Synthesis of imidazol[1,2-α]pyridine thioethers via using sulfur powder and halides as reactants

Article abstract of DOI:10.1016/j.tet.2017.02.065

Structure containing the C[sbnd]S bond exist widely in nature, drugs and chemical materials. Here, a novel sulfenylation protocol employing an aryl or alkyl halide and odorless and cheap S as reagents was developed, generating regioselective alkyl-S- and Ar-S-substituted imidazol[1,2-α]pyridine derivatives in good yields under relatively environmentally friendly and mild conditions. This protocol enriches current thioether-producing methods, making up for the shortcomings of previous sulfenylation methods which can only make MeS- and ArS-substituted imidazol[1,2-α]pyridine derivatives.

Full text of DOI:10.1016/j.tet.2017.02.065

Accepted Manuscript
Synthesis of imidazol[1,2-α]pyridine thioethers via using sulfur powder and halides as
reactants
Wei Wu, Yingcai Ding, Ping Xie, Qiujie Tang, Charles U. Pittman, Jr., Aihua Zhou
PII:
S0040-4020(17)30213-2
10.1016/j.tet.2017.02.065
TET 28506
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 11 December 2016
Revised Date: 27 February 2017
Accepted Date: 28 February 2017
Please cite this article as: Wu W, Ding Y, Xie P, Tang Q, Pittman Jr. CU, Zhou A, Synthesis of
imidazol[1,2-α]pyridine thioethers via using sulfur powder and halides as reactants, Tetrahedron (2017),
doi: 10.1016/j.tet.2017.02.065.
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Synthesis of imidazol[1,2-α]pyridine
thioethers via using sulfur powder and
halides as reactants
Leave this area blank for abstract info.
Wei Wua, Yingcai Dinga, Ping Xieb, Qiujie Tanga, Charles U. Pittman, Jr.c, Aihua Zhou*a
a Pharmacy School, Jiangsu University, Xuefu Road 301, Zhenjiang City, Jiangsu, China 212013.
E-mail: ahz@ujs.edn.cn.
b Jiangsu University Library, Xuefu Road 301, Jiangsu, China 212013
c Department of Chemistry, Mississippi State University, Mississippi State, MS, USA, 39762

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Graphical Abstract
To create your abstract, type over the instructions in the template box below.
Fonts or abstract dimensions should not be changed or altered.
Synthesis of imidazol[1,2-α]pyridine
thioethers via using sulfur powder and
halides as reactants
Leave this area blank for abstract info.
Wei Wua, Yingcai Dinga, Ping Xieb, Qiujie Tanga, Charles U. Pittman, Jr.c, Aihua Zhou*a
a Pharmacy School, Jiangsu University, Xuefu Road 301, Zhenjiang City, Jiangsu, China 212013.
E-mail: ahz@ujs.edn.cn.
b Jiangsu University Library, Xuefu Road 301, Jiangsu, China 212013
c Department of Chemistry, Mississippi State University, Mississippi State, MS, USA, 39762

1
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Tetrahedron
journal homepage: www.elsevier.com
Synthesis of imidazol[1,2-α]pyridine thioethers using sulfur powder and halides as
reactants
Wei Wua, Yingcai Dinga, Ping Xieb, Qiujie Tanga, Charles U. Pittman, Jr.c, Aihua Zhou*a
a Pharmacy School, Jiangsu University, Xuefu Road 301, Zhenjiang City, Jiangsu, China 212013.
E-mail: ahz@ujs.edn.cn.
b Jiangsu University Library, Xuefu Road 301, Jiangsu, China 212013.
c Department of Chemistry, Mississippi State University, Mississippi State, MS, USA, 39762
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
Structure containing the C-S bond exist widely in nature, drugs and chemical materials. Here, a
novel sulfenylation protocol employing an aryl or alkyl halide and odorless and cheap S as
reagents was developed, generating regioselective alkyl-S- and Ar-S-substituted imidazol[1,2-
α]pyridine derivatives in good yields under relatively environmentally friendly and mild
conditions. This protocol enriches current thioether-producing methods, making up for the
shortcomings of previous sulfenylation methods which can only make MeS- and ArS-substituted
imidazol[1,2-α]pyridine derivatives.
Available online
Keywords:
Sulfenylation
2-phenylimidazo[1,2-α]pyridine
Halide
2009 Elsevier Ltd. All rights reserved
.
Cuprous iodide
C-S bond formation
1. Introduction
Ar-S-substituted imidazol[1,2-α]pyridine derivatives in good
yields.
Imidazol[1,2-α]pyridine is a privileged structure in drug
discovery. Several drugs with this strcutural motif possess
important biological activities, including as sedative-hypnotics,
gout and in anticancer and Alzheimer’s disease agents.1 In Figure
1, some drug examples are shown with their bioactivities.2 A lot
of effort has been made to prepare different imidazol[1,2-
α]pyridine derivatives or develop methods to modify
imidazol[1,2-α]pyridine in order to discover valuable drug-like
imidazol[1,2-α]pyridine derivatives.3 Among the imidazol[1,2-
α]pyridine derivative research hot spots is the synthesis of their
thioethers. Despite several reported protocols to make ArS- and
MeS-substituted imidazol[1,2-α]pyridine derivatives, these routes
normally use ArSSAr,4 ArSH,5 ArSO2NHNH2,6 ArSO2Na,7
ArSO2Cl and DMSO8 as sulfur agents, with or without using
transition metal catalysts. Thus, these protocols are suitable only
for making MeS- and ArS-substituted imidazol[1,2-α]pyridine
derivatives. They can’t generate other alkyl-S-substituted
derivatives. Additionally, most of sulfur agents used by these
previous methods are expensive or inconvenient to make, and a
couple of these sulfur agents have powerful odors. Using DMSO
as a sulfur source is a good method,9 but only MeS-substituted
derivatives can be made. Here, we report a novel protocol which
uses halides (both alkyl and aryl halides) to make alkyl-S- and
Ar-S-substituted imidazol[1,2-α]pyridine derivatives. This
protocol is more practical and easier than previously reported
methods. It fills a gap left by previously reported methods. All
reactions proceeded well, affording regioselective alkyl-S- and
Figure 1. Biologically active imidazo[1,2-α]pyridine derivatives
2. Results/discussion
In order to find out suitable reaction conditions for our
sulfenylation reaction, 2-phenylimidazo[1,2-α]pyridine was used
as the standard reactant; S powder was selected as a sulfur agent,
and iodobenzene was employed as a representative halide. To
activate iodobenzene, different copper catalysts were screened.
