Efficient and expeditious synthesis of di- and trisubstituted thiazoles in PEG under catalyst-free conditions

Article abstract of DOI:10.1080/00397910802691874

An efficient and expeditious catalyst-free protocol was developed for the construction of di- and trisubstituted thiazoles from -haloketones and thioureas/thioamides in PEG. The reaction was carried out at ambient temperature, and the products were obtained in excellent isolated yields (91-98%). Additionally, PEG could be recovered easily and was reused without evident loss in activity.

Full text of DOI:10.1080/00397910802691874

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Efficient and Expeditious
Synthesis of Di- and
Trisubstituted Thiazoles in PEG
Under Catalyst-Free Conditions
Dongjian Zhu a , Jiuxi Chen a , Huilong Xiao a ,
Miaochang Liu a , Jinchang Ding a & Huayue Wu a
a College of Chemistry and Materials Engineering,
Wenzhou University, Wenzhou, China
Version of record first published: 14 Jul 2009.
To cite this article: Dongjian Zhu, Jiuxi Chen, Huilong Xiao, Miaochang Liu, Jinchang
Ding & Huayue Wu (2009): Efficient and Expeditious Synthesis of Di- and Trisubstituted
Thiazoles in PEG Under Catalyst-Free Conditions, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 39:16,
2895-2906
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Synthetic Communications1, 39: 2895–2906, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802691874
Efficient and Expeditious Synthesis of
Di- and Trisubstituted Thiazoles in PEG
Under Catalyst-Free Conditions
Dongjian Zhu, Jiuxi Chen, Huilong Xiao, Miaochang Liu,
Jinchang Ding, and Huayue Wu
College of Chemistry and Materials Engineering, Wenzhou University,
Wenzhou, China
Abstract: An efficient and expeditious catalyst-free protocol was developed for
the construction of di- and trisubstituted thiazoles from a-haloketones and
thioureas=thioamides in PEG. The reaction was carried out at ambient tem-
perature, and the products were obtained in excellent isolated yields (91–98%).
Additionally, PEG could be recovered easily and was reused without evident loss
in activity.
Keywords: a-Haloketone, PEG-400, thiazoles, thioamides, thioureas
INTRODUCTION
Thiazole derivatives have become increasingly important in the past few
years because they have proven to be extremely useful intermediates for
the preparation of new biological materials. The thiazole ring is present in
numerous pharmacologically important compounds, including those
used as inhibitors of HIV,[1] allergies,[2] and bacteria.[3]
A number of synthetic methods to prepare thiazoles have been
described.[4] The typical procedure for the synthesis of thiazoles involves
the reaction of readily available a-haloketones with thioureas=thioamides
Received August 31, 2008.
Address correspondence to Jiuxi Chen and Huayue Wu, College of Chemistry
and Materials Engineering, Wenzhou University, Wenzhou 335027, China.
E-mail: jiuxichen@wzu.edu.cn; huayuewu@wzu.edu.cn
2895

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D. Zhu et al.
using catalysts such as ammonium 12-molybdophosphate,[5] cyclodex-
trin,[6] iodine,[7] and silica chloride[8] in organic solvents at elevated
temperature, solvents such as 1-methyl-2-pyrrolidinone,[9] and with the
aid of microwaves.[10] Recently, Potewar et al.[11] reported the synthesis
of thiazoles using [bbim]BF4 as catalyst. However, ionic liquids, espe-
cially imidazolium-based systems containing BF4 anions, are toxic in
nature because they liberate hazardous HF, and their high cost and
disposability make their utility limited.[12] Although these methods are
suitable for certain synthetic conditions, many of these procedures are
associated with one or more disadvantages such as long reaction time,
low yield, use of hazardous organic solvents, excess costly reagents or
catalysts, and harsh reaction conditions, which leaves scope for further
development of new environmentally clean syntheses.
Polyethylene glycol (PEG) and its monomethyl ethers possess the
unique advantages of high thermal stability, negligible vapor pressure,
nontoxicity, and recyclability, and they find wide applications as media
for phase-transfer catalysts.[13] Their potential as reaction media and
promoters for organic reactions has attracted the attention of organic
chemists in recent years.[14]
RESULTS AND DISCUSSION
Aiming to develop green and efficient organic methodologies, we
have recently reported some organic reactions carried out using a green
reaction system.[15] Herein, we report a PEG-assisted, catalyst-free
synthesis of thiazoles under mild conditions.
Initially, we investigated the cyclization reaction of a-bromoaceto-
phenone with thiourea at room temperature under different reaction
conditions (Table 1).
Surprisingly, this reaction could be performed in PEG-400 for 15 min
in the absence of catalyst in excellent yield (Table 1, entry 7). However, 3a
was obtained with less yield in the presence of the additional solvent
(Table 1, entry 1), probably because of the reduced efficiency of
PEG-400 as a result of dilution. It was observed that the reaction of
a-bromoacetophenone with thiourea in organic solvents (toluene, acet-
one, acetonitrile, dichloromethane, alcohol) gave comparatively smaller
conversions (Table 1, entries 2–6). Therefore, PEG-400 was chosen as
the reaction media as the research was extended to other a-haloketones
and thioureas=thioamides without additional catalyst.
As shown in Table 2, a series of a-bromoacetophenones bearing either
electron-donating (entries 9–12) or electron-withdrawing (entries 5–8)
groups on the aromatic ring were investigated. The substitution groups

