CuBr2 mediated synthesis of 2-Aminothiazoles from dithiocarbamic acid salts and ketones

Article abstract of DOI:10.1080/10426507.2019.1633316

In a one-pot procedure, CuBr₂ has been used as a efficient desulfurizing agent in the synthesis of 2-aminothiazoles by the condensation of in situ-generated 1-substituted thioureas from their dithiocarbamic acid salts, with in situ-generated α-bromoketones from ketones. All reactions were carried out under optimized reaction conditions and gave the target products in 61–95% yield.

Full text of DOI:10.1080/10426507.2019.1633316

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: https://www.tandfonline.com/loi/gpss20
CuBr2 mediated synthesis of 2-Aminothiazoles
from dithiocarbamic acid salts and ketones
Baohua Zhang & Lanxiang Shi
To cite this article: Baohua Zhang & Lanxiang Shi (2019): CuBr2 mediated synthesis of 2-
Aminothiazoles from dithiocarbamic acid salts and ketones, Phosphorus, Sulfur, and Silicon and the
Related Elements, DOI: 10.1080/10426507.2019.1633316
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PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
https://doi.org/10.1080/10426507.2019.1633316
CuBr2 mediated synthesis of 2-Aminothiazoles from dithiocarbamic acid salts
and ketones
Baohua Zhang and Lanxiang Shi
College of Chemical Engineering, Shijiazhuang University, Shijiazhuang, China
ABSTRACT
ARTICLE HISTORY
Received 2 January 2019
Accepted 14 June 2019
In a one-pot procedure, CuBr2 has been used as a efficient desulfurizing agent in the synthesis of
2-aminothiazoles by the condensation of in situ-generated 1-substituted thioureas from their
dithiocarbamic acid salts, with in situ-generated a-bromoketones from ketones. All reactions were
carried out under optimized reaction conditions and gave the target products in 61–95% yield.
KEYWORDS
2-Aminothiazole;
desulfurizing agent;
dithiocarbamic acid salt;
ketone; CuBr2
GRAPHICAL ABSTRACT
Introduction
Results and discussion
Aminothiazoles constitute an important class of molecules, Initially, optimization of the reaction conditions was per-
which are frequently encountered in many natural products formed with dithiocarbamic acid triethylammonium
and pharmaceutical compounds.[1–4] In view of the import- salt (PhNHCSS-.Et3NHþ) (1a, 1 mmol) as a model sub-
ance of 2-aminothiazoles, several methods for the synthesis strate. Dithiocarbamic acid triethylammonium salt
of 2-aminothiazoles were developed. The most wildly used (PhNHCSS-.Et3NHþ) (1a, 1 mmol) and CuBr2 (0.5 mmol)
method is Hantzsch synthesis who originated it in 1887, reacted in the presence of aqueous ammonia (2.2 mmol, 25%)
involving the reaction of a-halocarbonyl compounds with and ethyl acetate at room temperature for 3 h to form isothio-
thioureas or thioamides.[5,6] Recently, 2-aminothiazoles cyanate in situ, isothiocyanate continue to react with ammo-
were synthesized by using catalyst such as ammonium 12- nia to obtain 1-phenyl thiourea (2a) with 98% conversion.
molybdophosphate,[7] cyclodextrin,[8] iodine,[9] palla-
After separated CuS and removed the excess ammonia from
dium,[10] ionic liquid [bbim]BF4
and 1,1’-(ethane-1,2-
[11]
mixture, CuBr2 (2.2 mmol) and acetophenone (3a, 1.1 mmol)
diyl)dipyridinium bistribromide[12] in organic solvents at was added and reacted under reflux condition for 3 hours. To
elevated temperature. Microwave irradiation can promote
the synthesis of 2-aminothiazoles.[13] In addition, 2-amino-
thiazoles can also be prepared by the reactions of a-diazo-
ketones with thiourea,[14] b-ketonitriles with aryl
bromides,[15] a-nitroepoxides with ammoniumthiocya-
nate[16] and amines, CS2 with alkyl halides.[17] These meth-
ods are generally efficient, but most of them possess
drawbacks such as using expensive catalyst, rigorous or
hazardous conditions, not easily available starting materials
or the generation of environmentally hazardous wastes.
Thus, there is still need for a commercially available and
simple methodology for the synthesis 2-aminothiazoles.
