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Abstract 4-Amino-5-aryl-1,2,4-triazole-3-thiones (XVI) react with aromatic acids in the presence of phosphorus oxychloride to afford 3,6-disubstituted--s -triazolo [3,4--b] [1,3,4]thiadiazole(CIII). XVI N-N R 1 4-Amino-5-ary1-1,2,4-triazo1e-3-thiones (XVI) react with phenyl isocyanate to form 3,7-disubstituted- 5H-s-- triazolo[3,4-b-]- s--t ria’zol-6(7-~ )-one(CIV). CIV ii. Similarly ethyl or phenyl isothiocyanate react with compounds XVI to afford 3,7-disubstituted-5-H --s - triazolo[3,4-b-]- s-- triazole-6(7H-) -thione (CVII ). N-N It is worth to mention that 3-(p-chloropheny1)- 7-phenyl-5&2-triiazolo [3;4 -b]-5-triazole-6(7H-) - thione (CVII is also obtained from treatment of 3- b (p-chlorophenyl)-7-phenyl-5-H --s -triazol0[3~4--b ]--~ - triazol-6(7-H) -one (CIVc) with phosphorus pentasulphide. The reaction of 4-amino-5-aryl-1,2,4-triazole- 3-thiones (XVI) with Cyanogen bromide affords 6-amino- 3-substituted--s- triazolo[3,4-b-] [1,3,4]thiadiazole (CvII). It is important to mention that the intermediate 3-(4-chlorophenyl)-4-cyanoamino-1~2f4-triazole- 3-thione (CX) is isolated when compound XVI is treated 9 with cyanogen bromide. |