Reactions of N-(1-chloro-2-oxo-2-phenylethyl) carboxamides with thiosemicarbazide and its derivatives

Article abstract of DOI:10.1134/S1070363208110236

N-(1-Chloro-2-oxo-2-phenylethyl)acet-, -benz-, and -4-methylbenzamides reacted with thiosemicarbazides and aromatic aldehyde thiosemicarbazones to give derivatives of 5-amino-2-hydrazino-1,3-thiazole. The latter underwent recyclization and acid hydrolysis

Full text of DOI:10.1134/S1070363208110236

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 11, pp. 2125–2131. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.G. Balya, A.N. Vasilenko, V.S. Brovarets, B.S. Drach, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 11,
pp. 1891–1896.
Reactions of N-(1-Chloro-2-oxo-2-phenylethyl) Carboxamides
with Thiosemicarbazide and Its Derivatives
A. G. Balya, A. N. Vasilenko, V. S. Brovarets, and B. S. Drach
Institute of Bioorganic and Petroleum Chemistry, National Academy of Sciences of Ukraine,
ul. Murmanskaya 1, Kiev, 02660 Ukraine
e-mail: drach@bpci.kiev.ua
Received March 25, 2008
Abstract—N-(1-Chloro-2-oxo-2-phenylethyl)acet-, -benz-, and -4-methylbenzamides reacted with
thiosemicarbazides and aromatic aldehyde thiosemicarbazones to give derivatives of 5-amino-2-hydrazino-1,3-
thiazole. The latter underwent recyclization and acid hydrolysis on heating with hydrochloric acid to produce
substituted 3-amino-2-thiohydantoins.
DOI: 10.1134/S1070363208110236
We previously found that accessible N-(1-chloro-2-
oxo-2-phenylethyl) carboxamides I (Scheme 1) react
with various thioamides and thiourea in a selective
fashion, following the general Hantzsch cyclocon-
densation pattern [1–3]. In the present work we found
that reactions of compounds I with thiosemicarbazide
are not selective. As a result, complex mixtures of
products are formed. Although expected 5-acylamino-
2-hydrazino-4-phenyl-1,3-thiazoles II were detected in
the product mixtures, we succeeded in isolating them
as individual substances by repeated recrystallizations
only in a few cases. On the other hand, reactions of N1-
benzylidene derivatives of thiosemicarbazide and its
analogs with α-chloro amides I were quite selective,
and the products were the corresponding substituted
1,3-thiazoles III or 2,3-dihydro-1,3-thiazoles IV
(Table 1). Some compounds III and IV turned out to
be suitable for further transformations of preparative
interest (see structures III–X in Scheme 1). For
instance, by heating compound IIIb (Ar = 4-MeOC6H4,
R1 = Me) with hydrazine hydrate we obtained 5-acetyl-
amino-2-hydrazino-1,3-thiazole II which was isolated
as analytically pure substance, so that we were able to
identify it in the product mixture formed in the
reaction of compound Ia with thiosemicarbazide. The
presence in molecule II of an unsubstituted hydrazino
group was proved by its condensation with acetyl-
acetone and ethyl acetoacetate according to Knorr,
which afforded the expected products, 5-acetylamino-
2-(3,5-dimethyl-1H-pyrazol-1-yl)-4-phenyl-1,3-thiazole
(V) and 5-acetylamino-2-(3-methyl-5-oxo-2,5-dihydro-
1H-pyrazol-1-yl)-4-phenyl-1,3-thiazole (VIII), respec-
tively. The structure of compounds V and VIII is beyond
doubt, for such reactions were studied in detail using
other substituted 2-hydrazino-1,3-thiazoles, and the
product structure was determined unambiguously [4, 5].
Some consecutive transformations of compounds
III and IV having an acetylamino group on C5 were
also important. Treatment of these compounds with
hydrochloric acid in ethanol at heating is likely to
involve opening of nonaromatic dihydrothiazole ring
with formation of intermediate products VI and VII
which are capable of undergoing recyclization to give
new 3-amino-2-thiohydantoin derivatives IX and X.
Analogous compounds were also obtained by other
methods [6–8]; nevertheless, the described recycliza-
tions III → IX and IV → X seem to be valuable from
the preparative viewpoint, for they ensure synthesis of
difficultly accessible substituted 2-thiohydantoins.
