A novel NH4OAc and CuBr(PPh3)3-induced intermolecular Pummerer-type reaction between free (NH)-indoles and dimethylsulfoxide: Facile synthesis of 3-methylthiomethyl substituted indoles

Article abstract of DOI:10.1016/j.tet.2011.12.002

A novel NH₄OAc/CuBr(PPh₃)₃-induced intermolecular Pummerer-type reaction between free (NH)-indoles and dimethylsulfoxide is first reported, which offers the 3-methylthiomethyl substituted indoles conveniently and efficient

Full text of DOI:10.1016/j.tet.2011.12.002

Tetrahedron 68 (2012) 1560e1565
Contents lists available at SciVerse ScienceDirect
Tetrahedron
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A novel NH4OAc and CuBr(PPh3)3-induced intermolecular Pummerer-type
reaction between free (NH)-indoles and dimethylsulfoxide: facile synthesis
of 3-methylthiomethyl substituted indoles
,
,
,
,
,
,b,
Jin Liu a b, Xianxue Wang a b, Han Guo a b, Xiaokang Shi a b, Xiaoyu Ren a b, Guosheng Huang a
*
a State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China
b Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou University, Lanzhou 730000, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel NH4OAc/CuBr(PPh3)3-induced intermolecular Pummerer-type reaction between free (NH)-in-
doles and dimethylsulfoxide is first reported, which offers the 3-methylthiomethyl substituted indoles
conveniently and efficiently.
Received 3 September 2011
Received in revised form 22 November 2011
Accepted 2 December 2011
Available online 8 December 2011
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Alkylation
Indoles
Dimethylsulfoxide
Intermolecular
Pummerer-type reaction
1. Introduction
valuable synthetic processes.6 Since the first report in the year of
1909, chemists have reported numerous Pummerer reaction
3-Alkyl substituted indoles have potentially high biological
activities.1 They have also been used to synthesis complex indole
derivatives that can be used as pharmaceuticals and agrochemicals.2
Among all the 3-alkyl substituted indoles, 3-methylthiomethyl
substituted indoles have attracted most interest because they are
naturally presented in some indole alkaloids and they show
excellent anti-insect activity.3 For instance, dithyreanitrile, which
had been isolated from the seeds of Dithyrea widizenii (Cruciferae),
was a useful insect antifeedant.3feh However, very few methods of
the synthesis of these 3-methylthiomethyl substituted indoles had
been reported. One of the practicable approaches towards 3-
methylthiomethyl substituted indoles is through the reaction of
gramine with methanethiol or sodium thiomethoxide,4 which is
limited by the not readily available substrates as well as the narrow
reaction scope. Thus our efforts to explore facile and new routes to
the 3-methylthiomethyl substituted indoles is significant.
examples using different nucleophiles, such as arenes, alkenes,
amides and phenols attacking the thionium ions either intra-7,9 or
intermolecularly.8 In addition, as a synthetic strategy to the natural
and complex heterocyclic compounds, the intramolecular
Pummerer reactions of electron-rich heterocycles have been widely
studied and reported.9 However, to the best of our knowledge, using
indoles as nucleophiles to trap the thionium ion intermediates by
intermolecular strategy have remained yet to be reported. This
perhaps because classical Pummerer reactions have to use harsh
acidic initiators, in which indoles usually can hardly tolerate and it
may induces side reactions. Another reason is the thionium ion
intermediates are more difficult to be trapped intermolecularly.
Therefore, it is of great importance to find novel routes to generate
thionium ions to expand the Pummerer reaction’s scope and
develop methodologies to achieve the intermolecular Pummerer
reactions between indoles and alkyl sulfoxides.
In our previous studies on the synthesis and functionalization of
bioactive heterocycles,10 we developed a simple and mild reaction
for the synthesis of 1H-indol-3-yl acetate.10e As the extension of
this reaction, we further examined whether NH4OAc could be used
as an acetoxylation reagent in this process. The reaction was per-
formed in DMSO in the presence of Pd(OAc)2 and base at 120 ꢀC.
Unexpectedly, we got the 3-(methylthiomethyl)-1H-indole other
than the desired 1H-indol-3-yl acetate product (Scheme 1). Given
The Pummerer reaction,5 which situ-generates thionium ion
intermediates through the reaction of alkyl sulfoxides with elec-
trophilic reagents, has been studied extensively and has established
itself as a very useful method for CeC bond construction in the
* Corresponding author. Fax: þ86 931 8912582; e-mail address: hgs@lzu.edu.cn
(G. Huang).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.12.002

J. Liu et al. / Tetrahedron 68 (2012) 1560e1565
1561
Table 1
the importance of 3-methylthiomethyl substituted indoles in syn-
thetic organic chemistry and biological chemistry, it is valuable to
develop a new synthetic strategy for these useful compounds.
Screening the conditions for the intermolecular Pummerer-type reaction between
indole and dimethylsulfoxidea
Herein, we report
a novel NH4OAc/CuBr(PPh3)3-induced in-
S
termolecular Pummerer-type reaction between free (NH)-indoles
and dimethylsulfoxide to efficiently give 3-methylthiomethyl
substituted indoles under simple conditions (Scheme 2).
conditions
O
S
+
N
H
N
H
1a
2a
OAc
N
Entry catalyst
Additive
Base
Temp (ꢀC)
Yieldb (%)
1
2
d
d
d
d
d
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
90
n.r.
7
NH4OAc
d
H
Pd(OAc)2, NH4OAc, base
DMSO, 120 °C
3
4
5
6
7
8
9
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
d
CH3ONa
d
ButOK
Cs2CO3
K2CO3
n.r.
48
68
60
64
71
58
20
48
46
46
28
57
48
56
63
56
64
71
n.r.
n.r.
n.r.
n.r.
n.r.
68
71
S
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
HCOONH4
CO(NH2)2
NH4HCO3
BnNH2
N
H
N
H
CH3ONa
yield: 48%
ButOLi
Scheme 1. Unexpected intermolecular Pummerer-type reaction between indole and
10
11
12
13
14
15
16
17
18
19c
20d
21e
22
23
24
25
26
27
28
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
CH3ONa
dimethylsulfoxide.
