Efficient synthesis of functionalized 2,4-diaminothiazoles from tetramethylguanidine, isothiocyanates, and α-bromoketones

Article abstract of DOI:10.1080/17415993.2010.525709

The Hantzsch method for thiazole synthesis is modified via the reaction of -bromocarbonyl compounds with 2-(amidosulfanylenemethyl)-1,1,3,3- tetramethylguanidines (prepared in situ from tetramethylguanidine and aroylisothiocyanates), to afford functionali

Full text of DOI:10.1080/17415993.2010.525709

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Efficient synthesis of functionalized
2,4-diaminothiazoles from
tetramethylguanidine, isothiocyanates,
and α-bromoketones
a
a
a
Issa Yavari , Ashraf S. Shahvelayati & Alaleh Malekafzali
a
Department of Chemistry, Tarbiat Modares University, PO Box
4115-175, Tehran, Iran
1
Version of record first published: 04 Nov 2010.
To cite this article: Issa Yavari , Ashraf S. Shahvelayati & Alaleh Malekafzali (2010): Efficient
synthesis of functionalized 2,4-diaminothiazoles from tetramethylguanidine, isothiocyanates, and
α-bromoketones, Journal of Sulfur Chemistry, 31:6, 499-508
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Journal of Sulfur Chemistry
Vol. 31, No. 6, December 2010, 499–508
Efficient synthesis of functionalized 2,4-diaminothiazoles from
tetramethylguanidine, isothiocyanates, and α-bromoketones
Issa Yavari*, Ashraf S. Shahvelayati and Alaleh Malekafzali
Department of Chemistry, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran
(Received 21 August 2010; final version received 18 September 2010)
The Hantzsch method for thiazole synthesis is modified via the reaction of α-bromocarbonyl compounds
with 2-(amidosulfanylenemethyl)-1,1,3,3-tetramethylguanidines (prepared in situ from tetramethylguani-
dine and aroylisothiocyanates), to afford functionalized 2,4-diaminothiazoles in good yields.
Keywords: diaminothiazole; aroylisothiocyanate; α-bromoketones; tetramethylguanidine; MCR
1
.
Introduction
The thiazole ring system is commonly found in many pharmaceutically important molecules.
Numerous natural products containing this heterocycle have been isolated and exhibit significant
biological activities (1). Among aromatic heterocycles, thiazoles occupy a prominent position in
the drug discovery process (2) and this ring structure is found in several marketed drugs.Aminoth-
iazoles are known to be ligands of estrogen receptors (3) as well as a novel class of adenosine
receptor antagonists (4). Thiazoles are also useful synthetic intermediates and common sub-
structures in numerous bioactive compounds. Thus, the thiazole nucleus has been much studied
in organic and medicinal chemistry. Several methods (5, 6) for the synthesis of thiazole derivatives
have been developed, among which the most widely used method is Hantzsch’s synthesis (7–9)
(reaction between α-halocarbonyl compounds and thioamides, thioureas, thiocarbamic acids, or
dithiocarbamic acids).
2
. Results and discussion
As part of our current studies on the development of new routes in thiazole synthesis (10–12),
we describe an efficient one-pot method for the synthesis of functionalized 2,4-diaminothiazole
derivatives using 1,1,3,3-tetramethylguanidine (1) as a nucleophile. The reaction of 1 and
isothiocyanates 2 in the presence of α-bromoketones 3 in acetone at room temperature
*
Corresponding author. Email: yavarisa@modares.ac.ir
ISSN 1741-5993 print/ISSN 1741-6000 online
2010 Taylor & Francis
©
DOI: 10.1080/17415993.2010.525709
http://www.informaworld.com

5
00 I. Yavari et al.
Table 1. Reaction of tetramethylguanidine, isothiocyanates, and α-bromoketones.
Me N
2
NH
O
N
R'
R
Br Acetone
r.t
Me N
NMe2
R
N
C
S
N
2
R'
S
H
O
1
2a–h
3a–f
4a–aa
Isothiocyanate 2
α-Bromoketone 3
ꢀ
R
R
Product 4
Yield (%)
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
a
a
a
b
b
b
c
d
d
d
e
e
e
f
PhCO
PhCO
PhCO
2-ClC6H4CO
2-ClC6H4CO
2-ClC6H4CO
4-O2NC6H4CO
4-MeC6H4CO
4-MeC6H4CO
4-MeC6H4CO
t-BuCO
t-BuCO
t-BuCO
Ph
Ph
Ph
3a
3b
3c
3a
3b
3c
3a
3a
3b
3c
3a
3b
3c
3d
3c
3e
3f
3b
3a
3c
3b
3a
3d
3c
3e
3f
CO2Et
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
4s
92
95
84
67
73
68
58
93
90
87
65
56
60
81
86
81
88
87
84
75
84
84
84
83
79
97
96
4-BrC6H4
4-MeOC6H4
CO2Et
4-BrC6H4
4-MeOC6H4
CO2Et
CO2Et
4-BrC6H4
4-MeOC6H4
CO2Et
4-BrC6H4
4-MeOC6H4
Ph
4-MeOC6H4
4-FC6H4
4-ClC6H4
4-BrC6H4
CO2Et
4-MeOC6H4
4-BrC6H4
CO2Et
f
f
f
f
Ph
Ph
Ph
f
g
g
g
h
h
h
h
h
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
Et
Et
Et
Et
Et
4t
4u
4v
4w
4x
4y
4z
4aa
Ph
4-MeOC6H4
4-FC6H4
4-ClC6H4
4-BrC6H4
3b
produced functionalized diaminothiazoles 4 in good yields after purification (Table 1). In this
procedure, we have modified the Hantzsch method for thiazole synthesis via the reaction of
2-(sulfanylenemethyl)-1,1,3,3-tetramethylguanidines (5; see Scheme 1) with α-bromocarbonyl
compounds. Thus, various thiourea derivatives were prepared from 1 and 2. Functionalized
2
,4-diaminothiazoles 4 were obtained from the reaction of these thioureas with 3.
The structures of compounds 4a–4aa were deduced from their IR, H NMR, and 13C NMR.
1
The mass spectra of these compounds displayed molecular ion peaks at appropriate m/z values.
