Synthesis of 3,3-disubstituted oxindoles by visible-light-mediated radical reactions of aryl diazonium salts with N-arylacrylamides

Article abstract of DOI:10.1021/jo401894b

A mild and efficient visible-light-mediated diarylation of N-arylacrylamides with aryl diazonium salts under mild conditions has been developed. This method provides convenient access to a variety of useful 3,3-disubstituted oxindoles by constructing two C-C bonds in one step.

Full text of DOI:10.1021/jo401894b

Note
pubs.acs.org/joc
Synthesis of 3,3-Disubstituted Oxindoles by Visible-Light-Mediated
Radical Reactions of Aryl Diazonium Salts with N‑Arylacrylamides
,†
‡
,†
†
†
†
,‡
Weijun Fu,* Fengjuan Xu, Yuqin Fu,* Mei Zhu, Jiaqi Yu, Chen Xu, and Dapeng Zou*
†
College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022, P. R. China
‡
College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, Henan 450052, P. R. China
*
S Supporting Information
ABSTRACT: A mild and efficient visible-light-mediated diarylation of N-arylacrylamides with aryl diazonium salts under mild
conditions has been developed. This method provides convenient access to a variety of useful 3,3-disubstituted oxindoles by
constructing two C−C bonds in one step.
he prevalence of the oxindole ring system that represents a
acetates, and heteroarenes using diazonium salts by photoredox
13
T
key structural component in natural products and
catalysis. Zhou and co-workers reported a metal-free, visible-
light-induced [4 + 2] benzannulation of biaryldiazonium salts
with alkynes to form phenanthrenes with eosin Y as the
1
pharmaceutical chemistry is well-established. Moreover,
functionalized oxindoles have also found wide utility as versatile
starting materials for the synthesis of a broad range of
heterocyclic compounds. As such, the search for sustainable
and more efficient methods for the preparation of oxindoles is of
14
photoredox catalyst. Inspired by these pioneering works and in
connection with radical-mediated cyclizations of N-arylacryla-
mides, we herein report an efficient procedure for the
preparation of a series of 3,3-disubstituted oxoindoles via
visible-light-promoted diarylation of N-arylacrylamides with
aryl diazonium salts (Scheme 1).
2
constant interest. Among many different approaches to 3,3′-
disubstituted oxindoles, palladium-catalyzed oxidative difunc-
tionalization alkenes in N-arylacrylamides provides direct and
3
potentially more efficient access to oxindoles, particularly
At first, we examined the reaction of N-arylacrylamide 1a with
diazonium salt 2a under various conditions, and the results are
summarized in Table 1. When the reaction of 1a with 2a was
because additional functional groups can be introduced into
the oxindole framework by a single transformation. These
methods, however, have always presented some limitations, such
as the use of equivalent oxidant and harsh reaction conditions. An
alternative method is the radical-mediated cyclization of N-
arylacrylamides, which is performed with or without the aid of
transition-metal catalysts. Yang and co-workers reported an
efficient carbon phosphorylation of N-arylacrylamides with silver
carried out in the presence of Ru(bpy)
under N in MeCN for 12 h, the yield of 3a was only 46% (Table
, entry 1). When the solvent was changed to MeOH, the yield
Cl ·6H O (5 mol %)
2 2
3
2
1
improved to 65%, whereas other solvents such as DMF and THF
were found to be less effective for this reaction (Table 1, entries
2
−4). Increasing the amount of diazonium salt 2a led to an
4
5
improvement in the yield (Table 1, entries 5 and 6). Using 2.5
equiv of 2a gave a good yield, but when the amount of 2a was
increased to 4.0 equiv, the yield of 3a did not increase further
catalysts under mild conditions. The radical alkylarylation,
6
7
8
arylcarbonylation, azidoarylation, and arylsulfonylation of N-
arylacrylamides have since been disclosed by several groups,
allowing the effective formation of oxindole framework. To the
best of our knowledge, the similar protocol using aryl diazonium
salts as aryl radicals is not well-documented.
(
Table 1, entry 7). Under the same reaction conditions,
employment of the catalyst Ru(bpy) (PF ) afforded a similar
3
6 2
result. In contrast, photocatalytic active organic dye eosin Y
resulted in low yield. As expected, no reaction occurred in the
absence of photocatalyst (entry 10). When the reaction was
carried out under ambient light, the reaction was much more
sluggish and had a dramatically decreased yield (entry 11). The
molecular structure of 3a was confirmed by its X-ray single-
crystal diffraction (see the Supporting Information).
Aryl radicals have been widely used to create carbon−carbon
and carbon−heteroatom bonds in organic synthesis over the past
9
several decades. Because they are one of the most powerful
synthetic tools, various methods for the generation of aryl
1
0
radicals have been developed. Among many different
approaches to aryl radicals, the photoinduced reduction of aryl
diazonium salts through electron transfer (PET) using [Ru-
Under the optimized conditions, N-arylacrylamide 1a was
reacted with various aryl diazonium salts 2a−h (2.5 equiv) to give
11
(
bpy) ]Cl or organic dyes are particularly attractive. Recently,
3 2
many examples for radical arylation by photoredox catalysis have
1
2
been reported. Ko
̈
nig and co-workers developed an efficient
Received: August 29, 2013
Published: October 16, 2013
visible-light-mediated arylation of alkenes, alkynes, enones, enol
©
2013 American Chemical Society
12202
dx.doi.org/10.1021/jo401894b | J. Org. Chem. 2013, 78, 12202−12206

The Journal of Organic Chemistry
Note
Scheme 1. Photocatalytic Radical-Mediated Cyclizations of N-Arylacrylamides
a
a
Table 1. Optimization of Reaction Conditions for 3a
Table 3. Scope of N-Arylacrylamides
b
entry
catalyst (mol %)
ratio (1a:2a)
solvent
yield (%)
entry
R1
Et
Ar
product
yield (%)
1
2
3
4
5
6
7
8
Ru(bpy) Cl ·6H O (5)
1:1.5
1:1.5
1:1.5
1:1.5
1:2
MeCN
DMF
46
51
45
65
71
80
81
80
52
1
Ph
Ph
Ph
Ph
Ph
Ph
4a
4b
4c
4d
4e
4f
72
67
70
63
0
3
2
2
Ru(bpy) Cl ·6H O (5)
2
i-Pr
n-Bu
Bn
3
2
2
Ru(bpy) Cl ·6H O (5)
THF
3
3
2
2
Ru(bpy) Cl ·6H O (5)
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
4
3
2
2
Ru(bpy) Cl ·6H O (5)
5
Ac
3
2
2
Ru(bpy) Cl ·6H O (5)
1:2.5
1:4
6
H
0
3
2
2
Ru(bpy) Cl ·6H O (5)
7
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
4-Me-Ph
4-MeO-Ph
4-Cl-Ph
4-Br-Ph
4-F-Ph
4g
4h
4i
70
75
63
60
61
50
47
72
55
64
45
66
53
3
2
2
Ru(bpy) (PF ) (5)
1:2.5
1:2.5
1:2.5
1:2.5
8
3
6 2
9
Eosin Y (5)
9
c
10
1
10
11
4j
d
1
Ru(bpy) Cl ·6H O (5)
36
4k
4l
3
2
2
a
1
2
4-CN-Ph
Reaction conditions: 1a (0.3 mmol), catalyst (5 mol %), and solvent
3.0 mL) under visible-light irradiation for 12 h. Isolated yield.