CuBr
CuI
CuCl
AlCl3
PdCl2(PPh3)3
Pd(OAc)2
CuCl(PPh3)3
Cu(phen)(PPh3)Br
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
CuBr(PPh3)3
Ac2O or (CF3CO)2O
S
"classical Pummerer reaction conditions"
O
S
+
N
H
N
H
NH4OAc, CuBr(PPh3)3, base
"this novel Pummerer reaction conditions"
Scheme 2. A novel NH4OAc and CuBr(PPh3)3-induced intermolecular Pummerer-type
reaction between indole and dimethylsulfoxide.
NH4OAc
NH4OAc
NH4OAc
2. Results and discussion
110
130
On the outset of this investigation, we used indole (1a) as
a model reactant to screen suitable reaction conditions. The impact
of the catalyst, base, additives, and temperature was investigated in
detail for the reaction (Table 1). It was found that no reaction was
observed in the absence of NH4OAc (Table 1, entries 1, 3) and no
products were detected while we used other ammonium salts
(HCOONH4, NH4HCO3) or organic amine, such as benzylamine, urea
as additives (Table 1, entries 22e25). On the other hand, it was
shown that some metal catalysts could promote the reaction.
Among the examined metal catalysts including copper, palladium
and aluminium salts, CuBr(PPh3)3 gave the best result, which 3-
(methylthiomethyl)-1H-indole could be afforded in 71% yield
(Table 1, entry 8). Additionally, we found that trace reaction could
also occur only in the presence of NH4OAc (7% yield, Table 1, entry
2), catalysts and bases made the reaction work better. Several bases
were screened in the experiments, with CH3ONa proving to be the
base of choice. In addition, to optimize the reaction conditions
further, we carried out the same reaction at temperatures ranging
from 90 to 130 ꢀC (Table 1, entries 26e28). At last, 120 ꢀC was
chosen to be the reaction temperature.
For the optimal reaction conditions, 1 was reacted with dry
dimethylsulfoxide in the presence of CuBr(PPh3)3 (15 mol %),
NH4OAc (4 equiv) and CH3ONa (1 equiv) at 120 ꢀC for 12 h and these
conditions were subsequently employed when we examined the
substrate scope of the reaction (Table 2). Gratifyingly, a variety of
free (NH)-indoles 1aes successfully reacted under the aforesaid
conditions to afford the desired 3-methylthiomethyl substituted
indoles 2aes in moderate to good yields.
In general, a majority of free (NH)-indoles with electron-rich
substituents were superior to those with electron-deficient sub-
stituents. Notably, 2-phenyl-1H-indoles (1r and 1s) were very re-
active to afford the corresponding 3-methylthiomethyl substituted
indoles in good yields (88% and 90% yields, respectively).
The bold values protrudes the optimal results of screening the conditions for the
reaction.
a
Reaction conditions: 1a (0.4 mmol), dry DMSO (1.2 mL), catalyst (15 mol %),
additive (4 equiv), base (1 equiv), 90e130 ꢀC for 12 h.
b
Isolated yield after column chromatography.
CuBr(PPh3)3 (5 mol %).
CuBr(PPh3)3 (10 mol %).
CuBr(PPh3)3 (20 mol %).
c
d
e
Conversely, indole with C2 having an alkyl substituent (1q) was not
very suitable in the reaction, giving the product only in 41% yield.
Unfortunately, because of their less reactivity, when 1-methyl-1H-
indole (1u), 3-methyl-1H-indole (1t) and ethyl methyl sulfoxide
were employed, there were almost a trace of product, respectively.
In addition, when other sulfoxides, such as methyl phenyl sulfoxide
and tetramethylene sulfoxide were examined in the reaction, there
were no desired products detected. The structure of these 3-
methylthiomethyl substituted indoles products were further con-
firmed by single-crystal X-ray analysis of 2f (Fig. 1).11
Trying to have an insight into this unusual Pummerer-type
reaction pathway, we carried out some experiments sub-
sequently. When methylthiomethyl acetate (I), the product of the
Pummerer rearrangement of dimethylsulfoxide in the presence of
acetic anhydride,5 was loaded instead of DMSO and NH4OAc in the
reaction, the desired product 2a was not observed (Scheme 3, the
left equation). However, to our delight, we got the desired 3-
(methylthiomethyl)-1H-indole product 2a in 73% yield when
putting ammonia gas through the reaction mixture for 3 h
(Scheme 3, the right equation). In addition, methylthiomethyl
acetate (I) was observed when we heated the mixture of DMSO,
AcOH and AcONa (AcOH/AcONa¼3:1, molar ratio, in 1.2 mL
DMSO) at 120 ꢀC for 12 h. A plausible reaction pathway is pro-
posed in Scheme 4, that is, based on previous reports6g,h,12 and
combined with our experiments results. As is shown in Scheme 4,

1562
J. Liu et al. / Tetrahedron 68 (2012) 1560e1565
Table 2
then rapidly ammonolyzed by NH3 yielding methylthiomethanol
(II). Methylthiomethanol (II) attacked CuBr(PPh3)3 leading to the
reactive intermediate (III), which was then trapped by indole (1a)
affording the indole 1-sulfonium ylide intermediate (IV). Then 3-
(methylthiomethyl)-1H-indole product (2a) was formed after the
[2,3]-sigmatropic rearrangement of the indole 1-sulfonium ylide
intermediate (IV).13
Synthesis of 3-methylthiomethyl substituted indoles 2 from free (NH)-indoles 1a
S
,
NH4OAc (4 equiv.) CuBr(PPh3)3 (15 mol %)
O
S
CH3ONa (1 equiv.)
R2
R1
R2
R1
+
N
H
Z
N
120 °C, 12 h
Z
b H
1
2
S
S
S
S
MeO
BnO
Me
S
CuBr(PPh3)3, CH3ONa
120 °C, 12 h
CuBr(PPh3)3, CH3ONa
NH3 (g), 120 °C, 3 h
N
H
N
N
N
H
S
OAc
H
H
+
2b, 73%
N
H
N
H
2c, 72%
2a
2d, 61%
OBn
, 71%
I
1a
2a
S
Me
S
S
S
yield: 73%
O2N
Br
Scheme 3. The reaction between indole 1a and methylthiomethyl acetate I in the
absence and in the presence of NH3 (g).
