Metal-Free Activation of DMF by Dioxygen: A Cascade Multiple-Bond-Formation Reaction to Synthesize 3-Acylindoles from 2-Alkenylanilines

Article abstract of DOI:10.1002/adsc.201700584

A cascade C?N, C?C and C?O multiple-bond-formation reaction to synthesize 3-acylindoles from 2-alkenylanilines with DMF (N,N-dimethylformamide) as a one-carbon synthon is described. This approach employed dioxygen as a terminal oxidant and oxygen donor, generally provided the 3-acylindoles in moderate to good yields. Moreover, the mechanistic investigation unambiguously revealed that the 2-carbon of 3-acylindole was derived from the N-methyl group of DMF. (Figure presented.).

Full text of DOI:10.1002/adsc.201700584

Title: Metal-Free Activation of DMF by Dioxygen: A Cascade Multiple-
Bond-Formation Reaction to Synthesize 3-Acylindoles from 2-
Alkenylanilines
Authors: Jun Deng, Ji-Bo Wang, and Yin-Long Li
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201700584
Link to VoR: http://dx.doi.org/10.1002/adsc.201700584

10.1002/adsc.201700584
Advanced Synthesis & Catalysis
UPDATE
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Metal-Free Activation of DMF by Dioxygen: A Cascade
Multiple-Bond-Formation Reaction to Synthesize 3-Acylindoles
from 2-Alkenylanilines
Ji-Bo Wang,a,† Yin-Long Li,a,† and Jun Deng a,b,*
a School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
b
School of Pharmaceutical Sciences and Innovative Drug Research Center, Chongqing University, Chongqing 401331,
China
Fax: (+86)-23-65678460, E-mail: jdeng@cqu.edu.cn
† These authors contributed equally to this work.
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please
delete if not appropriate))
Abstract: A cascade C-N, C-C and C-O multiple-bond-
formation reaction to synthesize 3-acylindoles from 2-
alkenylanilines with DMF (N,N-dimethylformamide) as a
one-carbon synthon is described. This approach employed
dioxygen as a terminal oxidant and oxygen donor,
generally provided the 3-acylindoles in moderate to good
yields.
Moreover,
the
mechanistic
investigation
unambiguously revealed that the 2-carbon of 3-acylindole
was derived from the N-methyl group of DMF.
Keywords: Dioxygen; 3-Acylindoles; DMF; Multiple-
bond-formation reaction
The development of novel methods to synthesize
complex compounds by employing simple and readily
available starting materials remains a top goal in
synthetic organic chemistry. As a common organic
polar solvent, DMF (N,N-dimethylformamide) has
attracted considerable attention as a multipurpose
reagent in organic reactions.[1] For example, DMF can
be used as a reaction precursor for cyanation,[2]
amination,[3] formylation,[4] cycloaddition,[5] and other
related reactions.[6] The utilization of DMF as a
carbon source to realize cyclization reactions also has
been investigated, especially mediated processes with
transition-metal catalysts such as Pd, Cu, Ni, or Ru
for the synthesis of nitrogen-containing heterocycles
(Figure 1).[7] Although this is a powerful strategy and
some successes have been achieved in this area, the
activation of DMF under transition-metal-free
conditions has rarely been documented.[5f, 8] Therefore,
the development of new chemical transformations to
replace these transition metals with more ecologically
and economically favorable reagents is highly
desirable. Additionally, as a highly atom-economical,
low-cost and “green” oxidant, dioxygen combined
with a metal (e.g., Pd and Cu) has been widely
explored for versatile oxidative C-C, C-N and
Figure 1. CH3 group of DMF as a one-carbon synthon in
cyclization reactions.
C-O bond formations in various aerobic reactions.[9]
Consequently, designing
a
cascade reaction
employing the activation of DMF by dioxygen under
metal-free conditions for the synthesis of bioactive
compounds has captured our interest. Herein, we
report our success in achieving a cascade C-C, C-N
and C-O bond-formation reaction to synthesize 3-
acylindoles from 2-alkenylanilines through the
activation of DMF using dioxygen as the sole oxidant.
Our optimization studies were initiated with (E)-
4-methyl-N-(2-styrylphenyl) benzenesulfonamide (1a)
as a model substrate for the cyclization reaction.
1
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10.1002/adsc.201700584
Advanced Synthesis & Catalysis
Table 1. Optimization of reaction conditions.[a]
Temp.
(°C)
Yield
(%)b
Entry Oxidants
Additives (equiv.)
1
O2
H2O2
TBHP
Air
-
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
125
125
125
125
125
150
170
150
150
150
150
150
150
150
150
150
150
150
---
---
---
---
---
---
---
---
---
43
Trace
N.D.e
7
0
57
23
48
42
62
60
81
58
75
39
37
13
Trace
2c
3d
4
5f
6
7
8g
9h
10
11
12
13
14
15
16
17
18
Benzoic acid (0.5)
Bu4NOTf (0.15)i
Bu4NOTf (0.15) j
Bu4NOTf (0.15)k
Bu4NOTf (0.30)j
Bu4NOAc (0.15)j
Bu4NBr (0.15)j
Bu4NOTf (0.15)l
Bu4NOTf (0.15)m
O2
[a]
[a] Reaction conditions: 1a (0.20 mmol), 1 atm O2 in DMF
(1.0 mL) under heating conditions.
[b] Isolated yields.
Reaction conditions: 1 (0.2 mmol), benzoic acid (0.1
mmol), Bu4NOTf (0.03 mmol), O2 (1 atm), DMF (1.0 mL,
0.2 M), isolated yields.
[c] H2O2: 10.0 equiv.
[d] TBHP: 10.0 equiv.
[e] N.D. = Not detected.
concentration did not provide any benefit to this
reaction (Table 1, entries 8 and 9). Based on our
previous report,[11] the addition of benzoic acid (0.5
equiv) or Bu4NOTf (0.15 equiv) slightly promoted
the reaction, approximately 60% yields of 2a were
provided (entries 10 and 11). The good yield was
obtained by adding Bu4NOTf possibly attributed to
the solubility enhancement of the dioxygen during the
reaction process.[12a] With our continuous efforts, the
yield of 2a finally reached to 81%, and the reaction
could be completed within 18 h (Table 1, entry 12).
Notably, the combination of 0.5 equiv. of benzoic
acid and 0.15 equiv. of Bu4NOTf was crucial for the
transformation and afforded higher yields (Table 1,
entries 12-14). The effects of other carboxylic acids
and quaternary ammonium salts were also explored
(Table 1, entries 15-18). However, none of them
provided favorable results.