Reaction was carried out without catalyst. Reaction was carried out
b
(
13
14
15
4-CF
−Ph
3
4m
4n
c
d
3,5-di-Me-Ph
3-Cl-Ph
under ambient light.
4o + 4o′ (5:2)
4p + 4p′ (6:5)
1
6
3-Me-Ph
2-Me-Ph
2-Naphtyl
2-Pyridyl
a
Table 2. Scope of Aryl Diazonium Salts
17
4q
4r
4s
1
1
8
9
a
Reaction conditions: 1 (0.3 mmol), Ru(bpy) Cl ·6H O (5 mol %),
3
2
2
and aryl diazonium salts 2 (0.75 mmol) in MeOH (3.0 mL) under
visible-light irradiation for 12 h.
entry
R
product
yield (%)
substrates, such as isopropyl, butyl, or benzyl could be used as an
effective substituent group for this transformation (entries 1−4).
However, the use of acetyl or N-free N-arylacrylamides resulted
in no reaction (entries 5 and 6). The effect of various groups on
the aromatic ring was also examined, and a strong dependence on
the position of the substituents was observed. Substrates with
both moderate electron-donating and electron-withdrawing
substituents in the para position worked comparatively well
1
2
3
4
5
6
7
8
H
3a
3b
3c
3d
3e
3f
80
82
76
63
58
71
67
60
4-F
4-Br
4-Me
2-Me
2-F
2-Cl
2-Br
3g
3h
(
entries 7−11). A strong electron-withdrawing group resulted in
a
Reaction conditions: 1 (0.3 mmol), Ru(bpy) Cl ·6H O (5 mol %),
and aryl diazonium salts 2 (0.75 mmol) in MeOH (3.0 mL) under
visible-light irradiation for 12 h.
3
2
2
slightly lower yields (entries 12 and 13). As was anticipated,
when the substrates were substituted in the meta position, a
mixture of 4o + 4o′ (5:2) and 4p + 4p′ (6:5) isomers was
observed. (entries 15 and 16). When N-arylacrylamide 1q
bearing a ortho-substitued group was checked, the desired
oxoindole 4q was obtained in low yield (entry 17). The substrate
disubstituted by methyl groups also gave a satisfactory yield of
72% (entry 14). Likewise, this reaction was also sustainable with
the naphtyl and pyridyl groups as substituents (entries 18 and
19).
the desired oxoindoles 3a−h in moderate to good yields (Table
). Aryl diazonium salts possessing electron-withdrawing groups
2
gave the desired products in higher yields than the substrates
with electron-donating groups. Moreover, the procedure seemed
to be sensitive to steric effects. Generally, substitutents in the
para position on the aryl group proceeded well (entries 2−4). In
comparison, ortho substituents on the aryl group reduced the
yields (entries 5−8).
To establish the scope of this developed radical-mediated
cyclization protocol, we subsequently tested a wide range of N-
arylacrylamides (Table 3). It was found that various N-protected
4
−8,14
On the basis of the above results and related literature,
a
plausible reaction mechanism is depicted in Scheme 2.
2+
Photoexcitation of [Ru(bpy)] by visible light generates excited
2+
[Ru(bpy)] *, which is oxidatively quenched via single-electron
3
+
transfer (SET) to the diazonium salt 2 to give [Ru(bpy)] and an
1
2203
dx.doi.org/10.1021/jo401894b | J. Org. Chem. 2013, 78, 12202−12206

The Journal of Organic Chemistry
Note
Scheme 2. Plausible Reaction Mechanism
ary radical. Subsequently, the addition of an aryl radical to N-
arylacrylamides 1 generates the alkyl radical A followed by an
intramolecular radical cyclization to give intermediate B. A
single-electron oxidation of the intermediate B by [Ru(bpy)]3+
regenerates the photocatalyst and forms the intermediate C,
which dehydrogenated to give the product, 3.
In conclusion, we have developed a visible-light-mediated
radical reaction that allows the assembly of 3,3-disubstituted
oxoindoles from two readily accessible building blocks, N-
arylacrylamides and aryl diazonium salts, in moderate to good
yields. The process showed considerable synthetic advantages in
terms of product diversity, simplicity of the reaction procedure,
and mild reaction conditions.
179.8, 161.2 (d, J = 242.4 Hz), 143.3, 132.9, 132.0 (d, J = 3.3 Hz), 131.3
(
4
d, J = 8.1 Hz), 128.0, 123.2, 122.3, 114.3 (d, J = 20.5 Hz), 107.9, 50.1,
3.8, 25.9, 22.8. MS (EI, 70 eV) m/z: 269 [M] . Anal. Calcd for
+
C H FNO: C, 75.82; H, 5.99; N, 5.20. Found: C, 76.07; H, 6.30; N,
17 16
5
.26.