N
H
N
H
N
N
H
H
2h, 56%
2g, 61%
2f, 70%
2e, 60%
Br
S
S
S
S
N
H
N
H
N
H
N
Me
N
Br
H
2j, 48%
2i, 55%
2k, 63%
2l, 53%
S
S
S
S
N
H
Cl
N
H
N
H
F
N
H
2m, 62%
OBn
2n, 51%
Me
2p, 66%
2o, 73%
S
S
S
Me
N
H
N
H
N
H
N
H
S
2q, 41%
2r, 88%
2s, 90%
2t
, trace
Ph
S
Scheme 4. A plausible pathway of this intermolecular Pummerer-type reaction.
S
S
S
Next, we investigated the Knoevenagel-type reaction of 3-
(methylthiomethyl)-1H-indoles with 1,3-diphenylpropane-1,3-
dione as shown in Scheme 5 referring to the previous report.14
Satisfactorily, the corresponding useful 2-((1H-indol-3-yl)methy-
lene)-1,3-diphenylpropane-1,3-dione products15 3a and 3r were
successfully prepared in a mild condition with 61% and 32% yields,
respectively.
N
N
H
n. d.
N
N
H
H
e
d
c
2u
2v
n. d.
, trace
, trace
aReaction conditions: 1 (0.4 mmol), NH4OAc (4 equiv), CuBr(PPh3)3 (15 mol %),
CH3ONa (1 equiv), dry DMSO (1.2 mL), 120 ꢀC for 12 h.
bIsolated yields after column chromatography.
cEthyl methyl sulfoxide was used instead of DMSO.
dTetramethylene sulfoxide was used instead of DMSO, n.d.¼not detected.
eMethyl phenyl sulfoxide was used instead of DMSO.
O
O
R
Ph
Ph
S
DDQ (1.0 equiv)
O
O
+
R
Ph
Ph
CH3NO2, 60 °C, 8 h
N
H
N
H
R=H, 3a yield: 61%
R=Ph, 3r yield: 32%
R=H, 2a
R=Ph, 2r
Scheme 5. The Knoevenagel-type reaction between 3-(methylthiomethyl)-1H-indoles
and 1,3-diphenylpropane-1,3-dione.
3. Conclusions
In conclusion, we have developed a novel and facile NH4OAc/
CuBr(PPh3)3-induced intermolecular Pummerer-type reaction be-
tween free (NH)-indoles and dimethylsulfoxide, which can not be
achieved through the classical Pummerer conditions. This is the
first example of the intermolecular Pummerer reaction between
free (NH)-indoles and dimethylsulfoxide. It provides a new and
efficient approach to the synthesis of 3-methylthiomethyl
substituted indoles of both biological and synthetic interest. The
present method may find some value in organic synthesis because
of simple manipulations as well as the ready availability of the
Fig. 1. X-ray crystallography structure of compound 2f.
NH4OAc, which releases AcOH and NH3 in the reaction, plays
a very important part in the whole reaction pathway. Initially,
dimethylsulfoxide was activated by AcOH in the presence of AcOꢁ
giving the product of methylthiomethyl acetate (I), which was

J. Liu et al. / Tetrahedron 68 (2012) 1560e1565
1563
starting materials. Moreover, we believe that our new Pummerer-
type reaction system may be utilized in the intermolecular Pum-
merer reactions between other electron-rich aromatic cycles and
alkyl sulfoxides, which are ongoingly under investigation in our
laboratory.
112.5, 111.9, 111.9, 100.9, 55.8, 29.0, 15.2. MS (ESI): m/z
[MþH]þ¼208, 160. Anal. Calcd for C11H13NOS: C, 63.74; H, 6.32; N,
6.76. Found: C, 63.78; H, 6.40; N, 6.69.
4.2.3. 5-Methyl-3-(methylthiomethyl)-1H-indole (2c). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2c (72% yield) as
a white solid; mp: 80e82 ꢀC. IR (KBr): 3395, 2915, 2244, 1586, 1456,
4. Experimental section
4.1. General
1308, 908, 797, 731 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼7.83 (s, 1H),
7.50 (s, 1H), 7.20 (d, J¼8.4 Hz, 1H), 7.03 (s, 1H), 7.01 (s, 1H), 3.87 (s,
2H), 2.45 (s, 3H), 2.02 (s, 3H). 13C NMR (100 MHz, CDCl3):
d¼134.7,
Melting points were determined using an XT-4 melting point
apparatus and were uncorrected. 1H NMR and 13C NMR spectra
were determined in CDCl3 and acetone-d6 on a Varian-Inova
400 MHz with TMS as an internal standard. IR spectra were ob-
tained on Nicolet NEXUS 670 FT-IR instrument and only major
peaks were reported in cmꢁ1. Elemental analyses were performed
on Elementar vario EL. HRMS data were performed on Bruker
Apex II mass instrument (ESI). Mass spectra were performed on
Thermo DSQ mass instrument (EI at 70 eV). Copies of their 1H
NMR and 13C NMR spectra were provided. Column chromatogra-
phy was performed with 200e300 mesh silica gel using flash
column techniques. DMSO was distilled over calcium hydride
(CaH2). CuBr(PPh3)3, 2-phenyl-1H-indoles (1r and 1s) and meth-
ylthiomethyl acetate (I) were prepared according to the literature
methods, respectively.16e18 Other materials were purchased from
common commercial sources and used without additional
purification.
128.8,126.8,123.9,123.0,118.7,111.6,110.8, 28.9, 21.5,15.2. MS (ESI):
m/z [MþH]þ¼192, 144. Anal. Calcd for C11H13NS: C, 69.07; H, 6.85;
N, 7.32. Found: C, 69.16; H, 6.90; N, 7.25.
4.2.4. 5-(Benzyloxy)-3-(methylthiomethyl)-1H-indole (2d). Purified
by flash chromatography (PE/EtOAc, v/v 8/1) to give 2d (61% yield)
as a white solid; mp: 106e108 ꢀC. IR (KBr): 3290, 2913, 1582, 1482,
1203, 1013, 734 cmꢁ1
.