1
The H NMR spectrum of 4a in CDCl3 showed two singlets for methyl (δ = 3.16) and NH
(
δ = 9.90) protons, along with characteristic signals for the ethyl and phenyl groups. The carbonyl
13
group resonances in the C NMR spectra of 4a appear at 165.4, 170.5, and 185.0 ppm. The mass
1
13
spectrumof 4a displayedthemolecularionpeakatm/z = 347.The HNMRand CNMRspectra
of 4b–4aa were similar to those for 4a except for the side chains, which exhibited characteristic
resonances in the appropriate regions of the spectrum.
Mechanistically, the reaction starts with the formation of 2-(sulfanylenemethyl)-1,1,3,3-
tetramethylguanidines (5) from tetramethylguanidine (1) and isothiocyanates (2). Subsequent
nucleophilic alkylation of thiourea derivative 5 with α-bromoketones (3) yields intermediate 6.
This intermediate undergoes HBr elimination and subsequent enolization to generate 7, which

Journal of Sulfur Chemistry 501
O
Br
H
N
R
O
S
NMe2
NMe2
3
Me N
R'
2
1
+
2
N
S
R
N
H
N
Me N
2
O
6
5
O
O
Me N
H
N
N
R
O
2
_
R'
Me NH
Me N
2
_
_
Me N
2
4
2
HBr
N
N
S
NH proton
shift
+
O
H
Me N
2
S
R'
R
8
7
Scheme 1. Proposed mechanism for the formation of compounds 4.
is transformed to the heterocyclic intermediate 8 by intramolecular cyclization reaction. Subse-
quent NH proton shift and loss of dimethylamine afford functionalized 2,4-diaminothiazoles 4
(Scheme1).
3
. Conclusions
In conclusion, we have described a convenient route for the synthesis of functionalized
,4-diaminothiazoles from tetramethylguanidine and isothiocyanates in the presence of α-
2
bromoketones. The advantage of the present procedure is that the reaction is performed
under neutral conditions by simple mixing of the starting materials. The procedure described
here also provides an efficient one-pot methodology for the preparation of functionalized
2
,4-diaminothiazoles.
4
4
.
Experimental
.1. General
All purchased solvents and chemicals were of analytical grade and used without further purifi-
cation. Melting points and IR spectra were measured on an Electrothermal 9100 apparatus and
1
13
a Shimadzu IR-460 spectrometer, respectively. The H and C spectra were obtained with a
BRUKER DRX-300 AVANCE instrument using CDCl3 as the applied solvent and TMS as the
internal standard at 300 and 75 MHz, respectively. Mass spectra were recorded on a FINNIGAN-
MAT 8430 mass spectrometer operating at an ionization potential of 70 eV. Elemental analyses
for C, H, and N were performed using a Heraeus CHN-O-Rapid analyzer.
4
.2. General procedure for the preparation of compounds 4
To a stirred solution of the isothiocyanate (2, 2 mmol) in acetone (10 ml) was added, at r.t.,
.23 g (2 mmol) of tetramethylguanidine (1). The mixture was stirred at r.t. for 30 min. Then, the
0

5
02 I. Yavari et al.
α-bromoketone 3 (2 mmol) was added to the reaction mixture and stirred at r.t. After completion
of the reaction (8–12 h; TLC (AcOEt/hexane 2:1)), the solvent was evaporated, and the residue
was purified by column chromatography (silica gel (230–240 mesh; Merck), hexane/AcOEt 4:1).
4
.2.1. Ethyl 2-benzoylamino-4-dimethylamino-thiazol-5-yl-oxo-acetate (4a)
◦
Orange powder, m.p. 177–178 C; yield: 0.64 g (92%). IR (KBr): 3437, 1724, 1676, 1616, 1542,
1
−
1
1
3
307, 1226, 1098 cm . H NMR: δ = 1.38 (3 H, t, J 7.1, Me), 3.16 (6 H, s, Me2N), 4.38 (2
3 3 3 3
H, q, J 7.1, CH2O), 7.52 (2 H, t, J 7.4, CH), 7.64 (1 H, t, J 7.4, CH), 8.01 (2 H, d, J 7.4, 2
CH), 9.90 (1 H, s, NH). 13C NMR: δ = 14.5 (Me), 43.0 (Me2N), 62.9 (CH2O), 99.5 (C), 128.0
(
1
4
2 CH), 129.5 (2 CH), 131.7 (CH), 133.8 (C), 164.1 (C), 165.2 (C), 165.4 (C=O), 170.5 (C=O),
+
85.0 (C=O). EI-MS: m/z (%) = 347 (M , 6), 332 (38), 302 (66), 242 (21), 105 (100), 77 (39),
5 (22). Anal. Calcd for C16H17N3O4S (347.39): C, 55.32; H, 4.93; N, 12.10%; found: C, 55.7;
H, 5.0; N, 11.9%.
4
.2.2. N-(5-(4-Bromobenzoyl)-4-dimethylamino-thiazol-2-yl)benzamide (4b)
◦
Yellow powder, m.p. 233–235 C; yield: 0.81 g (95%). IR (KBr): 3450, 1674, 1589, 1534, 1387,
1
−
1
1
3
251, 1211, 1170 cm . H NMR: δ = 3.15 (6 H, s, Me2N), 7.56 (2 H, t, J 7.3, 2 CH), 7.60 (2
3 3 3 3
H, d, J 8.4, 2 CH), 7.65 (1 H, t, J 7.3, CH), 7.73 (2 H, d, J 8.4, 2 CH), 7.95 (2 H, d, J 7.3,
2
1
1
CH), 9.90 (1 H, br s, NH). 13C NMR: δ = 42.7 (Me2N), 100.1 (C), 126.7 (C), 127.9 (2 CH),
28.6 (CH), 129.5 (2 CH), 130.5 (2 CH), 131.5 (C), 132.0 (2 CH), 133.8 (C), 133.9 (C), 140.5 (C),
+
+
60.9 (C), 165.1 (C=O), 184.2 (C=O). EI-MS: m/z (%) = 431 (M + 1, 8), 429 (M , 13), 416
(
33), 414 (30), 185 (11), 183 (11), 105 (100), 77 (43). Anal. Calcd for C19H16BrN3O2S (430.32):
C, 53.03; H, 3.75; N, 9.76%; found: C, 52.8; H, 3.8; N, 9.8%.