[f] Reaction under 1 atm N2.
[g] DMF: 2.0 mL.
[h] DMF: 0.5 mL.
[i] Bu4NOTf = tetrabutylammonium trifluoromethanesulfo-
nate.
[j] Benzoic acid (0.5 equiv).
[k] Benzoic acid (1.0 equiv).
[l] Pyromellitic acid (0.5 equiv).
[m] Citric acid (0.5 equiv).
When the reaction was performed in DMF (1.0 mL) at
125 °C under O2 (1 atm), the annulation product 2a
was obtained in 43% yield (entry 1). The structure of
2a was confirmed by X-ray crystallography.[10]
However, other oxidants, including H2O2 and t-
BuOOH, did not work well in this transformation
(Table 1, entries 2 and 3). When the reaction was
conducted in ambient air, the yield decreased
significantly to 7% (Table 1, entry 4). In addition, no
product was obtained after 36 h under N2 atmosphere
(Table 1, entry 5). The yield of 2a increased to 57%
while increasing the reaction temperature to 150 °C
but sharply decreased to 23% when the temperature
was further raised to 170 °C (Table 1, entries 6 and 7).
Furthermore, increasing or decreasing the
Under the optimized conditions, the scope of the
substrates was explored (Table 2). Initially, the effect
of different N-protecting groups on the 2-
alkenylanilines
was
investigated.
The
2-
alkenylanilines containing tosyl groups and other
sulfonamides with different substituents afforded the
desired 3-acylindoles in 18-72% yields (Table 2, 2b-
2f). Unfortunately, the substrate with a primary amine
group did not provide the target compound (Table 2,
2g). The substrates with other substituent groups on
Table 3. Scope of 2-alkenylanilines.[a]
Table 2. Scope of 2-alkenylanilines.[a]
2
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10.1002/adsc.201700584
Advanced Synthesis & Catalysis
Scheme 1. Gram-scale reaction.
[a]
Reaction conditions: 3 (0.2 mmol), benzoic acid (0.1
mmol), Bu4NOTf (0.03 mmol), O2 (1 atm), DMF (1.0 mL,
0.2 M), isolated yields.
Scheme 2. Investigation of the mechanism.
the nitrogen atom such as acetyl, Cbz, phenyl and
methyl were subjected to this optimal reaction
conditions, no desired products could be obtained. On
the other hand, the reaction exhibited good tolerance Gratifyingly, the introduction of methyl, methoxy,
to various substituents on the aniline ring as described tert-butyl and halogen groups on the phenyl ring of
in Table 2. The anilines bearing electron-donating the 2-alkenylanilines was also tolerated. The reaction
groups (p-OMe and p-Me) provided the occurred smoothly to give the desired indoles (4a-4g)
corresponding products (2h and 2i) in 74% and 71% in 29-79% yields. Moreover, good yields (61% and
yields. Not surprisingly, the yields decreased when 66%, Table 3, 4h and 4i) were obtained when 1-
the substrates were appended with electron- naphthyl and 2-naphthyl-substituted substrates were
withdrawing groups (p-Cl and p-F), products 2j and applied under the optimized conditions. Meanwhile, a
2k were isolated in 64% and 69% yields, respectively. substrate with two substituents was found to be
A closer investigation revealed that a strong electron- suitable for this reaction and delivered the desired 3-
withdrawing group (p-COOEt) could lead to a lower acylindole in 68% yield (Table 3, 4j). It should be
yield of 2l in 55% yield. However, a CF3 group noted that the cyclopropyl-substituted substrate was
appeared to retard the reaction, and only a trace also successful. The product 4k was uneventfully
amount of product was detected. In addition, the produced in 19% yield, and no ring-opening product
substrates bearing either electron-donating or was isolated.
electron-withdrawing groups at the meta position of
In addition, to demonstrate the potential synthetic
the anilines were compatible with these reaction utility of this method, a gram scale reaction has been
conditions. The corresponding products were formed carried out using 1a as the substrate under the
in slightly lower yields (21-55%).
developed conditions. The yield of the desired
To further demonstrate the flexibility of this product was slightly decreased to 63% (Scheme 1).
methodology, the effect of the substituent on the
alkene moiety (Table 3) was investigated.
To obtain insight into the mechanism of this
transformation, several control experiments have been
conducted. First, a deuterium-labeling experiment
with d7-DMF as the solvent was carried out. The
deuterated product was obtained in 68% yield
3
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10.1002/adsc.201700584
Advanced Synthesis & Catalysis
played two functional roles as the terminal oxidant
and oxygen supplier in the process. Furthermore, a
series of verification experiments unambiguously
revealed that the 2-carbon of the 3-acylindole was
derived from the methyl group of DMF. A detailed
mechanistic investigation and further application of
this method are currently underway in our laboratory.
Scheme 3. Further exploration of the reaction mechanism.
(Scheme 2, a). Furthermore, five other amides were
employed, the reaction could only proceed in N,N-
dimethylacetamide and N-methylformamide (NMF)
(Scheme 2, b). The results implied that the N-methyl
group of DMF is the carbon source of the C-2 in the
3-acylindoles. Meanwhile, to explore the source of
the oxygen atom in the resulting product, a reaction of
1a has been carried out in 18O-DMF under the
optimized conditions (Scheme 2, c). Only 76% of
16O-product 2a was generated and the result has been
confirmed by the HRMS spectra. (See Supporting
Information for the details). Therefore, we reasoned
that the dioxygen instead of DMF is the source of the
oxygen atom in the product.
Further control experiments have been carried out
to probe the mechanism (Scheme 3). There was no
reaction in the presence of 1.0 equiv. of TEMPO.
While using 1.0 equiv. of BHT (2,6-di-tert-butyl-4-
methylphenol), 16% yield of the product could be
obtained. In addition, no improvement of the yields
was observed by using paraformaldehyde or
dimethylamine as the additives. These results possibly
suggest that the oxidation of DMF to the
corresponding iminium ion is a two-step process.
DMF is first oxidized to the nitrogen radical cation
through single-electron transfer then further oxidized
to the iminium ion.[12b,c]
Scheme 4. A proposed mechanistic pathway.