1H NMR (400 MHz, CDCl3):
d¼7.96 (s, 1H),
7.53 (d, J¼7.2 Hz, 2H), 7.44 (t, J¼7.2 Hz, 2H), 7.37 (t, J¼7.2 Hz, 1H),
7.31 (s, 1H), 7.24 (d, J¼8.8 Hz, 1H), 7.07 (d, J¼2.4 Hz, 1H), 6.99 (d,
J¼8 Hz, 1H), 5.16 (s, 2H), 3.91 (s, 2H), 2.07 (s, 3H). 13C NMR
(100 MHz, CDCl3):
d
¼153.1, 137.5, 131.7, 128.5, 127.8, 127.7, 127.1,
123.7, 131.1, 111.9, 111.9, 102.4, 70.8, 28.9, 15.2. MS (ESI): m/z
[MþH]þ¼284, 236. Anal. Calcd for C17H17NOS: C, 72.05; H, 6.05; N,
4.94. Found: C, 72.18; H, 6.25; N, 4.89.
4.2.5. 3-(Methylthiomethyl)-5-nitro-1H-indole (2e). Purified by
flash chromatography (PE/EtOAc, v/v 5/1) to give 2e (60% yield) as
a yellow solid; mp: 100e102 ꢀC. IR (KBr): 3367, 2915, 1516, 1330,
4.2. General procedure for the synthesis
of 3-methylthiomethyl substituted indoles by using
dimethylsulfoxide
1091, 740 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼8.70 (d, J¼2 Hz, 2H),
8.10e8.12 (dd, J¼8.8, 2.2 Hz, 1H), 7.41 (d, J¼9.2 Hz, 1H), 7.31 (d,
J¼2 Hz, 1H), 3.92 (s, 2H), 2.06 (s, 3H). 13C NMR (100 MHz, CDCl3):
All reactions were performed on a 0.40 mmol scale relative to
1a. To a solution of ammonium acetate in dry DMSO (NH4OAc,
1.6 mmol in 1.2 mL DMSO) in a 10 mL general branch reaction vial
was added indole 1a (0.40 mmol), CuBr(PPh3)3 (0.06 mmol) and
CH3ONa (0.40 mmol). The reaction vial was strictly sealed with
the air in it drived away. Then the reaction vial was heated in an
oil bath at 120 ꢀC for 12 h with stirring. Following, to the reaction
mixture was added H2O (2 mL) and it was extracted with
methylene dichloride (3ꢂ10 mL). The combined organic phases
were washed with saturated brine (2ꢂ3 mL), dried over anhy-
drous NaSO4 and concentrated in vacuo. The residue was sub-
jected to flash column chromatography on silica gel with
petroleum ether/EtOAc (v/v 8/1) as eluent to obtain the pure 3-
d
¼141.6, 139.5, 126.3, 125.9, 117.9, 116.7, 115.2, 111.3, 28.5, 15.4. MS
(ESI): m/z [MþH]þ¼223, 175. Anal. Calcd for C10H10N2O2S: C, 54.04;
H, 4.53; N, 12.60. Found: C, 54.10; H, 4.61; N, 12.56.
4.2.6. 5-Bromo-3-(methylthiomethyl)-1H-indole (2f). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2f (70% yield) as
a white solid; mp: 118e120 ꢀC. IR (KBr): 3310, 2915, 1655, 1450,
1096, 796 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼8.06 (s, 1H), 7.85 (d,
J¼1.6 Hz, 1H), 7.26e7.29 (dd, J¼8.4, 1.8 Hz, 1H), 7.20 (d, J¼8.4 Hz,
1H), 7.10 (d, J¼2 Hz, 1H), 3.84 (s, 2H), 2.03 (s, 3H). 13C NMR
(100 MHz, CDCl3):
d
¼135.0, 128.5, 125.1, 124.0, 121.8, 112.9, 112.6,
112.1, 28.7, 15.2. MS (ESI): m/z [MþH]þ¼256, 208. Anal. Calcd for
C10H10BrNS: C, 46.89; H, 3.93; N, 5.47. Found: C, 46.92; H, 3.96; N,
5.39.
(methylthiomethyl)-1H-indole product 2a as
a white solid
(50 mg, 71% yield).19
4.2.7. 4-Methyl-3-(methylthiomethyl)-1H-indole (2g). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2g (61% yield) as
a white solid; mp: 92e94 ꢀC. IR (KBr): 3318, 2915, 1435, 1116, 1060,
4.2.1. 3-(Methylthiomethyl)-1H-indole (2a). Purified by flash
chromatography (PE/EtOAc, v/v 8/1) to give 2a (71% yield) as
a white solid; mp: 86e88 ꢀC; IR (KBr): 3406, 2915, 2245, 1619,
752 cmꢁ1.1H NMR (400 MHz, CDCl3):
d
¼7.950 (s,1H), 7.19 (d, J¼8 Hz,
1458, 908, 736 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d
¼7.92 (s, 1H),
1H), 7.11 (t, J¼7.6 Hz,1H), 7.05 (d, J¼2.4 Hz,1H), 6.90 (d, J¼7.2 Hz,1H),
7.72 (d, J¼8 Hz, 1H), 7.31 (d, J¼8 Hz, 1H), 7.20 (t, J¼7.4 Hz, 1H), 7.13
4.02 (s, 2H), 2.83 (s, 3H), 2.09 (s, 3H). 13C NMR (100 MHz, CDCl3):
(t, J¼7.4 Hz, 1H), 7.05 (d, J¼2 Hz, 1H), 3.89 (s, 2H), 2.02 (s, 3H); 13C
d
¼137.0, 131.1, 125.2, 123.4, 122.4, 121.3, 112.8, 109.0, 30.9, 20.1, 14.9.
NMR (100 MHz, CDCl3):
d
¼136.4, 126.8, 122.8, 122.2, 119.5, 119.1,
MS (ESI): m/z [MþH]þ¼192, 144. Anal. Calcd for C11H13NS: C, 69.07;
112.3, 111.2, 28.9, 15.2; MS (ESI): m/z [MþH]þ¼178, 130; Anal.
Calcd for C10H11NS: C, 67.76; H, 6.25; N, 7.90. Found: C, 67.81; H,
6.29; N, 7.86.
H, 6.85; N, 7.32. Found: C, 69.15; H, 6.94; N, 7.23.
4.2.8. 4-(Benzyloxy)-3-(methylthiomethyl)-1H-indole (2h). Purified
by flash chromatography (PE/EtOAc, v/v 8/1) to give 2h (56% yield)
as a white solid; mp: 92e94 ꢀC. IR (KBr): 3417, 2913, 2244, 1504,
4.2.2. 5-Methoxy-3-(methylthiomethyl)-1H-indole (2b). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2b (73% yield) as
a white solid; mp: 56e58 ꢀC. IR (KBr): 3415, 2918, 2250, 1585, 1485,
1256, 1093, 733 cmꢁ1
.