-(4-Bromobenzyl)-1,3-dimethylindolin-2-one (3c). White
3
1
solid (75.0 mg, 76%). mp 110−112 °C. H NMR (400 MHz,
CDCl ): δ 7.14−7.21 (m, 4H), 7.04 (t, J = 7.6 Hz, 1H), 6.70 (d, J =
3
7
3
.6 Hz, 2H), 6.63 (d, J = 7.6 Hz, 1H), 3.10 (d, J = 12.8 Hz, 1H), 2.99 (s,
13
H), 2.94 (d, J = 12.8 Hz, 1H), 1.46 (s, 3H). C NMR (100 MHz,
CDCl ): δ 179.7, 143.2, 135.3, 132.7, 131.6, 130.7, 128.1, 123.2, 122.3,
3
+
1
20.6, 108.1, 49.9, 43.9, 26.0, 23.0. MS (EI, 70 eV) m/z: 329 [M] . Anal.
Calcd for C H BrNO: C, 61.83; H, 4.88; N, 4.24. Found: C, 61.70; H,
17
16
5
.03; N, 4.10.
-(4-Methylbenzyl)-1,3-dimethylindolin-2-one (3d). White
3
1
EXPERIMENTAL SECTION
General Methods. Chemicals used were obtained from commercial
suppliers and used without further purifications. H and C NMR
solid (50.1 mg, 63%). mp 116−118 °C. H NMR (400 MHz,
CDCl ): δ 7.17 (t, J = 7.6 Hz, 1H), 7.10 (d, J = 7.2 Hz, 1H), 7.01 (t, J
■
3
1
13
= 7.2 Hz, 1H), 6.85 (d, J = 7.2 Hz, 2H), 6.73 (d, J = 7.6 Hz, 2H), 6.62 (d,
J = 7.6 Hz, 1H), 3.06 (d, J = 13.2 Hz, 1H), 3.00 (s, 3H), 2.97 (d, J = 13.2
spectra were measured in CDCl and recorded at 400 or 100 MHz, with
3
Hz, 1H), 2.20 (s, 3H), 1.45 (s, 3H). 13C NMR (100 MHz, CDCl
): δ
TMS as an internal standard. Column chromatography over silica gel
3
(
300−400 mesh) and a petroleum ether/ethyl acetate combination was
180.2, 143.3, 135.9, 133.3, 133.2, 129.9, 128.3, 127.8, 123.5, 122.1, 107.9,
+
used as the eluent.
49.99, 44.2, 26.0, 22.9, 21.1. MS (EI, 70 eV) m/z: 265 [M] . Anal. Calcd
General Procedure for the Synthesis of 3,3-Disubstituted
Oxoindoles. To a mixture of N-arylacrylamides 1 (0.30 mmol) and aryl
diazonium tetrafluoroborate (0.75 mmol) in methanol (3.0 mL) was
added Ru (bpy) Cl ·6H O (0.0015 mmol). The solution was stirred at
for C H NO: C, 81.47; H, 7.22; N, 5.28. Found: C, 81.07; H, 7.58; N,
18
19
5.40.
-(2-Methylbenzyl)-1,3-dimethylindolin-2-one (3e). Colorless
3
1
3
2
2
oil (46.1 mg, 58%). H NMR (400 MHz, CDCl ): δ 7.20 (t, J = 7.6 Hz,
3
room temperature under visible-light irradiation for 12 h. The solvent
was evaporated under vacuum. Then, the crude products were directly
purified using flash column chromatography on silica gel (petroleum
ether/ethyl acetate 10:1 as the eluant) to afford the desired oxindoles.
1
1
H), 6.90−7.04 (m, 5H), 6.86 (d, J = 7.2 Hz, 1H), 6.71 (d, J = 8.0 Hz,
13
H), 3.07−3.11 (m, 5H), 2.01 (s, 3H), 1.47 (s, 3H). C NMR (100
MHz, CDCl ): δ 180.7, 143.2, 137.3, 134.9, 133.3, 130.6, 130.3, 127.9,
3
1
26.7, 125.2, 123.8, 122.1, 107.9, 49.5, 40.1, 26.2, 22.7, 20.1. MS (EI, 70
3
h
3
-Benzyl-1,3-dimethylindolin-2-one (3a). White solid (60.2
+
eV) m/z: 265 [M] . Anal. Calcd for C H NO: C, 81.47; H, 7.22; N,
1
18 19
mg, 80%). mp 86−88 °C. H NMR (400 MHz, CDCl ): δ 7.18 (t, J = 7.6
3
5
.28. Found: C, 81.20; H, 7.01; N, 5.21.
-(2-Fluorobenzyl)-1,3-dimethylindolin-2-one (3f). White
Hz, 1H), 7.12 (d, J = 7.6 Hz, 1H), 7.01−7.06 (m, 4H), 6.84 (d, J = 5.6
3
Hz, 2H), 6.60 (d, J = 7.6 Hz, 1H), 3.11 (d, J = 13.2 Hz, 1H), 3.00 (d, J =
1
3.2 Hz, 1H), 2.98 (s, 3H), 1.47 (s, 3H). 13C NMR (100 MHz, CDCl ):
3
solid (57.3 mg, 71%). mp 103−105 °C. H NMR (400 MHz,
1
CDCl ): δ 7.16 (t, J = 8.0 Hz, 1H), 7.11 (d, J = 7.6 Hz, 1H), 6.98−
3
δ 180.1, 143.3, 136.3, 133.2, 123.0, 127.9, 127.6, 126.6, 123.4, 122.2,
+
7.06 (m, 3H), 6.88 (t, J = 7.2 Hz, 1H), 6.79 (t, J = 8.8 Hz, 1H), 6.64 (d, J
1
07.9, 50.1, 44.7, 26.0, 22.9. MS (EI, 70 eV) m/z: 251 [M] . Anal. Calcd
=
7.6 Hz, 1H), 3.24 (d, J = 13.2 Hz, 1H), 3.08 (s, 3H), 3.03 (d, J = 13.2
for C H NO: C, 81.24; H, 6.82; N, 5.57. Found: C, 81.63; H, 6.47; N,
17
17
13
Hz, 1H), 1.47 (s, 3H). C NMR (100 MHz, CDCl ): δ 180.2, 160.9 (d,
5
.60.