Experimental Section
General Information
Based on the above results and previous reports,[12]
a possible mechanism is proposed as illustrated in
Scheme 4. Initially, DMF is oxidized to the iminium
ion, which is attacked by the electron pair of the
nitrogen atom of 1a to form intermediate A, and the
peroxide anion is formed simultaneously. Then, the
iminium ion is generated again under the oxygen
atmosphere to form intermediate D. Subsequently, the
addition of the peroxide anion to the alkene and
intramolecular nucleophilic addition of the iminium
ion occurred and formed intermediate E. With the aid
of the carboxylic acid, the N-methyl formamide could
be eliminated through C-N bond cleavage to form the
iminium-cation intermediate F.[13] Finally, the desired
product 2a is generated through aromatization and
oxidation.
All reactions were performed in standard glassware.
Solvents were distilled prior to use. All commercially
available reagents were used as purchased without further
purification. Flash column chromatography was performed
over silica gel 200-300 mesh. Infrared spectra were
measured on a FT/IR instrument. Melting points were
determined with a micromelting point apparatus without
corrections. High-resolution mass spectrometry (HRMS)
1
was obtained on a Q-TOF microspectrometer. H and 13C
NMR spectra were obtained on 600 MHz spectrometer
(151 MHz for 13C NMR) or 400 MHz spectrometer (100
MHz for 13C NMR) at 25 °C, using CDCl3 with TMS or
residual solvent as standard unless otherwise noted.
Chemical-shift values were given in ppm and referenced to
the internal standard TMS (tetramethylsilane). The peak
patterns are indicated as follows: s, singlet; d, doublet; t,
triplet; q, quadruplet; m, multiplet; dd, doublet of doublets,
and br s, broad singlet. The coupling constants (J) are
reported in hertz (Hz).
In summary, we developed a cascade C-N, C-C
and C-O multiple-bond-formation reaction to
synthesize 3-acylindoles from 2-alkenylanilines with
DMF as a one-carbon synthon through C-N bond
cleavage, and a series of 3-acylindoles were afforded
in moderate to good yields. Additionally, dioxygen
General procedure for synthesis of 3-acylindoles
To a 10 mL Schlenk tube with a stirring bar was added
successively 2-alkeneanilines (1 or 3) (0.2 mmol, 1.0
equiv), benzoic acid (12.2 mg, 0.1 mmol, 0.5 equiv),
tetrabutylammonium trifluoromethanesulfonate (11.7 mg,
4
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10.1002/adsc.201700584
Advanced Synthesis & Catalysis
0.03 mmol, 0.15 equiv) and DMF (1.0 mL). The tube was white solid; mp 118-120 oC; Rf
=
0.72 (20%
1
capped with a rubber septum, evacuated and backfilled EtOAc/petroleum ether). H NMR (600 MHz, CDCl3) δ
with O2 (1 atm), then the reaction mixture was stirred at 3.81 (s, 3H), 7.39 (t, J = 7.2 Hz, 1H), 7.43 (t, J = 7.8 Hz,
150 °C for the reported time. The resulting mixture was 1H), 7.55 (t, J = 7.8 Hz, 2H), 7.64 (t, J = 7.2 Hz, 1H), 7.85
allowed to cool to room temperature and then directly (d, J = 6.6 Hz, 2H), 7.87 (d, J = 4.8 Hz, 2H), 7.98 (d, J =
purified by flash column chromatography on silica gel, 8.4 Hz, 1H), 8.03 (s, 1H), 8.31 (d, J = 7.8 Hz, 1H); 13C
eluting with EtOAc/petroleum ether (1:100 ~ 5:100, v/v) to NMR (151 MHz, CDCl3) δ 55.8, 113.2, 114.8, 120.3, 123.0,
afford the corresponding products 2 or 4.
124.8, 125.9, 128.5, 128.68, 128.74, 129.0, 129.5, 132.4,
133.6, 134.9, 139.2, 164.4, 190.9; HRMS (ESI) m/z calcd
for C22H17NNaO4S (M+Na)+ 414.0776, found 414.0779.
Phenyl(1-tosyl-1H-indol-3-yl)methanone
(2a).[14]
Reaction time: 18 h; 61 mg, 81% yield, white solid, mp
o
1
119-121 C; Rf = 0.55 (20% EtOAc/petroleum ether). H (5-Methoxy-1-tosyl-1H-indol-3-yl)(phenyl)methanone
NMR (600 MHz, CDCl3) δ 2.36 (s, 3H), 7.27 (d, J = 7.6 Hz, (2h). Reaction time: 18 h; 58 mg, 74% yield, white solid;
o
1
2H), 7.43 (m, 2H), 7.56 (t, J = 7.4 Hz, 2H), 7.65 (t, J = 7.4 mp 98-99 C; Rf = 0.63 (20% EtOAc/petroleum ether). H
Hz, 1H), 7.81 (d, J = 8.4 Hz, 2H), 7.87 (d, J = 7.0 Hz, 2H), NMR (600 MHz, CDCl3) δ 2.36 (s, 3H), 3.86 (s, 3H), 7.02
7.99 (d, J = 8.0 Hz, 1H), 8.02 (s, 1H), 8.31 (d, J = 8.1 Hz, (dd, J = 2.4, 9.0 Hz, 1H), 7.55 (t, J = 7.8 Hz, 2H), 7.64 (t, J
1H); 13C NMR (151 MHz, CDCl3) δ 21.6, 113.2, 120.4, = 7.8 Hz, 2H), 7.77 (d, J = 8.4 Hz, 2H), 7.81 (d, J = 2.4 Hz,
123.0, 124.9, 126.0, 127.2, 128.5, 128.7, 129.0, 130.2, 1H), 7.86 (dd, J = 4.2, 7.2 Hz, 3H), 7.98 (s, 1H); 13C NMR
132.4, 133.6, 134.5, 135.0, 139.2, 145.9, 190.8; HRMS (151 MHz, CDCl3) δ 21.6, 55.7, 104.4, 114.1, 115.9, 120.2,
(ESI) m/z calcd for C22H17NNaO3S (M+Na)+ 398.0827, 127.1, 128.7, 129.0, 129.55, 129.6, 130.2, 132.3, 134.1,
found 398.0828.
134.5, 139.2, 145.9, 157.7, 191.0; HRMS (ESI) m/z calcd
for C23H19NNaO4S (M+Na)+ 428.0932, found 428.0925.
Phenyl(1-(phenylsulfonyl)-1H-indol-3-yl)methanone
(2b).[15] Reaction time: 18 h; 26 mg, 36% yield, light (5-Methyl-1-tosyl-1H-indol-3-yl)(phenyl)methanone
yellow solid; mp 108-110 oC; Rf
=
0.65 (20% (2i).[14] Reaction time: 18 h; 50 mg, 71% yield, white solid;
o
1
EtOAc/petroleum ether). H NMR (600 MHz, CDCl3) δ mp 143-145 C; Rf = 0.58 (20% EtOAc/petroleum ether).
