SYNTHESIS OF SOME 1H-1,2,4-TRIAZOLE, 4H-1,2,4-TRIAZOLE, THIAZOLO[2,3-C]-1,2,4-TRIAZOLE AND 5H-1,2,4-TRIAZOLO-[3,4-B][1,3]THIAZINE DERIVATIVES BY METAL COMPOUND MEDIATED OXIDATIVE CYCLIZATION OF DERIVATIVES OF 2-(PHENYLMETHYLIDENE)HYDRAZINECARBOXIMIDOTHIOIC ACID

Reaction of the methyl 2-(phenylmethylidene)hydrazinecarboximidothioat e derivatives (3a-d) and (6a,b) with iron(III) chloride afforded the 5 -methylsulfanyl-3-phenyl-4H-1,2,4-triazole derivatives (4a-d) and the 5-methylsulfanyl-3-phenyl-1H-1,2,4-triazole derivatives (7a,b). This r eaction was extended to the synthesis of the 3-phenyl-5,6-dihydrothiaz olo[2,3-c]-1,2,4-triazole derivatives (10a,b) and the -6,7-dihydro-5H- 1,2,4-triazolo[3,4-b][1,3]thiazine derivatives (10c,d). Reaction of lo rophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (12a) with 1,2-dibrom oethane gave (10a) together with the isomeric ophenyl)-5,6-dihydrothia zolo[3,2-b][1,2,4]triazole (13a); similarly, reaction of (12a) with 1, 3-dibromopropane afforded (10c) along with hlorophenyl)-6,7-dihydro-5H -[1,2,4]triazolo[5,1-b] [1,3]thiazine (13b). The use of nickel peroxid e and lead tetraacetate in place of iron(III) chloride was investigate d for some of these oxidative cyclization reactions.