Herein we report the one-pot synthesis of 2-aminothiazoles
by the condensation of in situ-generated 1-substituted thio-
our delight, the 4-phenyl-N-phenylthiazol-2-amino (4a) was
obtained in 90% yield. Then the solvents were screened
(Table 1). Among them, EtOAc:H2O (3:1) was the best solv-
ent for this reaction and it could give the target product in
92% yield (Table 1, entry 9). Other solvents like EtOH,
EtOAc, CHCl3 and CH3CN can also give final product in
high yield. Unfortunately, the H2O couldn’t give target prod-
uct. Non-polar solvents gave no product. In the absence of
solvent, the reaction does not occur. Some mixed solvents,
such as EtOAc:H2O (2:1), EtOH:H2O (2:1) and CH3CN:H2O
(2:1), could yield product in high yields, while others, such as
EtOAc:H2O (1:2), EtOH:H2O (1:2) and CH3CN:H2O (1:2),
could not obtain products.
Other dithiocarbamic acid salts, such as PhNHCSS- ꢀ
ureas from their dithiocarbamic acid salts with in situ-gen- C5H5NHþ PhNHCSS- ꢀ Kþ PhNHCSS- ꢀ NH4 and
þ
,
,
erated a-bromoketones from ketones using efficient and PhNHCSS- ꢀ Naþ, yielded similar results as 1a. (Table 2,
readily available CuBr2 as a desulfurizing agent.
entries 1-5). The molar ratio of dithiocarbamic acid salt (1a)
CONTACT Lanxiang Shi
kedashilanxiang@126.com
College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2019 Taylor & Francis Group, LLC

2
B. ZHANG AND L. SHI
Table 1. Solvent Screen.
Entry
Solvent
Yield (%)a
1
2
3
4
5
6
7
8
EtOH
EtOAc
DCM
CHCl3
H2O
86
90
NR
85
NR
88
47
90
92
NR
NR
NR
NR
88
NR
89
NR
CH3CN
EtOAc : H2O (1:1)
EtOAc : H2O (2:1)
EtOAc : H2O (3:1)
EtOAc : H2O (1:2)
n-Hexane
Petroleum ether
Solvent free
EtOH : H2O (2:1)
EtOH : H2O (1:2)
CH3CN : H2O (2:1)
CH3CN : H2O (1:2)
9
10
11
12
13
14
15
16
17
NR ¼ No reaction.
variety of substrates and the target 2-aminothiazoles are
obtained in high yields. The established protocol makes a
valuable contribution to those already described for the syn-
thesis of 2-aminothiazoles.
Table 2. Optimization of Reaction Conditions.
Dithiocarbamic
acid salt
Reaction
CuBr2
(equiv)
Isolated
Yield (%)
Entry
Temp (ꢁC)
1
2
3
4
5
6
7
8
PhNHCSS- ꢀ Et3NHþ
PhNHCSS- ꢀ C5H5NHþ
PhNHCSS- ꢀ Kþ
25
25
25
25
25
25
25
10
2.7
2.7
2.7
2.7
2.7
2.9
2.5
2.7
92
92
90
89
90
92
89
86
PhNHCSS- ꢀ NH4
þ
PhNHCSS- ꢀ Naþ
Experimental
PhNHCSS- ꢀ Et3NHþ
PhNHCSS- ꢀ Et3NHþ
PhNHCSS- ꢀ Et3NHþ
All reagents and solvents were purchased from Sigma-Aldrich
and used as obtained. Flash chromatography was performed
with a glass column packed with Baker silica gel (30–60 lm).
NMR spectra were measured on a Bruker Avance II Plus spec-
trometer (400 MHz for 1H NMR, 100 MHz for 13C NMR).
NMR spectra are referenced according to the residual peak of
the solvent based on literature data. Mass data were obtained
with a WATERS MS system, Q-tof premier and data analyzed
using Mass Lynx4.1. Elemental analysis was performed with a
Perkin-Elmer 2400 elemental analyzer.
to CuBr2 was investigated. The results showed that the opti-
mum molar ratio of dithiocarbamic acid salt (1a) to CuBr2
was 1:2.7 (Table 2, entry 1). Reducing the reaction tempera-
ture of desulfurization to 10 ꢁC, the yield of target product
was decreased slightly (Table 2, entry 8).