7.38 (t, J = 7.2 Hz, 1H), 7.43 (t, J = 7.4 Hz, 1H), 7.49 (t, J 1H NMR (600 MHz, CDCl3) δ 2.36 (s, 3H), 2.46 (s, 3H),
= 7.9 Hz, 2H), 7.55 (t, J = 7.8 Hz, 2H), 7.60 (t, J = 7.2 Hz, 7.24 (d, J = 9.0 Hz, 1H), 7.25 (d, J = 8.4 Hz, 2H), 7.55 (t, J
1H), 7.65 (t, J = 7.2 Hz, 1H), 7.87 (d, J = 7.2 Hz, 2H), 7.92 = 7.8 Hz, 2H), 7.64 (t, J = 7.8 Hz, 1H), 7.77 (d, J = 8.4 Hz,
(d, J = 7.8 Hz, 1H), 8.00 (d, J = 7.8 Hz), 8.03 (s, 1H), 8.31 2H), 7.85 (d, J = 8.4 Hz, 3H), 7.97 (s, 1H), 8.12 (s, 1H);
(d, J = 7.2 Hz); 13C NMR (151 MHz, CDCl3) δ 113.2, 13C NMR (151 MHz, CDCl3) δ 21.4, 21.6, 112.8, 120.2,
120.6, 123.0, 125.0, 126.1, 127.1, 128.5, 128.7, 129.1, 122.7, 127.1, 127.4, 128.7, 128.7, 129.0, 130.2, 132.3,
129.7, 132.5, 133.5, 134.6, 135.0, 137.5, 139.1, 190.9; 133.3, 133.7, 134.5, 134.8, 139.3, 145.8, 191.0; HRMS
HRMS (ESI) m/z calcd for C21H15NNaO3S (M+Na)+ (ESI) m/z calcd for C23H19NNaO3S (M+Na)+ 412.0983,
361.0773, found 361.0769.
found 412.0988.
(1-((4-Chlorophenyl)sulfonyl)-1H-indol-3-yl)(phenyl)-
(5-Chloro-1-tosyl-1H-indol-3-yl)(phenyl)methanone (2j).
methanone (2c). Reaction time: 18 h; 25 mg, 32% yield, Reaction time: 18 h; 58 mg, 64% yield, white solid; mp 98-
white solid; mp 119-121 oC; Rf
=
0.82 (20% 99 C; Rf = 0.26 (20% EtOAc/petroleum ether). H NMR
o
1
1
EtOAc/petroleum ether). H NMR (600 MHz, CDCl3) δ (600 MHz, CDCl3) δ 2.38 (s, 3H), 7.29 (d, J = 8.4 Hz, 1H),
7.42 (t, J = 9.0 Hz, 2H), 7.45 (d, J = 8.4 Hz, 2H), 7.56 (t, J 7.38 (dd, J = 1.8, 8.4 Hz, 1H), 7.56 (t, J = 7.8 Hz, 2H), 7.65
= 7.8 Hz, 2H), 7.65 (t, J = 7.2 Hz, 1H), 7.86 (t, J = 8.4 Hz, (t, J = 7.2 Hz, 1H), 7.77 (d, J = 8.4 Hz, 2H), 7.85 (d, J =
4H), 7.98 (d, J = 7.8 Hz, 1H), 8.00 (s, 1H), 8.31 (d, J = 7.8 7.2 Hz, 2H), 7.92 (d, J = 9.0 Hz, 1H), 8.03 (s, 1H); 13C
Hz, 1H); 13C NMR (151 MHz, CDCl3) δ 113.1, 120.9, NMR (151 MHz, CDCl3) δ 21.7, 114.2, 119.8, 122.8, 126.4,
123.2, 125.2, 126.2, 128.5, 128.6, 128.7, 129.0, 130.0, 127.1, 128.8, 129.0, 130.4, 131.0, 132.6, 133.3, 134.4,
132.5, 133.2, 134.9, 135.8, 139.0, 141.5, 190.7; HRMS 138.9, 146.3, 191.0; HRMS (ESI) m/z calcd for
(ESI) m/z calcd for C21H14ClNNaO3S (M+Na)+ 418.0281, C22H16ClNNaO3S (M+Na)+ 432.0437, found 432.0431.
found 418.0289.
(5-Fluoro-1-tosyl-1H-indol-3-yl)(phenyl)methanone (2k).
(1-((4-Bromophenyl)sulfonyl)-1H-indol-3-yl)(phenyl)-
Reaction time: 18 h; 54 mg, 69% yield, white solid; mp 97-
o
1
methanone (2d). Reaction time: 18 h; 34 mg, 39% yield, 101 C; Rf = 0.73 (20% EtOAc/petroleum ether). H NMR
light yellow solid; mp 120-122 oC; Rf = 0.78 (20% (600 MHz, CDCl3) δ 2.37 (s, 3H), 7.14 (td, J = 9.0, 2.4 Hz,
1
EtOAc/petroleum ether). H NMR (600 MHz, CDCl3) δ 1H), 7.27 (d, J = 7.2 Hz, 2H), 7.64 (t, J = 7.8 Hz, 1H), 7.79
7.42 (m, 2H), 7.56 (t, J = 7.8 Hz, 2H), 7.62 (d, J = 9.0 Hz, (d, J = 8.4 Hz, 2H), 7.85 (d, J = 7.2 Hz, 2H), 7.93 (dd, J =
2H), 7.64 (t, J = 7.8 Hz, 1H), 7.77 (d, J = 8.4 Hz, 2H), 7.87 4.2, 9.0 Hz, 1H), 8.00 (dd, J = 2.4, 9.0 Hz, 1H), 8.05 (s,
(d, J = 7.2 Hz, 2H), 7.97 (d, J = 8.4 Hz, 1H), 7.99 (s, 1H); 1H); 13C NMR (151 MHz, CDCl3) δ 21.7, 108.9 (d, J =
13C NMR (151 MHz, CDCl3) δ 113.1, 121.0, 123.2, 125.2, 25.5 Hz), 114.1 (d, J = 31.5 Hz), 114.3 (d, J = 3.0 Hz),
126.2, 126.6, 128.5, 128.6, 128.7, 129.0, 130.1, 132.5, 120.1 (d, J = 3.0 Hz), 127.1, 127.8, 128.8, 129.0, 129.7 (d,
133.0, 133.2, 134.9, 136.4, 139.0, 190.7; HRMS (ESI) m/z J = 10.5 Hz), 130.3, 131.3, 132.5, 134.3, 134.8, 138.9,
calcd for C21H14BrNNaO3S (M+Na)+ 461.9775, found 146.2, 159.8 (d, J = 241.5 Hz), 190.5; HRMS (ESI) m/z
461.9779.
calcd for C22H16FNNaO3S (M+Na)+ 416.0733, found
416.0733.