4
.2.3. N-(4-Dimethylamino-5-(4-methoxy-benzoyl)thiazol-2-yl)benzamide (4c)
◦
Yellow powder, m.p. 217–218 C; yield: 0.64 g (84%). IR (KBr): 3445, 1679, 1591, 1520, 1367,
1
−
1
1
3
221, 1157 cm . H NMR: δ = 3.11 (6 H, s, Me2N), 3.89 (3 H, s, MeO), 6.95 (2 H, d, J 8.7, 2
3 3 3
CH), 7.53 (2 H, d, J 7.8, 2 CH), 7.63 (1 H, t, J 7.8, CH), 7.86 (2 H, d, J 8.7, 2 CH), 7.94 (2
3
13
H, t, J 7.8, 2 CH), 9.10 (1 H, br s, NH). C NMR: δ = 42.6 (Me2N), 55.9 (MeO), 100.4 (C),
1
(
14.0 (2 CH), 127.9 (2 CH), 128.4 (CH), 129.5 (2 CH), 131.6 (2 CH), 131.7 (C), 133.7 (C), 134.4
+
C), 160.3 (C), 160.9 (C), 162.8 (C), 165.0 (C=O), 184.9 (C=O). EI-MS: m/z (%) = 381 (M ,
1
2), 366 (41), 276 (35), 246 (12), 135 (22), 105 (100), 77 (37). Anal. Calcd for C20H19N3O3S
(381.45): C, 62.97; H, 5.02; N, 11.02%; found: C, 63.2; H, 5.1; N, 11.1%.
4
.2.4. Ethyl (2-(2-chloro-benzoylamino)-4-dimethylamino-thiazol-5-yl)oxoacetate (4d)
◦
Orange powder, m.p. 153–155 C; yield: 0.51 g (67%). IR (KBr): 3439, 1723, 1624, 1545, 1394,
1
(
(
−
1
1
3
307, 1232, 1116 cm . H NMR: δ = 1.43 (3 H, t, J 7.1, Me), 3.18 (6 H, s, Me2N), 4.40
3
1
3
2 H, q, J 7.1, CH2O), 7.41–7.92 (4 H, m, 4 CH), 9.85 (1 H, s, NH). C NMR: δ = 14.5
Me), 43.0 (Me2N), 63.0 (CH2O), 99.4 (C), 128.0 (CH), 131.2 (CH), 131.5 (C), 131.7 (C),
1
31.9 (CH), 133.7 (CH), 164.0 (C), 164.2 (C), 164.3 (C=O), 170.5 (C=O), 184.7 (C=O). EI-
+
MS: m/z (%) = 381 (M , 13), 366 (45), 336 (65), 242 (14), 139 (100), 111 (18), 45 (21).
Anal. Calcd for C16H16ClN3O4S (381.83): C, 50.33; H, 4.22; N, 11.01%; found: C, 50.1; H,
4
.3; N, 11.1%.

Journal of Sulfur Chemistry 503
4
.2.5. N-(5-(4-Bromo-benzoyl)-4-dimethylamino-thiazol-2-yl)-2-chlorobenzamide (4e)
◦
Yellow powder, m.p. 206–207 C; yield: 0.67 g (73%). IR (KBr): 3385, 1688, 1610, 1539, 1386,
−
1 1
1
263, 1129 cm . H NMR: δ = 3.17 (6 H, s, Me2N), 7.41–7.91 (4 H, m, 4 CH), 7.61 (2 H, d,
3
3
1
3
J 8.4, 2 CH), 7.74 (2 H, d, J 8.4, 2 CH), 9.78 (1 H, br s, NH). C NMR: δ = 42.3 (Me2N),
1
00.5 (C), 126.5 (C), 127.7 (CH), 128.0 (C), 128.7 (CH), 130.4 (2 CH), 130.4 (C), 131.5 (CH),
1
1
1
9
32.0 (2 CH), 132.8 (CH), 132.9 (C), 133.5 (C), 140.7 (C), 162.5 (C), 164.1 (C), 166.4 (C=O),
+
+
84.2 (C=O). EI-MS: m/z (%) = 465 (M + 1, 6), 463 (M , 12), 450 (45), 448 (34), 185 (21),
83 (21), 139 (100), 43 (9). Anal. Calcd for C19H15BrClN3O2S (464.76): C, 49.04; H, 3.25; N,
.04%; found: C, 49.4; H, 3.3; N, 9.1%.
4
.2.6. N-[4-Dimethylamino-5-(4-methoxybenzoyl)thiazol-2-yl]-2-chlorobenzamide (4f)
◦
Yellow powder, m.p. 203–205 C; yield: 0.56 g (68%). IR (KBr): 3410, 1679, 1608, 1541, 1391,
−
1
1
3
1
255, 1117 cm . H NMR: δ = 3.13 (6 H, s, Me2N), 3.89 (3 H, s, MeO), 6.96 (2 H, d, J 8.7,
3
1
3
2
CH), 7.41–7.86 (4 H, m, 4 CH), 7.87 (2 H, d, J 8.7, 2 CH), 9.79 (1 H, br s, NH). C NMR:
δ = 42.5 (Me2N), 55.8 (MeO), 100.5 (C), 113.9 (2 CH), 127.9 (CH), 131.2 (2 CH), 131.5 (CH),
1
32.0 (CH), 132.6 (C), 132.9 (C), 133.4 (CH), 133.5 (CH), 134.4 (C), 159.6 (C), 161.8 (C), 162.8
+
+
(
3
C), 164.1 (C=O), 184.9 (C=O). EI-MS: m/z (%) = 417 (M + 1, 8), 415 (M , 20), 400 (48),
04 (33), 276 (24), 139 (100), 135 (19). Anal. Calcd for C20H18ClN3O3S (415.89): C, 57.76; H,
.36; N, 10.10%; found: C, 58.0; H, 4.4; N, 10.2%.
4
4
.2.7. Ethyl (4-dimethylamino-2-(4-nitro-benzoylamino)-thiazol-5-yl)oxoacetate (4g)
Viscous oil; yield: 0.45 g (58%). IR (KBr): 3460, 1729, 1682, 1621, 1562, 1317, 1216, 1078 cm 1.