1H NMR (400 MHz, CDCl3):
d
¼8.00 (s, 1H),
7.60 (d, J¼7.6 Hz, 2H), 7.46 (t, J¼7.6 Hz, 2H), 7.38 (t, J¼7.6 Hz, 1H),
7.13 (t, J¼8 Hz, 1H), 6.98 (d, J¼3.2 Hz, 1H), 6.96 (s, 1H), 6.62 (d,
J¼8 Hz, 1H), 5.33 (s, 2H), 4.10 (s, 2H), 2.07 (s, 3H). 13C NMR
1216, 909, 734 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼7.95 (s, 1H), 7.20
(d, J¼8.8 Hz, 1H), 7.15 (d, J¼2.4 Hz, 1H), 7.05 (d, J¼2.4 Hz, 1H),
6.85e6.87 (dd, J¼8.4 Hz, 2.4 Hz, 1H), 3.87 (s, 2H), 3.86 (s, 3H), 2.03
(100 MHz, CDCl3):
d
¼153.7, 138.1, 137.4, 128.4, 127.7, 127.4, 116.7,
(s, 3H). 13C NMR (100 MHz, CDCl3):
d¼154.0, 131.6, 127.2, 123.7,
113.0, 104.7, 101.0, 69.8, 30.2, 15.0. MS (ESI): m/z [MþH]þ¼284, 236.

1564
J. Liu et al. / Tetrahedron 68 (2012) 1560e1565
Anal. Calcd for C17H17NOS: C, 72.05; H, 6.05; N, 4.94. Found: C,
72.09; H, 6.11; N, 4.89.
Calcd for C10H10FNS: C, 61.51; H, 5.16; N, 7.17. Found: C, 61.56; H,
5.20; N, 7.09.
4.2.9. 4-Bromo-3-(methylthiomethyl)-1H-indole (2i). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2i (55% yield) as
a white solid; mp: 92e94 ꢀC. IR (KBr): 3415, 2914, 2241, 1556, 1422,
4.2.15. 7-Methyl-3-(methylthiomethyl)-1H-indole (2o). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2o (73% yield) as
a white solid; mp: 110e112 ꢀC. IR (KBr): 3399, 2916, 2250, 1895,
1335, 910, 740 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼8.13 (s, 1H), 7.27
1432, 908, 733 cmꢁ1 1H NMR (400 MHz, CDCl3):
d
¼7.95 (s, 1H), 7.63
(d, J¼8 Hz, 1H), 7.11e7.15 (m, 2H), 7.07 (d, J¼6.8 Hz, 1H), 3.95 (s, 2H),
2.51 (s, 3H), 2.09 (s, 3H). 13C NMR (100 MHz, CDCl3):
(d, J¼7.6 Hz, 1H), 7.23 (d, J¼8 Hz, 1H), 7.09e7.12 (m, 1H), 6.98 (t,
J¼8 Hz, 1H), 4.13 (s, 2H), 2.08 (s, 3H). 13C NMR (100 MHz, CDCl3):
d
¼136.0, 126.3,
d
¼137.7, 124.7, 124.5, 124.3, 123.1, 114.1, 113.2, 110.6, 29.7, 15.0. MS
122.8, 122.5, 120.3, 119.8, 116.8, 112.8, 29.0, 16.5, 15.2. MS (ESI): m/z
[MþH]þ¼192, 144. Anal. Calcd for C11H13NS: C, 69.07; H, 6.85; N,
7.32. Found: C, 69.12; H, 6.93; N, 7.28.
(ESI): m/z [MþH]þ¼256, 208. Anal. Calcd for C10H10BrNS: C, 46.89;
H, 3.93; N, 5.47. Found: C, 46.96; H, 3.98; N, 5.40.
4.2.10. 3-(Methylthiomethyl)-1H-pyrrolo[2,3-b]pyridine
(2j). Purified by flash chromatography (PE/EtOAc, v/v 6/1) to give 2j
(48% yield) as a white solid; mp: 118e120 ꢀC. IR (KBr): 3394, 2907,
4.2.16. 7-(Benzyloxy)-3-(methylthiomethyl)-1H-indole
(2p). Purified by flash chromatography (PE/EtOAc, v/v 8/1) to give
2p (66% yield) as a white solid; mp: 90e92 ꢀC. IR (KBr): 3431, 3033,
2913, 2873, 2244, 1577, 1260, 1028, 732 cmꢁ1. 1H NMR (400 MHz,
1580, 1416, 1118, 769 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d¼11.52 (s,
1H), 8.36 (d, J¼4.8 Hz, 1H), 8.10e8.12 (dd, J¼8 Hz, 0.8 Hz, 1H), 7.33
CDCl3):
(d, J¼8 Hz, 1H), 7.07 (d, J¼2.4 Hz, 1H), 6.77 (d, J¼8 Hz, 1H), 5.22 (s,
2H), 3.92 (s, 2H), 2.07 (s, 3H). 13C NMR (100 MHz, CDCl3):
d¼8.28 (s, 1H), 7.51 (d, J¼6.8 Hz, 2H), 7.38e7.47 (m, 4H), 7.10
(s, 1H), 7.11e7.14 (dd, J¼8 Hz, 4.8 Hz, 1H), 3.91 (s, 2H), 2.03 (s, 3H).
13C NMR (100 MHz, CDCl3):
d
¼149.3, 142.6, 128.0, 123.8, 119.7, 115.4,
d¼145.3,
110.5, 29.1, 15.1. MS (ESI): m/z [MþH]þ¼179, 131. Anal. Calcd for
C9H10N2S: C, 60.64; H, 5.65; N, 15.72. Found: C, 60.68; H, 5.69; N,
15.66.
137.0, 128.5, 128.3, 128.1, 127.8, 127.1, 122.4, 119.9, 112.7, 112.1, 103.3,
70.1, 29.0, 15.2. MS (ESI): m/z [MþH]þ¼284, 236. Anal. Calcd for
C17H17NOS: C, 72.05; H, 6.05; N, 4.94. Found: C, 72.02; H, 6.08; N,
4.86.