-(4-Fluorobenzyl)-1,3-dimethylindolin-2-one (3b). White
3
JC−F = 244.7 Hz), 142.9, 132.8, 131.8 (d, JC−F = 4.1 Hz), 128.4 (d, JC−F
=
3
1
solid (66.2 mg, 82%). mp 126−127 °C. H NMR (400 MHz,
8.4 Hz), 127.9, 123.8 (d, JC−F = 15.0 Hz), 123.7, 123.3 (d, JC−F = 3.7 Hz),
CDCl ): δ 7.15−7.20 (m, 2H), 7.04 (t, J = 7.2 Hz, 1H), 6.70−6.80
122.2, 115.0 (d, JC−F = 23.3 Hz), 107.7, 49.5, 36.3, 26.1, 22.9. MS (EI, 70
3
+
(
2
m, 4H), 6.61 (d, J = 7.6 Hz, 1H), 3.11 (d, J = 13.2 Hz, 1H), 2.97 (s, 3H),
.96 (d, J = 13.2 Hz, 1H), 1.47 (s, 3H). C NMR (100 MHz, CDCl ): δ
eV) m/z: 269 [M] . Anal. Calcd for C17
H16FNO: C, 75.82; H, 5.99; N,
13
5.20. Found: C, 76.01; H, 5.76; N, 5.08.
3
1
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dx.doi.org/10.1021/jo401894b | J. Org. Chem. 2013, 78, 12202−12206

The Journal of Organic Chemistry
Note
3
-(2-Chlorobenzyl)-1,3-dimethylindolin-2-one (3g). White
136.3, 134.5, 130.0, 127.6, 126.6, 112.1, 111.1, 108.1, 55.9, 50.4, 44.6,
1
+
solid (57.3 mg, 67%). mp 98−100 °C. H NMR (400 MHz, CDCl ):
26.1, 22.9. MS (EI, 70 eV) m/z: 281 [M] . Anal. Calcd for C H NO :
3
18 19
2
δ 7.15−7.19 (m, 2H), 7.07−7.11 (m, 2H), 7.02−7.04 (m, 2H), 6.94−
C, 76.84; H, 6.81; N, 4.98. Found: C, 77.13; H, 7.05; N, 5.01.
6
.98 (m, 1H), 6.66 (d, J = 7.6 Hz, 1H), 3.40 (d, J = 13.6 Hz, 1H), 3.19 (d,
3-Benzyl-5-chloro-1,3-dimethylindolin-2-one (4i). Colorless
13
1
J = 13.6 Hz, 1H), 3.13 (s, 3H), 1.48 (s, 3H). C NMR (100 MHz,
CDCl ): δ 180.3, 142.9, 134.8, 134.7, 132.6, 131.4, 129.5, 128.0, 127.9,
26.1, 124.2, 122.1, 107.7, 49.6, 39.8, 26.2, 23.2. MS (EI, 70 eV) m/z:
85 [M] . Anal. Calcd for C H ClNO: C, 71.45; H, 5.64; N, 4.90.
oil (53.9 mg, 63%). H NMR (400 MHz, CDCl ): δ 7.07−7.15 (m,
3
5H), 6.84−6.85 (m, 2H), 6.51 (d, J = 8.0 Hz, 1H), 3.12 (d, J = 12.8 Hz,
1H), 2.97 (d, J = 12.8 Hz, 1H), 2.95 (s, 3H), 1.46 (s, 3H). C NMR
3
1
3
1
2
+
(100 MHz, CDCl ): δ 179.5, 141.8, 135.8, 134.9, 129.9, 127.8, 127.7,
17
16
3
Found: C, 71.76; H, 5.93; N, 4.96.
-(2-Bromobenzyl)-1,3-dimethylindolin-2-one (3h). Colorless
127.6, 126.7, 123.9, 108.7, 50.4, 44.7, 26.1, 22.7. MS (EI, 70 eV) m/z:
+
3
285 [M] . Anal. Calcd for C H ClNO: C, 71.45; H, 5.64; N, 4.90.
17
16
1
oil (59.2 mg, 60%). mp 103−105 °C. H NMR (400 MHz, CDCl ): δ
Found: C, 71.69; H, 5.31; N, 4.99.
3
7
6
3
.36 (d, J = 8.4 Hz, 1H), 7.17 (t, J = 7.6 Hz, 1H), 7.09−7.11 (m, 3H),
3-Benzyl-5-bromo-1,3-dimethylindolin-2-one (4j). White solid
1
.94−6.97 (m, 2H), 6.67 (d, J = 8.4 Hz, 1H), 3.40 (d, J = 13.6 Hz, 1H),
(59.2 mg, 60%). mp 96−98 °C. H NMR (400 MHz, CDCl ): δ 7.23−
3
13
.24 (d, J = 13.6 Hz, 1H), 3.14 (s, 3H), 1.48 (s, 3H). C NMR (100
7.31 (m, 2H), 7.07−7.08 (m, 3H), 6.84−6.85 (m, 2H), 6.47 (d, J = 8.0
Hz, 1H), 3.11 (d, J = 13.2 Hz, 1H), 2.97 (d, J = 13.2 Hz, 1H), 2.95 (s,
MHz, CDCl ): δ 180.3, 142.9, 136.5, 132.9, 132.5, 131.2, 128.3, 127.9,
3
3H), 1.46 (s, 3H). 13C NMR (100 MHz, CDCl ): δ 179.4, 142.4, 135.8,
1
26.8, 125.9, 124.4, 122.1, 107.7, 49.5, 42.3, 26.2, 23.2. MS (EI, 70 eV)
3
+
m/z: 329 [M] . Anal. Calcd for C H BrNO: C, 61.83; H, 4.88; N, 4.24.
135.3, 130.7, 129.9, 127.8, 126.8, 126.7, 114.9, 109.3, 50.3, 44.7, 26.1,
17
16
+
Found: C, 61.70; H, 5.11; N, 4.15.
-Benzyl-1-ethyl-3-methylindolin-2-one (4a). White solid (57.2
22.7. MS (EI, 70 eV) m/z: 329 [M] . Anal. Calcd for C H BrNO: C,
1
7
16
3
61.83; H, 4.88; N, 4.24. Found: C, 61.58; H, 5.09; N, 4.39.
