H NMR, δ: 7.49 (s, 1 H); 7.33—7.27 (m, 3 H); 7.11—7.04
(m, 4 H); 5.18 (s, 2 H); 2.44 (s, 3 H); 2.35 (s, 3 H). 13C NMR,
δ: 166.0, 147.2, 135.0, 132.4, 129.8, 129.0, 128.1, 126.5, 125.4,
125.2, 119.3, 114.0, 110.4, 75.8, 46.5, 21.4, 20.2. IR, ν/cm–1
:
2216 (CN), 1798 (C=O). MS (ESI), m/z: 305.1290 [M + H]+.
Calculated for C19H17N2O2: 305.1285 [M + H]+.
1ꢀBenzylꢀ3ꢀcyanoꢀ5ꢀmethoxyꢀ1Hꢀindolꢀ2ꢀyl acetate (6l).
Colorless crystals. Yield 160 mg (50%), m.p. 114—116 °C. 1H NMR,
δ: 7.33—7.28 (m, 3 H); 7.14—7.08 (m, 4 H); 6.86 (dd, 1 H,
J = 8.8 Hz, J = 2.4 Hz); 5.17 (s, 2 H); 3.84 (s, 3 H); 2.35 (s, 3 H).
13C NMR, δ: 166.0, 156.2, 147.1, 135.0, 129.0, 128.2, 126.5,
126.1, 126.0, 114.1, 114.0, 111.7, 101.2, 76.2, 55.7, 46.6, 20.2.
IR, ν/cm–1: 2216 (CN), 1794 (C=O). MS (ESI), m/z: 343.1038
[M + H]+. Calculated for C19H16N2NaO3: 343.1053 [M + H]+.
6. H. L. Wang, Z. Li, G. W. Wang, S. D. Yang, Chem. Comꢀ
mun., 2011, 47, 11336.
7. S. Y. Mo, Z. H. Yang, J. X. Xu, Eur. J. Org. Chem., 2014,
3923 (and the references therein).
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Mo, X. H. Li, J. X. Xu, J. Org. Chem., 2014, 79, 9186; (c) S. Y.
Mo, C. C. Xu, J. X. Xu, Adv. Synth. Catal., 2016, 358, 1767.
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A. A. Svishchuk, Chem. Heterocycl. Compd., 1979, 15, 116
[Khim. Geterotsikl. Soedin., 1979, 129].
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P. J. Scammells, J. Med. Chem., 2003, 45, 1870.
11. Y. Kobayashi, T. Harayama, Org. Lett., 2009, 11, 1603.
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2009, 131, 6970.
This work was supported in part by the National Basic
Research Program of China (Project No.2013CB328905)
and the National Natural Science Foundation of China
(Project Nos 21372025 and 21572017).
References
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Received January 10, 2015;
in revised form February 21, 2016