We succeeded in isolating with satisfactory yields
intermediate products VI in the transformation III →
IX (see Experimental). Compounds VI, as well as III,
were smoothly converted into the corresponding
substituted 3-amino-2-thiohydantoins IX on prolonged
heating in a more concentrated solution of hydro-
chloric acid in ethanol. The structure of VI was
1
determined on the basis of the IR, H NMR (Table 2),
and mass spectra. The structure of compound VIb was
unambiguously proved using various two-dimensional
2125

2126
BALYA et al.
Scheme 1.
R2NH
S
H2N
S
;
(1)
NHN
(1)
NHNH2;
Ph
O
O
Ph
(2) NaHCO3
(2) NaHCO3
R1
N
Cl
H
Ia−Ic
H2N
S
(1)
NHN
;
Ar
(2) NaHCO3
Ph
Ph
R2
Ph
O
O
N
O
N
N
H2NNH2 H2O, Δ
NHNH2
NHN
NN
R1 = Me
R1
R1
Me
N
N
H
Ar
N
S
S
S
Ph
H
H
IIIa−IIIf
IVa−IVo
II
HCl, EtOH, Δ
R1 = Me
HCl, H2O, Δ
HCl, H2O, Δ
R1 = Me
R1 = Me
O
O
, Δ
R2
N
Me
Me
H
Ph
Ph
N
S
S
EtO
HN
Ph
Me
O H
N
N
O H
N
N
O
N
O
Me
N
Me
Me
N
S
N
H
Ar
VIa, VIb
Ph
V
VIIa−VIIe
O
O
HCl, H2O, Δ
HCl, H2O, Δ
, Δ
Me
OEt
R2
H
Ph
Ph
N
N
Ph
O
O
S
O
S
N
N
N
N
O
N
N
Me
Me
N
S
N
Ar
IXa, IXb
H
Ph
Xa−Xe
H
VIII
IIIa, IIIc, IIIe, VIa, IXa, Ar = Ph; IIIb, IIId, IIIf, VIb, IXb, Ar = 4-MeOC6H4; Ia, IIIa, IIIb, IVa–IVe, R1 = Me; Ib, IIIc,
IIId, IVf–IVj, R1 = Ph; Ic, IIIe, IIIf, IVk–IVo, R1 = 4-MeC6H4; IVa, IVf, IVk, VIIa, Xa, R2 = Me; IVb, IVg, IVl;, VIIb,
Xb, R2 = CH2=CHCH2; IVc, IVh, IVm, VIIc, Xc, R2 = PhCH2; IVd, IVi, IVn, VIId, Xd, R2 = Ph; IVe, IVj, IVo, VIIe, Xe,
R2 = 4-MeC6H4.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 11 2008

REACTIONS OF N-(1-CHLORO-2-OXO-2-PHENYLETHYL) CARBOXAMIDES
Table 1. Yields, melting points, and elemental analyses of compounds II–VI and VIII–X
2127
Found, %
Calculated, %
Comp.
no.
Yield,a %
mp, °C (solvent)
Formula
N
S
N
S
25 (70)
77
81
71
78
69
75
72
76
81
86
91
81
79
87
83
90
79
85
91
78
81
68
184–186 (MeCN)
22.38
16.49
15.29
13.89
12.93
13.41
12.51
15.83
14.71
13.05
13.41
13.03
13.41
12.63
11.31
11.63
11.29
13.01
12.21
11.05
11.27
11.02
17.79
12.79
9.43
8.73
7.93
7.41
7.69
7.17
9.05
8.42
7.39
7.63
7.45
7.61
7.19
6.41
6.63
6.49
7.39
7.01
6.21
6.41
6.23
10.21
C11H12N4OS
C18H16N4OS
C19H14N4O2S
C23H18N4OS
C24H20N4O2S
C24H20N4OS
C25H22N4O2S
C19H18N4OS
C21H20N4OS
C25H22N4OS
C24H20N4OS
C25H22N4OS
C24H20N4OS
C25H22N4OS
C30H24N4OS
C29H22N4ОS
C30H24N4OS
C25H22N4OS
C27H24N4OS
C31H26N4OS
C30H24N4OS
C31H26N4OS
C16H16N4OS
22.56
16.65
15.45
14.06
13.07
13.58
12.66
15.99
14.88
13.13
13.58
13.13
13.58
12.77
11.46
11.80
11.46
13.13
12.38
