Structural modification studies of 3-piperonylsydnone I. synthesis of piperonyl-substituted pyrazoles,isoxazoles, triazoles,oxadiazoles and thiadiazoles

As a structural modification study of the antimalarial compound 3-piperonylsydnone, a number of pyrazoles, isoxazoles, 1,2,4-triazoles, ψ-1,2,4-triazoles, 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and their intermediates all of which contain the piperonyl moiety have been synthesized. The antimalarial activity of these compounds was found to be less than that of the original sydnone. With the exception of 2,4-diamino-5-piperonylpyrimidine, among the compounds tested, those which showed survival time of eleven days or over all possess a N-N linkage.