1
mg, 72%). mp 76−78 °C. H NMR (400 MHz, CDCl ): δ 7.16−7.21
3-Benzyl-5-fluoro-1,3-dimethylindolin-2-one (4k). Colorless
3
1
(
m, 2H), 7.01−7.06 (m, 4H), 6.81 (d, J = 6.8 Hz, 2H), 6.61 (d, J = 8.0
oil (47.8 mg, 61%). H NMR (400 MHz, CDCl ): δ 7.07 (bs, 3H),
3
Hz, 1H), 3.67−3.72 (m, 1H), 3.34−3.39 (m, 1H), 3.14 (d, J = 12.8 Hz,
6.86 (bs, 4H), 6.49−6.51 (m, 2H), 3.13 (d, J = 12.8 Hz, 1H), 2.97 (d, J =
13
13
1
H), 3.01 (d, J = 12.8 Hz, 1H), 1.48 (s, 3H), 0.86 (t, J = 7.2 Hz, 3H). C
12.8 Hz, 1H), 2.96 (s, 3H), 1.46 (s, 3H). C NMR (100 MHz, CDCl ):
3
NMR (100 MHz, CDCl ): δ 179.5, 142.4, 136.3, 133.4, 129.9, 127.8,
δ 179.7, 159.2 (d, J = 239.1 Hz), 139.2, 135.9, 134.9 (d, J = 15.3 Hz),
129.8, 127.7, 126.7, 114.0 (d, J = 23.2 Hz), 111.5 (d, J = 24.4 Hz), 108.2
3
1
27.6, 126.5, 123.4, 121.9, 108.0, 49.9, 44.8, 34.3, 23.0, 12.2. MS (EI, 70
+
+
eV) m/z: 265 [M] . Anal. Calcd for C H NO: C, 81.47; H, 7.22; N,
(d, J = 8.7 Hz), 50.6, 44.6, 26.1, 22.8. MS (EI, 70 eV) m/z: 269 [M] .
18
19
5
.28. Found: C, 81.30; H, 7.61; N, 5.19.
Anal. Calcd for C H FNO: C, 75.82; H, 5.99; N, 5.20. Found: C,
17
16
3
-Benzyl-1-isopropyl-3-methylindolin-2-one (4b). White solid
75.58; H, 6.23; N, 5.04.
1
(
(
6
1
3
1
56.1 mg, 67%). mp 119−121 °C. H NMR (400 MHz, CDCl ): δ 7.23
3-Benzyl-1,3-dimethyl-2-oxoindoline-5-carbonitrile (4l).
3
1
d, J = 7.6 Hz, 1H), 7.15 (d, J = 7.6 Hz, 1H), 6.99−7.05 (m, 4H), 6.75−
White solid (41.5 mg, 50%). mp 122−124 °C. H NMR (400 MHz,
.79 (m, 3H), 4.39−4.46 (m, 1H), 3.15 (d, J = 12.8 Hz, 1H), 2.98 (d, J =
CDCl ): δ 7.50 (dd, J = 8.4 Hz, J = 1.6 Hz, 1H), 7.37 (d, J = 1.2 Hz, 1H),
3
2.8 Hz, 1H), 1.48 (s, 3H), 1.27 (d, J = 7.2 Hz, 3H), 1.02 (d, J = 7.2 Hz,
7.07−7.09 (m, 3H), 6.80 (dd, J = 7.6 Hz, J = 1.6 Hz, 2H), 6.60 (d, J = 8.0
H). 13C NMR (100 MHz, CDCl ): δ 179.4, 141.9, 136.3, 133.7, 129.9,
3
Hz, 1H), 3.16 (d, J = 13.2 Hz, 1H), 3.01 (d, J = 13.2 Hz, 1H), 3.00 (s,
3H), 1.49 (s, 3H). 13C NMR (100 MHz, CDCl ): δ 179.7, 147.0, 135.2,
27.6, 126.5, 123.5, 121.6, 109.7, 49.7, 45.1, 43.2, 23.1, 19.3, 18.9. MS
3
+
(
EI, 70 eV) m/z: 279 [M] . Anal. Calcd for C H NO: C, 81.68; H,
134.1, 133.2, 129.6, 127.8, 126.9, 126.6, 119.4, 108.2, 105.1, 49.9, 44.5,
19
21
+
7
.58; N, 5.01. Found: C, 81.34; H, 7.29; N, 5.12.
2
6.1, 22.5. MS (EI, 70 eV) m/z: 276 [M] . Anal. Calcd for C H N O:
1
8
16
2
3
-Benzyl-1-butyl-3-methylindolin-2-one (4c). Colorless oil
C, 78.24; H, 5.84; N, 10.14. Found: C, 78.60; H, 5.58; N, 10.25.
1
(
7
61.5 mg, 70%). H NMR (400 MHz, CDCl ): δ 7.15−7.19 (m, 2H),
3
3-Benzyl-5-(trifluoromethyl)-1,3-dimethylindolin-2-one
1
.02−7.05 (m, 4H), 6.83 (d, J = 7.2 Hz, 2H), 6.62 (d, J = 7.6 Hz, 1H),
.57−3.62 (m, 1H), 3.30−3.38 (m, 1H), 3.13 (d, J = 13.2 Hz, 1H), 3.02
(4m). White solid (45.0 mg, 47%). mp 85−87 °C. H NMR (400 MHz,
3
CDCl ): δ 7.45 (d, J = 8.0 Hz, 1H), 7.33 (s, 1H), 7.05−7.06 (m, 3H),
3
(
d, J = 13.2 Hz, 1H), 1.47 (s, 3H), 1.19−1.30 (m, 2H), 1.06−1.14 (m,
6.81 (d, J = 7.2 Hz, 2H), 6.65 (d, J = 8.0 Hz, 1H), 3.14 (d, J = 12.8 Hz,
H), 0.83 (t, J = 7.2 Hz, 3H). 13C NMR (100 MHz, CDCl ): δ 179.7,
13
2
1
4
1H), 3.01 (d, J = 12.8 Hz, 1H), 3.00 (s, 3H), 1.49 (s, 3H). C NMR
3
42.9, 136.3, 133.4, 123.0, 127.8, 127.6, 126.5, 123.4, 121.9, 108.2, 49.9,
(100 MHz, CDCl ): δ 179.9, 146.2, 135.6, 133.7, 129.8, 127.8, 127.4 (q,
3
+
4.6, 39.6, 29.4, 23.4, 20.1, 13.9. MS (EI, 70 eV) m/z: 293 [M] . Anal.