11.14
11.46
11.14
17.93
12.91
9.53
8.84
8.04
7.48
7.77
7.24
9.15
8.51
7.51
7.77
7.51
7.77
7.31
6.56
6.75
6.56
7.51
7.08
6.38
6.56
6.38
10.26
II
201–203 (MeCN–DMF)
215–217 (MeCN–DMF)
246–247 (MeCN–DMF)
231–233 (MeCN–DMF)
239–240 (MeCN–DMF)
233–234 (MeCN–DMF)
226–228 (MeCN)
IIIa
IIIb
IIIc
IIId
IIIe
IIIf
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IVh
IVi
183–185 (EtOH)
185–187 (MeCN)
253–255 (MeCN–DMF)
251–252 (MeCN–DMF)
191–192 (MeCN–DMF)
165–167 (EtOH)
235–237 (MeCN–DMF)
243–245 (АсОН)
242–243 (MeCN)
IVj
IVk
IVl
247–249 (MeCN–DMF)
139–141 (EtOH)
226–228 (MeCN–DMF)
207–209 (АсОН)
IVm
IVn
IVo
V
191–193 (MeCN)
199–201 (АсОН)
58
54
161–163 (EtOH)
159–160 (EtOH)
12.16
11.16
9.30
8.49
C18H19N3O2S
C19H21N3O3S
12.30
11.31
9.39
8.63
VIа
VIb
56
57 (61)
53 (59)
85
234–236 (AcOH)
196–198 (EtOH)
163–165 (EtOH)
142–144 (MeCN)
102–103 (EtOH)
192–193 (MeCN)
221–223 (MeCN)
218–219 (MeCN)
17.65
14.06
12.79
13.41
12.39
10.73
11.19
10.79
10.11
10.77
9.71
C15H14N4O2S
C16H13N3OS
C17H15N3O2S
C17H15N3OS
C19H17N3OS
C23H19N3OS
C22H17N3OS
C23H19N3OS
17.82
14.22
12.91
13.58
12.52
10.90
11.31
10.90
10.20
10.85
9.85
VIII
IXа
IXb
Xа
10.25
9.38
10.36
9.56
79
Xb
Xc
93
8.19
8.31
87
8.51
8.63
Xd
Xe
88
8.25
8.31
a
The yield according to method b is given in parentheses.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 11 2008

2128
BALYA et al.
Table 2. IR and 1H NMR spectra of compounds II–VI and VIII–Xa
Compound
1H NMR spectrum (DMSO-d6), δ, ppm
no.
IIb
2.00 s (3H, CH3), 4.73 br.s (2H, NH2), 7.24–7.73 m (5Harom), 8.28 s (1H, NH), 9.74 s (1H, NH)
2.07 s (3H, CH3), 7.28–7.73 m (10Harom), 7.99 s (1H, CH), 10.13 s (1H, NH), 11.97 br.s (1H, NH)
2.06 s (3H, CH3), 3.80 s (3H, CH3), 6.91–7.74 m (9Harom), 7.90 s (1H, CH), 9.96 s (1H, NH), 11.67 br.s (1H, NH)
3.81 s (3H, CH3), 6.95–7.97 m (15H, 14Harom, NH), 8.20 s (1H, CH), 10.71 s (1H, NH)
IIIa
IIIbb
IIIdb
IVbb
1.88 s (3H, CH3), 4.26 d (2H, CH2), 4.89–5.08 m (2H, CH2), 5.73 m (1H, CH), 7.32–7.70 m (10Harom), 8.21 s (1H, CH), 9.52 s
(1H, NH)
1.91 s (3H, CH3), 4.93 s (2H, CH2), 6.93–7.72 m (15Harom), 8.23 s (1H, CH), 9.66 s (1H, NH)
1.96 s (3H, CH3), 7.17–7.70 m (15Harom), 8.14 s (1H, CH), 9.79 s (1H, NH)
IVc
IVd
IVe
IVf
IVg
IVi
1.95 s (3H, CH3), 2.25 s (3H, CH3), 7.10–7.69 m (14Harom), 8.13 s (1H, CH), 9.75 s (1H, NH)
3.27 s (3H, CH3), 7.39–7.79 m (15Harom), 8.34 s (1H, CH), 10.02 s (1H, NH)
4.37 d (2H, CH2), 4.89–5.13 m (2H, CH2), 5,72 m (1H, CH), 7.38–7.77 m (15Harom), 8.32 s (1H, CH), 10.00 s (1H, NH)