Catalyst-Free Synthesis of Thiazoles
2897
Table 1. Reaction of a-bromoacetophenone with thiourea
under different reaction conditionsa
Entry
Solvent
Yield (%)b
1
2
3
4
5
6
7
PEG-400=Toluene (1:1)
Toluene
Acetone
CH3CN
CH2Cl2
58
35
31
33
29
41
97
C2H5OH
PEG-400
aReaction conditions: a-bromoacetophenone (1.0 mmol),
thiourea (1.0 mmol), and solvent (0.5 mL) at room temperature
for 15 min.
bIsolated yield.
on the phenyl ring did not make any difference on the yields. In all cases, the
products were afforded with excellent yields in very short reaction time
(5–15 min). Moreover, the reaction of a-bromo-4-nitroacetophenone with
thioacetamide=thiobenzamide was conducted successfully in 95% and 91%
yields, respectively (entries 13 and 14). To the best of our knowledge, it
has not been reported that the reaction could be conducted without the use
of any catalyst with very short reaction times (5 min) at room temperature,
except for Kabalka and mereddy,[10] who reported microwave-promoted
synthesis of thiazoles. When employing the hindered a-methylphenacyl
bromide and thiourea=phenylthiourea, excellent yields (entries 15 and 16)
were obtained after slightly prolonging the reaction time to 25 min.
To further confirm the structure of product, the x-ray diffraction
analysis of 3p was carried out (Scheme 1). (CCDC-674761; these data
can be obtained from the Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk).
Encouraged by the results, we also screened a few reactions of the
commercially available and deactivated a-chloroketone with thiourea=
phenylthiourea. To our delight, when employing a-chloroacetophenone
and thiourea=phenylthiourea, excellent yields were obtained after slightly
longer reaction times (entries 17 and 18). Furthermore, the reaction of
2-chloro-1-(2,4-dichlorophenyl)ethanone with thiourea=phenylthiourea
also could give the products 3q–r in excellent yields (entries 19 and 20).

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D. Zhu et al.
Table 2. Catalyst-free synthesis of di- and trisubstituted thiazoles in PEGa
a-Haloketone
Time
(min) Product
Yield
(%)b
Mp
(ꢀC)
Entry Ar
1
R1
H
X
R2
C6H5
Br NH2
15
60
10
5
10
10
10
5
138
10
150
10
5
3a
3a
3b
3c
3d
3e
3f
97
88c
95
91
96
97
96
95
84c
93
84c
98
98
97
98
95
91
150–151
2
3
4
5
6
7
C6H5
C6H5
C6H5
H
H
H
H
H
H
Br NHPh
Br CH3
Br Ph
Br NH2
Br NHPh
Br CH3
135–136
67–69
90–91
167–168
144–146
118–119
p-ClC6H4
p-ClC6H4
p-ClC6H4
3g
3g
3h
3h
3i
8
p-ClC6H4
H
Br Ph
131–132
9
10
11
12
13
14
15
16
17
18
19
20
p-OMeC6H4
p-OMeC6H4
p-OMeC6H4
p-OMeC6H4
p-NO2C6H4
p-NO2C6H4
C6H5
C6H5
C6H5
C6H5
2,4-Cl2C6H3
2,4-Cl2C6H3
H
H
H
H
H
H
Br NH2
Br NHPh
Br CH3
Br Ph
Br CH3
Br Ph
208–209
139–140
67–69
127–129
141–143
128–129
3j
5
5
3k
3l
5
3m
3n
3o
3p
3a
3b
3q
3r
10
25
25
20
30
30
35
CH3 Br NH2
CH3 Br NHPh
H
H
H
H
96 (65)d 115–116
98 (85)e 170–171
95 (89)d 150–151
92 (78)e 135–136
97
94
Cl NH2
Cl NHPh
Cl NH2
Cl NHPh
161–163
123–124
aReaction conditions: a-haloketone (1.0 mmol), thiourea=thioamide (1.0 mmol),
and PEG-400 (0.5 mL) at room temperature.
bIsolated yield.
cSee Ref. 6a.
dAt room temperature for 15 min.
eAt room temperature for 10 min.
Finally, we investigated the recycling of PEG-400 in a subsequent
reaction, for example, the synthesis of 3d from the reaction of 2-bromo-1-
phenylethanone with benzothioamide (Scheme 2). PEG-400 was reused
for five runs without any appreciable loss of activity.