J = 269.6 Hz), 126.8, 125.6 (q, J = 4.6 Hz), 124.4 (q, J = 31.8 Hz), 120.5
(q, J = 3.6 Hz), 107.5, 50.1, 44.6, 26.1, 22.5. MS (EI, 70 eV) m/z: 319
Calcd for C H NO: C, 81.87; H, 7.90; N, 4.77. Found: C, 81.73; H,
20
23
+
8
.10; N, 4.83.
,3-Dibenzyl-3-methylindolin-2-one (4d). Colorless oil (61.8
[M] . Anal. Calcd for C H F NO: C, 67.70; H, 5.05; N, 4.39. Found:
18
16 3
3
i
1
C, 67.48; H, 5.22; N, 4.21.
1
mg, 63%). H NMR (400 MHz, CDCl ): δ 7.25 (d, J = 7.2 Hz, 2H),
3-Benzyl-1,3,4,6-tetramethylindolin-2-one (4n). White solid
3
1
7
.11−7.15 (m, 4H), 7.04−7.07 (m, 4H), 6.88 (d, J = 7.6 Hz, 2H), 6.66
(60.3 mg, 72%). mp 77−79 °C. H NMR (400 MHz, CDCl ): δ 6.98−
3
(
d, J = 7.2 Hz, 2H), 6.41 (d, J = 7.2 Hz, 1H), 4.98 (d, J = 16.0 Hz, 1H),
7.00 (m, 3H), 6.78−6.80 (m, 2H), 6.63 (s, 1H), 6.25 (s, 1H), 3.22 (d, J =
13.2 Hz, 1H), 3.16 (d, J = 13.2 Hz, 1H), 2.89 (s, 3H), 2.47 (s, 3H), 2.26
(s, 3H), 1.57 (s, 3H). C NMR (100 MHz, CDCl ): δ 180.1, 143.6,
4
1
1
1
.47 (d, J = 16.0 Hz, 1H), 3.24 (d, J = 12.8 Hz, 1H), 3.12 (d, J = 12.8 Hz,
H), 1.54 (s, 3H). 13C NMR (100 MHz, CDCl ): δ 179.9, 142.5, 136.4,
13
3
3
35.5, 133.2, 130.2, 128.7, 127.9, 127.8, 127.2, 126.7, 126.6, 123.3, 122.3,
137.7, 136.8, 133.8, 129.2, 127.6, 126.9, 126.4, 125.5, 106.6, 51.0, 42.6,
+
+
09.3, 50.3, 44.4, 43.6, 24.2. MS (EI, 70 eV) m/z: 327 [M] . Anal. Calcd
25.9, 21.8, 21.6, 18.5. MS (EI, 70 eV) m/z: 279 [M] . Anal. Calcd for
for C H NO: C, 84.37; H, 6.46; N, 4.28. Found: C, 84.51; H, 6.20; N,
C H NO: C, 81.68; H, 7.58; N, 5.01. Found: C, 81.35; H, 7.86; N,
23
21
19 21
4
.35.
-Benzyl-1,3,5-trimethylindolin-2-one (4g). White solid (55.6
5.12.
3
3-Benzyl-4-chloro-1,3-dimethylindolin-2-one and 3-Benzyl-
1
mg, 70%). mp 72−74 °C. H NMR (400 MHz, CDCl ): δ 7.04−7.05
6-chloro-1,3-dimethylindolin-2-one (4o + 4o′). Colorless oil (47.0
3
1
(
(
m, 3H), 6.97 (d, J = 8.0 Hz, 1H), 6.93 (s, 1H), 6.84−6.85 (m, 2H), 6.49
d, J = 8.0 Hz, 1H), 3.09 (d, J = 13.2 Hz, 1H), 2.98 (d, J = 13.2 Hz, 1H),
mg, 55%). H NMR (400 MHz, CDCl ): δ 7.05−7.08 (m, 2H), 6.96−
3
6.99 (m, 5H), 6.89−6.92 (m, 2H), 6.84−6.85 (m, 0.9H), 6.61 (s, 0.4H),
13
2
1
5
.95 (s, 3H), 2.33 (s, 3H), 1.45 (s, 3H). C NMR (100 MHz, CDCl ): δ
6.43 (d, J = 7.6 Hz, 1H), 3.51 (d, J = 12.8 Hz, 1H), 3.17 (d, J = 12.8 Hz,
3
80.0, 140.9, 136.4, 133.2, 131.6, 129.9, 128.1, 127.6, 126.5 124.3, 107.6,
1H), 3.10 (d, J = 13.6 Hz, 0.4H), 2.94−3.00 (m, 2H), 2.92 (s, 3H), 1.65
+
13
0.0, 44.7, 26.0, 22.9, 21.3. MS (EI, 70 eV) m/z: 265 [M] . Anal. Calcd
(s, 3H), 1.45 (s, 1.2H). C NMR (100 MHz, CDCl ): δ 180.0, 179.3,
3
for C H NO: C, 81.47; H, 7.22; N, 5.28. Found: C, 81.22; H, 7.53; N,
145.0, 144.4, 136.5, 135.9, 133.6, 131.5, 130.8, 129.9, 129.7, 129.12,
129.1, 127.8, 127.6, 126.7, 126.5, 124.3, 123.4, 121.9, 115.6, 108.6, 106.3,
18
19
5
.36.
-Benzyl-5-methoxy-1,3-dimethylindolin-2-one (4h). Color-
3
52.3, 49.8, 44.5, 41.4, 26.14, 26.10, 22.8, 20.8. MS (EI, 70 eV) m/z: 285
1
+
less oil (63.2 mg, 75%). H NMR (400 MHz, CDCl ): δ 7.06−7.07 (m,
[M] . Anal. Calcd for C H ClNO: C, 71.45; H, 5.64; N, 4.90. Found:
3
17 16
3
3
3
H), 6.87−6.89 (m, 2H), 6.69−6.71 (m, 2H), 6.51 (d, J = 8.0 Hz, 1H),
C, 71.80; H, 5.93; N, 4.71.