4.2.11. 6-Methyl-3-(methylthiomethyl)-1H-indole (2k). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2k (63% yield) as
a white solid; mp: 64e66 ꢀC. IR (KBr): 3386, 2912, 1623, 1455, 1092,
4.2.17. 2-Methyl-3-(methylthiomethyl)-1H-indole (2q). Purified by
flash chromatography (PE/EtOAc, v/v 6/1) to give 2q (41% yield) as
802, 731 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼7.86 (s, 1H), 7.65 (d,
J¼8 Hz, 1H), 7.15 (s, 1H), 7.04 (s, 1H), 7.03 (d, J¼8 Hz, 2H), 3.93 (s,
2H), 2.50 (s, 3H), 2.07 (s, 3H). 13C NMR (100 MHz, CDCl3):
a yellow oil. IR (neat): 3399, 2913, 1619, 1461, 1227, 744 cmꢁ1 1H
.
NMR (400 MHz, CDCl3):
7.21e7.23 (dd, J¼6.2, 2.6 Hz, 1H), 7.08e7.11 (m, 2H), 3.86 (s, 2H),
2.36 (s, 3H), 2.01 (s, 3H). 13C NMR (100 MHz, CDCl3):
d¼7.74 (s, 1H), 7.60 (d, J¼8.8 Hz, 1H),
d¼136.8,
132.1, 124.6, 122.2, 121.3, 118.8, 112.1, 111.1, 29.0, 21.7, 15.1. MS (ESI):
m/z [MþH]þ¼192, 144. Anal. Calcd for C11H13NS: C, 69.07; H, 6.85;
N, 7.32. Found: C, 69.10; H, 6.89; N, 7.30.
d¼135.1, 132.6,
128.2, 121.2, 119.4, 118.2, 110.2, 107.8, 27.6, 15.1, 11.6. MS (ESI): m/z
[MþH]þ¼192, 144. Anal. Calcd for C11H13NS: C, 69.07; H, 6.85; N,
7.32. Found: C, 69.01; H, 6.95; N, 7.25.
4.2.12. 6-Bromo-3-(methylthiomethyl)-1H-indole (2l). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2l (53% yield) as
a white solid; mp: 68e70 ꢀC. IR (KBr): 3290, 2916, 2248, 1612, 1452,
4.2.18. 3-(Methylthiomethyl)-2-phenyl-1H-indole (2r). Purified by
flash chromatography (PE/EtOAc, v/v 10/1) to give 2r (88% yield) as
a yellow oil. IR (neat): 3407, 3058, 2915, 2245, 1706, 1604, 1454,
909, 734 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼7.99 (s, 1H), 7.58 (d,
J¼8 Hz, 1H), 7.48 (d, J¼1.2 Hz, 1H), 7.22e7.25 (dd, J¼8.8 Hz, 1.8 Hz,
1238, 908, 736 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼8.01 (s, 1H), 7.73
1H), 7.08 (d, J¼2 Hz, 1H), 3.86 (s, 2H), 2.02 (s, 3H). 13C NMR
(d, J¼7.6 Hz, 1H), 7.59 (d, J¼7.6 Hz, 2H), 7.43 (t, J¼7.6 Hz, 2H), 7.34 (t,
J¼7.4 Hz, 1H), 7.27 (d, J¼7.6 Hz, 1H), 7.16 (qn, J¼8.2, 6.8 Hz, 2H), 4.00
(100 MHz, CDCl3):
d
¼137.2, 125.7, 123.4, 122.9, 120.5, 115.9, 114.1,
112.7, 28.7, 15.2. MS (ESI): m/z [MþH]þ¼256, 208. Anal. Calcd for
C10H10BrNS: C, 46.89; H, 3.93; N, 5.47. Found: C, 46.92; H, 3.96; N,
5.41.
(s, 2H), 2.04 (s, 3H). 13C NMR (100 MHz, CDCl3):
132.4, 128.9, 128.7, 128.0, 127.9, 122.5, 119.9, 119.3, 110.8, 109.0, 28.4,
15.7. MS (ESI): m/z [MþH]þ¼254, 206. Anal. Calcd for C16H15NS: C,
75.85; H, 5.97; N, 5.53. Found: C, 75.90; H, 5.93; N, 5.46.
d
¼135.7, 135.6,
4.2.13. 6-Chloro-3-(methylthiomethyl)-1H-indole (2m). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2m (62% yield) as
a white solid; mp: 38e40 ꢀC. IR (KBr): 3285, 2953, 1646, 1455, 1334,
4.2.19. 5-Methyl-3-(methylthiomethyl)-2-phenyl-1H-indole
(2s). Purified by flash chromatography (PE/EtOAc, v/v 10/1) to give
2s (90% yield) as a yellow solid; mp: 98e100 ꢀC. IR (KBr): 3400,
1059, 800, 657 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼8.01 (s, 1H), 7.65
(d, J¼8.4 Hz, 1H), 7.32 (d, J¼1.2 Hz, 1H), 7.12e7.14 (dd, J¼8.6 Hz,
2915, 1603, 1450, 1309, 1239, 764, 699 cmꢁ1 1H NMR (400 MHz,
.
1.8 Hz, 1H), 7.09 (d, J¼2 Hz, 1H), 3.88 (s, 2H), 2.05 (s, 3H). 13C NMR
CDCl3):
d
¼7.94 (s, 1H), 7.62 (d, J¼7.2 Hz, 2H), 7.52 (s, 1H), 7.45 (t,
(100 MHz, CDCl3):
d
¼136.7, 128.2, 125.3, 123.4, 120.3, 120.1, 112.5,
J¼7.6 Hz, 2H), 7.35 (t, J¼7.4 Hz, 1H), 7.21 (d, J¼6.4 Hz, 1H), 7.02 (d,
111.1, 28.7, 15.2. MS (ESI): m/z [MþH]þ¼212, 164. Anal. Calcd for
C10H10ClNS: C, 56.73; H, 4.76; N, 6.62. Found: C, 56.78; H, 4.80; N,
6.56.
