Department of Chemistry Shibli National P.G. College Azamgarh India

3-Aryl-4-amino-5-mercapto-s-triazoles (I) were synthesized by the method of Reid & Heindel1. These were treated with cyanogen bromide in ethanol which on refluxing on a water bath (6 hrs) was neutralized with saturated aqueous solution of K2CO3 to give 6-amino-3-aryl-s-traizolo-[3,4-b]-1,3,4-thiadiazoles (IIa-d), which were further treated with aromatic aldehydes to gives 6-arylidene-amino-3- aryl-s-triazolo-[3,4-b]-1,3,4-thiadi- azoles (IIIa-p) is treated with pchlorophenylisothiocyanate to give 3,4,6-triaryl-1,2,4-triazolo-[3,4-b]- 1,3,4-thiadiazolo-[3,2-a]-1,3,5-triazine-5-thione (IVa-p). Fungitoxicity of the prepared compounds have been compared with Dithane M-45 a commercial fungicide, for their fungitoxic action against Puccinia recondita and Ustilagonuda var. maydis and the screening results have been correlated with the structural features of the prepared compounds