3-Benzyl-1,3,4-trimethylindolin-2-one and 3-Benzyl-1,3,6-
trimethylindolin-2-one (4p + 4p′). Colorless oil (51.0 mg, 64%).
.77 (s, 3H), 3.09 (d, J = 13.2 Hz, 1H), 2.98 (d, J = 13.2 Hz, 1H), 2.96 (s,
H), 1.45 (s, 3H). 13C NMR (100 MHz, CDCl ): δ 179.7, 155.8, 136.9,
3
1
2205
dx.doi.org/10.1021/jo401894b | J. Org. Chem. 2013, 78, 12202−12206

The Journal of Organic Chemistry
Note
1
H NMR (400 MHz, CDCl ): δ 6.97−7.07 (m, 7.3H), 6.76−6.87 (m,
(3) (a) Mu, X.; Wu, T.; Wang, H.-Y.; Guo, Y.-L.; Liu, G.-S. J. Am. Chem.
Soc. 2012, 134, 878. (b) Jaegli, S.; Dufour, J.; Wei, H.-L.; Piou, T.; Duan,
X.-H.; Vors, J.-P.; Neuville, L.; Zhu, J. Org. Lett. 2010, 12, 4498. (c) Wu,
T.; Mu, X.; Liu, G.-S. Angew. Chem., Int. Ed. 2011, 50, 12578. (d) Wei,
H.-L.; Piou, T.; Dufour, J.; Neuville, L.; Zhu, J. Org. Lett. 2011, 13, 2244.
(e) Fabry, D. C.; Stodulski, M.; Hoerner, S.; Gulder, T. Chem.Eur. J.
2012, 18, 10834. (f) Liu, L.; Ishida, N.; Ashida, S.; Murakami, M. Org.
Lett. 2011, 13, 1666. (g) Ueda, S.; Okada, T.; Nagasawa, H. Chem.
Commun. 2010, 46, 2462. (h) Mekhaela, M. K. G.; Bienza, S.; Lindena,
A.; Heimgartner, H. Helv. Chim. Acta 2004, 87, 2385. (i) Anwar, U.;
Fielding, M. R.; Grigg, R.; Sridharan, V.; Urch, C. J. J. Organomet. Chem.
2006, 691, 1476.
3
5
2
1
1
1
4
.7H), 6.45 (S, 0.8H), 6.37 (d, J = 7.6 Hz, 1H), 3.00−3.22 (m, 3.7H),
.97 (s, 2.5H), 2.89 (s, 3H), 2.52 (s, 3H), 2.32 (s, 2.5H), 1.59 (s, 3H),
.44 (s, 2.5H). 13C NMR (100 MHz, CDCl ): δ 180.5, 179.8, 143.6,
3
43.3, 137.9, 136.6, 136.5, 134.2, 130.2, 130.0, 129.9, 129.2, 127.7, 127.6,
27.5, 126.5, 126.4, 124.9, 123.2, 122.7, 108.9, 105.6, 51.3, 49.8, 44.6,
+
2.6, 25.98, 25.96, 23.1, 21.9, 21.6, 18.7. MS (EI, 70 eV) m/z: 265 [M] .
Anal. Calcd for C H NO: C, 81.47; H, 7.22; N, 5.28. Found: C, 81.85;
18
19
H, 7.60; N, 5.06.
3
-Benzyl-1,3,7-trimethylindolin-2-one (4q). Colorless oil (35.8
1
mg, 45%). H NMR (400 MHz, CDCl ): δ 7.05−7.07 (m, 3H), 6.89−
6
1
(
3
.95 (m, 3H), 6.82 (d, J = 6.4 Hz, 2H), 3.25 (s, 3H), 3.09 (d, J = 12.8 Hz,
H), 2.97 (d, J = 12.8 Hz, 1H), 2.39 (s, 3H), 1.44 (s, 3H). 13C NMR
(4) Li, Y.-M.; Sun, M.; Wang, H.-L.; Tian, Q.-P.; Yang, S.-D. Angew.
Chem., Int. Ed. 2013, 52, 3972.
100 MHz, CDCl ): δ 180.8, 141.1, 136.4, 133.8, 131.5, 129.9, 127.5,
3
1
26.5,122.0, 121.3, 119.4, 49.4, 45.0, 29.3, 23.2, 18.9. MS (EI, 70 eV) m/
(5) (a) Xie, J.; Xu, P.; Li, H.; Xue, Q.; Jin, H.; Cheng, Y.; Zhu, C. Chem.
Commun. 2013, 49, 5672. (b) Wei, W.-T.; Zhou, M.-B.; Fan, J.-H.; Liu,
W.; Song, R.-J.; Liu, Y.; Hu, M.; Xie, P.; Li, J.-H. Angew. Chem., Int. Ed.
2013, 52, 3638. (c) Zhou, S.-L.; Guo, L.-N.; Wang, H.; Duan, X.-H.
Chem.−Eur. J. 2013, 19, 12970. (d) Meng, Y.; Guo, L.-N.; Wang, H.;
Duan, X.-H. Chem. Commun. 2013, 49, 7540. (e) Wang, H.; Guo, L.-N.;
Duan, X.-H. Chem. Commun. 2013, 49, 10370.
(6) (a) Zhou, M.-B.; Song, R.-J.; Ouyang, X.-H.; Liu, Y.; Wei, W.-T.;
Deng, G.-B.; Li, J.-H. Chem. Sci. 2013, 4, 2690. (b) Wang, H.; Guo, L.-
N.; Duan, X.-H. Adv. Synth. Catal. 2013, 355, 2222.
+
z: 265 [M] . Anal. Calcd for C H NO: C, 81.47; H, 7.22; N, 5.28.
Found: C, 81.72; H, 7.62; N, 5.08.
18
19
3
-Benzyl-1,3-dimethyl-1H-benzo[g]indol-2(3H)-one (4r).