(1-((4-Nitrophenyl)sulfonyl)-1H-indol-3-yl)(phenyl)-
methanone (2e). Reaction time: 18 h; 15 mg, 18% yield, Ethyl-3-benzoyl-1-tosyl-1H-indole-5-carboxylate
(2l).
white solid; mp 161-164 oC; Rf
=
0.43 (20% Reaction time: 18 h; 49 mg, 55% yield, white solid; mp
1
o
1
EtOAc/petroleum ether). H NMR (600 MHz, CDCl3) δ 133-135 C; Rf = 0.52 (20% EtOAc/petroleum ether). H
7.43 (t, J = 7.2 Hz, 1H), 7.47 (t, J = 7.2 Hz, 1H), 7.57 (m, J NMR (600 MHz, CDCl3) δ 1.40 (t, J = 7.2Hz, 3H), 2.37 (s,
= 7.2 Hz, 2H), 7.67 (t, J = 7.2 Hz, 1H), 7.87 (d, J = 7.2 Hz, 3H), 4.40 (dd, J = 7.2, 14.4 Hz, 2H), 7.29 (d, J = 7.8 Hz,
1H), 7.99 (s, 1H), 8.01 (d, J = 9.0 Hz, 1H), 8.10 (d, J = 7.8 2H), 7.56 (t, J = 7.8 Hz, 2H), 7.66 (t, J = 7.2 Hz, 1H), 7.81
Hz, 2H), 8.30 (d, J = 7.8 Hz, 1H), 8.32 (d, J = 9.0 Hz, 1H); (d, J = 7.8 Hz, 1H), 7.88 (d, J = 7.8 Hz, 2H), 8.02 (d, J =
13C NMR (151 MHz, CDCl3) δ 113.0, 121.7, 123.4, 124.4, 9.0 Hz, 1H), 8.07 (s, 1H), 8.13 (dd, J = 0.6, 8.4 Hz, 1H),
124.9, 125.5, 126.6, 128.3, 128.4, 128.7, 128.8, 129.1, 8.99 (s, 1H); 13C NMR (151 MHz, CDCl3) δ 14.4, 21.7,
132.7, 134.9, 138.8, 142.7, 151.0, 190.4; HRMS (ESI) m/z 61.1, 113.0, 120.6, 125.1, 127.2, 127.3, 127.4, 128.4, 128.8,
calcd for C21H14N2NaO5S (M+Na)+ 406.0623, found 129.1, 130.4, 132.6, 134.2, 134.3, 137.4, 138.9, 146.3,
406.0625.
166.5, 190.3; HRMS (ESI) m/z calcd for C25H21NNaO5S
(M+Na)+ 470.1083, found 470.1089.
(1-((4-Methoxyphenyl)sulfonyl)-1H-indol-3-yl)(phenyl)-
methanone (2f). Reaction time: 18 h; 56 mg, 72% yield,
5
This article is protected by copyright. All rights reserved.

10.1002/adsc.201700584
Advanced Synthesis & Catalysis
(6-Methoxy-1-tosyl-1H-indol-3-yl)(phenyl)methanone
p-Tolyl(1-tosyl-1H-indol-3-yl)methanone (4c). Reaction
(2n). Reaction time: 10 h; 17 mg, 21% yield, yellow solid; time: 18 h; 49 mg, 63% yield, white solid; mp 105-108 oC;
o
1
1
mp 49-51 C; Rf = 0.62 (20% EtOAc/petroleum ether). H Rf = 0.57 (20% EtOAc/petroleum ether). H NMR (600
NMR (600 MHz, CDCl3) δ 2.37 (s, 3H), 3.90 (s, 3H), 7.01 MHz, CDCl3) δ 2.34 (s, 3H), 2.47 (s, 3H), 7.24 (d, J = 9.0
(dd, J = 2.4, 9.0 Hz, 1H), 7.28 (d, J = 9.6 Hz, 2H), 7.50 (d, Hz, 2H), 7.36 (td, J = 1.2, 7.2 Hz, 1H), 7.40 (td, J = 1.2,
J = 1.8 Hz, 1H), 7.54 (t, J = 7.2 Hz, 1H), 7.63 (t, J = 7.2 Hz, 8.4Hz, 1H), 7.79 (m, 4H), 7.98 (d, J = 8.4 Hz, 1H), 8.02 (s,
2H), 7.79 (d, J = 8.4 Hz, 2H), 7.86 (d, J = 8.4 Hz, 1H), 7.90 1H), 8.27 (d, J = 7.8 Hz, 1H); 13C NMR (151 MHz, CDCl3)
(s, 1H), 8.18 (d, J = 9.0 Hz, 1H); 13C NMR (151 MHz, δ 21.6, 21.7, 113.2, 120.6, 123.0, 124.8, 125.9, 127.1,
CDCl3) δ 21.6, 55.8, 97.5, 113.7, 120.5, 122.2, 123.6, 128.6, 129.2, 129.4, 130.2, 133.2, 134.6, 135.0, 136.5,
127.1, 128.6, 129.0, 130.2, 132.3, 132.5, 134.5, 136.1, 143.2, 145.9, 190.5; HRMS (ESI) m/z calcd for
139.2, 145.9, 158.7, 190.9; HRMS (ESI) m/z calcd for C23H19NNaO3S (M+Na)+ 412.0983, found 412.0985.
C21H15NNaO3S (M+Na)+ 361.0773, found 361.0769.