−
1
3
3
H NMR: δ = 1.40 (3 H, t, J 7.2, Me), 3.19 (6 H, s, Me2N), 4.40 (2 H, q, J 7.2, CH2O), 8.23
3
3
13
(
2 H, d, J 8.7, 2 CH), 8.41 (2 H, d, J 8.7, 2 CH), 10.21 (1 H, br s, NH). C NMR: δ = 14.5
(
1
1
Me), 43.1 (Me2N), 63.1 (CH2O), 100.1 (C), 124.6 (2 CH), 129.4 (2 CH), 132.1 (C), 137.0 (C),
+
51.1 (C), 163.5 (C), 164.0 (C=O), 170.6 (C=O), 184.2 (C=O). EI-MS: m/z (%) = 392 (M ,
1), 377 (39), 347 (59), 242 (24), 150 (100), 122 (16), 45 (23). Anal. Calcd for C16H16N4O6S
(392.39): C, 48.97; H, 4.11; N, 14.28%; found: C, 49.3; H, 4.2; N, 14.4%.
4
.2.8. Ethyl (4-dimethylamino-2-(4-methyl-benzoylamino)-thiazol-5-yl)oxoacetate (4h)
◦
Orange powder, m.p. 168–169 C; yield: 0.67 g (93%). IR (KBr): 3426, 1689, 1604, 1556, 1377,
1
−
1
1
3
273, 1120 cm . H NMR: δ = 1.42 (3 H, t, J 7.1, Me), 2.46 (3 H, s, Me), 3.18 (6 H, s, Me2N),
3 3 3
4
.39 (2 H, q, J 7.1, CH2O), 7.34 (2 H, d, J 8.2, 2 CH), 7.88 (2 H, d, J 8.2, 2 CH), 9.72 (1 H,
1
3
br s, NH). C NMR: δ = 14.5 (Me), 22.1 (Me), 43.0 (NMe2), 62.9 (CH2O), 99.9 (C), 128.0 (2
CH), 128.8 (C), 130.2 (2 CH), 144.8 (C), 164.1 (C), 165.1 (C), 165.2 (C=O), 170.5 (C=O), 185.1
+
(
(
C=O). EI-MS: m/z (%) = 361 (M , 17), 346 (40), 316 (73), 242 (18), 119 (100), 91 (31), 45
19). Anal. Calcd for C17H19N3O4S (361.42): C, 56.50; H, 5.30; N, 11.63%; found: C, 56.3; H,
5
.4; N, 11.7%.
4
.2.9. N-(5-(4-Bromobenzoyl)-4-(dimethylamino)thiazol-2-yl)-4-methylbenzamide (4i)
◦
Yellow powder, m.p. 185–187 C; yield: 0.80 g (90%). IR (KBr): 3443, 1678, 1598, 1543, 1390,
1
−
1
1
3
246, 1136 cm . H NMR: δ = 2.45 (3 H, s, Me), 3.16 (6 H, s, Me2N), 7.34 (2 H, d, J 8.1, 2
3 3 3
CH), 7.59 (2 H, d, J 8.4, 2 CH), 7.73 (2 H, d, J 8.4, 2 CH), 7.84 (2 H, d, J 8.1, 2 CH), 9.62 (1
1
3
H, br s, NH). C NMR: δ = 22.1 (Me), 42.7 (NMe2), 100.1 (C), 126.6 (C), 127.9 (2 CH), 128.7

5
04 I. Yavari et al.
(
C), 130.2 (2 CH), 130.5 (2 CH), 132.0 (2 CH), 140.6 (C), 144.8 (C), 161.1 (C), 161.1 (C), 165.1
+
+
(
1
C=O), 184.2 (C=O). EI-MS: m/z (%) = 445 (M + 1, 8), 443 (M , 18), 430 (31), 428 (32),
85 (13), 183 (13), 119 (100), 91 (45). Anal. Calcd for C20H18BrN3O2S (444.34): C, 54.06; H,
.08; N, 9.46%; found: C, 54.3; H, 4.2; N, 9.5%.
4
4
.2.10. N-(4-(Dimethylamino)-5-(4-methoxybenzoyl)thiazol-2-yl)-4-methylbenzamide (4j)
◦
Yellow powder, m.p. 211–212 C; Yield: 0.68 g (87%). IR (KBr): 3434, 1681, 1595, 1539, 1389,
1
−
1 1
258, 1150 cm . H NMR: δ = 2.44 (3 H, s, Me), 3.11 (6 H, s, Me2N), 3.89 (3 H, s, MeO), 6.94
3 3 3 3
(
7
1
2 H, d, J 8.2, 2 CH), 7.32 (2 H, d, J 8.2, 2 CH), 7.84 (2H, d, J 7.1, 2 CH), 7.87 (2 H, d, J
.1, 2 CH), 9.68 (1 H, br s, NH). 1 C NMR: δ = 22.0 (Me), 42.5 (Me2N), 55.8 (MeO), 100.3 (C),
3
14.0 (2 CH), 127.9 (2 CH), 128.9 (C), 130.2 (2 CH), 131.1 (2 CH), 134.4 (C), 144.6 (C), 160.4
+
(
(
C), 161.7 (C), 162.8 (C), 164.9 (C=O), 184.9 (C=O). EI-MS: m/z (%) = 395 (M , 15), 380
38), 276 (25), 260 (18), 135 (27), 119 (100), 91 (57). Anal. Calcd for C21H21N3O3S (395.47):
C, 63.78; H, 5.35; N, 10.63%; found: C, 64.1; H, 5.4; N, 10.8%.
4
.2.11. Ethyl 2-(4-(dimethylamino)-2-pivalamidothiazol-5-yl)-2-oxoacetate (4k)
Viscous oil, yield: 0.42 g (65%). IR (KBr): 3430, 1724, 1680, 1610, 1543, 1407, 1310, 1231,
−
1
1
3
1
4
3
(
1
105 cm . H NMR: δ = 1.36 (9 H, s, Me3C), 1.41 (3 H, t, J 7.1, Me), 3.18 (6 H, s, Me2N),
3
1
3
.37 (2 H, q, J 7.1, CH2O), 8.97 (1 H, br s, NH). C NMR: δ = 14.5 (Me), 27.5 (Me3C),
9.9 (Me3C), 43.1 (Me2N), 62.9 (CH2O), 100.0 (C), 164.0 (C), 164.9 (C), 170.5 (C=O), 177.1
+
+
C=O), 185.0 (C=O). EI-MS, m/z (%): 381 (M , 13), 366 (45), 336 (65), 242 (14), 139 (100),
11 (18), 45 (21). EI-MS: m/z (%) = 327 (M , 17), 312 (35), 282 (36), 239 (100), 57 (66).