The scope of this reaction was investigated. Structurally
diverse alkyl and aryl 2-aminothiazoles were obtained in
good yields from the parent dithiocarbamic acid salts under
the optimized reaction conditions. The electron donating
groups, such as 4-methoxy, 4-methyl and 2-methyl, on the
aryl rings of dithiocarbamic acid salts could give their
General procedure for synthesis of 2-aminothiazoles
(4a-4m)
respective 2-aminothiazoles in high yields (Table 3, entries To a stirred mixture of solvent (6 mL), aqueous ammonia
5, 8 and 9). The unsubstituted aryl ring also gave target (2.2 mmol, 25%) and dithiocarbamic acid salt 1 (1 mmol),
products in high yields (Table 3, entries 1 and 4). The elec- CuBr2 (0.5 mmol) was added slowly, and the reaction mix-
tron donating and electron withdrawing substituents on aro- ture was stirred at room temperature for 3 h, thioureas (2)
matic rings of ketones have little effect on the yield of were generated in situ. During this period, a black precipi-
tate was observed and settled at the bottom of the round-
bottom flask. The reaction mixture was transferred into cen-
trifuged tubes and the mixture was centrifuged for 10 min
products (Table 3, entries 2, 3 and 7). When aliphatic
ketones are the substrates, the yield of the products was
medium to high (Table 3, entries 15 and 16).
In conclusion, CuBr2 has been used as a desulfurizing by using a centrifugation machine. The black solid settled in
agent for the preparation of 2-aminothiazoles by the con- the bottom of the centrifuge tubes. Excess ammonia was
densation of in situ-generated thioureas from their dithio- removed by heating the reaction mixture on a hot-water
carbamic acid salts and in situ-generated a-bromoketones bath (50 ꢁC) for 10 min. Then CuBr2 (2.2 mmol) and ketone
from ketones in one pot. The method is compatible with a (3, 1.1 mmol) was added and continue reflux. The progress

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
3
Table 3. Substrate Scope.
Entry
1
R1
R2
Product
Yield (%) [Ref]
[12]
C6H5
C6H5
92
[12]
2
3
C6H5
4-CH3OC6H5
93
[12]
C6H5
4-BrC6H5
87
[6]
4
C6H5
b-C10H7
93
[12]
5
6
4-CH3OC6H5
C6H5
95
[6]
CH3
4-FC6H5
82
[13]
7
C6H5
4-CH3C6H5
91
[12]
8
9
4-CH3C6H5
2-CH3C6H5
C6H5
93
C6H5
86
10
2-ClC6H5
C6H5
81
(continued)

4
B. ZHANG AND L. SHI
Table 3. Continued.
Entry
11
R1
R2
Product
Yield (%) [Ref]
[8]
4-ClC6H5
C6H5
85
12
13
4-NO2C6H5
C6H5
67
[6]
C6H5CH2
b-C10H7
90
[12]
14
15
C6H5
C2H5OCOCH2
66
[12]
C6H5
C2H5
61
16
C6H5
(CH2)4
82
of the reaction was investigated by TLC (2% ethyl acetate in (m, 2 H), 7.30-7.26 (m, 2 H), 6.91 (d, J ¼ 8.4 Hz, 2 H), 6.89
hexane). After finishing the reaction, the reaction mixture (m, 1 H), 6.83 (s, 1 H), 3.82 (s, 3 H); 13C NMR (100 MHz,
was filtered at 50 ꢁC and the filter was extracted with ethyl CDCl3): d ¼ 160.7, 160.1, 148.1, 143.0, 129.6, 129.5, 128.5,
acetate (2 ꢂ 20 mL). The ethyl acetate layer was washed with 128.5, 125.5, 125.4, 118.1, 116.5, 116.3, 115.0, 114.7, 101.1,
a saturated solution of NaHCO3 (5 mL), dried over anhyd- 55.9. Elemental analyses: calcd for C16H14N2OS: C, 68.06; H,
rous Na2SO4, concentrated under reduced pressure, and 5.00; N, 9.92; O, 5.67; S, 11.36. found: C, 68.03; H, 5.02; N,
purified over a silica-gel column (hexane - EtOAc, 9:1:) to 9.90; O, 5.68; S, 11.33.
4c: White solid; m.p. 137-140 ꢁC; White Solid;
give 2-Aminothiazoles 4a-4m.