(3-Methoxyphenyl)(1-tosyl-1H-indol-3-yl)methanone
(6-Methyl-1-tosyl-1H-indol-3-yl)(phenyl)methanone
(4d). Reaction time: 18 h; 28 mg, 34% yield, white solid;
o
(2o). Reaction time: 18 h; 34 mg, 43% yield, white solid; mp 149-154 C; Rf = 0.65 (20% EtOAc/petroleum ether).
mp 102-104 C; Rf = 0.49 (20% EtOAc/petroleum ether). 1H NMR (600 MHz, CDCl3) δ 2.37 (s, 3H), 3.90 (s, 3H),
o
1H NMR (600 MHz, CDCl3) δ 2.35 (s, 3H), 2.50 (s, 3H), 7.17 (d, J = 7.8 Hz, 1H), 7.28 (d, J = 7.8 Hz, 2H), 7.38 –
7.21 (d, J = 7.8 Hz, 1H), 7.27 (d, J = 7.8 Hz, 2H), 7.53 (t, J 7.47 (m, 5H), 7.80 (d, J = 7.2 Hz, 2H), 7.98 (d, J = 7.8 Hz,
= 7.8 Hz, 2H), 7.63 (t, J = 7.8 Hz, 1H), 7.79 (s, 1H), 7.80 1H), 8.05 (s, 1H), 8.30 (d, J = 7.8 Hz, 1H); 13C NMR (151
(d, J = 8.4 Hz, 2H), 7.86 (d, J = 8.4 Hz, 2H), 7.96 (s, 1H), MHz, CDCl3) δ 21.7, 55.5, 113.2, 113.5, 118.8, 120.4,
8.17 (d, J = 7.8 Hz, 1H); 13C NMR (151 MHz, CDCl3) δ 121.6, 123.0, 124.9, 126.0, 127.2, 128.5, 129.7, 130.3,
21.6, 22.0, 113.2, 120.4, 122.5, 126.2, 126.4, 127.1, 128.6, 133.7, 134.5, 135.0, 140.5, 146.0, 159.8, 190.6; HRMS
129.0, 130.2, 132.3, 133.1, 134.7, 135.4, 136.3, 139.3, (ESI) m/z calcd for C23H19NNaO4S (M+Na)+ 428.0932,
145.8, 190.8; HRMS (ESI) m/z calcd for C23H19NNaO3S found 428.0939.
(M+Na)+ 412.0983, found 412.0986.
(4-(tert-Butyl)phenyl)(1-tosyl-1H-indol-3-yl)methanone
(6-Chloro-1-tosyl-1H-indol-3-yl)(phenyl)methanone
(4e). Reaction time: 18 h; 25 mg, 29% yield, white solid;
o
(2p). Reaction time: 18 h; 34 mg, 49% yield, colorless oil; mp 190-194 C; Rf = 0.51 (20% EtOAc/petroleum ether).
Rf = 0.63 (20% EtOAc/petroleum ether). H NMR (600 1H NMR (600 MHz, CDCl3) δ 1.40 (s, 9H), 2.36 (s, 3H),
1
MHz, CDCl3) δ 2.38 (s, 3H), 7.29 (d, J = 9.6 Hz, 2H), 7.36 7.25 (d, J = 8.4 Hz, 2H), 7.38 (t, J = 7.2 Hz, 1H), 7.41 (t, J
(dd, J = 1.8, 8.4 Hz, 1H), 7.55 (t, J = 7.8 Hz, 2H), 7.63 (t, J = 7.8 Hz, 1H), 7.55 (d, J = 8.4 Hz, 2H), 7.81 (dd, J = 8.4,
= 7.8 Hz, 1H), 7.79 (d, J = 8.4 Hz, 2H), 7.86 (d, J = 7.2 Hz, 16.2 Hz, 4H), 7.98 (d, J = 8.4 Hz, 1H), 8.05 (s, 1H), 8.30 (d,
2H), 8.00 (s, 1H), 8.01 (d, J = 1.8 Hz, 1H), 8.22 (d, J = 9.0 J = 7.8 Hz, 1H); 13C NMR (151 MHz, CDCl3) δ 21.6, 31.2,
Hz, 1H); 13C NMR (151 MHz, CDCl3) δ 21.7, 113.4, 120.1, 35.2, 113.2, 120.5, 123.0, 124.8, 125.7, 125.9, 127.1, 128.7,
123.9, 125.6, 127.1, 127.2, 128.8, 129.0, 130.4, 132.0, 129.1, 130.2, 133.3, 134.5, 135.0, 136.4, 145.9, 156.2,
132.6, 133.8, 134.2, 135.3, 138.9, 146.3, 190.5; HRMS 190.5; HRMS (ESI) m/z calcd for C26H19NO3S (M+Na)+
(ESI) m/z calcd for C22H16ClNNaO3S (M+Na)+ 432.0437, 454.1453, found 454.1456.
found 432.0433.
(4-Chlorophenyl)(1-tosyl-1H-indol-3-yl)methanone (4f).
(6-Fluoro-1-tosyl-1H-indol-3-yl)(phenyl)methanone (2q). Reaction time: 18 h; 34 mg, 41% yield, white solid; mp
o
1
Reaction time: 18 h; 43 mg, 55% yield, white solid; mp 99- 134-136 C; Rf = 0.73 (20% EtOAc/petroleum ether). H
o
1
101 C; Rf = 0.78 (20% EtOAc/petroleum ether). H NMR NMR (600 MHz, CDCl3) δ 2.37 (s, 3H), 7.28 (d, J = 8.4 Hz,
(600 MHz, CDCl3) δ 2.39 (s, 3H), 7.14 (td, J = 9.0, 2.4 Hz, 2H), 7.38 (t, J = 7.2 Hz, 1H), 7.42 (t, J = 8.4 Hz, 1H), 7.53
1H), 7.29 (d, J = 7.8 Hz, 2H), 7.55 (t, J = 7.8 Hz, 2H), 7.65 (d, J = 8.4 Hz, 2H), 7.80 – 7.82 (m, 4H), 7.98 (d, J = 7.2
(t, J = 7.8 Hz, 1H), 7.70 (dd, J = 1.8, 9.0 Hz, 1H), 7.79 (d, J Hz, 1H), 7.99 (s, 1H), 8.26 (d, J = 7.8 Hz, 1H); 13C NMR
= 8.4 Hz, 2H), 7.85 (d, J = 7.8 Hz, 1H), 7.99 (s, 1H), 8.27 (151 MHz, CDCl3) δ 21.7, 113.2, 120.2, 122.9, 124.9,
(dd, J = 4.8, 8.4 Hz, 1H); 13C NMR (151 MHz, CDCl3) δ 126.1, 127.2, 128.3, 129.0, 130.3, 130.4, 133.3, 134.4,
21.7, 100.5 (d, J = 28.5 Hz), 113.3 (d, J = 23.9 Hz), 120.2, 135.0, 137.5, 138.8, 146.0, 189.5; HRMS (ESI) m/z calcd
124.1 (d, J = 9.7 Hz), 124.8, 127.2, 128.7, 129.0, 130.4, for C22H16ClNNaO3S (M+Na)+ 432.0437, found 432.0429.
