Department of Chemistry, Shri Durga Ji P.G. College, Chandeswhar Azamgarh, and
R. P.G. College, Jamuhai, Jaunpur U.P. (INDIA)

6-Amino-3-aryl-s-triazolo [3,4-b]-1,3,4-thiadiazoles (IIa-c) were obtained from 3-aryl-4-amino-5-mercapto-s-triazoles (Ia-c) by treating it with cynogen bromide in ethanol. Which in turn were treated with aromatic aldehydes to gives 3-aryl-6-(arylideneamino)-s-triazole-[3,4-b]- 1,3,4-thiadiazoles (IIIa-f). Compounds III were further treated with aryl isothiocyanates to yield 3,4,6-triaryl-s-triazolo [3,4-b]-1,3,4-thiadiazolo-[3,2- b]-s-triazine-5-thiones (IVa-r). Structure of all these unknown compounds were confirmed by their spectral studies and elemental analysis. The compounds (IVa-r) were screened for their antifungal activity against Phytophthora infestans and Aspergillus niger.