4a: White solid; m.p. 135-136 ꢁC.1H NMR (400 MHz, mp156–158 ꢁC. 1H NMR (400 MHz, CDCl3): d ¼ 7.71 (d,
CDCl3): d ¼ 7.94 (s, 1 H), 7.64-7.53 (m, 3 H), 7.30-7.26 (m, J ¼ 8.4 Hz, 2 H), 7.51 (d, 2 H, J ¼ 8.4 Hz), 7.36 (m, 4 H), 7.08
4 H), 6.98-6.86 (m, 3 H); 13C NMR (100 MHz, CDCl3): (m, 1 H), 6.72 (s, 1 H). 13C NMR (100 MHz, CDCl3):
d ¼ 165.7, 152.2, 143.1, 133.0, 129.7, 129.6, 129.5, 129.3, d ¼ 165.1, 150.5, 140.5, 133.6, 132.0, 129.7, 128.0, 123.5,
129.0, 127.6, 127.5, 119.0, 116.6, 116.6, 101.1. Elemental 122.0, 118.6, 102.3. EI-MS m/z [M þ H]þ calcd for
analyses: calcd for C15H12N2S: C, 71.40; H, 4.79; N, 11.10; S, C15H11BrN2S: 330.99: found: 330.97. Elemental analyses:
12.71. found: C, 71.39; H, 4.77; N, 11.08; S, 12.69. Elemental calcd for C15H11BrN2S: C, 54.39; H, 3.35; Br, 24.12; N, 8.46;
analyses: calcd for C16H14N2OS: C, 71.40; H, 4.79; N, 11.10; S, 9.68. found: C, 54.42; H, 3.34; Br, 24.10; N, 8.45; S, 9.66.
4d: White solid; m.p. 148-150 ꢁC; 1H NMR (400 MHz,
S, 12.71. found；C, 71.41; H, 4.81; N, 11.13; S, 12.69.
4b: White solid; m.p. 137-140 ꢁC; 1H NMR (400 MHz, CDCl3): d ¼ 8.33 (s, 1 H), 7.90-7.78 (m, 1 H), 7.45-7.29 (m,
CDCl3): d ¼ 7.93 (s, 1 H), 7.67 (d, J ¼ 8.8 Hz, 2 H), 7.64-7.53 7 H), 6.82 (s, 1 H), 5.73 (s,1H). 13C NMR (100 MHz, CDCl3):

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
5
d ¼ 169.1, 151.3, 143.1, 133.6, 132.9, 132.1, 128.7, 128.3, 6 H); 13C NMR (100 MHz, CDCl3): d ¼ 160.6, 148.3, 141.2,
127.6, 127.5, 126.1, 125.8, 124.9, 124.0, 101.6. EI-MS m/z 133.2, 129.7 (2 C), 129.5 (2 C), 128.9, 127.6 (2 C), 124.3,
[M þ H]þ calcd for C19H14N2S: 303.09: found: 303.11.
Elemental analyses: calcd for C19H14N2S: C, 75.47; H, 4.67;
N, 9.26; S, 10.60. found: C, 75.45; H, 4.66; N, 9.28; S, 10.62.
4e: White solid; m.p. 157-160 ꢁC;1H NMR (400 MHz,
CDCl3): d ¼ 7.94 (s, 1H), 7.64-7.53 (m, 3H), 7.30 (dd, J ¼
7.3, 2.1 Hz, 2H), 7.14 (dd, J ¼ 6.5, 1.9 Hz, 2H), 6.93 (dd, J ¼
6.5, 2.1 Hz, 2H), 3.74 (s, 3H); 13C NMR (100 MHz, CDCl3):
d ¼ 160.5, 150.7, 148.2, 135.4, 133.2, 129.5, 129.4, 128.9,
127.6, 127.5, 117.5, 117.3, 115.5, 115.1, 100.1, 55.9.
Elemental analyses: calcd for C16H14N2OS: C, 68.06; H, 5.00;
N, 9.92; S, 11.36. found: C, 68.09; H, 5.01; N, 9.94; S, 11.37.