J¼8 Hz, 1H), 4.00 (s, 2H), 2.46 (s, 3H), 2.07 (s, 3H). 13C NMR
(100 MHz, CDCl3):
d
¼135.9, 134.0, 132.6, 129.2, 129.0, 128.9, 128.0,
127.8, 124.2, 118.9, 110.5, 108.5, 28.6, 21.6, 15.7. MS (ESI): m/z
[MþH]þ¼268, 220. Anal. Calcd for C17H17NS: C, 76.36; H, 6.41; N,
5.24. Found: C, 76.40; H, 6.36; N, 5.16.
4.2.14. 6-Fluoro-3-(methylthiomethyl)-1H-indole (2n). Purified by
flash chromatography (PE/EtOAc, v/v 8/1) to give 2n (51% yield) as
a white solid; mp: 74e76 ꢀC. IR (KBr): 3281, 2915, 1871, 1623,
4.3. General procedure for the Knoevenagel-type reactions of
3-(methylthiomethyl)-1H-indole 2a with 1,3-
1453, 1090, 808, 646 cmꢁ1. 1H NMR (400 MHz, CDCl3):
d
¼8.00 (s,
1H), 7.63e7.66 (dd, J¼8.6, 5.4 Hz, 1H), 7.09 (d, J¼2.4 Hz, 1H),
702e7.05 (dd, J¼9.6, 2.4 Hz, 1H), 6.92 (tt, J¼8.8, 2 Hz, 1H), 3.88 (s,
diphenylpropane-1,3-dione-synthesis of 2-((1H-indol-3-yl)
methylene)-1,3-diphenylpropane-1,3-dione 3a14
2H), 2.04 (s, 3H). 13C NMR (100 MHz, CDCl3):
d
¼160.1 (d,
4
1JCeF¼236 Hz), 136.3 (d, 3JCeF¼12 Hz), 123.3, 123.0 (d, JCeF¼3 Hz),
To a mixture of 1,3-diphenylpropane-1,3-dione (0.1 mmol), 4,5-
3
2
120.0 (d, JCeF¼11 Hz), 112.5, 108.3 (d, JCeF¼25 Hz), 97.5 (d,
2JCeF¼26 Hz), 28.9, 15.2. MS (ESI): m/z [MþH]þ¼196, 148. Anal.
dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile
(DDQ)
(0.1 mmol) and 3-(methylthiomethyl)-1H-indole 2a (0.2 mmol),

J. Liu et al. / Tetrahedron 68 (2012) 1560e1565
1565
S. M.; Mantus, E. K.; Clardy, J. Cell. Mol. Life Sci. 1991, 47, 304; (h) Mantus, E. K.;
Clardy, J. Tetrahedron Lett. 1993, 34, 1085.
4. (a) Licari, J. J.; Dougherty, G. J. Am. Chem. Soc. 1954, 76, 4039; (b) Pedras, M. S. C.;
Zheng, Q.-A.; Strelkov, S. J. Agric. Food Chem. 2008, 56, 9949.
5. (a) Pummerer, R. Chem. Ber. 1909, 42, 2282; (b) Pummerer, R. Chem. Ber. 1910,
43, 1401.
nitromethane (0.8 mL) was added. The resulting mixture was stir-
red at 60 ꢀC for 8 h. The resulting mixture was diluted with diethyl
ether and purified by flash column chromatography on silica gel
with petroleum ether/EtOAc (v/v 5/1) as eluent to obtain the de-
sired product 3a as a yellow solid (21 mg, 61% yield). 3r was syn-
thesized according to the same procedure.
6. For selected recent reviews see: (a) Smith, L. H. S.; Coote, S. C.; Sneddon, H. F.;
Procter, D. T. Angew. Chem., Int. Ed. 2010, 49, 5832; (b) Bur, S. K.; Padwa, A. Chem.
Rev. 2004, 104, 2401; (c) Feldman, K. S. Tetrahedron 2006, 62, 5003; (d) Akai, S.;
Kita, Y. Top. Curr. Chem. 2007, 274, 35; (e) Padwa, A.; Gunn Jr., D. E.; Osterhout,
M. H. Synthesis 1997, 1353; (f) Padwa, A.; Bur, S. K.; Danca, D. M.; Ginn, J. D.;
Lynch, S. M. Synlett 2002, 851; (g) Fedorov, N. V.; Anisimov, A. V.; Viktorova, E. A.
Chem. Heterocycl. Compd. 1989, 25, 1083; (h) Lucchi, O. D.; Miotti, U.; Modena, G.
In Organic Reactions; Paquette, L. A., Ed.; John Wiley: New York, NY,1991; Vol. 40,
p 157.
7. For selected recent examples see: (a) Feldman, K. S.; Vidulova, D. B.; Karatias, A.
G. J. Org. Chem. 2005, 70, 6429; (b) Feldman, K. S.; Fodor, M. D. J. Am. Chem. Soc.
2011, 133, 752; (c) Feldman, K. S.; Vidulova, D. B. Org. Lett. 2004, 6, 1869; (d)
Feldman, K. S.; Fodor, M. D. J. Org. Chem. 2009, 74, 3449; (e) McAllister, L. A.;
Brand, S.; Gentile, R.; Procter, D. J. Chem. Commun. 2003, 2380; (f) Padwa, A.;
Heidelbaugh, T. M.; Kuethe, J. T.; McClure, M. S.; Wang, Q. J. Org. Chem. 2002, 67,
5928.
8. For selected examples see: (a) Zaraiskii, A. P.; Velichko, L. I.; Zaraiskaya, N. A.;
Anikeeva, N. M. Russ. J. Gen. Chem. 2007, 77, 149; (b) Zaraiskii, A. P.; Kachurin, O.
I. Russ. J. Org. Chem. 2003, 39, 1572; (c) Akai, S.; Kawashita, N.; Satoh, H.; Wada,
Y.; Kakiguchi, K.; Kuriwaki, I.; Kita, Y. Org. Lett. 2004, 6, 3793; (d) Laleu, B.;
Machado, M.; Lacour, J. Chem. Commun. 2006, 2786; (e) Bates, D. K. J. Org. Chem.
1977, 42, 3452; (f) Stamos, I. K. Tetrahedron Lett. 1985, 26, 2787; (g) Ishibashi, H.;
Uehara, C.; Komatsu, H.; Ikeda, M. Chem. Pharm. Bull. 1987, 35, 2750.
9. For selected recent examples see: (a) Zhang, Y.; Lee, J. H.; Danishefsky, S. J. J. Am.
Chem. Soc. 2008, 130, 14964; (b) Feldman, K. S.; Nuriye, A. Y. Org. Lett. 2010, 12,
4532; (c) Feldman, K. S.; Nuriye, A. Y. Tetrahedron Lett. 2009, 50, 1914; (d)
McAllister, L. A.; McCormick, R. A.; Brand, S.; Procter, D. J. Angew. Chem., Int. Ed.
