Department of Chemistry, Shibli National P.G. College, Azamgarh, UP (INDIA)

3-Methyl-1-phenylpyrazol-5-one (I) were prepared by mixing ethyl acetoacetate and phenyl hydrazine. These methyl phenyl pyrazolone was treated with bromine in glacial acetic acid to get 4-bromo-3-methyl-1-phenyl pyrazole-5-one (II). These were treated with ammonium N-(phenyldithiocarbamate) and sodium acetate in absolute ethanol to give 3-Methyl-1-phenylpyrazole-5-one-4-yl-N-(phenyl)-dithiocarbamates (IIIa-c). These carbamates when treated with concentrate H2SO4 give 4-methyl-6-phenyl-2-phenylimino-1,3,-dithiolo-[4,5-a]-pyrazole (IVa-c) and on treatment with methyl iodide in methanol gave 4-methyl-6-phenyl- 2-phenylimino-1,3-oxathialo [4,5-d] pyrazole (Va-c). Fungitoxicity of the prepared compounds have been compared with Dithane M-45 a commercial fungicide for their fungitoxic action against Puccinia recondita and Ustilago nuda maydis and the screening results have been correlated with the structural features of the prepared compounds