THIRUPAIAH, RAJESWAR RAO
138
due to methylene protons adjacent to the endocyclic
sulfur atom. No SH proton signal characteristic of
initial compound III was present in the H NMR
Calculated, %: C 48.16; H 2.92; N 12.48; S 14.29.
M 448.90.
1
3-{3-[2-(4-Bromophenyl)-2-oxoethylsulfanyl]-
7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl}-4-hy-
droxy-6-methyl-2H-pyran-2-one (Vb). Yield 0.419 g
(85%), yellow solid, mp 108–110°C. IR spectrum, ν,
spectra of Va–Vj.
In conclusion, we have described an efficient and
regioselective method for the synthesis of a series of
new [1,2,4]triazolo[3,4-b][1,3,4]thiadiazine deriva-
tives. This protocol is characterized by a reaction time
of 6 to 10 h, good yield, and simple isolation proce-
dure. Our ongoing efforts for the synthesis of other
compounds starting from intermediate product III will
be reported elsewhere.
−
1
1
cm : 3265 (OH), 1740 (C=O), 1681 (C=O). H NMR
spectrum, δ, ppm: 2.26 s (3H, CH3), 4.43 s (2H, CH2),
4.97 s (2H, CH2), 6.17 s (1H, CH), 7.79 d (2H, Harom
,
J = 6.0 Hz), 7.90 d (2H, Harom, J = 8.8 Hz), 14.00 s
(1H, OH). 13C NMR spectrum, δC, ppm: 22.1, 24.2,
38.0, 100.4, 101.1, 127.8, 129.3, 131.8, 132.3, 141.9,
149.3, 155.7, 163.9, 165.0, 172.8, 192.3. Mass spec-
trum, m/z (Irel, %): 495 (23) [M + 2]+, 493 (23) [M]+,
417 (16), 395 (18), 46 (46). Found, %: C 43.78;
H 2.69; N 11.3; S 13.10. C18H13BrN4O4S2. Calculated,
%: C 43.82; H 2.66; N 11.36; S 13.00. M 493.35.
4-Hydroxy-3-(3-sulfanyl-7H-[1,2,4]triazolo-
[3,4-b][1,3,4]thiadiazin-6-yl)-6-methyl-2H-pyran-2-
one (III). A mixture of 1 mmol of 3-bromoacetyl-4-
hydroxy-6-methyl-2H-pyran-2-one (I) and 1 mmol of
4-amino-4H-1,2,4-triazole-3,5-dithiol (II) was dis-
solved in 10 mL of anhydrous ethanol, and the mixture
was refluxed for 6 h. A solid separated and was
collected by filtration, dried, and recrystallized from
ethanol. Yield 0.251 g (85%), yellow solid, mp 231–
4-Hydroxy-3-{3-[2-(4-methoxyphenyl)-2-oxo-
ethylsulfanyl]-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadi-
azin-6-yl}-6-methyl-2H-pyran-2-one (Vc). Yield
0.386 g (87%), yellow solid, mp 109–111°C. IR spec-
−
−
1
1
233°C. IR spectrum, ν, cm : 3448 (OH), 2749 (SH),
trum, ν, cm : 3464 (OH), 1740 (C=O), 1670 (C=O).
1H NMR spectrum, δ, ppm: 2.28 s (3H, CH3), 4.40 s
(2H, CH2), 4.93 s (2H, CH2), 6.19 s (1H, CH), 7.09 d
(2H, Harom, J = 6.8 Hz), 7.95 d (2H, Harom, J = 8.4 Hz).
13C NMR spectrum, δC, ppm: 22.0, 24.4, 38.1, 55.5,
100.4, 101.1, 114.4, 128.1, 129.2, 130.7, 141.9, 149.2,
154.6, 162.3, 163.5, 174.4, 191.4. Found, %: C 51.38;
H 3.69; N 12.64; S 14.52. C19H16N4O5S2. Calculated,
%: C 51.34; H 3.63; N 12.60; S 14.43.