The weak base K2CO3 was introduced in order to promote the
formation of RSSR from S and RX in the initial reaction. Various

2
Tetrahedron
solvents and temperatures were also tested. Example screening
phenylimidazo-[1,2-α]pyridines or the different iodobenzene
ACCEPTED MANUSCRIPT
results were presented in Table 1.
homologues selected didn’t have any obvious impact on reaction
yields. When 2-methylimidazo-[1,2-α]pyridines was used as a
reactant, the reaction still produced an 85% yield of 2o.
However, when the iodobenzene homologues, bromobenzene and
chlorobenzene were used in for this sulfenylation, these reactions
did not proceed.
Table 1
Screening for suitable reaction conditionsa
Table 2
Sulfenylation of 2-phenylimidazo[1,2-α]pyridine with Iodobenzenea
Entry
Catalyst
(or
Base
Temperature
(oC)
Solvent Yield
b(%)
Inducer)
1
2
CuI
CuI
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NaHCO3
NaH2PO4
K2CO3
60
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DCE
trace
trace
89
61
60
57
55
0
90
3
CuI
120
120
120
120
120
120
120
120
120
120
120
120
120
120
4
CuCl
CuBr
CuBr2
CuO
I2
5
6
7
8
9
TBAI
NH4I
CuI
0
10
11
12
13
14
15
10
20
40
50
75
55
0
CuI
EtOAC
CH3CN
DMF
DMF
DMF
CuI
CuI
CuI
16
FeCl3
a
Reaction conditions: 2-phenylimidazo[1,2-α]pyridine (1.0 mmol, 1.0
equiv.), iodidebenzene (1.0 equiv.), S (2.0 equiv.), CuI (0.2 equiv.),
K2CO3 (1.0equiv.), DMF (0.5 mL). b Isolated yields are based on reactant
1a, all reactions were run under air atmosphere for 12 h at 120 oC
Trace amounts of expected product 2a was generated, when
CuI and K2CO3 were used in DMF at 60 and 90oC (Table 1,
entries 1, 2). However, when the temperature was increased to
120oC, the reaction proceeded well and gave a 89% yield of PhS-
substituted 2-phenylimidazo[1,2-a]pyridine (entry 3). Therefore,
the reaction temperature was set at 120oC after entry 3. The use
of CuCl or CuBr as a catalyst in DMF afforded 60% and 61% of
2a, respectively (entries 4, 5). When CuBr2 or CuO was used as a
catalyst in DMF at 120oC, 57% or 55% yield of product 2a was
produced, respectively (entries 6, 7). Using I2 or TBAI as a
reaction inducer gave no product 2a (entries 8, 9). When NH4I
was used as a reaction inducer, only 10% yield of the expected
2a was isolated. Switching solvent from DMF to DCE or EtOAc
(entries 11, 12) gave a moderate yield of 20% and 40%
respectively. When CH3CN was employed as a solvent, a 50%
yield of 2a was generated (entry 13). Using NaHCO3 or
NaH2PO4 as the base gave a 75% or 55% yield (entries 14, 15),
respectively. Using FeCl3 as a catalyst didn't afford expected
product 2a at all (entry 16). Suitable conditions for the
sulfenylation of 2-phenylimidazo[1,2-a]pyridine using S and
iodobenzene from this screening are: 2-phenylimidazo[1,2-
a]pyridine (1.0 equiv.), S (2 equiv.), iodobenzene (1 equiv.), and
CuI (0.2 equiv.), in solvent DMF at 120 oC.
To explore this sulfenylation was further explored under the
optimized conditions above. Several 2-phenylimidazo[1,2-
α]pyridines with different substituents were synthesized,
employing several aromatic iodobenzene homologues (Table 2).
All reactions proceeded well, giving 70-90% yields of
regioselective ArS-substituted 2-phenylimidazo[1,2-α]pyridine
derivatives. The functional groups employed on the 2-
aReaction conditions: 2-phenylimidazo[1,2-α]pyridine (1.0 mmol, 1.0
equiv.), benzeneiodide (1.0 equiv.), S (2.0 equiv.), CuI (0.2 equiv.),
b
K2CO3 (1.0equiv.), DMF (0.5 mL). Isolated yields are based on reactant
1a, all reactions were run under air atmosphere for 12 h at 120 oC

3
Besides imidazo[1,2-α]pyridine stuctures, indole and
To further extend the scope of this sulfenylation, we wanted to
know if alkyl halides were also suitable for this method. Several
halides, including chlorobutane, iodomethane, 3-chloro-2-
methylprop-1-ene, benzyl chloride, benzylbromide and benzyl
iodide were used instead of iodoaromatic homologues. Under the
same reaction conditions, these primary alkyl halides (I, Br and
Cl halides) were also found suitable for this sulfenylation. All
reactions proceeded well and gave good yields of expected
products, whether iodo, bromo or chloro alkyl halides were
employed. Interestingly, when 2-bromopropane was used,
sulfenylation also proceeded well, producing 2z in a 78% yield
without observing any competing elimination reaction. Although
several sulfenylation methods have previously been reported,
none could easily and conveniently generate alkyl thioethers.
This new method fills a gap left by other methods.
ACCEPTED MANUSCRIPT
benzofuran were also tried for this sulfenylation reaction,
unfornately both reactions didn’t proceeded well.
Based on the above experimental results and previous related
reports,11 a plausible mechanism was proposed below. We
thought that the reaction between S and alkyl halides generated
disulfides in the presence of K2CO3, then resultant disulfide
intermediate was reacted with CuI to give [RSCuI]- and RS+
cation which continued to react with imidazol[1,2-α]pyridine, at
last gave RS-substituted 2-phenylimidazo[1,2-α]pyridine
thioether derivatives, the oxidation of RSH by the air reproduces
disulfides
Table 2
Sulfenylation of 2-arylimidazo[1,2-α]pyridine with alkyl halidesa
S
base
R
X
S22
RSH
2 + CuI
RSSR
Cul
H2O
O2
[RSCuI]-
[RSCuI]-
N
N
RS+
H
SR
N
N
1
Figure 2. Proposed reaction mechanism
3. Conclusion
In summary, a novel and efficient method of using easily
available alkyl/aryl halides and inorganic S powder as reactants
to make alkyl/aryl-S-substituted imidazol[1,2-α]pyridine
derivatives was developed. The reaction proceeded well,
affording regioselective products in high yields under
environmentally friendly and relatively mild conditions. Most
importantly, this method fills a gap left by other sulfenylation
methods, providing one set of reaction conditions to generate
both alkyl/aryl thioether-2-arylimidazo[1,2-a]pyridines from
easily available and environmentally friendly reactants.
aReaction conditions: 2-arylimidazo[1,2-a]pyridine (1.0 mmol, 1.0
equiv), alkyl halide (1.0 equiv.), S (2.0 equiv.), CuI (0.2 equiv.), K2CO3
(1.0equiv.), DMF (0.5 mL). bIsolated yields are based on reactant 1a. All
reactions were run under air atmosphere for 12 h at 120 oC.