7.24–7.83 m (20Harom), 8.20 s (1H, CH), 10.19 s (1H, NH)
2.36 s (3H, CH3), 3.46 c (3H, CH3), 7.29–7.79 m (14Harom), 8.68 s (1H, CH), 10.56 s (1H, NH)
IVk
IVl
2.34 s (3H, CH3), 4.37 d (2H, CH2), 4.89–5.13 m (2H, CH2), 5.71 m (1H, CH), 7.25–7.75 m (14Harom), 8.31 s (1H, CH),
9.90 s (1H, NH)
2.27 s (3H, CH3), 2.36 s (3H, CH3), 7.14–7.73 m (18Harom), 8.18 s (1H, CH), 10.05 s (1H, NH)
IVo
V
2.15 s (3H, CH3), 2.20 s (3H, CH3), 2.64 s (3H, CH3), 6.18 s (1H, CHpir), 7.35–7.79 m (5Harom), 10.65 s (1H, NH)
VIac
1.17 t (3H, CH3), 4.18 m (2H, CH2), 6.18 d, 8.72 d (2H, CH, NH, J = 8.0 Hz), 7.35–7.79 m (10Harom), 8.15 s (1H, CH), 11.94 s
(1H,NH)
VIbd
1.16 t (3H, CH3), 3.80 s (3H, CH3), 4.17 m (2H, CH2), 6.17 d, 8.62 d (2H, CH, NH, J = 8.0 Hz), 7.00–7.72 m (9Narom), 8.09 s
(1H, CH), 11.82 s (1H, NH)
VIIIb
IXa
2.11 s (3H, CH3), 2.21 s (3H, CH3), 5.14 s (1H, CHpir), 7.31–7.78 m (5Harom), 10.34 s (1H, NH), 12.16 br.s (1H, NH)
5.59 s (1H, CH), 7.37–7.90 m (10Harom), 9.07 s (1H, CH), 11.04 s (1H, NH)
3.84 s (3H, CH3), 5.57 s (1H, CH), 7.00–7.85 m (9Harom), 9.00 s (1H, CH), 10.99 s (1H, NH)
3.13 s (3H, CH3), 5.59 s (1H, CH), 7.34–7.91 m (10Harom), 9.10 s (1H, CH)
IXb
Xa
Xbb
3.70 m (2H, CH2), 5.16 m (2H, CH2), 5.49 s (1H, CH), 5.75 m (1H, CH), 7.31–7.91 m (10Harom), 9.08 s (1H, CH)
4.29 d and 5.43 d (1H each, CH2, J = 15.2 Hz), 5.47 s (1H, CH), 7.24–7.93 m (15Harom), 9.13 s (1H, CH)
6.27 s (1H, CH), 7.35–7.95 m (15Harom), 9.14 s (1H, NH)
Xc
Xd
2.26 s (3H, CH3), 6.22 s (1H, CH), 7.17–7.95 m (14Harom), 9.13 s (1H, CH)
Xe
a
IR spectra, ν, cm–1: II, IIIb: 3100–3400 (NHas), 1660 (C=O); IVc: 3100–3400 (NHas), 1660 (C=O), 1600 (C=N); IVd: 3100–3400
(NHas), 1640 (C=O), 1600 (C=N); IVf: 3100–3400 (NHas), 1650 (C=O), 1600 (C=N); IVi: 3100–3400 (NHas), 1670 (C=O), 1590 (C=N);
V: 3100–3400 (NHas), 1660 (C=O); VIa: 3100–3400 (NHas), 1730 (C=O); VIb: 3100–3400 (NHas), 1730 (C=O), 1610 (C=N); VIII:
3100–3300 (NHas), 1660 (C=O), 1640 (C=O); IXa: 3100–3300 (NHas), 1740 (C=O); Xa: 1740 (C=O, band with a shoulder); Xd: 1730
(C=O, band with a shoulder). b The 1H NMR spectra were recorded on a Varian VXR-300 instrument. c Mass spectrum: m/z 341 [M]+. d Mass
spectrum: m/z 371 [M]+.
NMR techniques (COSY, NOESY, HMQC, HMBC),
relations is given in Table 3. Acyclic structure of
compounds VI provides one more support to the
proposed mechanism of the transformations III → IX
and IV → X.
1
which allowed us to assign all H and 13C signals.
