SYNTHESIS AND TRANSFORMATIONS OF 5-SUBSTITUTED 2-ARYL-...
111
8.17 d (2H, Harom, J = 3.1 Hz). Found, %: C 66.75;
H 3.51; N 13.98. C17H11N3OS. Calculated, %: C 66.87;
H 3.63; N 13.76.
compound IVa was deposited to the Cambridge Crystal
Structure Database (entry no. CCDC 211159).
5-Substituted 2-aryl-7H-[1,2,4]triazolo[3,2-b]-
[1,3]thiazin-7-ones IVaIVh (general procedure).
Dimethyl acetylenedicarboxylate or methyl 3-phenyl-
propynoate, 0.012 mol, was added dropwise at 20°C to a
solution of 0.01 mol of 3-aryl-1,2,4-triazole-5-thione in
25 ml of methanol, and the mixture was heated for 2 h
under reflux. The mixture was cooled, and the precipitate
was filtered off, washed with diethyl ether, dried, and
recrystallized from acetic acid.
2-(4-Fluorophenyl)-5-phenyl-7H-[1,2,4]triazolo-
[3,2-b][1,3]thiazin-7-one (IVf). Yield 2.00 g (62%),
1
mp 213214°C. H NMR spectrum, d, ppm: 7.30
7.46 m (3H, Harom), 7.577.76 m (3H, Harom), 7.89 d (2H,
Harom, J = 7.2 Hz), 8.21 m (2H, Harom). Found, %: C 63.11;
H 2.92; N 13.19. C17H10FN3OS. Calculated, %: C 63.15;
H 3.12; N 13.00.
2-(4-Methoxyphenyl)-5-phenyl-7H-[1,2,4]tri-
azolo[3,2-b][1,3]thiazin-7-one (IVg). Yield 2.28 g
Methyl 7-oxo-2-phenyl-7H-[1,2,4]triazolo-
[3,2-b][1,3]thiazine-5-carboxylate (IVa). Yield 2.01 g
(70%), mp 196198°C; published data: mp 196°C [4],
195196°C [6]. 1H NMR spectrum, d, ppm: 3.99 s (3H,
COOCH3), 7.55 s (1H, 6-H), 7.57 m (3H, Harom), 8.16 m
(2H, Harom). 13C NMR spectrum (75 MHz, CDCl3), dC,
ppm: 54.38 (OCH3), 122.16 (Cp), 127.74 (C° ), 128.53
(Ci), 128.78 (Cm), 131.19 (C6), 139.83 (C7), 152.03 (C2),
155.02 (C8a), 161.32 (COO), 164.71 (C5). Found, %:
C 54.46; H 3.05; N 14.80. C13H9N3O3S. Calculated, %:
C 54.35; H 3.16; N 14.63.
1
(68%), mp 248250°C. H NMR spectrum, d, ppm:
3.83 s (3H, CH3O), 7.09 d (2H, Harom, J = 8.6 Hz),
7.24 s (1H, 6-H), 7.537.72 m (3H, Harom), 7.82 m (2H,
Harom), 8.11 d (2H, Harom, J = 8.6 Hz). Found, %: C 64.40;
H 4.04; N 12.39. C18H13N3O2S. Calculated, %: C 64.46;
H 3.91; N 12.53.
2-(4-Nitrophenyl)-5-phenyl-7H-[1,2,4]triazolo-
[3,2-b][1,3]thiazin-7-one (IVh). Yield 1.89 g (54%),
mp 244246°C. 1H NMR spectrum, d, ppm: 7.37 s (1H,
6-H), 7.64 m (2H, Harom), 7.87 d (2H, Harom, J = 7.2 Hz),
8.16 m (2H, Harom), 8.39 m (3H, Harom). Found, %:
C 58.32; H 2.91; N 16.18. C17H10N4O3S. Calculated, %:
C 58.28; H 2.88; N 15.99.