Anal. Calcd for C14H21N3O4S (327.40): C, 51.36; H, 6.47; N, 12.83%; found: C, 51.6; H,
6
.6; N, 12.9%.
4
.2.12. N-(5-(4-Bromobenzoyl)-4-(dimethylamino)thiazol-2-yl)pivalamide (4l)
−
1 1
Viscous oil, yield: 0.46 g (56%). IR (KBr): 3420, 1687, 1602, 1538, 1390, 1297, 1134 cm . H
3
3
NMR: δ = 1.34 (9 H, s, Me3C), 3.17 (6 H, s, Me2N), 7.57 (2 H, d, J 8.3, 2 CH), 7.69 (2 H, d, J
13
8
.3, 2 CH), 9.22 (1 H, br s, NH). C NMR: δ = 27.4 (CMe3), 39.7 (Me3C), 42.6 (Me2N), 100.2
(
(
(
C), 126.3 (C), 130.4 (2 CH), 131.9 (2 CH), 140.8 (C), 160.9 (C), 162.5 (C), 177.2 (C=O), 184.1
+
+
C=O). EI-MS: m/z (%) = 411 (M + 2, 13), 409 (M , 12), 396 (31), 394 (31), 239 (100), 185
21), 183 (21), 57 (54). Anal. Calcd for C17H20BrN3O2S (410.33): C, 49.76; H, 4.91; N, 10.24%;
found: C, 50.1; H, 5.0; N, 10.1%.
4
.2.13. N-(4-(Dimethylamino)-5-(4-methoxybenzoyl)thiazol-2-yl)pivalamide (4m)
◦
Yellow powder, m.p. 88–89 C; yield: 0.43 g (60%). IR (KBr): 3427, 1686, 1604, 1542, 1383,
1
6
−
1 1
252, 1137 cm . H NMR: δ = 1.34 (9 H, s, Me3C), 3.15 (6 H, s, Me2N), 3.88 (3 H, s, MeO),
3 3 13
.93 (2 H, d, J 8.7, 2 CH), 7.83 (2 H, d, J 8.7, 2 CH), 9.15 (1 H, br s, NH). C NMR: δ = 27.4
(
(
Me3C), 39.7 (Me3C), 42.5 (Me2N), 55.8 (MeO), 100.3 (C), 113.9 (2 CH), 131.0 (2 CH), 134.5
+
C), 160.4 (C), 161.8 (C), 162.7 (C), 177.1 (C=O), 184.8 (C=O). EI-MS: m/z (%) = 361 (M ,
1
5
0), 346 (40), 276 (25), 239 (100), 135 (32), 57 (62). Anal. Calcd for C18H23N3O3S (361.46): C,
9.81; H, 6.41; N, 11.63%; found: C, 60.2; H, 6.3; N, 11.7%.

Journal of Sulfur Chemistry 505
4
.2.14. (4-(Dimethylamino)-2-(phenylamino)thiazol-5-yl)(phenyl)methanone (4n)
Yellow powder, m.p. 136–138 C; yield: 0.52 g (81%). IR (KBr): 3412, 1516, 1394 cm . 1H
◦
−1
3
3
NMR: δ = 3.00 (6 H, s, Me2N), 7.03 (1 H, t, J 7.4 Hz, CH), 7.33 (2 H, t, J 8.4 Hz, CH), 7.43
3
3
3
(
2 H, t, J 6.3 Hz, CH), 7.49 (1 H, t, J 6.8 Hz, CH), 7.58 (2 H, d, J 7.7 Hz, CH), 7.61 (2 H, d,
3
13
J 8.4 Hz, CH), 10.67 (1 H, s, NH). C NMR: δ = 41.9 (Me2N), 94.9 (C), 118.4 (CH), 122.8
(
(
(
CH), 127.5 (CH), 128.1 (CH), 129.0 (CH), 130.6 (CH), 139.7 (C), 142.3 (C), 163.2 (C), 164.8
+
C), 181.9 (C=O). EI-MS: m/z (%) = 323 (M , 5), 308 (40), 246 (25), 218 (59), 105 (100), 77
42). Anal. Calcd for C18H17N3OS (323.41): C, 66.85; H, 5.30; N, 12.99%; found: C, 66.2; H,
5
.3; N, 12.8%.
4
.2.15. (4-(Dimethylamino)-2-(phenylamino)thiazol-5-yl)(4-methoxyphenyl)methanone (4o)
◦
−1
.
Yellow powder, m.p. 149–152 C; yield: 0.60 g (86%). IR (KBr): 3250, 1592, 1518, 1398 cm
1
3
H NMR: δ = 2.99 (6 H, s, Me2N), 3.79 (3 H, s, MeO), 6.97 (2 H, d, J 8.7 Hz, CH), 7.02
3
3
3
(
1 H, t, J 7.4 Hz, CH), 7.32 (2 H, t, J 8.4 Hz, CH), 7.58 (2 H, d, J 7.8 Hz, CH), 7.62 (2 H, d,
3
13
J 8.7 Hz, CH), 10.64 (1 H, s, NH). C NMR: δ = 41.8 (Me2N), 55.2 (MeO), 94.5 (C), 113.3
(
(
CH), 118.4 (CH), 122.7 (CH), 129.0 (CH), 129.6 (CH), 134.5 (C), 139.8 (C), 161.2 (C), 162.7
+
C), 164.4 (C), 181.4 (C=O). EI-MS: m/z (%) = 353 (M , 3), 338 (40), 276 (25), 218 (100),
1
35 (32), 77 (48). Anal. Calcd for C19H19N3O2S (353.44): C, 64.57; H, 5.42; N, 11.89%; found:
C, 64.8; H, 5.3; N, 11.8%.