4
Tetrahedron
4. Experimental section
δ 8.28-8.24 (m, 1H), 8.21-8.18 (m, 1H), 7.77 (dd, J=8.8, 1.2 Hz,
ACCEPTED MANUSCRIPT
1H), 7.49-7.45 (m, 2H), 7.43-7.36 (m, 2H), 7.22-7.19 (m,
2H),6.96-6.90 (m, 3H); 13C-NMR (CDCl3, 100 MHz): δ 151.6,
147.2, 133.7, 133.1, 132.1, 129.6, 128.8, 128.5, 128.3, 126.9,
126.8, 124.3, 117.8, 113.3, 105.7. HRMS (ESI-TOF) m/z
calculated for C19H14ClN2S+ 337.0561 (M+H)+, found 337.0550.
4.1 General methods
All reactions were carried out in sealed tubes; stirring was
achieved with an oven-dried magnetic stirring bar. Solvents were
purified by standard methods unless otherwise noted.
Commercially available reagents were purchased from Aladdin
Company in China and used throughout without further
purification other than those detailed below. Flash column
chromatography was performed on silica gel (200-300 mesh). All
reactions were monitored by TLC analysis. Deuterated solvents
4.2.5.
3-((4-Nitrophenyl)thio)-2-phenylimidazo[1,2-α]pyridine
(2e). Yellow liquid，yield 75%, FTIR: 3025, 2920, 2837, 1460,
1333, 1080, 770 cm-1; H-NMR (CDCl3, 400 MHz): δ 8.23 (dt,
1
J=6.9, 1.2 Hz, 1H), 8.19-8.04 (m, 4H), 7.87-7.76 (m, 1H), 7.54-
7.36 (m, 4H), 7.17-7.04 (m, 2H), 6.96 (td, J=6.8, 1.2 Hz, 1H).
13C-NMR (CDCl3, 100 MHz): δ 152.3, 147.6, 146.1, 145.0, 132.7,
129.1, 128.6, 128.3, 127.4, 125.3, 124.6, 124.1, 118.0, 113.8,
103.6. HRMS (ESI-TOF) m/z calculated for C19H14N3O2S+
348.0801(M+H)+, found 348.0800.
1
were purchased from Cambridge Isotope laboratories. H- and
13C-NMR spectra were recorded on
a Bruker DRX-400
spectrometer operating at 400 MHz and 100 MHz respectively.
HRMS spectrometry (LC-HRMS) was recorded on a LXQ
Spectrometer (Thermo Scientific) operating on ESI-TOF (MeOH
as a solvent). Flavones derivatives were synthesized according to
the literature.
4.2.6.
2-(3-(Phenylthio)imidazo[1,2-α]pyridin-2-yl)phenol
(2f). yellow liquid，Yield 80%, FTIR: 3328, 3053, 3018, 2358,
1457, 1349, 1098, 734 cm-1; H-NMR (CDCl3, 400 MHz): δ
1
4.2 General procedure
13.13 (s, 1H), 8.64 (dd, J=8.0, 2.0 Hz, 1H), 8.39 (d, J=6.8 Hz,
1H), 7.70 (d, J=8.8 Hz, 1H), 7.44-7.39 (m, 1H), 7.33-7.29 (m,
1H), 7.27-7.22 (m, 2H), 7.20-7.16 (m, 1H), 7.12-7.06 (m, 3H),
6.98-6.95 (m, 1H), 6.92-6.87 (m, 1H); 13C-NMR (CDCl3, 100
MHz): δ 158.4, 149.5, 144.7, 134.4, 130.6, 129.6, 127.8, 127.5,
126.4, 125.9, 124.2, 118.9, 117.8, 116.7, 116.1, 113.8, 105.5;
HRMS (ESI-TOF) m/z calculated for C19H15N2OS+ 319.0900
(M+H)+, found 319.0902.
2-Phenylimidazo[1,2-α]pyridine 1a (0.5 mmol, 1.0 equiv.),
sulfur (2.0 equiv.), K2CO3(0.5 equiv.) and halide (1.0 equiv.)
were added to a dried flask with DMF (0.5 mL) , followed by the
addition of CuI (0.2 equiv.) The mixture was stirred under air at
120 oC. After 12 h, the reaction was cooled down to room
temperature, diluted with ethyl acetate, washed with brine, dried
over anhydrous Na2SO4 and concentrated under vacuum. The
residue was purified by flash chromatography (Petroleum ether:
EtOAc =30:1) on silica gel to give the desired product 2a as a
yellow oil in an 89% yield.
4.2.7.
2-(4-Methoxyphenyl)-3-(phenylthio)imidazo[1,2-
α]pyridine (2g). Yellow liquid，yield 75%,FTIR: 2920, 2847,
1
2357, 1469, 1249, 1035, 744 cm-1; H-NMR (CDCl3, 400 MHz):
δ 8.27 (d, J=6.8 Hz, 1H), 8.22-8.18 (m, 2H), 7.73 (d, J=9.2 Hz,
1H), 7.35-7.31 (m, 1H), 7.25-7.20 (m, 2H),7.16-7.12 (m,
1H), ,7.036-6.97 (m, 4H), 3.85 (s, 3H); 13C-NMR (CDCl3, 100
MHz): δ 160.0, 151.3, 147.1, 135.3, 129.7, 129.4, 126.6, 126.0,
125.9, 125.5, 124.4, 117.4, 113.9, 112.9, 105.3, 55.3. HRMS
(ESI-TOF) m/z calculated for C20H17N2OS+ 333.1056 (M+H)+,
found 333.1064.