1
White solid (59.6 mg, 66%). mp 115−117 °C. H NMR (400 MHz,
CDCl ): δ 7.59−7.62 (m, 1H), 7.45 (t, J = 7.6 Hz, 1H), 7.31−7.36 (m,
3
2
1
(
H), 7.16 (t, J = 8.0 Hz, 1H), 6.74−6.83 (m, 3H), 6.52 (t, J = 7.6 Hz,
H), 6.36 (t, J = 7.2 Hz, 2H), 3.32 (d, J = 12.8 Hz, 1H), 3.25 (s, 3H), 2.83
d, J = 12.8 Hz, 1H), 1.82 (s, 3H). 13C NMR (100 MHz, CDCl ): δ
3
1
1
72.6, 137.2, 136.5, 136.4, 132.8, 129.5, 127.2, 126.6, 126.4, 126.1,
26.09, 123.2, 122.1, 120.3, 107.9, 52.8, 49.2, 29.4, 26.9. MS (EI, 70 eV)
(7) (a) Matcha, K.; Narayan, R.; Antonchick, A. P. Angew. Chem., Int.
+
m/z: 301 [M] . Anal. Calcd for C H NO: C, 83.69; H, 6.35; N, 4.65.
21
19
Ed. 2013, 52, 7985. (b) Wei, X.-H.; Li, Y.-M.; Zhou, A.-X.; Yang, T.-T.;
Yang, S.-D. Org. Lett. 2013, 15, 4158. (c) Yuan, Y.; Shen, T.; Wang, K.;
Jiao, N. Chem.−Asian J. 2013, DOI: 10.1002/asia.201300960.
Found: C, 83.36; H, 6.05; N, 4.78.
-Benzyl-1,3-dimethyl-1H-pyrrolo[2,3-b]pyridin-2(3H)-one
3
1
(4s). Colorless oil (40.1 mg, 53%). H NMR (400 MHz, CDCl ): δ 8.08
3
(8) Li, X.-Q.; Xu, X.-S.; Hu, P.; Xiao, X.-Q.; Zhou, C. J. Org. Chem.
(
d, J = 4.8 Hz, 1H), 7.26 (s, 1H), 7.10 (bs, 3H), 6.87−6.92 (m, 3H), 3.12
d, J = 13.6 Hz, 1H), 3.10 (s, 3H), 3.02 (d, J = 13.6 Hz, 1H), 1.48 (s, 3H).
2
(
013, 78, 7343.
9) (a) Galli, C. Chem. Rev. 1988, 88, 765. (b) Pratsch, G.; Heinrich, M.
(
1
3
C NMR (100 MHz, CDCl ): δ 179.8, 156.8, 146.8, 135.7, 130.8, 129.9,
3
R. In Radicals in Synthesis III; Heinrich, M. R., Gansauer, A., Eds.;
̈
Springer: Heidelberg, 2012; Vol. 320, pp 33−59. (c) Heinrich, M. R.
Chem.Eur. J. 2009, 15, 820.
1
2
27.9, 127.5, 126.9, 117.7, 49.6, 44.1, 25.2, 22.3. MS (EI, 70 eV) m/z:
+
52 [M] . Anal. Calcd for C H N O: C, 76.16; H, 6.39; N, 11.10.
16
16
2
Found: C, 76.42; H, 6.01; N, 10.89.
(10) (a) Curran, D. P.; Keller, A. I. J. Am. Chem. Soc. 2006, 128, 13706.
(
b) Baralle, A.; Fensterbank, L.; Goddard, J.-P.; Ollivier, C. Chem.Eur.
ASSOCIATED CONTENT
J. 2013, 19, 33. (c) Sahoo, B.; Hopkinson, M. N.; Glorius, F. J. Am. Chem.
Soc. 2013, 135, 5505. (d) Basavanag, U. M. V.; Dos Santos, A.; El Kaim,
L.; Gamez-Montano, R.; Grimaud, L. Angew. Chem., Int. Ed. 2013, 52,
7
2
■
*
S
Supporting Information
1
H and 13C NMR spectra for all compounds and X-ray crystal
194. (e) Taniguchi, T.; Zaimoku, H.; Ishibashi, H. Chem.Eur. J.
structure of 3a (CIF). This material is available free of charge via
the Internet at http://pubs.acs.org.
011, 17, 4307.
(11) For reviews on recent developments in photoredox catalysis in
organic synthesis, see: (a) Prier, C. K.; Rankic, D. A.; MacMillan, D. W.
C. Chem. Rev. 2013, 113, 5322. (b) Xuan, J.; Xiao, W.-J. Angew. Chem.,
Int. Ed. 2012, 51, 6828. (c) Shi, L.; Xia, W.-J. Chem. Soc. Rev. 2012, 41,
AUTHOR INFORMATION
■
Corresponding Author
E-mail: wjfu@lynu.edu.cn (W.F.).
7
687. (d) Narayanam, J. M. R.; Stephenson, C. R. J. Chem. Soc. Rev.
011, 40, 102. (e) Yoon, T. P.; Ischay, M. A.; Du, J. Nat. Chem. 2010, 2,
*
2
Notes
527. (f) Ravelli, D.; Fagnoni, M. ChemCatChem 2012, 4, 169.
12) For reviews, see: (a) Hari, D. P.; Konig, B. Angew. Chem., Int. Ed.
013, 52, 4734. (b) Mo, F.; Dong, G.; Zhang, Y.; Wang, J. Org. Biomol.
Chem. 2013, 11, 1582.
13) (a) Hari, D. P.; Schroll, P.; Ko
2958. (b) Schroll, P.; Hari, D. P.; Konig, B. ChemistryOpen 2012, 1, 130.
(c) Hering, T.; Hari, D. P.; Konig, B. J. Org. Chem. 2012, 77, 10347.
14) Xiao, T.; Dong, X.; Tang, Y.; Zhou, L. Adv. Synth. Catal. 2012,
54, 3195.
(
2
̈
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
(
̈
nig, B. J. Am. Chem. Soc. 2012, 134,
We are grateful to the National Natural Science Foundation of
China (project nos. U1204205, 21202078, and 21272110).
̈
̈
(
3
REFERENCES
■
(
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References 5−7 were updated on November 7, 2013.
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1
2206
dx.doi.org/10.1021/jo401894b | J. Org. Chem. 2013, 78, 12202−12206