132.5, 133.6 (d, J = 3.2 Hz), 134.2, 135.2 (d, J = 12.4 Hz),
139.0, 146.3, 160.6 (d, J = 244.5 Hz), 190.6; HRMS (ESI)
(4-Fluorophenyl)(1-tosyl-1H-indol-3-yl)methanone (4g).
m/z calcd for C22H16FNNaO3S (M+Na)+ 416.0733, found
Reaction time: 18 h; 41 mg, 52% yield, white solid; mp
o
1
416.0739.
139-141 C; Rf = 0.76 (20% EtOAc/petroleum ether). H
NMR (600 MHz, CDCl3) δ 2.36 (s, 3H), 7.22 (t, J = 8.4 Hz,
o-Tolyl(1-tosyl-1H-indol-3-yl)methanone (4a). Reaction 2H), 7.27 (d, J = 7.8 Hz, 1H), 7.38 (t, J = 7.2 Hz, 1H), 7.42
time: 18 h; 61 mg, 79% yield, white solid; mp 104-107 oC; (t, J = 7.2 Hz, 1H), 7.80 (d, J = 8.4 Hz, 2H), 7.89 – 7.91 (m,
1
Rf = 0.73 (20% EtOAc/petroleum ether). H NMR (600 2H), 8.01 (s, 1H), 8.26 (d, J = 7.8 Hz, 1H); 13C NMR (151
MHz, CDCl3) δ 2.37 (s, 3H), 2.39 (s, 3H), 7.27 (d, J = 8.4 MHz, CDCl3) δ 21.6, 113.2, 115.8 (d, J = 21.5 Hz), 120.3,
Hz, 2H), 7.32 (d, J = 7.8 Hz, 1H), 7.33 (d, J = 7.8 Hz, 1H), 122.9, 124.9, 126.0, 127.2, 128.5, 130.3, 131.5 (d, J = 9.0
7.37 – 7.45 (m, 4H), 7.79 (d, J = 8.4 Hz, 2H), 7.82 (s, 1H), Hz), 133.2, 134.4, 135.0, 135.4 (d, J = 1.8 Hz), 146.0,
7.97 (d, J = 7.2 Hz, 1H), 8.36 (d, 7.2 Hz, 1H); 13C NMR 164.5 (d, J = 254.3 Hz), 189.2; HRMS (ESI) m/z calcd for
(151 MHz, CDCl3) δ 19.8, 21.7, 113.2, 121.8, 123.1, 125.0, C22H16FNNaO3S (M+Na)+ 416.0733, found 416.0737.
125.5, 125.9, 127.2, 128.0, 128.1, 130.3, 130.4, 131.3,
134.5, 134.7, 135.1, 136.5, 139.4, 146.0, 193.2; HRMS
Naphthalen-2-yl(1-tosyl-1H-indol-3-yl)methanone (4h).
(ESI) m/z calcd for C23H19NNaO3S (M+Na)+ 412.0983,
Reaction time: 36 h; 52 mg, 61% yield, light yellow solid;
o
1
found 412.0986.
mp 83-85 C; Rf = 0.56 (20% EtOAc/petroleum ether). H
NMR (600 MHz, CDCl3) δ 2.37 (s, 3H), 7.25 (d, J = 6.0 Hz,
m-Tolyl(1-tosyl-1H-indol-3-yl)methanone (4b). Reaction 2H), 7.27 (d, J = 7.8 Hz, 1H), 7.40 – 7.45 (m, 2H), 7.52 (t,
time: 18 h; 60 mg, 77% yield, white solid; mp 105-108 oC; J = 7.8 Hz, 1H), 7.57 (dd, J = 6.6, 14.4 Hz, 2H), 7.72 (d, J
1
Rf = 0.76 (20% EtOAc/petroleum ether). H NMR (600 = 7.2 Hz, 1H), 7.75 (d, 8.4 Hz, 2H), 8.85 (s, 1H), 7.97 (d, J
MHz, CDCl3) δ 2.35 (s, 3H), 2.45 (s, 3H), 7.23 (d, J = 9.0 = 8.4 Hz, 1H), 7.98 – 7.99 (m, 1H), 8.05 (d, J = 8.4 Hz,
Hz, 1H), 7.26 (d, J = 8.4 Hz, 2H), 7.54 (t, J = 7.2 Hz, 2H), 1H,), 8.18 (d, J = 8.4 Hz, 1H), 8.46 (dd, J = 2.4, 5.4 Hz,
7.63 (t, J = 7.2 Hz, 1H), 7.78 (d, J = 8.4 Hz, 2H), 7.86 (d, J 1H); 13C NMR (151 MHz, CDCl3) δ 21.7, 113.2, 122.2,
= 7.8 Hz, 3H), 7.97 (s, 1H), 8.12 (s, 1H); 13C NMR (151 123.2, 124.6, 125.0, 125.5, 126.0, 126.6, 127.16, 127.23,
MHz, CDCl3) δ 21.4, 21.6, 112.8, 120.2, 122.7, 127.1, 127.26, 128.1, 128.5, 130.3, 130.6, 131.4, 134.3, 134.9,
127.3, 128.6, 128.7, 129.0, 130.2, 132.3, 133.3, 133.7, 135.1, 137.2, 146.0, 192.4; HRMS (ESI) m/z calcd for
134.6, 134.8, 139.3, 145.8, 190.9; HRMS (ESI) m/z calcd C26H19NNaO3S (M+Na)+ 448.0983, found 448.0980.
for C23H19NNaO3S (M+Na)+ 412.0983, found 412.0982.
6
This article is protected by copyright. All rights reserved.

10.1002/adsc.201700584
Advanced Synthesis & Catalysis
Naphthalen-1-yl(1-tosyl-1H-indol-3-yl)methanone (4i).
5007; i) J. Kim, S. Chang, J. Am. Chem. Soc. 2010,
132, 10272-10274.