4.2.1. 2-Phenyl-3-(phenylthio)imidazo[1,2-α]pyridine (2a) . Yellow
liquid，yield 89%, FTIR: 2979, 2921, 2338, 1591, 1463, 1047,
684 cm-1; 1H-NMR (CDCl3, 400 MHz): δ 8.30 (dt, J=6.9, 1.2 Hz,
1H), 8.26-8.21 (m, 2H), 7.77 (dt, J=9.0, 1.1 Hz, 1H), 7.50-7.43
(m, 2H), 7.43-7.35 (m, 2H), 7.27-7.19 (m, 2H), 7.15 (ddt, J=8.5,
6.7, 2.5 Hz, 1H), 7.06-6.99 (m, 2H), 6.89 (td, J=6.8, 1.2 Hz, 1H).
13C-NMR (CDCl3, 100 MHz) δ 151.3, 147.1, 135.2, 133.3, 129.5,
128.6, 128.4, 128.4, 126.7, 126.1, 125.6, 124.5, 117.7, 113.1,
106.4. HRMS (ESI-TOF) m/z calculated for C19H15N2S+
303.0950 (M+H)+, found 303.0941.
4.2.8.
5-Chloro-2-(3-(phenylthio)imidazo[1,2-α]pyridin-2-
yl)phenol (2h). Yellow liquid，yield 71%, FTIR: 3350, 2975,
2901, 1407, 1050, 881 cm-1; 1H-NMR (CDCl3, 400 MHz): δ
13.15 (s, 1H), 8.72-8.61 (m, 1H), 8.39 (d, J =6.8 Hz, 1H), 7.73-
7.65 (m, 1H), 7.49-7.39 (m, 1H), 7.28-7.13 (m, 4H), 7.10-7.05
(m, 2H), 7.04-6.93 (m, 2H). 13C-NMR (CDCl3, 100 MHz): δ
157.1, 147.8, 144.5, 133.9, 130.3, 129.6, 127.7, 126.3, 124.3,
119.0, 118.3, 117.1, 116.8, 116.7, 114.0, 113.9, 106.4. HRMS
(ESI-TOF) m/z calculated for C19H14ClN2OS+ 353.0510 (M+H)+,
found 353.0511.
4.2.2.
2-Phenyl-3-(p-tolylthio)imidazo[1,2-α]pyridine
(2b).
Yellow liquid，yield 77%, FTIR: 2975, 2927, 1343, 1090, 1463,
1
1050, 882 cm-1; H-NMR (CDCl3, 400 MHz): δ 8.29-8.26 (m,
3H), 7.74 (d, J=9.2 Hz, 1H), 7.48-7.45 (m, 2H), 7.39 (t, J=7.2 Hz,
4H), 7.31-7.27 (m, 1H), 7.02 (d, J=8.0 Hz, 2H), 6.93 (d, J=8.4
Hz, 2H), 6.82 (t, J=6.8 Hz, 1H), 2.26 (s, 3H); 13C-NMR (CDCl3,
100 MHz): δ 151.1, 147.0, 136.0, 133.4, 131.5, 130.2, 128.4,
128.4, 128.4, 126.6, 125.8, 124.5, 117.6, 113.0,106.9, 20.90.
HRMS (ESI-TOF) m/z calculated for C20H17N2S+ 317.1107
(M+H)+, found 317.1113.
4.2.9.
2-(4-Chlorophenyl)-3-(p-tolylthio)imidazo[1,2-
α]pyridine (2i). Yellow liquid，yield 78%,FTIR: 3025, 2928,
1
2863, 1479, 1345, 1083, 786 cm-1; H-NMR (CDCl3, 400 MHz):
δ 8.30 (dt, J=6.8, 1.2 Hz, 1H), 8.25-8.18 (m, 2H), 7.77-7.72 (m,
1H), 7.46-7.40 (m, 2H), 7.36 (ddd, J=9.0, 6.8, 1.3 Hz, 1H), 7.08-
7.01 (m, 2H), 6.96-6.85 (m, 3H), 2.28 (s, 3H). 13C-NMR (CDCl3,
100 MHz): δ 149.8, 147.0, 136.3, 134.6, 131.8, 131.1, 130.3,
129.6, 128.7, 126.9, 125.9, 124.6, 117.6, 113.2, 107.2, 20.9.
HRMS (ESI-TOF) m/z calculated for C20H16ClN2S+ 351.0717
(M+H)+, found 351.0710.
4.2.3.
3-((4-Methoxyphenyl)thio)-2-phenylimidazo[1,2-
α]pyridine (2c). Yellow liquid，yield 82%, FTIR: 3027, 2928,
2857, 1460, 1345, 1086, 798 cm-1; 1H-NMR (CDCl3, 400 MHz):δ
8.34 (d, J=6.8 Hz, 1H), 8.26 (dd, J=7.2, 1.8 Hz, 2H), 7.77 (d,
J=9.0 Hz, 1H), 7.48 (t, J=7.4 Hz, 2H), 7.46-7.31 (m, 2H), 7.06–
6.97 (m, 2H), 6.91 (td, J=6.8, 1.1 Hz, 1H), 6.83-6.75 (m, 2H),
3.75 (s, 3H). 13C-NMR (CDCl3, 100 MHz): δ 158.6, 150.6, 146.7,
133.2, 128.6, 128.5, 128.0, 126.7, 125.4, 124.5, 117.5, 115.2,
114.1, 113.1, 107.9, 55.3. HRMS (ESI-TOF) m/z calculated for
C20H17N2OS+ 333.1056(M+H)+, found 333.1042.
4.2.10. 2-(4-Bromophenyl)-6-methyl-3-(phenylthio)imidazo[1,2-
α]pyridine (2j). Yellow liquid，yield 76%, FTIR: 3028, 2929,
1
2857, 1470, 1345, 1086, 796 cm-1; H-NMR (CDCl3, 400 MHz):
δ 8.22-8.13 (m, 2H), 8.10-8.03 (m, 1H), 7.70 (d, J=9.1 Hz, 1H),
7.46 (dd, J=8.3, 6.4 Hz, 2H), 7.42-7.39 (m, 1H), 7.39-7.33 (m,
2H), 7.25 (dd, J=9.2, 1.7 Hz, 1H), 6.88 (d, J=8.6 Hz, 2H), 2.36 (s,
3H). 13C-NMR (CDCl3, 100 MHz): δ 151.2, 146.1, 134.7, 133.0,
4.2.4.
3-((4-Chlorophenyl)thio)-2-phenylimidazo[1,2-
α]pyridine (2d). Yellow liquid，yield 78%, FTIR: 3038, 2924,
2857, 1470, 1345, 1086, 692 cm-1; H-NMR (CDCl3, 400 MHz):
1

5
132.5, 130.3, 128.7, 128.5, 128.2, 127.0, 123.4, 122.1, 119.8,
117.0, 105.1, 18.4. HRMS (ESI-TOF) m/z calculated for
C20H16BrN2S+ 395.0212(M+H)+, found 395.0210.