2005, 44, 452; (e) Ovens, C.; Martin, N. G.; Procter, D. J. Org. Lett. 2008, 10, 1441;
(f) Feldman, K. S.; Karatjas, A. G. Org. Lett. 2006, 8, 4137; (g) Amat, M.; Hadida,
S.; Pshenichnyi, G.; Bosch, J. J. Org. Chem. 1997, 62, 3158; (h) Eggers, M. E.; Jog, P.
V.; Bates, D. K. Tetrahedron 2007, 63, 12185; (i) Padwa, A.; Danca, M. D.;
Hardcastle, K. I.; McClure, M. S. J. Org. Chem. 2003, 68, 929.
10. (a) Yang, M.; Wu, L.; She, D.; Hui, H.; Zhao, Q.; Chen, M.; Huang, G.; Liang, Y.
Synlett 2008, 448; (b) Liu, J.; Wang, C.; Wu, L.; Liang, F.; Huang, G. Synthesis
2010, 4228; (c) Yan, R.; Huang, J.; Luo, J.; Wen, P.; Huang, G.; Liang, Y. Synlett
2010, 1071; (d) Yan, R.-L.; Luo, J.; Wang, C.-X.; Ma, C.-W.; Huang, G.-S.; Liang, Y.-
M. J. Org. Chem. 2010, 75, 5395; (e) Liu, K.; Wen, P.; Liu, J.; Huang, G. Synthesis
2010, 3623; (f) Ma, C.; Li, Y.; Wen, P.; Yan, R.; Ren, Z.; Huang, G. Synlett 2011,
1321; (g) Huo, X.; Pan, X.; Huang, G.; She, X. Synlett 2011, 1149.
4.3.1. 2-((1H-Indol-3-yl)methylene)-1,3-diphenylpropane-1,3-dione
(3a). Purified by flash chromatography (PE/EtOAc, v/v 5/1) to give
3a (61% yield) as a yellow solid; mp: 206e208 ꢀC. IR (KBr): 3300,
2924, 1664, 1594, 1330, 1246, 1124, 741 cmꢁ1 1H NMR (400 MHz,
.
acetone-d6):
d
¼10.98 (s,1H), 8.06 (s,1H), 8.04 (d, J¼4.8 Hz, 2H), 7.89
(d, J¼8.4 Hz, 2H), 7.63e7.67 (m, 1H), 7.57e7.61 (m, 5H), 7.46e7.50
(m, 3H), 7.20 (t, J¼7.2 Hz, 1H), 7.15 (t, J¼7.2 Hz, 1H). 13C NMR
(100 MHz, acetone-d6):
d¼199.3, 195.9, 140.2, 138.3, 138.2, 137.8,
134.9, 133.1, 130.5, 130.5, 130.4, 130.2, 129.8, 129.0, 124.3, 122.5,
119.3, 113.6, 111.4. HRMS (ESI): m/z [MþNa]þ Calcd for
C24H17NO2Na: 374.1151; found: 374.1152.
4.3.2. 1,3-Diphenyl-2-((2-phenyl-1H-indol-3-yl)methylene)propane-
1,3-dione (3r). Purified by flash chromatography (PE/EtOAc, v/v
5/1) to give 3r (32% yield) as a yellow solid; mp: 198e200 ꢀC. IR
(KBr): 3288, 2923, 1656, 1564, 1452, 1244, 1108, 736 cmꢁ1. 1H NMR
(400 MHz, CDCl3):
d
¼8.62 (s, 1H), 7.92 (s, 1H), 7.82e7.86 (m, 4H),
7.33e7.47 (m, 10H), 7.25e7.29 (m, 2H), 7.15 (t, J¼7.2 Hz, 1H), 7.02 (t,
J¼7.2 Hz, 1H). 13C NMR (100 MHz, CDCl3):
¼196.6, 195.5, 142.3,
d
140.9, 138.3, 137.7, 136.2, 136.1, 132.9, 132.1, 131.1, 129.4, 129.2, 129.2,
129.0, 128.9, 128.3, 128.2, 126.3, 123.4, 121.4, 121.3, 111.2, 109.7.
HRMS (ESI): m/z [MþNa]þ Calcd for C30H21NO2Na: 450.1466;
found: 450.1468.
Acknowledgements
We thank the State Key Laboratory of Applied Organic Chem-
istry and Key Laboratory of Nonferrous Metal Chemistry and Re-
sources Utilization of Gansu Province for financial support. We are
also appreciated our reviewers for their useful comments and
suggestions.
11. The CCDC number is 837264. The data were collected on a Kappa CCD dif-
ꢀ
fractometer equipped with a graphite mono-chromated Mo K
a
(
l
¼0.71073 A)
radiation by using Envaf Nonius 591 Kappa CCD single crystal diffraction (1.
49<q<27.7ꢀ) at 296 K. Orthorhombic crystals; C10H10BrNS; unit cell parame-
ters: a¼10.169(11), b¼8.736(10), c¼12.714(14) A,
a
¼90.00ꢀ,
b
¼107.479(11)ꢀ,
ꢀ
3
ꢀ
ꢁ3
ꢀ
g
¼90.00 , Z¼4, V¼1077(2) A , space group P 21/n, Dx¼1.579 Mg m
, m (Mo
Ka
)¼3.963 mmꢁ1, F(000)¼512. The structure was refined to the final R¼0.0396
Supplementary data
and wR2¼0.0830 for 5602 independent reflections (Rint¼0.0415) and 1988
observed reflections (I>2d(I)).
12. (a) Kenney, W. J.; Walsh, J. A.; Davenport, D. A. J. Am. Chem. Soc. 1961, 83, 4019;
(b) Becker, H. D.; Mikol, G. J.; Russell, G. A. J. Am. Chem. Soc. 1963, 85, 3410; (c)
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H.; Qi, X.; Tambar, U. K. J. Am. Chem. Soc. 2011, 133, 1206; (b) Murakami, M.;
Katsuki, T. Tetrahedron Lett. 2002, 43, 3947; (c) Meyer, O.; Cagle, P. C.; Weick-
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15. A selected example for the synthesis of these compounds see: Sener, A.;
Supplementary data related to this article can be found online
version, at doi:10.1016/j.tet.2011.12.002. These data include MOL
files and InChiKeys of the most important compounds described in
this article.
References and notes
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