Catalyst-Free Synthesis of Thiazoles
2899
Scheme 1. Crystal structure of 3p.
In conclusion, we have developed an efficient and high-yielding
PEG-promoted protocol for the synthesis of di- and trisubstituted thia-
zoles. Moreover, this protocol was extended to the reaction of deacti-
vated a-chloroketones with thioureas=thioamides in excellent yields.
These results further demonstrate the value of PEG-promoted synthesis
in avoiding hazardous organic solvents and toxic catalysts, increasing
yields, short reaction times, and streamlining high-throughput chemistry.
EXPERIMENTAL
Melting points were recorded on a digital melting-point apparatus
(WRS-1B) and are uncorrected. Infrared (IR) spectra were recorded on
an Avatar 370 Fourier transform–IR spectrophotometer. Mass spectra
(MS) were measured with a Thermo Finnigan LCQ-Advantage. 1H
NMR and 13C NMR spectra were recorded on a Varian Mercury
Plus-300 instrument using CDCl3 as the solvent with tetramethylsilane
(TMS) as an internal standard at room temperature. Chemical shifts
are given in d relative to TMS; the coupling constants J are given in hertz.
X-ray diffraction data were collected on a Bruker Smart Apex diffract-
˚
ometer with graphite-monochromated (Mo Ka, k ¼ 0.70173 A) radiation
using SMART.
Scheme 2. Reusing PEG-400. Run 1, 96%; run 2, 96%; run 3, 94%; run 4, 93%;
and run 5: 93%.

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D. Zhu et al.
General Procedure for the Synthesis of Thiazoles
A mixture of a-haloketone (1.0 mmol), thiourea=thioamide (1.0 mmol),
and PEG-400 (0.5 mL) was stirred at room temperature until comple-
tion of the reaction [monitored by thin-layer chromatography (TLC)].
The mixture was washed with water (4.0 mL) and extracted with
ethyl acetate (3 ꢁ 15 mL); the organic phase was separated, dried over
anhydrous sodium sulfate, and filtered. The solvent was removed under
vacuum. The crude product was purified by silica-gel column chromato-
graphy using ethyl acetate–petroleum ether. After extraction with ethyl
acetate, the solution of H2O and PEG-400 was concentrated and
subjected to subsequent reaction of a-bromoacetophenone with
benzothioamide.
Characterization Data of All the Products
4-Phenylthiazol-2-amine (3a)[8]
White solid; mp 150–151 ꢀC. IR n (cmꢂ1): 3432, 2974, 1624, 1524, 1388,
1
1337, 1045, 670. H NMR (300 MHz, CDCl3): d ¼ 7.81–7.78 (m, 2H,
ArH), 7.42–7.37 (m, 2H, ArH), 7.33–7.28 (m, 1H, ArH), 6.74 (s, 1H,
thiazole), 5.05 (br s, 2H, NH2). 13C NMR (75 MHz, CDCl3):
d ¼ 167.3, 151.3, 134.7, 128.5, 127.7, 126.0, 102.7. MS (EI) m=z: (Mþ)
176, 134, 89.
N,4-Diphenylthiazol-2-amine (3b)[10]
White solid; mp 135–136 ꢀC. IR n (cmꢂ1): 3432, 2927, 1606, 1562, 1461,
1
1422, 1310, 692. H NMR (300 MHz, CDCl3): d ¼ 7.89–7.86 (m, 2H,
ArH), 7.60 (s, 1H, ArH), 7.44–7.30 (m, 7H, ArH), 7.10–7.06 (m, 1H, thia-
zole), 6.84 (br s, 1H, NH). 13C NMR (75 MHz, CDCl3): d ¼ 164.4, 151.3,
140.2, 134.5, 129.3, 128.5, 127.8, 126.0, 122.9, 118.1, 101.7.
2-Methyl-4-phenylthiazole (3c)[11]
White solid; mp 67–69 ꢀC. IR n (cmꢂ1): 3436, 2924, 1640, 1387, 1169,
1
1028, 676. H NMR (300 MHz, CDCl3): d ¼ 7.89–7.86 (m, 2H, ArH),
7.42–7.37 (m, 3H, ArH), 7.33–7.27 (m, 1H, ArH), 2.75 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): d ¼ 165.7, 155.1, 134.5, 128.6, 127.8,
126.3, 112.1, 19.2.

