1.2.4- Triazole-3-thione

A general photochemical-based synthesis of [l,2,4]triazolo[3,4- ]benzothiazoles 347 from 4,5-disubstituted 1,2,4-triazole-3-thione 346 has been described (Equation 67) <1997JOC5766>. 

Amino-l,2,4-triazines (86) react with phenylhydrazine to afford 2-phenyl-l,2,3-triazoles (135) (60MI21900). 3-Thioxo-l,2,4-triazin-5-ones (76) are transformed into 1,2,4-triazole-3-thiones (136) by treatment with sodium methoxide (72BSF1511). Treatment of compound (137) with acetic anhydride in the presence of sulfuric acid led to the isolation of the pyrazole (138) (10JA1499). 

Artemov and Shvaika treated a number of 2-aryl-l,3,4-oxadiazoIe-5(4//)-thiones (293) with methylhydrazine (R = Me) and obtained a mixture of 1-methyl-1,4-dihydro-1,2,4,5-tetrazine-6(5//)-thiones (294) and 4-methylamino-l,2,4-triazole-3-thiones (295 R = Me) (71KGS905). A similar reaction was reported by Konig and his coworkers, who treated 5-(4-pyridyl)-l,3,4-oxadiazole-2-thione (293 Ar = py) with hydrazine (R = H) and obtained a compound which was either the l,2,4,5-tetrazine-6-thione (294 R = H) or the 4-amino-1,2,4-triazole-3-thione (295 R = H) (54CB825, 56GEP953801). 

The acetylation of 1,4-diphenylthiosemicarbazide has been carefully reinvestigated, and the controversial structures of the products have been established as 5-methyl-4-phenyl-2-anilino-l,3,4-thiadiazolium chloride and meso-ionic 1,4-diphenyl-1,2,4-triazole-3-thione. ... 

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