Synthesis and Antifungal Activity of New 7H-l,3,4-Oxadiazolo[3,2-a] [l,3,5]-triazine-7-thiones

A number of 2,5-disubstituted-7H-l, 3, 4-Oxadiazolo [3,2-a] [l,3,5]-triazine-7-thiones have been prepared by 1,4-dipolar cycloaddition of 5-substituted-l,3,4-oxadiazol-2-yl isothiocyanates to aceto/benzo-nitrile, and their fungitoxicitics determined in vitro against Helminthosporium oryzae or Drechslera oryzae and Fusarium oxysporium. A standard commercial fungicide Dithane M-45 (mancozeb) was also tested under similar conditions for comparision. Based on screening data, a possible structure activity relationship has been deduced.