Reaction time: 70 h; 56 mg, 66% yield, light yellow solid;
o
1
mp 74-76 C; Rf = 0.55 (20% EtOAc/petroleum ether). H
NMR (600 MHz, CDCl3) δ 2.37 (s, 3H), 7.25 (d, J = 7.2 Hz,
2H), 7.41 – 7.45 (m, 2H), 7.52 (t, J = 7.8 Hz, 1H), 7.57 (dd,
J = 7.2, 14.4 Hz, 2H), 7.71 (d, J = 6.6 Hz, 1H), 7.75 (d, 8.4
Hz, 2H), 7.84 (s, 1H), 7.96 (d, J = 7.8 Hz, 1H), 7.98 – 7.99
(m, 1H), 8.05 (d, J = 8.4 Hz, 1H,), 8.18 (d, J = 8.4 Hz, 1H),
8.46 (dd, J = 2.4, 5.4 Hz, 1H); 13C NMR (151 MHz, CDCl3)
δ 21.7, 113.2, 122.3, 123.2, 124.6, 125.0, 125.5, 126.0,
126.6, 127.1, 127.22, 127.25, 128.2, 128.5, 130.2, 130.6,
131.4, 133.9, 134.4, 134.9, 135.1, 137.2, 146.0, 192.4;
HRMS (ESI) m/z calcd for C26H19NNaO3S (M+Na)+
448.0983, found 448.0978.
[3] DMF as a precursor in amination reactions: a) W.-X.
Chen, L.-X. Shao, J. Org. Chem. 2012, 77, 9236-
9239; b) J. Wang, J.-T. Hou, J. Wen, J. Zhang, X.-Q.
Yu, Chem. Commun. 2011, 47, 3652-3654; c) Y. Li, Y.
Xie, R. Zhang, K. Jin, X. Wang, C. Duan, J. Org.
Chem. 2011, 76, 5444-5449; d) S. H. Cho, J. Y. Kim,
S. Y. Lee, S. Chang, Angew. Chem. 2009, 121, 9291-
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Z. Liu, J. Zhang, S. Chen, E. Shi, Y. Xu, X. Wang,
Angew. Chem. 2012, 124, 3285-3289; Angew. Chem.
Int. Ed. 2012, 51, 3231-3235.
[4] DMF as a precursor in formylation reactions: a) Y.
Wang, F. Wang, C. Zhang, J. Zhang, M. Li, J. Xu,
Chem. Commun. 2014, 50, 2438-2441; b) L. Liu, D.
Zhang-Negrerie, Y. Du, K. Zhao, Org. Lett. 2014, 16,
436-439; c) T. He, H. Li, P. Li, L. Wang, Chem.
Commun. 2011, 47, 8946-8948; d) M. Suchý, A. A. H.
Elmehriki, R. H. E. Hudson, Org. Lett. 2011, 13,
3952-3955; e) M. J. Johansson, K. H. O. Andersson, N.
Kann, N. J. Org. Chem. 2008, 73, 4458-4463.
(6-Methyl-1-tosyl-1H-indol-3-yl)(p-tolyl)methanone (4j).
Reaction time: 18 h; 55 mg, 68% yield, white solid; mp
o
1
122-124 C; Rf = 0.63 (20% EtOAc/petroleum ether). H
NMR (600 MHz, CDCl3) δ 2.35 (s, 3H), 2.45 (s, 3H), 2.48
(s, 3H), 7.21 (d, J = 8.4 Hz, 1H), 7.24 (d, J = 7.8 Hz, 2H),
7.33 (d, J = 7.8 Hz, 2H), 7.77 (dd, J = 4.8, 8.4 Hz, 4H),
7.85 (d, J = 8.4 Hz, 1H), 7.96 (s, 1H), 8.09 (s, 1H); 13C
NMR (151 MHz, CDCl3) δ 21.4, 21.61, 21.64, 112.8, 120.4,
122.7, 127.1, 127.3, 128.8, 129.2, 129.3, 130.2, 133.25,
133.34, 134.6, 134.7, 136.6, 143.1, 145.8, 190.6; HRMS
(ESI) m/z calcd for C24H21NNaO3S (M+Na)+ 426.1140,
found 426.1133.
[5] Selected examples of cycloadditions of DMF: a) P.
Scrimin, F. D’Angeli, A. C. Veronese, V. Baioni,
Tetrahedron Lett. 1983, 24, 4473-4476; b) F. Maran,
E. Vianello, G. Cavicchioni, F. D’Angeli, J. Chem.
Soc., Chem. Commun. 1985, 660-660; c) F. Maran, E.
Vianello, F. D’Angeli, G. Cavicchioni, G. Vecchiati, J.
Chem. Soc., Perkin Trans. 2 1987, 33-38; d) M.
Hanack, B. Wilhelm, Angew. Chem. 1989, 101, 1083-
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1059; e) H. Yoshida, Y. Ito, J. Ohshita, Chem.
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Man, W.-K. Yuan, M. Li, J. Org. Chem. 2016, 81,
5942-5948; g) E. Yoshioka, S. Kohtani, H. Miyabe,
Angew. Chem. 2011, 123, 6768-6772; Angew. Chem.
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Lin, F. Liang, Org. Biomol. Chem. 2014, 12, 6389-
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Cyclopropyl(1-tosyl-1H-indol-3-yl)methanone
(4k).
Reaction time: 48 h; 13 mg, 19% yield, white solid; mp
o
1
159-161 C; Rf = 0.75 (20% EtOAc/petroleum ether). H
NMR (600 MHz, CDCl3) δ 1.03 (m, 2H), 1.25 (m, 2H),
2.36 (s, 1H), 2.50 (m, 1H), 7.27 (d, J = 8.4 Hz, 2H), 7.33
(m, 1H), 7.38 (m, 1H), 7.84 (d, J = 7.8 Hz, 2H), 7.93 (d, J
= 8.4 Hz, 1H), 8.32 (d, J = 7.2 Hz, 1H), 8.36 (s, 1H); 13C
NMRpp (151 MHz, CDCl3) δ 11.0, 18.6, 21.7, 113.0, 122.1,
123.2, 124.8, 125.7, 127.2, 127.7, 130.2, 131.6, 134.6,
134.9, 145.9, 195.7; HRMS (ESI) m/z calcd for
C19H17NNaO3S (M+Na)+ 362.0287, found 362.0289.
Acknowledgements
This work is financially supported by the Scientific Research
Foundation for the Returned Overseas Chinese Scholars, State
Education Ministry, and the National Natural Science Foundation
of China (Grant No. 21572154). We thank Professor Richard P.
Hsung [University of Wisconsin at Madison] for invaluable
discussions.
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UPDATE
Metal-Free Activation of DMF by Dioxygen: A
Cascade Multiple-Bond-Formation Reaction to
Synthesize 3-Acylindoles from 2-Alkenylanilines
Adv. Synth. Catal. Year, Volume, Page – Page
Ji-Bo Wang, Yin-Long Li, Jun Deng *
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