2922, 2358, 1328, 1070, 695 cm-1; 1H-NMR (CDCl3, 400 MHz):
ACCEPTED MANUSCRIPT
δ 13.20 (s, 1H), 8.97-8.82 (m, 1H), 8.58 (d, J=6.8 Hz, 1H), 7.61
(dt, J=9.0, 1.1 Hz, 1H), 7.38 (ddd, J=8.9, 6.8, 1.3 Hz, 1H), 7.26-
7.20 (m, 1H), 7.05-6.93 (m, 2H), 2.73 (t, J=7.1 Hz, 2H), 1.55-
1.47 (m, 2H), 1.47-1.40 (m, 2H), 0.85 (t, J=7.1 Hz, 3H). 13C-
NMR (CDCl3, 100 MHz): δ 157.0, 146.1, 143.8, 130.0, 126.9,
126.9, 124.1, 123.3, 118.9, 117.6, 116.7, 116.6, 113.6, 35.5, 31.5,
21.8, 13.5. HRMS (ESI-TOF) m/z calculated for C17H18ClN2OS+
333.0823 (M+H)+, found 333.0821.
4.2.11. 6-Methyl-3-((4-nitrophenyl)thio)-2-phenylimidazo[1,2-
α]pyridine (2k). Yellow liquid，yield 74%, FTIR: 3023, 2921,
1
2835, 1467, 1335, 1079, 778 cm-1; H-NMR (CDCl3, 400 MHz):
δ 8.14-8.08 (m, 3H), 8.02 (d, J=1.8 Hz, 1H), 7.79-7.73 (m, 1H),
7.50-7.36 (m, 3H), 7.30 (d, J=12.7 Hz, 2H), 7.17-7.07 (m, 2H),
2.37 (d, J=1.1 Hz, 3H). 13C-NMR (CDCl3, 100 MHz): δ 146.4,
146.1, 145.1, 132.6, 130.7, 129.0, 128.6, 128.2, 125.2, 124.7,
124.5, 124.0, 121.8, 117.3, 103.2, 22.7. HRMS (ESI-TOF) m/z
calculated for C20H16N3O2S+ 362.0958(M+H)+, found 362.0956.
4.2.18. 6-Bromo-3-(butylthio)-2-phenylimidazo[1,2-α]pyridine
(2r). Yellow liquid，yield 70%, FTIR: 3004, 2928, 2345, 1310,
1080, 679 cm-1; H-NMR (CDCl3, 400 MHz): δ 8.64 (dd, J=2.0,
1
0.8 Hz, 1H), 8.36-8.26 (m, 2H), 7.57 (dd, J=9.4, 0.8 Hz, 1H),
7.53-7.45 (m, 2H), 7.44-7.37 (m, 1H), 7.35 (dd, J=9.4, 2.0 Hz,
1H), 2.67 (t, J=7.1 Hz, 2H), 1.48-1.38 (m, 2H), 1.38-1.30 (m,
2H), 0.79 (t, J=7.2 Hz, 3H). 13C-NMR (CDCl3, 100 MHz): δ
150.0, 144.7, 133.4, 129.3, 128.5, 128.4, 128.3, 124.6, 118.2,
111.1, 107.6, 35.5, 31.5, 21.7, 13.5. HRMS (ESI-TOF) m/z
calculated for C17H18BrN2S+ 361.0369 (M+H)+, found 361.0346.
4.2.12. 2-(4-Chlorophenyl)-6-methyl-3-(phenylthio)imidazo[1,2-
α]pyridine (2l). Yellow liquid，yield 82%, FTIR: 3025, 2927,
1
2863, 1478, 1346, 1085, 786 cm-1; H-NMR (CDCl3, 400 MHz):
δ 8.18-8.16 (m, 2H), 8.09 (t, J=1.4 Hz, 1H), 7.65 (d, J=9.1 Hz,
1H), 7.46-7.35 (m, 2H), 7.27-7.12 (m, 4H), 7.05-6.96 (m, 2H),
2.33 (s, 3H). 13C-NMR (CDCl3, 100 MHz): δ 149.9, 146.1, 135.2,
134.4, 132.0, 130.1, 129.5, 129.5, 128.6, 126.1, 125.5, 123.2,
122.2, 117.0, 106.0, 18.4. HRMS (ESI-TOF) m/z calculated for
C20H16ClN2S+ 351.0717 (M+H)+, found 351.0709.
4.2.19. 3-(Methylthio)-2-phenylimidazo[1,2-α]pyridine
(2s).
Yellow liquid，yield 87%, FTIR: 3066, 2920, 2364, 1345, 756,
695 cm-1; 1H-NMR (CDCl3, 400 MHz): δ 8.51 (d, J=6.8 Hz, 1H),
8.37-8.26 (m, 2H), 7.70 (dt, J=9.0, 1.1 Hz, 1H), 7.57-7.47 (m,
2H), 7.45-7.36 (m, 1H), 7.36-7.26 (m, 1H), 6.96 (td, J=6.8, 1.2
Hz, 1H), 2.28 (s, 3H). 13C-NMR (CDCl3, 100 MHz): δ 148.7,
146.3, 133.7, 128.4, 128.3, 128.3, 126.0, 124.3, 117.6, 112.8,
111.4, 18.2. HRMS (ESI-TOF) m/z calculated for C14H13N2S+
241.0794 (M+H)+, found 241.0780.
4.2.13. 6-Bromo-2-phenyl-3-(p-tolylthio)imidazo[1,2-
α]pyridine (2m). Yellow liquid，yield 76%, FTIR: 3026, 2928,
1
2869, 1478, 1349, 1080, 783 cm-1; H-NMR (CDCl3, 400 MHz):
δ 8.45 (s, 1H), 8.23 (d, J=7.0 Hz, 14H), 7.63 (dd, J=9.4, 0.8 Hz,
14H), 7.46 (dd, J=8.2, 6.4 Hz, 27H), 7.43-7.38 (m, 25H), 7.07 (d,
J=8.0 Hz, 28H), 6.94 (d, J=8.2 Hz, 24H), 2.30 (s, 41H). 13C-
NMR ((CDCl3, 100 MHz): δ 151.7, 145.3, 136.4, 132.9, 130.9,
130.4, 130.1, 128.8, 128.5, 128.3, 126.0, 124.7, 118.3, 108.0,
107.7, 20.91. HRMS (ESI-TOF) m/z calculated for C20H16BrN2S+
395.0212 (M+H)+, found 395.0210.