4
.2.16. (4-(Dimethylamino)-2-(phenylamino)thiazol-5-yl)(4-fluorophenyl)methanone (4p)
Yellow powder, m.p. 208–211 C; yield: 0.56 g (81%). IR (KBr): 3278, 1596, 1525, 1394 cm . 1H
◦
−1
3
3
NMR: δ = 3.11 (6 H, s, Me2N), 7.07 (2 H, t, J 8.4 Hz, CH), 7.12 (1 H, t, J 7.2 Hz, CH), 7.34 (2
3
3
13
H, d, J 8.2 Hz, CH), 7.40 (2 H, d, J 7.8 Hz, CH), 7.54–7.94 (2 H, m, CH), 8.03 (1 H, s, NH).
C
2
NMR: δ = 42.4 (Me2N), 96.4 (C), 115.2 (d, JCF 21.3 Hz, CH), 119.5 (CH), 124.3 (CH), 129.5
3
3
4
(
CH), 130.4 (d, J 8.5, CH), 132.8 (d, JCF 9.9 Hz, CH), 138.5 (d, JCF 2.5 Hz, C), 138.8 (C),
1
+
1
5
6
63.3 (C), 165.3 (C), 165.4 (d, JCF 287 Hz, CF), 182.2 (C=O). EI-MS: m/z (%) = 341 (M ,
), 326 (67), 264 (51), 218 (100), 123 (100), 77 (38). Anal. Calcd for C18H16FN3OS (341.40): C,
3.32; H, 4.72; N, 12.31%; found: C, 63.2; H, 4.8; N, 12.4%.
4
.2.17. (4-Chlorophenyl)(4-(dimethylamino)-2-(phenylamino)thiazol-5-yl)methanone (4q)
◦
−1
.
Yellow powder, m.p. 214–217 C; yield: 0.63 g (88%). IR (KBr): 3271, 1593, 1520, 1392 cm
1
3
3
H NMR: δ = 3.02 (6 H, s, Me2N), 7.05 (1 H, t, J 7.4 Hz, CH), 7.34 (2 H, t, J 7.6 Hz, CH),
3
3
3
7
(
.51 (2 H, d, J 8.4 Hz, CH), 7.57 (2 H, d, J 8.1 Hz, CH), 7.64 (2 H, d, J 8.4 Hz, CH), 10.75
1
3
1 H, s, NH). C NMR: δ = 41.9 (Me2N), 94.7 (C), 118.5 (CH), 122.9 (CH), 128.2 (CH), 128.9
(
CH), 129.4 (CH), 135.2 (C), 139.7 (C), 140.9 (C), 163.5 (C), 164.9 (C), 180.4 (C=O). EI-MS:
+
m/z (%) = 359 (M , 7), 357 (30), 344 (32), 342 (35), 239 (100), 282 (32), 218 (100), 77 (37).
Anal. Calcd for C18H16ClN3OS (357.86): C, 60.41; H, 4.51; N, 11.74%; found: C, 60.2; H, 4.6;
N, 11.8%.
4
.2.18. (4-Bromophenyl)(4-(dimethylamino)-2-(phenylamino)thiazol-5-yl)methanone (4r)
◦
−1
.
Yellow powder, m.p. 211–214 C; yield: 0.70 g (87%). IR (KBr): 3270, 1587, 1520, 1396 cm
1
3
3
H NMR: δ = 3.01 (6 H, s, Me2N), 7.04 (1 H, t, J 7.3 Hz, CH), 7.34 (2 H, t, J 7.8 Hz, CH),
3
3
3
7
.56 (2 H, d, J 8.5 Hz, CH), 7.57 (2 H, d, J 8.2 Hz, CH), 7.65 (2 H, d, J 8.2 Hz, CH), 10.67

5
06 I. Yavari et al.
(
(
1 H, s, NH); 13C NMR: δ = 41.9 (Me2N), 94.6 (C), 118.5 (CH), 123.0 (CH), 124.1 (C), 129.1
CH), 129.6 (CH), 131.2 (CH), 139.6 (C), 141.2 (C), 163.5 (C), 164.9 (C), 180.5 (C=O). EI-MS:
+
m/z (%) = 403 (M , 6), 401 (7), 388 (22), 386 (25), 326 (43), 324 (45), 218 (100), 185 (37), 77
(
32). Anal. Calcd for C18H16BrN3OS (402.31): C, 53.74; H, 4.01; N, 10.44%; found: C, 53.5; H,
4
.2; N, 10.3%.
4
.2.19. Ethyl 2-(4-(dimethylamino)-2-(phenylamino)thiazol-5-yl)-2-oxoacetate (4s)
◦
Yellow powder, m.p. 196–197 C; yield: 0.64 g (84%). IR (KBr): 3440, 1667, 1594, 1362, 1290,
−
1
1
3
1
221, 1157 cm . H NMR: δ = 1.35 (3 H, t, J 7.1, Me), 3.24 (6 H, s, Me2N), 4.33 (2 H, q,
3
13
J 7.1, CH2O), 7.16–7.46 (5 H, m, 5 CH), 7.99 (1 H, br s, NH). C NMR: δ = 14.5 (Me), 43.1
(
1
Me2N), 62.7 (CH2O), 101.8 (C), 120.5 (2 CH), 121.9 (C), 125.2 (CH), 129.3 (C), 129.9 (2 CH),
+
38.8 (C), 165.1 (C=O), 183.3 (C=O). EI-MS: m/z (%) = 319 (M , 7), 279 (40), 251 (33), 223
(
18), 92 (100), 91 (56), 45 (12). Anal. Calcd for C15H17N3O3S (319.38): C, 56.41; H, 5.37; N,
1
3.16%; found: C, 56.2; H, 5.3; N, 13.3%.