Catalyst-Free Synthesis of Thiazoles
2901
2,4-Diphenylthiazole (3d)[6a]
White solid; mp 90–91 ꢀC. IR n (cmꢂ1): 3435, 2925, 1643, 1519, 1471,
1
1391, 1058, 673. H NMR (300 MHz, CDCl3): d ¼ 8.08–8.00 (m, 4H,
ArH), 7.49–7.44 (m, 6H, ArH), 7.39–7.37 (m, 1H, thiazole). 13C NMR
(75 MHz, CDCl3): d ¼ 167.8, 156.3, 134.5, 133.7, 130.0, 128.9, 128.7,
128.2, 126.6, 126.4, 112.6.
4-(4-Chlorophenyl)thiazol-2-amine (3e)[11]
White solid; mp 167–168 ꢀC. IR n (cmꢂ1): 3433, 2924, 1628, 1532, 1466,
1
1395, 1041, 730. H NMR (300 MHz, CDCl3): d ¼7.74–7.70 (m, 2H,
ArH), 7.38–7.33 (m, 2H, ArH), 6.73 (s, 1H, thiazole), 5.07 (br s, 2H,
NH2). 13C NMR (75 MHz, CDCl3): d ¼167.3, 150.2, 133.4, 133.1,
128.8, 127.3, 103.3.
4-(4-Chlorophenyl)-N-phenylthiazol-2-amine (3f)[16]
White solid; mp 144–146 ꢀC. IR n (cmꢂ1): 3383, 2974, 1559, 1473, 1399,
1
1304, 1089, 1053, 834, 691. H NMR (300 MHz, CDCl3): d ¼ 7.85–7.73
(m, 3H, ArH), 7.33–7.28 (m, 6H, ArH), 7.08–7.02 (m, 1H, thiazole),
6.77 (br s, 1H, NH). 13C NMR (75 MHz, CDCl3): d ¼ 164.8, 150.2,
140.2, 133.6, 133.1, 129.5, 128.8, 127.4, 123.2, 118.4, 102.2.
4-(4-Chlorophenyl)-2-methylthiazole (3g)[11]
White solid; mp 118–119 ꢀC. IR n (cmꢂ1): 3442, 1647, 1523, 1391, 1166,
989, 672. 1H NMR (300 MHz, CDCl3): d ¼ 7.81 (d, J ¼ 8.63 Hz, 2H,
ArH), 7.37 (d, J ¼ 8.63 Hz, 2H, ArH), 7.28 (s, 1H, thiazole), 2.76 (s, 3H,
CH3). 13C NMR (75 MHz, CDCl3): d ¼ 166.1, 153.9, 133.7, 133.0, 128.9,
127.6, 112.6, 19.3. MS (EI) m=z: (Mþ þ 2) 211, (Mþ) 209, 170, 168, 133,
89.
4-(4-Chlorophenyl)-2-phenylthiazole (3h)[5]
White solid; mp 131–132 ꢀC. IR n (cmꢂ1): 3434, 2922, 1638, 1518, 1470,
1
1394, 1089, 1051, 760, 678. H NMR (300 MHz, CDCl3): d ¼ 8.06–8.02
(m, 2H, ArH), 7.96–7.93 (m, 2H, ArH), 7.48–7.43 (m, 5H, ArH), 7.41
(s, 1H, thiazole). 13C NMR (75 MHz, CDCl3): d ¼ 168.1, 155.0, 133.9,
133.6, 133.0, 130.2, 129.0, 128.9, 127.7, 126.6, 113.0.

