Synthesis, Characterization and Fungitoxicity of 3,4,6-triayl-s-triazolo [3,4-b]-1,3,4-thiadiazolo [1,3,5]-triazine-5-thiones

In the present work 3,4,6-triayl-s-triazolo [3,4-b]-1,3,4-thiadiazolo [1,3,50-triazine-5-thiones (IVa-n) were synehsized by 4+2 cycloaddition of 6-arylidine amino-3-aryl-s-triazolo [3,4-b]-1,3,4-thiadiazoles (IIIa-n) are arylisothiocynate in dry tolune as solvent. 6-Arylidine amino-3-aryl-s-triazolo [3,4-b]-1,3,4-thiadiazoles (IIIa-n) were prepared from aromatic aldehyde refluxing in absolute ethanol with 6-amino-3-aryl-s-triazole [3,4-b]-1,3,4-thiadiazoles (IIa-g), which are prepared from 3-aryl, 4-amino-5-mercapto-s-triazole (Ia-g) by treating it with cyanogen bromide in ethanol. Starting material 3-aryl, 4-amino-5-mercapto-s-triazoles (Ia-g) wre prepred in excellent yield following the method of Ried and Heindel(1). The reaction sequence leading to the formation of titled compounds are given in the scheme 1. All the synthesized fourteen titled compounds were well characterized by their analytical and spectral data. Fungitoxicity of titled compounds (IVa-n) have been evaluated against two fungal species i.e. Helminthosporium orayzee and Alternaria solanai.