1
1716 (C=O). H NMR spectrum, δ, ppm: 2.28 s (3H,
CH3), 2.44 s (1H, SH), 4.49 s (2H, CH2), 6.34 s (1H,
CH), 14.07 s (1H, OH). Mass spectrum, m/z (Irel, %):
297 (100) [M + 1]+, 241 (18). Found, %: C 48.53;
H 2.72; N 18.91; S 21.64. C10H8N4O3S2. Calculated,
%: C 48.57; H 2.74; N 18.90; S 21.68. M 296.32.
4-Hydroxy-6-methyl-3-(3-R-sulfanyl-7H-[1,2,4]-
triazolo[3,4-b][1,3,4]thiadiazin-6-yl)-2H-pyran-
2-ones Va–Vj (general procedure). Thiol III, 1 mmol,
was dissolved in a mixture of 5 mL of dimethyl-
formamide and 5 mL of anhydrous ethanol, 1 mmol of
alkylating agent IVa–IVj was added, and the mixture
was heated for 8 h under reflux (80–90°C), cooled, and
poured into water. The precipitate was filtered off,
dried, and recrystallized from methanol.
4-Hydroxy-6-methyl-3-{3-[2-(4-methylphenyl)-
2-oxoethylsulfanyl]-7H-[1,2,4]triazolo[3,4-b][1,3,4]-
thiadiazin-6-yl}-2H-pyran-2-one (Vd). Yield 0.363 g
(85%), yellow solid, mp 86–88°C. IR spectrum, ν,
−
1
1
cm : 3449 (OH), 1730 (C=O), 1684 (C=O). H NMR
spectrum, δ, ppm: 2.19 s (3H, CH3), 2.40 s (3H, CH3),
4.42 s (2H, CH2), 4.97 s (2H, CH2), 6.24 s (1H, CH),
7.38 d (2H, Harom, J = 7.6 Hz), 7.88 d (2H, Harom, J =
3-{3-[2-(4-Chlorophenyl)-2-oxoethylsulfanyl]-
7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl}-4-hy-
droxy-6-methyl-2H-pyran-2-one (Va). Yield 0.358 g
(80%), yellow solid, mp 157–159°C. IR spectrum, ν,
13
8.4 Hz). C NMR spectrum, δ, ppm: 22.4, 23.1, 24.8,
38.1, 100.3, 105.5, 129.5, 130.3, 132.7, 142.2, 144.2,
149.3, 155.0, 162.8, 163.5, 174.5, 192.5. Found, %:
C 53.39; H 3.79; N 13.12; S 14.92. C19H16N4O4S2. Cal-
culated, %: C 53.26; H 3.76; N 13.08; S 14.97.
−
1
1
cm : 3433 (OH), 1732 (C=O), 1686 (C=O). H NMR
spectrum, δ, ppm: 2.25 s (3H, CH3), 4.06 s (2H, CH2),
4-Hydroxy-6-methyl-3-[3-(2-oxo-2-phenylethyl-
sulfanyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-
6-yl]-2H-pyran-2-one (Ve). Yield 0.310 g (75%),
yellow solid, mp 88–90°C. IR spectrum, ν, cm : 3451
(OH), 1738 (C=O), 1679 (C=O). 1H NMR spectrum, δ,
ppm: 2.26 s (3H, CH3), 4.45 s (2H, CH2), 5.02 s (2H,
CH2), 6.15 s (1H, CH), 7.59–7.69 m (3H, Harom), 7.97–
4.95 s (2H, CH2), 6.18 s (1H, CH), 7.62 d (2H, Harom
,
13
J = 8.4 Hz), 8.03 d (2H, Harom, J = 8.4 Hz). C NMR
spectrum, δC, ppm: 22.1, 24.4, 38.0, 97.0, 100.6, 129.1,
130.2, 133.9, 138.6, 142.5, 148.5, 154.2, 161.6, 164.8,
170.2, 192.2. Mass spectrum, m/z (Irel, %): 449 (93)
[M + 1]+, 435 (35), 284 (10), 225 (26). Found, %:
C 48.11; H 2.89; N 12.4; S 14.25. C18H13ClN4O4S2.
−
1
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 1 2014