2902
D. Zhu et al.
4-(4-Methoxyphenyl)thiazol-2-amine (3i)[11]
White solid; mp 208–209 ꢀC. IR n (cmꢂ1): 3435, 2924, 1625, 1528, 1386,
1
1245, 1042, 670. H NMR (300 MHz, CDCl3): d ¼ 7.74–7.71 (m, 2H,
ArH), 6.94–6.91 (m, 2H, ArH), 6.61 (s, 1H, thiazole), 5.03 (br s, 2H,
NH2), 3.85 (s, 3H, OCH3). 13C NMR (75 MHz, CDCl3): d ¼ 167.1,
159.4, 150.9, 127.5, 127.3, 114.0, 101.0, 55.3.
4-(4-Methoxyphenyl)-N-phenylthiazol-2-amine (3j)[17]
White solid; mp 139–140 ꢀC. IR n (cmꢂ1): 3436, 2972, 1608, 1555, 1466,
1
1393, 1049, 678. H NMR (300 MHz, CDCl3): d ¼ 7.80–7.77 (m, 2H,
ArH), 7.43–7.32 (m, 5H, ArH), 7.09–7.06 (m, 1H, thiazole), 6.95–6.92
(m, 2H, ArH), 6.69 (br s, 1H, NH), 3.84 (s, 3H, OCH3). 13C NMR
(75 MHz, CDCl3): d ¼ 164.2, 159.4, 151.1, 140.3, 129.4, 127.6, 127.3,
122.9, 118.1, 114.0, 100.0, 55.3. MS (EI) m=z: (Mþ) 282, 165, 149, 77.
4-(4-Methoxyphenyl)-2-methylthiazole (3k)[11]
White solid; mp 67–69 ꢀC. IR n (cmꢂ1): 3434, 2926, 1612, 1505, 1249,
1173, 1032, 834, 747. 1H NMR (300 MHz, CDCl3): d ¼ 7.80 (d,
J ¼ 8.88 Hz, 2H, ArH), 7.16 (s, 1H, thiazole), 6.93 (d, J ¼ 8.86 Hz, 2H,
ArH), 3.83 (s, 3H, OCH3), 2.75 (s, 3H, CH3). 13C NMR (75 MHz,
CDCl3): d ¼ 165.6, 159.5, 154.9, 127.59, 127.56, 114.0, 110.5, 55.3, 19.3.
4-(4-Methoxyphenyl)-2-phenylthiazole (3l)[18]
White solid; mp 127–129 ꢀC. IR n (cmꢂ1): 3432, 2928, 1608, 1525, 1477,
1248, 1174, 1028, 836, 766, 690. 1H NMR (300 MHz, CDCl3): d ¼ 8.05–8.02
(m, 2H, ArH), 7.95–7.92 (m, 2H, ArH), 7.46–7.44 (m, 3H, ArH), 7.34 (s, 1H,
thiazole), 6.99–6.96 (m, 2H, ArH), 3.86 (s, 3H, OCH3). 13C NMR (75MHz,
CDCl3): d ¼167.7, 159.7, 156.1, 133.8, 130.0, 128.9, 127.8, 127.5, 126.6,
114.1, 110.9, 55.4.
2-Methyl-4-(4-nitrophenyl)thiazole (3m)[18]
Yellow solid; mp 141–143 ꢀC. IR n (cmꢂ1): 3438, 2973, 1640, 1597, 1505,
1
1335, 1164, 1055, 847, 740, 659. H NMR (300 MHz, CDCl3): d ¼ 8.28
(d, J ¼ 9.02 Hz, 2H, ArH), 8.05 (m, J ¼ 9.01 Hz, 2H, ArH), 7.54 (s, 1H,
thiazole), 2.80 (s, 3H, CH3). 13C NMR (75 MHz, CDCl3): d ¼ 166.9,
152.7, 147.2, 140.3, 126.8, 124.2, 116.0, 19.4.