Figure shows principal homo- and heteronuclear correla-
tions in molecule VIb, and the complete list of cor-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 11 2008

REACTIONS OF N-(1-CHLORO-2-OXO-2-PHENYLETHYL) CARBOXAMIDES
2129
The structure of compounds IX and X is consistent
1
with the IR and H NMR data (Table 2). Their IR
7.36
H
spectra contained a strong absorption band at 1720–
1740 cm–1, which was assigned to stretching vibrations
of the carbonyl group in the 2-thiohydantoin system
(cf. [6]). Singlets at δ 5.4–6.3 and 9.0–9.2 ppm in the
1H NMR spectra of IX and X are typical of 5-H and
7.32
H
7.43
O
H
62.11 4.14
H
H
128.91
60.59
170.92
129.41
O
H
1
benzylidene N=CH protons. The IR and H NMR data
137.44
14.62
H
128.36
H
clearly demonstrate disappearance of the N-acetyl
group during the transformations III → IX and IV →
X and of the ethoxy group (δ 1.1–4.2 ppm) in the
transformation VI → IX.
S
H
N
1.13
H
177.17
8.61
N
11.81 H
N
Finally, it should be noted that recyclization
analogous to the transformation III → IX was recently
reported for the condensation products of compounds
like I with N,N′-disubstituted thioureas [9], which may
be regarded as an additional proof for the structure of
new 2-thiohydantoin derivatives IX and X.
129.64
126.90
144.09
H
115.04
H
3.77
8.06
H
55.99
161.66
O
H
H
7.68
H
6.98
EXPERIMENTAL
Principal correlations (shown with arrows) and signal
The IR spectra were recorded in KBr on a Specord
M-80 spectrometer. The 1H NMR spectra were
measured on Varian Mercury-400 and Varian VXR-300
1
assignment (δ, δC, ppm) in the H and 13C NMR spectra of
compound VIb.
1
instruments, and the H–13C heteronuclear correlation
spectra were obtained on a Varian Mercury-400
spectrometer; DMSO-d6 was used as solvent, and
tetramethylsilane, as internal reference. The mass
spectra were recorded on a Varian MAT-311A mass
spectrometer.
Table 3. Correlations in the COSY, NOESY, HMQC, and
HMBC spectra for compound VIba
13C, δС, ppm
1Н,
N-(1-Chloro-2-oxo-2-phenyl) carboxamides Ia–
Ic were synthesized according to the procedure
described in [1].
δ, ppm
COSY NOESY HMQC
HMBC
7.32
7.36
7.43
6.15
–
–
–
–
–
128.91 128.36
129.41 137.44; 129.41
N-(2-Hydrazino-4-phenyl-1,3-thiazol-5-yl)acet-
amide (II). a. Compound Ia, 0.008 mol, was added to
a suspension of 0.008 mol of thiosemicarbazide in
25 ml of anhydrous tetrahydrofuran. The mixture was
stirred for 24 h at 20–25°C, the precipitate was filtered
off and treated with 100 ml of a saturated aqueous
solution of sodium hydrogen carbonate, and the
precipitate was filtered off, washed with water, and
purified by recrystallization from acetonitrile.
6.15; 8.61 128.36 128.91; 60.59; 128.36
8.61 7.43; 8.61
60.59 128.36; 137.44; 170.92;
177.17
8.61
4.14
1.13
11.81
8.06
7.68
6.98
3.77
6.15 7.43; 6.15
–
60.59; 170.92
1.13
4.14
–
1.13
4.14
62.11 170.92; 14.62
14.62 62.11
8.06
–
177.17; 144.09
The reactions of compounds Ib and Ic with thio-
semicarbazide resulted in the formation of mixtures of
products, and we failed to isolate the corresponding
thiazoles as individual substances.
–
11.81
144.09 126.90; 129.64
6.98 6.98; 3.77 129.64 144.09; 129.64; 161.66
7.68
–
7.68
6.98
115.04 126.90; 115.04; 55.99
55.99 161.66
b. The synthesis was performed according to the
procedure described in [10]. A mixture of 0.011 mol of
compound IIIb, 4 ml of hydrazine hydrate, and 40 ml
a
For signal assignment, see figure.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 11 2008

2130
BALYA et al.
of ethanol was heated for 6 h under reflux. The mix-
ture was then left to stand overnight in a refrigerator,
and the precipitate was filtered off, washed with cold
ethanol, and recrystallized from acetonitrile. Samples
of compound II prepared as described in a and b
showed no depression of the melting point on mixing,
and their IR and 1H NMR spectra were identical.