Methyl 2-(4-fluorophenyl)-7-oxo-7H-[1,2,4]tri-
azolo[3,2-b][1,3]thiazine-5-carboxylate (IVb). Yield
2.1 g (69%), mp 207208°C. 1H NMR spectrum, d, ppm:
4.00 s (3H, COOCH3), 7.41 m (2H, Harom), 7.54 s (1H,
6-H), 8.23 m (2H, Harom). Found, %: C 51.10; H 2.50;
N 13.90. C13H8FN3O3S. Calculated, %: C 51.15; H 2.64;
N 13.76.
Reaction of methyl 7-oxo-2-phenyl-7H-[1,2,4]-
triazolo[3,2-b][1,3]thiazine-5-carboxylate (IVa) with
potassium hydroxide. A solution of 0.019 mol of
potassium hydroxide in 9 ml of water was added dropwise
at 20°C to a solution of 0.009 mol of compound IVa in
20 ml of methanol, and the mixture was left to stand for
48 h. The mixture was diluted with 20 ml of water,
1.5 ml of 95% sulfuric acid was added, and the precipitate
of 3-phenyl-1,2,4-triazole-5-thione (Ia) was filtered off,
dried, and recrystallized from acetic acid. Yield of Ia
0.94 g (59%), mp 258260°C; published data [2]:
mp 256°C. Found, %: C 54.08; H 4.06; N 23.81.
C8H7N3S. Calculated, %: C 54.22; H 3.98; N 23.71. The
filtrate was evaporated, 20 ml of methanol was added to
the residue, and the mixture was kept for 4 days at 20°C.
The mixture was evaporated, the residue was treated
with chloroform (2´10 ml), the combined extracts were
evaporated, and the residue was distilled under reduced
pressure (water-jet pump) to isolate 0.5 g of dimethyl
Methyl 2-(4-methoxyphenyl)-7-oxo-7H-[1,2,4]-
triazolo[3,2-b][1,3]thiazine-5-carboxylate (IVc). Yield
2.28 g (72%), mp 247249°C. 1H NMR spectrum, d, ppm:
3.84 s (3H, CH3O), 3.99 (3H, COOCH3), 7.08 d (2H,
Harom, J = 9.1 Hz), 7.50 s (1H, 6-H), 8.10 d (2H, Harom
,
J = 9.1 Hz). Found, %: C 52.86; H 3.41; N 13.52.
C14H11N3O4S. Calculated, %: C 52.99; H 3.49; N 13.24.
Methyl 2-(4-nitrophenyl)-7-oxo-7H-[1,2,4]-
triazolo[3,2-b][1,3]thiazine-5-carboxylate (IVd).
Yield 1.93 g (58%), mp 230232°C. 1H NMR spectrum,
d, ppm: 4.01 (3H, COOCH3), 7.58 s (1H, 6-H), 8.31 d
(2H, Harom, J = 8.8 Hz), 8.40 d (2H, Harom, J = 8.8 Hz).
Found, %: C 47.16; H 2.62; N 16.94. C13H8N4O5S.
Calculated, %: C 46.99; H 2.43; N 16.86.
acetylenedicarboxylate, bp 100105°C (20 mm), nD25
1.4454; published data [13]: bp 9598°C (19 mm), nD25
=
=
2,5-Diphenyl-7H-[1,2,4]triazolo[3,2-b][1,3]thia-
zin-7-one (IVe). Yield 2.01 g (66%), mp 218220°C.
1H NMR spectrum, d, ppm: 7.29 s (1H, 6-H), 7.44
7.71 m (6H, Harom), 7.86 d (2H, Harom, J = 7.0 Hz),
1.4450. Found, %: C 50.93; H 4.38. C6H6O4. Calculated,
%: C 50.71; H 4.26.
RUSSIAN JOURNALOF ORGANIC CHEMISTRY Vol. 41 No. 1 2005