4.2.20. 6-Methyl-3-(methylthio)-2-phenylimidazo[1,2-
α]pyridine (2t). Yellow liquid，yield 83%, FTIR: 3057, 2920,
1
2360, 1338, 816, 776 699 cm-1; H-NMR (CDCl3, 400 MHz): δ
8.37-8.23 (m, 3H), 7.60 (dd, J=9.1, 0.9 Hz, 1H), 7.54-7.45 (m,
2H), 7.45-7.35 (m, 1H), 7.17 (dd, J=9.1, 1.7 Hz, 1H), 2.43 (s,
3H), 2.28 (s, 3H). 13C-NMR (CDCl3, 100 MHz): δ 148.5, 145.3,
133.9, 129.1, 128.4, 128.2, 128.1, 122.6, 122.0, 116.9, 111.0,
18.5, 18.2. HRMS (ESI-TOF) m/z calculated for C15H15N2S+
255.0950 (M+H)+, found 255.0950.
4.2.14. 6-Bromo-3-((4-bromophenyl)thio)-2-
phenylimidazo[1,2-α]pyridine (2n). Yellow liquid，yield 70%,
FTIR: 3040, 2945, 2857, 1480, 1340, 1082, 692 cm-1; H-NMR
1
(CDCl3, 400 MHz): δ 8.42 (s, 1H), 8.18 (d, J=6.6 Hz, 2H), 7.51-
7.41 (m, 4H), 7.38 (d, J=8.5 Hz, 3H), 6.89 (d, J=8.6 Hz, 2H).
13C-NMR (CDCl3, 100 MHz):151.7, 147.7, 133.6, 130.8, 129.7,
128.8, 128.5, 128.3, 128.3, 126.7, 126.5, 125.6, 117.5, 113.1,
4.2.21. 3-((2-Methylallyl)thio)-2-phenylimidazo[1,2-α]pyridine
(2u). Yellow liquid，yield 76%, FTIR: 2913, 2362, 2341, 669
cm-1; 1H-NMR (CDCl3, 400 MHz): δ 8.49 (dt, J=6.9, 1.2 Hz, 1H),
8.31-8.21 (m, 2H), 7.66 (dt, J=9.0, 1.2 Hz, 1H), 7.48 (dd, J=8.4,
6.8 Hz, 2H), 7.42-7.34 (m, 1H), 7.31-7.23 (m, 1H), 6.90 (td,
J=6.8, 1.2 Hz, 1H), 4.51 (t, J=1.6 Hz, 1H), 4.34 (s, 1H), 3.21 (s,
2H), 1.71 (s, 3H). 13C-NMR (CDCl3, 100 MHz): δ 150.2, 146.4,
133.9, 128.5, 128.3, 128.2, 125.9, 124.5, 117.5, 112.5, 110.0,
43.0, 29.1, 20.9, 20.6. HRMS (ESI-TOF) m/z calculated for
C17H17N2S+ 281.1107 (M+H)+, found 281.1109.
102.9.
HRMS
(ESI-TOF)
m/z
calculated
for
C19H13BrN2S+458.9161 (M+H)+, found 458.9160.
4.2.15 2-Methyl-3-(phenylthio)imidazo[1,2-a]pyridine (2o).
Yellow liquid，yield 85%, FTIR: 3041, 2925, 2847, 1483, 1341,
1
1081, 679 cm-1; H-NMR (CDCl3, 400 MHz): δ 8.07 (dt, J=6.8,
1.2 Hz, 1H), 7.52 (dd, J=9.0, 1.2 Hz, 1H), 7.18 (ddd, J=8.7, 6.8,
1.3 Hz, 1H), 7.11 (dd, J=8.3, 6.7 Hz, 2H), 7.06-6.99 (m, 1H),
6.89-6.80 (m, 2H), 6.73 (td, J=6.8, 1.2 Hz, 1H), 2.50 (s, 3H). 13C-
NMR (CDCl3, 100 MHz): 150.6, 145.9, 134.6, 128.2, 125.0,
124.9, 124.6, 123.3, 116.0, 111.6, 106.3, 13.0. HRMS (ESI-TOF)
m/z calculated for C14H13N2S+241.0794 (M+H)+, found 241.0792.
4.2.22. 6-Bromo-3-((2-methylallyl)thio)-2-phenylimidazo[1,2-
α]pyridine (2v). Yellow liquid，yield 70%, FTIR: 2922, 2851,
1
2362, 2340, 699 cm-1; H-NMR (CDCl3, 400 MHz): δ 8.64 (d,
4.2.16. 3-(Butylthio)-2-phenylimidazo[1,2-α]pyridine
(2p).
J=1.8 Hz, 1H), 8.33-8.21 (m, 2H), 7.56 (dd, J=9.0, 2.6 Hz, 1H),
7.49 (t, J=7.4 Hz, 2H), 7.45-7.40 (m, 1H), 7.36 (dd, J=9.4, 1.9 Hz,
1H), 4.54 (t, J=1.5 Hz, 1H), 4.37 (s, 1H), 3.24 (s, 2H), 1.74 (s,
3H). 13C-NMR (CDCl3, 100 MHz) δ 150.7, 144.7, 133.3, 129.4,
128.5, 128.4, 128.3, 124.8, 118.2, 110.7, 107.5, 43.1, 30.2, 22.7,
20.8. HRMS (ESI-TOF) m/z calculated for C17H16BrN2S+
359.0212 (M+H)+, found 359.0209.
Yellow liquid，yield 80%, FTIR: 2975, 2913, 2365, 2341, 1345,
1051, 669 cm-1; 1H-NMR (CDCl3, 400 MHz): δ 8.53 (d, J=6.9 Hz,
1H), 8.35 (dd, J=8.4, 1.3 Hz, 2H), 7.67 (dd, J=9.0, 1.2 Hz, 1H),
7.49 (t, J=7.6 Hz, 2H), 7.41-7.30 (m, 1H), 7.28 (ddd, J=9.0, 6.8,
1.3 Hz, 1H), 6.91 (td, J=6.8, 1.2 Hz, 1H), 2.66 (t, J=7.2 Hz, 2H),
1.45-1.39 (m, 2H), 1.32 (dt, J=8.6, 7.1 Hz, 2H), 0.77 (t, J=7.3 Hz,
3H). 13C-NMR (CDCl3, 100 MHz): δ 149.5, 146.4, 133.9, 128.4,
128.3, 128.1, 125.9, 124.4, 117.5, 112.6, 110.4, 35.5, 31.5, 21.7,
13.5. HRMS (ESI-TOF) m/z calculated for C17H19N2S+ 283.1263
(M+H)+, found 283.1265.