4
.2.20. (4-(Dimethylamino)-2-(4-methoxyphenylamino)thiazol-5-yl)(4-methoxyphenyl)
methanone (4t)
◦
Yellow powder, m.p. 207–208 C; yield: 0.57 g (75%). IR (KBr): 3410, 1670, 1581, 1320, 1245,
1
−
1 1
132 cm . H NMR: δ = 3.12 (6 H, s, Me2N), 3.77 (3 H, s, MeO), 3.85 (3 H, s, MeO), 6.87 (2
3 3 3 3
H, d, J 8.3, 2 CH), 7.28 (2 H, d, J 8.5, 2 CH), 7.49 (2 H, d, J 8.3, 2 CH), 7.76 (2 H, d, J
3
8
.5, 2 CH), 8.05 (1 H, br s, NH). 1 C NMR: δ = 42.5 (Me2N), 55.7 (MeO), 56.2 (MeO), 92.7
(
1
C), 114.4 (2 CH), 115.5 (2 CH), 124.6 (C), 128.2 (C), 129.7 (C), 130.6 (2 CH), 132.6 (2 CH),
+
60.0 (C), 166.1 (C), 174.8 (C), 192.7 (C=O). EI-MS: m/z (%) = 383 (M , 15), 260 (40), 247
(
25), 136 (100), 123 (52), 45 (23). Anal. Calcd for C20H21N3O3S (383.46): C, 62.64; H, 5.52; N,
1
0.96%; found: C, 62.3; H, 5.4; N, 11.0%.
4
.2.21. (4-Bromophenyl)(4-(dimethylamino)-2-(4-methoxyphenylamino)thiazol-5-yl)
methanone (4u)
◦
Yellow powder, m.p. 200–202 C; yield: 0.64 g (84%). IR (KBr): 3512, 1710, 1601, 1520, 1343,
−
1
1
3
1
2
7
250, 1105 cm . H NMR: δ = 3.15 (6 H, s, Me2N), 3.82 (3 H, s, MeO), 6.91 (2 H, d, J 9.0,
3 3 3
CH), 7.19 (2 H, d, J 9.0, 2 CH), 7.53 (2 H, d, J 8.8, 2 CH), 7.62 (2 H, d, J 8.8, 2 CH),
.7 (1 H, br s, NH). 13C NMR: δ = 42.7 (Me2N), 55.8 (MeO), 96.7 (C), 114.8 (2 CH), 123.8 (2
CH), 127.1 (C), 130.1 (2 CH), 131.7 (2 CH), 137.3 (C), 141.7 (C), 159.5 (C), 165.5 (C), 170.5
+
+
(
(
C), 192.8 (C=O). EI-MS: m/z (%) = 433 (M + 1, 6), 432 (M , 7), 387 (29), 309 (34), 185
21), 186 (100), 123 (50), 43 (21). Anal. Calcd for C19H18BrN3O2S (432.33): C, 52.78; H, 4.20;
N, 9.72%; found: C, 52.5; H, 4.3; N, 9.8%.
4
.2.22. Ethyl 2-(4-(dimethylamino)-2-(4-methoxyphenylamino)thiazol-5-yl)-2-oxoacetate (4v)
◦
Yellow powder, m.p. 220–222 C; yield: 0.64 g (84%). IR (KBr): 3342, 1675, 1531, 1505, 1317,
1
−
1
1
3
261, 1137 cm . H NMR: δ = 1.35 (3 H, t, J 7.1, Me), 3.23 (6 H, s, Me2N), 3.84 (3 H, s,
3 3 3
MeO), 4.31 (2 H, q, J 7.1, CH2O), 6.94 (2 H, d, J 9.0, 2 CH), 7.33 (2 H, d, J 9.0, 2 CH),
7
.85 (1 H, br s, NH). 13C NMR: δ = 14.5 (Me), 43.1 (Me2N), 55.9 (MeO), 62.8 (CH2O), 98.9
(
(
C), 115.3 (2 CH), 124.1 (2 CH), 131.8 (C), 155.6 (C), 161.4 (C), 163.7 (C), 170.4 (C=O), 182.3
+
C=O). EI-MS: m/z (%) = 349 (M , 8), 248 (40), 226 (73), 198 (18), 123 (100), 101 (31), 73

Journal of Sulfur Chemistry 507
(31), 45 (34). Anal. Calcd for C16H19N3O4S (349.40): C, 55.00; H, 5.48; N, 12.03%; found: C,
5
5.3; H, 5.4; N, 11.9%.
4
.2.23. (4-(Dimethylamino)-2-(ethylamino)thiazol-5-yl)(phenyl)methanone (4w)
◦
−1
1
Yellow powder, m.p. 170–175 C; yield: 0.46 g (84%). IR (KBr): 3206, 1520, 1393 cm . H
3
3
NMR: δ = 1.10 (3 H, t, J 7.2 Hz, Me), 2.94 (6 H, s, Me2N), 3.17 (2 H, s, CH2), 7.39 (2 H, t, J
3
3
13
7
.3 Hz, CH), 7.43 (1 H, t, J 7.0 Hz, CH), 7.55 (2 H, d, J 7.0 Hz, CH), 8.50 (1 H, s, NH).
C
NMR: δ = 14.1 (Me), 33.9 (CH2), 41.8 (Me2N), 94.3 (C), 127.4 (CH), 128.0 (CH), 130.2 (CH),
+
1
(
42.8 (C), 164.6 (C), 169.3 (C), 181.1 (C=O). EI-MS: m/z (%) = 275 (M , 5), 230 (36), 198
25), 170 (49), 105 (100), 77 (22), 45 (30). Anal. Calcd for C14H17N3OS (275.37): C 61.06, H
6
.22, N 15.26%; found: C, 61.3; H, 6.3; N, 15.4%.
4
.2.24. (4-(Dimethylamino)-2-(ethylamino)thiazol-5-yl)(4-methoxyphenyl)methanone (4x)
◦
−1
.
Yellow powder, m.p. 175–180 C; yield: 0.50 g (83%). IR (KBr): 3206, 1551, 1540, 1406 cm
1
3
H NMR: δ = 1.11 (3 H, t, J 7.2 Hz, Me), 2.92 (6 H, s, Me2N), 3.17 (2 H, s, CH2), 6.93 (2 H,
3
3
13
d, J 8.6 Hz, CH), 7.55 (2 H, d, J 8.6 Hz, CH), 8.4 (1 H, s, NH). C NMR: δ = 14.1 (Me),
3
1
4.2 (CH2), 41.7 (Me2N), 55.2 (MeO), 93.9 (C), 113.2 (CH), 129.4 (CH), 135.1 (C), 160.9 (C),
+
64.1 (C), 169.0 (C), 180.6 (C=O). EI-MS: m/z (%) = 305 (M + 1, 5), 360 (42), 197 (39), 269
(
24), 135 (100), 108 (19), 45 (23). Anal. Calcd for C15H19N3O2S (305.40): C, 58.99; H, 6.27; N,
1
3.76%; found: C, 59.2; H, 6.3; N, 13.8%.