Catalyst-Free Synthesis of Thiazoles
2903
4-(4-Nitrophenyl)-2-phenylthiazole (3n)[18]
Yellow solid; mp 128–129 ꢀC. IR n (cmꢂ1): 3434, 2924, 1599, 1510, 1338,
1104, 1054, 844, 734, 685. 1H NMR (300 MHz, CDCl3): d ¼ 8.31
(d, J ¼ 8.69 Hz, 2H, ArH), 8.17 (d, J ¼ 8.75 Hz, 2H, ArH), 8.07–8.04
(m, 2H, ArH) 7.69 (s, 1H, thiazole), 7.50–7.48 (m, 3H, ArH). 13C
NMR (75 MHz, CDCl3): d ¼168.8, 153.8, 147.3, 140.3, 133.2, 130.6,
129.1, 127.0, 126.7, 124.2, 116.0. MS (EI) m=z: (Mþ) 282, 252, 236, 149, 89.
5-Methyl-4-phenylthiazol-2-amine (3o)[10]
White solid; mp 115–116 ꢀC. IR n (cmꢂ1): 3413, 2924, 1632, 1532, 1440,
1320, 1098, 765, 698. 1H NMR (300 MHz, CDCl3): d ¼ 7.55–7.53 (m, 2H,
ArH), 7.40–7.35 (m, 2H, ArH), 7.30–7.25 (m, 1H, ArH), 5.17 (br s, 2H,
NH2), 2.37 (s, 3H, CH3). 13C NMR (75 MHz, CDCl3): d ¼ 165.1, 146.5,
135.8, 128.9, 128.7, 127.7, 117.6, 12.9.
5-Methyl-N,4-diphenylthiazol-2-amine (3p)[10]
White solid; mp 170–171 ꢀC. IR n (cmꢂ1): 3435, 2921, 1603, 1567, 1455,
1
1311, 1216, 1170, 755, 694. H NMR (300 MHz, CDCl3): d ¼ 7.64–7.61
(m, 2H, ArH), 7.43–7.38 (m, 2H, ArH), 7.34–7.23 (m, 6H, ArH), 7.02
(br s, 1H, NH), 2.45 (s, 3H, CH3). 13C NMR (75 MHz, CDCl3):
d ¼161.1, 140.6, 135.0, 129.4, 129.3, 128.5, 128.3, 127.4, 122.6, 118.0,
116.6, 12.3. MS (EI) m=z: (Mþ) 266, 251, 150, 115, 104, 77.
4-(2,4-Dichlorophenyl) thiazol-2-amine (3q)[19]
White solid; mp 161–163 ꢀC. IR n (cmꢂ1): 3446, 2924, 1628, 1536, 1460,
1382, 1330, 1093, 695. 1H NMR (300 MHz, CDCl3): d ¼ 7.83
(d, J ¼ 8.47 Hz, 1H, ArH), 7.46 (s, 1H, ArH), 7.31–7.28 (m, 1H, ArH),
7.10 (s, 1H, thiazole), 5.02 (br s, 2H, NH2). 13C NMR (75 MHz, CDCl3):
d 166.0, 146.4, 133.4, 132.2, 132.0, 131.8, 130.1, 127.1, 108.6. MS (EI)
m=z: (Mþ þ 4) 248, (Mþ þ 2) 246, (Mþ) 244, 206, 204, 202, 167, 132, 123.
4-(2,4-Dichlorophenyl)-N-phenylthiazol-2-amine (3r)
White solid; mp 123–124 ꢀC. IR n (cmꢂ1): 3434, 2928, 1557, 1458, 1418,
1
1308, 1094, 1039, 693. H NMR (300 MHz, CDCl3): d ¼8.15 (s, 1H,
ArH), 7.83–7.80 (m, 1H, ArH), 7.42 (m, 1H, ArH), 7.33–7.18 (m, 5H,

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D. Zhu et al.
ArH), 7.10–7.08 (m, 1H, thiazole), 7.06 (br s, 1H, NH). 13C NMR
(75 MHz, CDCl3): d ¼ 163.8, 146.5, 140.2, 133.7, 132.4, 132.1, 131.7,
130.2, 129.5, 127.2, 123.3, 118.5, 107.4. MS (ESI) m=z: (M þ 4 þ H)þ
325, (M þ 2 þ H)þ 323, (M þH)þ 321. Anal. Calcd. for C15H10Cl2N2S:
C, 56.09; H, 3.14; N, 8.72. Found: C, 56.20; H, 3.14; N, 8.66.
ACKNOWLEDGMENTS
We are grateful to the National Key Technology Research and Develop-
ment Program (No. 2007BAI34B00), the Natural Science Foundation of
Zhengjiang Province (No. Y4080107), and Wenzhou University Post-
graduate Innovation Foundation (No. YCX0716) for financial support.
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