4.2.23. 3-(Benzylthio)-2-phenylimidazo[1,2-α]pyridine
(2w).
Yellow liquid，yield 75%, FTIR: 3024, 2925, 2362, 2341, 1453,
1
1143, 737 cm-1; H-NMR (CDCl3, 400 MHz): δ 8.33-8.21 (m,
2H), 8.09 (d, J=6.9 Hz, 1H), 7.62 (d, J=9.0 Hz, 1H), 7.51-7.44
(m, 2H), 7.43-7.37 (m, 1H), 7.21 (ddd, J=9.0, 6.7, 1.3 Hz, 1H),
7.14-7.04 (m, 3H), 6.97-6.89 (m, 2H), 6.69 (td, J=6.8, 1.2 Hz,
4.2.17. 2-(3-(Butylthio)imidazo[1,2-α]pyridin-2-yl)-4-
chlorophenol (2q). Yellow liquid，yield 67%, FTIR: 3405, 2954,

6
Tetrahedron
ACCEPTED MANUSCRIPT
1H), 3.83 (s, 2H). 13C-NMR (CDCl3, 100 MHz): δ 150.1, 146.4,
M.; Banno, H.; Kakei, H.; Ohashi, A.; Iwai, K.; Ohori, M.;
Mori, K.; Gotou, M.; Kawamoto, T.; Yokota, A.; Ishikawa,
T. J. Med. Chem. 2015, 58, 8036. (c) Xi, G.-L.; Liu, Z.-Q.
Tetrahedron 2015, 71, 9602.
137.1, 133.7, 129.4, 128.7, 128.4, 128.3, 128.3, 127.3, 126.0,
124.2, 117.2, 112.2, 109.4, 40.6. HRMS (ESI-TOF) m/z
calculated for C20H17N2S+ 317.1107 (M+H)+, found 317.1113.
2. (a) Blunt, J. W.; Copp, B. R.; Keyzers, R. A.; Munro, M. H.;
Prinsep, M. R. Nat. Prod. Rep. 2015, 32, 116. (b) Gu, B.;
Zhang, Y.; Ding, L.; He, S.; Wu, B.; Dong, J.; Zhu, P.; Chen,
J.; Zhang, J.; Yan, X. Mar. Drugs 2015, 13, 354. (c) cIlardi,
E. A.; Vitaku, E.; Njardarson, J. T. J. Med. Chem. 2014, 57,
2832. (d) Kucher, O. V.; Kolodyazhnaya, A. O.; Smolii, O.
B.; Nazarenko, N. K.; Kubyshkin, V.; Mykhailiuk, P. K.;
Tolmachev, A. A. Tetrahedron: Asymmetry 2016, 27, 341. (e)
eLiu, R.; Yu, X.; Wallqvist, A. J. Cheminform 2015, 7, 4; (f)
Matsutomo, T.; Kodera, Y. J. Nutr. 2016, 146, 450S. (g)
Nakabayashi, R.; Sawada, Y.; Aoyagi, M.; Yamada, Y.;
Hirai, M. Y.; Sakurai, T.; Kamoi, T.; Rowan, D. D.; Saito, K.
J. Nutr. 2016, 146, 397S. (h) Ritchie, T. J.; Macdonald, S. J.
J. Med. Chem. 2014, 57, 7206. (i) Yus, M.; Gonzalez-Gomez,
J. C.; Foubelo, F. Chem. Rev. 2013, 113, 5595.
4.2.24. 2-(3-(Benzylthio)imidazo[1,2-α]pyridin-2-yl)phenol
(2x). Yellow liquid，yield 85%, FTIR: 3329, 2974, 2926, 2362,
2341, 1509, 1051, 692 cm-1; 1H-NMR (CDCl3, 400 MHz): δ
13.22 (s, 1H), 8.86 (dd, J=7.9, 1.7 Hz, 1H), 8.09 (dd, J=6.8, 1.2
Hz, 1H), 7.52 (dt, J=8.9, 1.1 Hz, 1H), 7.33 (ddd, J=8.6, 7.2, 1.6
Hz, 1H), 7.23 (ddd, J=8.9, 6.8, 1.3 Hz, 1H), 7.15-7.04 (m, 4H),
7.02-6.92 (m, 3H), 6.70 (td, J=6.8, 1.2 Hz, 1H), 3.88 (s, 2H). 13C-
NMR (CDCl3, 100 MHz): δ 158.4, 148.1, 143.9, 137.0, 130.3,
128.7, 128.5, 127.5, 127.4, 126.8, 123.9, 118.7, 117.7, 116.6,
116.2, 112.9, 108.4, 40.5. HRMS (ESI-TOF) m/z calculated for
C20H17N2OS+ 333.1056 (M+H)+, found 333.1064.
4.2.25. 3-(Benzylthio)-6-bromo-2-phenylimidazo[1,2-
3. (a) Bagdi, A. K.; Rahman, M.; Santra, S.; Majee, A.; Hajra,
A. Adv. Synth. Catal. 2013, 355, 1741. (b) Ge, W.; Zhu, X.;
Wei, Y. Eur. J. Org. Chem. 2013, 2013, 6015. (c) Meng, X.;
Wang, Y.; Yu, C.; Zhao, P. RSC Adv. 2014, 4, 27301. (d)
Yadav, J. S.; Subba Reddy, B. V.; Gopal Rao, Y.; Srinivas,
M.; Narsaiah, A. V. Tetrahedron Lett. 2007, 48, 7717.
4. (a) Gao, Z.; Zhu, X.; Zhang, R. RSC Adv. 2014, 4, 19891. (b)
Wang, X.; Qiu, R.; Yan, C.; Reddy, V. P.; Zhu, L.; Xu, X.;
Yin, S. F. Org. Lett., 2015, 17, 1970. (c) Yan, S. Y.; Liu, Y.
J.; Liu, B.; Liu, Y. H.; Zhang, Z. Z.; Shi, B. F. Chem.
Commun. 2015, 51, 7341.