4
.2.25. (4-(Dimethylamino)-2-(ethylamino)thiazol-5-yl)(4-fluorophenyl)methanone (4y)
◦
−1
.
Yellow powder, m.p. 223–227 C; yield: 0.46 g (79%). IR (KBr): 3205, 1581, 1514, 1398 cm
1
3
3
H NMR: δ = 1.24 (3 H, t, J 7.2 Hz, Me), 3.08 (6 H, s, Me2N), 3.23 (2 H, dq, J 7.2 and
3
3
3
6
.0 Hz, CH2), 7.06 (2 H, t, J 8.5 Hz, CH), 7.73 (2 H, t, J 5.6 Hz, CH), 8.01 (1 H, br t, J 6.0,
1
3
2
NH). C NMR: δ = 14.4 (Me), 40.0 (CH2), 42.2 (Me2N), 96.1 (C), 115.0 (d, JCF 21.3 Hz, CH),
3
1
1
(
(
30.2 (d, JCF 8.6 Hz, CH), 138.9 (C), 164.2 (d, JCF 289 Hz, CF), 165.1 (C), 170.8 (C), 181.5
+
C=O). EI-MS: m/z (%) = 293 (M , 5), 248 (37), 216 (48), 190 (45), 123 (100), 77 (38), 45
27). Anal. Calcd for C14H16FN3OS (293.36): C, 57.32; H, 5.50; N, 14.32%; found: C, 57.1; H,
5
.4; N, 14.4%.
4
.2.26. (4-Chlorophenyl)(4-(dimethylamino)-2-(ethylamino)thiazol-5-yl)methanone (4z)
◦
−1
.
Yellow powder, m.p. 206–209 C; yield: 0.60 g (97%). IR (KBr): 3202, 1551, 1518, 1406 cm
1
3
3
H NMR: δ = 1.12 (3 H, t, J 7.2 Hz, Me), 2.94 (6 H, s, Me2N), 3.18 (2 H, s, CH2), 7.47 (2 H, d,
3
13
J 8.3 Hz, CH), 7.57 (2 H, d, J 8.3 Hz, CH), 8.54 (1 H, s, NH). C NMR: δ = 14.0 (Me), 34.0
(
(
(
CH2), 41.8 (Me2N), 94.1 (C), 128.1 (CH), 129.3 (CH), 134.8 (C), 141.5 (C), 164.8 (C), 169.4
+
C), 179.5 (C=O). EI-MS: m/z (%) = 309 (M , 7), 264 (19), 173 (42), 136 (100), 77 (17), 45
32). Anal. Calcd for C14H16ClN3OS (309.81): C, 54.27; H, 4.21; N, 13.56%; found: C, 54.0; H,
4
.3; N, 13.7%.
4
.2.27. (4-Bromophenyl)(4-(dimethylamino)-2-(ethylamino)thiazol-5-yl)methanone (4aa)
◦
−1
.
Yellow powder, m.p. 214–216 C; yield: 0.68 g (96%). IR (KBr): 3203, 1551, 1517, 1407 cm
1
3
H NMR: δ = 1.11 (3 H, t, J 7.2 Hz, Me), 2.94 (6 H, s, Me2N), 3.18 (2 H, s, CH2), 7.50 (2 H, d,

5
3
08 I. Yavari et al.
J 8.3 Hz, CH), 7.60 (2 H, d, J 8.3 Hz, CH), 8.51 (1 H, s, NH). 13C NMR: δ = 14.1 (Me), 34.3
3
(
(
(
CH2), 41.9 (Me2N), 94.1 (C), 123.6 (C), 129.4 (CH), 131.1 (CH), 141.8 (C), 164.7 (C), 169.4
+
+
C), 179.6 (C=O). EI-MS: m/z (%) = 356 (M + 2, 8), 354 (M , 7), 311 (31), 309 (31), 185
100), 183 (91), 45 (24). Anal. Calcd for C14H16BrN3OS (354.27): C, 47.46; H, 4.55; N, 11.86%;
found: C, 47.71; H, 4.62; N, 11.9%.
References
(
(
(
(
1) Jin, Z. Nat. Prod. Rep. 2003, 20, 584–605.
2) Sperry, J.B.; Wright, D.L. Curr. Opin. Drug. Discov. Dev. 2005, 8, 723–740.
3) Fink, B.A.; Mortensen, D.S.; Stauffer, S.R.; Aron, Z.D.; Katzenellenbogen, J.A. Chem. Biol. 1999, 6, 205–219.
4) Van Muijlwijk-Koezen, J.E.; Timmerman, H.; Vollinga, R.C.; Von Drabbe-Kunzel, J.F.; De Groote, M.; Visser, S.;
Ijzerman, A.P. J. Med. Chem. 2001, 44, 749–762.
(
(
5) Millan, D.S.; Prager, R.H.; Brand, C.; Hart, P.H. Tetrahedron 2000, 56, 811–816.
6) Wang, W.L.; Yao, D.Y.; Gu, M.; Fan, M.Z.; Li, J.W.; Xing, Y.C.; Nan, F.J. Bioorg. Med. Chem. Lett. 2005, 15,
5284–5287.
(7) Hantzsch, A.; Weber, J.H. Dtsch. Chem. Ges. 1887, 20, 3118–3130.
(8) Aguilar, E.; Meyers, A.I. Tetrahedron Lett. 1994, 35, 2473–2476.
(9) Varma, R.S. Pure Appl. Chem. 2001, 73, 193–198.
(10) Yavari, I.; Seyfi, S.; Hossaini, Z.; Sabbaghan, M.; Shirgahi-Talari, F. Monatsh. Chem. 2008, 139, 1479–1482.
(11) Yavari, I.; Hossaini, Z.; Seyfi, S.; Shirgahi-Talari, F. Helv. Chim. Acta 2008, 91, 1177–1180.
(12) Yavari, I.; Sanaeishoar, T.; Ghazvini, M.; Iravani, N. J. Sulfur Chem. 2010, 31, 169–176.