4f: White solid; m.p. 136-138 ꢁC； 1H NMR (400 MHz,
CDCl3) d (ppm): 7.77-7.70 (m, 2 H), 7.09-7.01 (m, 2 H), 6.61
(s, 1 H), 2.47 (s, 3 H). 13C NMR (100 MHz, CDCl3): d
(ppm): 167.2, 163.3, 150.1, 130.9, 130.0, 128.5, 116.1, 116.0,
102.1, 29.5; Elemental analyses: calcd for C10H9FN2S: C,
57.67; H, 4.36; F, 9.12; N, 13.45; S, 15.40. found:
117.8, 117.7, 100.1; IR (KBr) ꢀ ¼ 3424, 3050, 1606, 1498,
1280, 1029 cmꢃ1; Elemental analyses: calcd for C15H11ClN2S:
C, 62.82; H, 3.87; Cl, 12.36; N, 9.77; S, 11.18. found: C,
62.78; H, 3.85; Cl, 12.34; N, 9.75; S, 11.19.
4l: Yellow solid; m.p. 201-204 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 8.23 (dd, J ¼ 6.4, 1.9Hz, 2 H), 7.94 (s, 1 H),
7.64-7.53 (m, 3 H), 7.31-7.28 (m, 4 H); 13C NMR (100 MHz,
CDCl3): d ¼ 160.6, 149.2, 148.3, 138.4, 133.1, 129.5 (2 C),
128.8, 127.5 (2 C), 121.9 (2 C), 117.2 (2 C), 100.1; IR (KBr)
ꢀ ¼ 3453, 3040, 1611, 1509, 1267, l035 cmꢃ1; Elemental anal-
yses: calcd for C20H16N2S: C, 60.59; H, 3.73; N, 14.13; S,
10.78. found: C, 60.56; H, 3.74; N, 14.11; S, 10.76.
4m: White solid; mp 131-132 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 8.33 (s, 1 H), 7.90-7.78 (m, 4 H), 7.45-7.29 (m,
7 H), 6.83 (s, 1 H), 4.56-4.54 (d, J ¼ 4.7Hz, 2 H); 13C NMR
(100 MHz, CDCl3): d ¼ 169.5, 151.3, 137.5, 133.6, 132.9,
132.2, 128.6, 1289.3, 128.0, 127.6, 127.5, 126.1, 125.8, 124.9,
124.0, 101.7, 49.8. Elemental analyses: calcd for C20H16N2S:
C, 75.92; H, 5.10; N, 8.85. Found: C, 75.81; H, 5.23; N, 8.72.
C, 57.69; H, 4.35; F, 9.11; N, 13.42; S, 15.37.
4g: Gummy；1H NMR (400 MHz, CDCl3): d ¼ 7.30-7.26
(m, 2H), 7.24 (d, J ¼ 7.6Hz, 2H), 7.12 (d, J ¼ 7.0Hz, 2H),
6.91 (m, 2H), 6.89 (m, 1H), 6.63 (s, 1H), 2.28 (s, 3H); 13C
NMR (100 MHz, CDCl3): d ¼ 160.8, 148.9, 143.1, 138.5,
130.2, 129.6, 129.6, 129.5, 129.5, 127.5, 127.4, 118.8, 116.3,
116.1, 100.7, 24.3; Elemental analyses: calcd for C16H14N2S:
C, 72.15; H, 5.30; N, 10.52; S, 12.04. found: C, 72.12; H,
5.29; N, 10.50; S, 12.01.
1
4n: Gummy; H NMR (400 MHz, CDCl3): d ¼ 7.79-7.32
(m, 4 H), 7.03 (m, 1 H), 6.44 (s, 1 H), 4.17 (q, J ¼ 7.2Hz,
2 H), 3.64 (s, 2 H), 1.26 (t, J ¼ 7.2Hz, 3 H); 13C NMR
(100 MHz, CDCl3): d ¼ 170.4, 165.1, 144.6, 140.5, 129.6,
123.1, 118.6, 104.6, 61.2, 37.5, 14.3; IR (KBr) ꢀ ¼ 3337, 3064,
2981, 1731, 1603, l526, 1497, 1370, 1246, 1030 cmꢃ1
;
Elemental analyses: calcd for C13H14N2O2S: C, 59.52; H,
5.38; N, 10.68; S, 12.22. found: C, 59.50; H, 5.36; N, 10.67;
S, 12.20.