N-[2-(3-Methyl-5-oxo-2,5-dihydro-1H-pyrazol-1-
yl)-4-phenyl-1,3-thiazol-5-yl]acetamide (VIII). A mix-
ture of 0.004 mol of compound II, 0.004 mol of ethyl
acetoacetate, and 10 ml of glacial acetic acid was
heated for 7 h under reflux. The mixture was cooled,
and the precipitate was filtered off, washed with
ethanol, and dried.
2-[2-(Arylmethylidene)hydrazino]-5-acylamino-
4-phenyl-1,3-thiazoles IIIa–IIIf (general procedure).
Compound Ia–Ic, 0.01 mol, was added to a suspension
of 0.01 mol of 1-(arylmethylidene)thiosemicarbazide
in 25 ml of anhydrous THF, and the mixture was
stirred for 24 h at 20–25°C. The precipitate was
filtered off and dissolved in 30 ml of anhydrous
methanol, and the solution was heated for 1 h under
reflux. The solvent was removed under reduced
pressure, the residue was treated with 100 ml of a
saturated aqueous solution of sodium hydrogen
carbonate, and the precipitate was filtered off, washed
with water, and recrystallized from an appropriate solvent.
3-(Arylmethylideneamino)-2-thioxo-5-phenylimid-
azolidin-4-ones IXa and IXb (general procedure). a.
Concentrated hydrochloric acid, 40 ml, was added to a
solution of 0.004 mol of compound IIIa or IIIb in 25 ml
of ethanol, and the mixture was heated for 6 h under
reflux. The mixture was cooled, 150 ml of a saturated
aqueous solution of sodium hydrogen carbonate was
added, and the precipitate was filtered off and purified
by recrystallization.
b. Concentrated hydrochloric acid, 40 ml, was
added to a solution of 0.004 mol of compound VIa or
VIb in 25 ml of ethanol, and the mixture was heated
for 6 h under reflux. The mixture was cooled, 150 ml
of a saturated aqueous solution of sodium hydrogen
carbonate was added, and the precipitate was filtered
off and purified by recrystallization. Samples of com-
pounds IXa and IXb prepared as described in a and b
showed no depression of the melting point on mixing,
and their IR and 1H NMR spectra were identical.
3-Alkyl(aryl)-5-acylamino-2-(2-benzylidenehyd-
razono)-4-phenyl-2,3-dihydro-1,3-thiazoles IVa–IVo
(general procedure). Compound Ia–Ic, 0.002 mol, was
added to a suspension of 0.002 mol of 4-alkyl(aryl)-1-
benzylidenethiosemicarbazide in 20 ml of anhydrous
THF, and the mixture was stirred for 24 h at 20–25°C.
The solvent was removed under reduced pressure, 20 ml
of anhydrous methanol was added to the residue, and
the mixture was heated for 1 h under reflux. The
solvent was removed under reduced pressure, the
residue was treated with 100 ml of a saturated aqueous
solution of sodium hydrogen carbonate, and the
precipitate was filtered off, washed with water, and
purified by recrystallization.
1-Alkyl(aryl)-3-(benzylideneamino)-2-thioxo-5-
phenylimidazolidin-4-ones Xa–Xe (general procedure).
Concentrated hydrochloric acid, 15 ml, was added to a
solution of 0.006 mol of compound IVa–IVe in 40 ml
of ethanol, and the mixture was heated for 2 h under
reflux. The mixture was cooled, 100 ml of a saturated
aqueous solution of sodium hydrogen carbonate was
added, and the precipitate was filtered off and purified
by recrystallization.
N-[2-(3,5-Dimethyl-1H-pyrazol-1-yl)-4-phenyl-1,3-
thiazol-5-yl]acetamide (V). A mixture of 0.004 mol of
compound II, 0.004 mol of acetylacetone, and 10 ml of
glacial acetic acid was heated for 2 h under reflux. The
mixture was cooled, and the precipitate was filtered
off, washed with ethanol, and dried.
REFERENCES
1. Drach, B.S., Dolgushina, I.Yu., and Kirsanov, A.V., Zh.
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Ethyl 2-[1-(arylmethylidene)thiosemicarbazido]-
2-phenylacetates VIa and VIb (general procedure).
Concentrated hydrochloric acid, 15 ml, was added to a
solution of 0.006 mol of compound IIIa or IIIb in 40 ml
of ethanol, the mixture was heated for 2 h under reflux,
cooled, and treated with 100 ml of a saturated aqueous
solution of sodium hydrogen carbonate, and the
precipitate was filtered off and purified by recrystal-
lization.
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