HETEROCYCLES, Vol. 83, No. 2, 2011
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1H, exchangeable, SH); MS: m/z (%): 284 (100, M+), 256 (7, M+ -N2), 255 (11, M+ -HN2), 227 (15, M+
-HN5), 185 (50, M+ -CH3N7), 129 (60, M+ -C3H3N7S) and 103 (14, M+ -C4H3N8S); Anal. Calcd for
C11H8N8S (284.30): C, 46.47; H, 2.84; N, 39.41; S, 11.28%. Found: C, 46.70; H, 2.54; N, 39.11; S,
11.78%.
3-(1,2,4-Triazolo[4,3-c]quinazolin-3-yl)-6-(3-bromophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole
(13). A mixture of 5-(1,2,4-triazolo[4,3-c]quinazolin-3-yl)-4-amino-4H-1,2,4-triazole-3-thiol (12, 0.28 g,
1 mmol) and m-bromobenzoic acid (0.22 g, 1.1 mmol) in POCl3 (5 mL) was refluxed for 7 h. The
reaction mixture was slowly quenched onto crushed ice with stirring and neutralized with 10% aqueous
sodium bicarbonate solution. The product which separated after standing overnight was filtered, washed
with cold water, dried and crystallized from CHCl3-EtOH to give the titled compound 13 as yellow
needles (0.2 g, 56% yield); mp 131-132 °C; IR: 1560, 1541 (triazole ring C=N), 1505 (pyrimidine ring
C=N), 1461 (pyrimidine ring C=C), 1261 (N-N=C) and 679 cm-1 (C –S-C); 1H NMR (DMSO-d6): =
7.25 (s, 1H, aromatic-H), 7.31 (t, 1H, aromatic-H), 7.42 (t, 1H, aromatic-H), 7.52 (t, 1H, aromatic-H),
7.84 (d, 2H, aromatic-H), 8.12 (d, 2H, aromatic-H) and 8.33 (s, 1H, pyrimidine-H); Anal. Calcd for
C18H9BrN8S (449.29): C, 48.12; H, 2.02; Br, 17.78; N, 24.94; S, 7.14%. Found: C, 48.20; H, 2.22; Br,
17.54; N, 24.87; S, 7.61%.
3-([1,2,4]Triazolo[4,3-c]quinazolin-3-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole-6(5H)-thione (14). A
mixture of 5-(1,2,4-triazolo[4,3-c]quinazolin-3-yl)-4-amino-4H-1,2,4-triazole-3-thiol (12, 0.28 g, 10
mmol), KOH (0.6 g, 10 mmol ) and carbon disulfide (4 mL) in MeOH (100 mL) was refluxed for 24 h,
and then evaporated to dryness and 50% aqueous HCl (50 mL) was added, the product was filtered off,
washed with water, dried and crystallized from MeOH to give the titled compound 14 as yellow needles
(0.2 g, 61% yield); mp 259-260 °C; IR: 3414 (NH), 1593, 1538 (triazole ring C=N), 1472 (pyrimidine
ring C=N), 1429 (pyrimidine ring C=C) and 1304 cm-1 (C=S); MS: m/z (%): 326 (2, M+), 197 (2, M+
-C8H5N2), 198 (2, M+ -C8H4N2), 122 (2, M+ -C9H4N2S2), 123 (2, M+ -C9H3N2S2), 108 (13, M+ -C9H4N3S2),
109 (2, M+ -C9H3N3S2) and 68 (13, M+ -C10H4N5S2); Anal. Calcd for C12H6N8S2 (326.36): C, 44.16; H,
1.85; N, 34.33; S, 19.65%. Found: C, 44.00; H, 2.01; N, 34.62; S, 19.34%.
3-(1,2,4-Triazolo[4,3-c]quinazolin-3-yl)-6-(methylthio)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (15). A
solution of 3-([1,2,4]triazolo[4,3-c]quinazolin-3-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole-6(5H)-thione
(14, 0.3 g, 1 mmol) and anhydrous sodium acetate (1 g, 15 mmol ) in dioxan (100 mL) was treated with
CH3I (0.14 mL, 1 mmol) gradually with constant stirring for 24 h. The solvent was removed and the
residue was poured into ice-cold water. The compound that precipitated was filtered, washed, dried and
crystallized from EtOH to give the titled compound 15 as pale green needles (0.2 g, 64% yield); mp 229-