α]pyridine (2y). Yellow liquid，yield 75%, FTIR: 3053, 2966,
2364, 2355, 1603, 1029, 801cm-1; 1H-NMR (CDCl3, 400 MHz): δ
8.32-8.23 (m, 2H), 8.04 (d, J=2.0 Hz, 1H), 7.55-7.38 (m, 4H),
7.22 (dd, J=9.4, 1.9 Hz, 1H), 7.17-7.04 (m, 3H), 6.96-6.88 (m,
2H), 3.83 (s, 2H). 13C-NMR (CDCl3, 100 MHz): δ 150.7, 144.7,
137.1, 133.3, 129.4, 128.8, 128.6, 128.6, 128.5, 128.4, 128.2,
127.7, 124.6, 117.7, 110.0, 107.1, 41.0. HRMS (ESI-TOF) m/z
calculated for C20H16BrN2S+ 395.0212 (M+H)+, found 395.0210.
4.2.26. 3-(Isopropylthio)-6-methyl-2-phenylimidazo[1,2-
5. (a) Hiebel, M.-A.; Berteina-Raboin, S. Green Chem. 2015,
17, 937. (b) Ravi, C.; Mohan, D. C.; Adimurthy, S. Org. Lett.
2014, 16, 2978. (c) Yan, K.; Yang, D.; Sun, P.; Wei, W.; Liu,
Y.; Li, G.; Lu, S.; Wang, H. Tetrahedron Lett. 2015, 56,
4792.
6. (a) Bagdi, A. K.; Mitra, S.; Ghosh, M.; Hajra, A. Org.
Biomol. Chem. 2015, 13, 3314. (b) Li, X.; Xu, Y.; Wu, W.;
Jiang, C.; Qi, C.; Jiang, H. Chem. Eur. J. 2014, 20, 7911. (c)
Singh, R.; Allam, B. K.; Singh, N.; Kumari, K.; Singh, S. K.;
Singh, K. N. Org. Lett. 2015, 17, 2656; (d) Xu, K.;
Khakyzadeh, V.; Bury, T.; Breit, B. J. Am. Chem. Soc. 2014,
136, 16124. (e) Yang, Y.; Zhang, S.; Tang, L.; Hu, Y.; Zha,
Z.; Wang, Z. Green Chem. 2016, 18, 2609.
α]pyridine (2z). Yellow liquid，yield 78%, FTIR: 3021, 2989,
2366, 2355, 1606, 1025, 831cm-1; 1H-NMR (CDCl3, 400 MHz): δ
8.42-8.30 (m, 3H), 7.58 (dd, J=9.0, 0.9 Hz, 1H), 7.53-7.42 (m,
2H), 7.42-7.33 (m, 1H), 7.14 (dd, J=9.1, 1.8 Hz, 1H), 3.18 (hept,
J=6.7 Hz, 1H), 2.40 (d, J=1.1 Hz, 3H), 1.16 (d, J=6.7 Hz, 6H).
13C-NMR (CDCl3, 100 MHz): δ 145.4, 134.1, 129.0, 128.3, 128.2,
128.0, 122.3, 116.8, 40.5, 23.1, 18.5. HRMS (ESI-TOF) m/z
calculated for C17H18N2NaS+ 305.1083 (M+H)+, found 305.1080.
4.2.27. 2-((2-(4-Methoxyphenyl)imidazo[1,2-a]pyridin-3-
yl)thio)acetate (2aa). Yellow liquid，yield 70%, FTIR: 3403,
2951, 2922, 2358, 1802, 1328, 1070, 694 cm-1; 1H-NMR (CDCl3,
400 MHz): δ 8.35-8.29 (m, 3H), 7.64-7.59 (m, 1H), 7.52-7.44 (m,
2H), 7.42-7.36 (m, 1H), 7.17 (dd, J=9.1, 1.8 Hz, 1H), 3.41 (s,
1H), 3.29 (s, 1H), 2.71 (q, J=7.4 Hz, 2H), 2.42 (d, J=1.1 Hz, 3H),
1.13 (t, J=7.4 Hz, 3H). 13C-NMR (CDCl3, 100 MHz): δ 164.2,
149.1, 145.3, 133.8, 129.2, 128.3, 128.2, 128.1, 122.5, 122.2,
116.8, 109.7, 62.6, 29.8, 18.5, 14.7. HRMS (ESI-TOF) m/z
calculated for C18H19N2O3S+ 343.1111 (M+H)+, found 343.1111.
7. (a) Huang, X.; Wang, S.; Li, B.; Wang, X.; Ge, Z.; Li, R.
RSC Adv. 2015, 5, 22654. (b) Liu, J.; Yu, L.; Zhuang, S.; Gui,
Q.; Chen, X.; Wang, W.; Tan, Z. Chem. Commun. 2015, 51,
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Org. Chem. 2015, 80, 7652. (d) Zhu, H.; Shen, Y.; Deng, Q.;
Tu, T. Chem. Commun. 2015, 51, 16573.
.
8. (a) Liang, H. W.; Jiang, K.; Ding, W.; Yuan, Y.; Shuai, L.;
Chen, Y. C.; Wei, Y. Chem. Commun. 2015, 51, 16928. (b)
Liu, X.; Chen, X.; Mohr, J. T. Org. Lett. 2015, 17, 3572. (c)
Ravi, C.; Chandra Mohan, D.; Adimurthy, S. Org. Biomol.
Chem. 2016, 14, 2282. (d) Yuan, K.; Doucet, H. Chem. Sci.
2014, 5, 392. (e) Zhao, W.; Zhou, A. ChemCatChem. 2015, 7,
3464.
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Lett. 2015, 17, 1038. (b) Liu, F. L.; Chen, J. R.; Zou, Y. Q.;
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P.; Rohilla, S.; Jain, N. J. Org. Chem. 2015, 80, 4116. (d)
Zhao, W.; Xie, P.; Bian, Z.; Zhou, A.; Ge, H.; Zhang, M.;
Ding, Y.; Zheng, L. J. Org. Chem. 2015, 80, 9167.
Author Contributions
W.W. and Y.D. contributed equally
Acknowledgments
Aihua Zhou acknowledge Jiangsu University for financial
support (1281290006).
Supplementary data
10. (a) Chen, J.; Li, G.; Xie, Y.; Liao, Y.; Xiao, F.; Deng, G. J.
Org. Lett. 2015, 17, 5870. (b) Chen, F. J.; Liao, G.; Li, X.;
Wu, J.; Shi, B. F. Org. Lett. 2014, 16, 5644. (c) Chen, J.;
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17, 976. (e) Li, J.; Li, C.; Yang, S.; An, Y.; Wu, W.; Jiang, H.
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Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2014.12.029.
References and notes
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ACCEPTED MANUSCRIPT
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