4h: White solid; m.p. 135-137 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 7.94 (s, 1 H), 7.64-7.53 (m, 3 H), 7.31 (dd,
J ¼ 7.3, 2.0Hz, 2 H), 7.15 (dd, J ¼ 6.4, 1.9Hz, 2 H), 7.02 (dd,
J ¼ 6.4, 2.3Hz, 2 H), 2.29 (s, 3 H); 13C NMR (100 MHz,
CDCl3): d ¼ 160.5, 148.3, 142.1, 136.3, 130.2, 129.9, 129.3,
129.1, 128.8, 128.5, 127.4, 127.3, 116.3, 116.1, 100.1, 24.3; IR
(KBr) ꢀ ¼ 3 411, 3 069, 2 975, 1611, l485, 1385, 1290,
1025 cmꢃ1; Elemental analyses: calcd for C16H14N2S: C,
72.15; H, 5.30; N, 10.52; S, 12.04. found: C, 72.12; H, 5.29;
N, 10.50; S, 12.01.
4o: Yellow solid; mp 111-114 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 7.34-7.25 (m, 4 H), 7.02 (t, J ¼ 6.8Hz, 1 H), 2.33
(s, 3 H), 2.18 (s, 3 H); 13C NMR (100 MHz, CDCl3):
d ¼ 161.8, 143.0, 141.1, 129.5, 122.6, 118.3, 114.2, 14.8, 11.2;
IR (KBr) ꢀ ¼ 3241, 3194, 3138, 3068, 2916, 1605, 1569, 1499,
1424, 1376, 1297, 1222, 991, 847 cmꢃ1; Elemental analyses:
calcd for C11H12N2S: C, 64.67; H, 5.92; N, 13.71; S, 15.70.
found: C, 64.68; H, 5.91; N, 13.74; S, 15.72.
4p: White solid; mp 130-132 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 7.36-7.28 (m, 4 H), 7.04-7.00 (m, 1 H), 2.63-2.61
(m, 4 H), 1.85-1.82 (m, 4 H); 13C NMR (100 MHz, CDCl3):
d ¼ 158.4, 149.1, 143.6, 129.8, 129.6, 119.9, 118.8, 116.5
(2 C), 25.2, 24.6, 22.5 (2 C); IR (KBr) ꢀ ¼ 3254, 3184, 2934,
2855, 1601, 1550, 1529, 1459, 1313, 750; Elemental analyses:
calcd for C13H14N2S: C, 67.79; H, 6.13; N, 12.16; S, 13.92.
found: C, 67.82; H, 6.12; N, 12.13; S, 13.90.
4i: White solid; m.p. 106-108 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 7.91 (s, 1 H), 7.64-7.53 (m, 3 H), 7.30 (dd,
J ¼ 7.5, 2.2 Hz, 2 H), 7.14-7.01 (m, 3 H), 6.62 (t, J ¼ 7.3, 1 H),
2.15 (s, 3 H);13C NMR (100 MHz, CDCl3): d ¼ 160.5, 148.2,
142.1, 133.3, 130.2, 129.3, 129.2, 129.1, 128.8, 127.5, 127.4,
126.7, 118.7, 116.1, 100.1, 15.5; IR (KBr) ꢀ ¼ 3427, 3071,
2956, 161 l, 1488, l385, 1285, 1026 cmꢃ1; Elemental analyses:
calcd for C16H14N2S: C, 72.15; H, 5.30; N, 10.52; S, 12.04.
found: C, 72.13; H, 5.28; N, 10.49; S, 12.00.
4j: White solid; m.p. 76-78 ꢁC; 1H NMR (400 MHz,
CDCl3): d ¼ 7.90 (s, 1 H), 7.64-7.53 (m, 4 H), 7.36-7.30 (m,
3 H), 7.18 (t, J ¼ 6.4, 1 H), 6.67 (t, J ¼ 7.3, 1 H); 13C NMR
(100 MHz, CDCl3): d ¼ 160.6, 148.3, 136.6, 133.2, 129.4,
129.3, 128.9, 127.9, 127.6, 127.5, 125.4, 120.7, 117.7, 100.1;
Funding
We thank the Hebei province science and technology support program
(grant no. 18271404 D).
IR (KBr) ꢀ ¼ 3435, 3052, 1610, 1491, 1276, 1022 cmꢃ1
;
Elemental analyses: calcd for C15H11ClN2S: C, 62.82; H,
3.87; Cl, 12.36; N, 9.77; S, 11.18. found: C, 62.79; H, 3.86;
Cl, 12.33; N, 9.79; S, 11.20.
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