Synthesis, Antibacterial and Antifungal Activities of Some Pyrazole-1-Carbothioamides and Pyrimidine-2(1H)-Thiones

Abstract

A series of 3,5-disubstituted pyrazole-1-carbothioamides 2a-d, 4a-d, 5a-d and pyrimidine-2(1H)-thiones 6a-d were prepared by cyclocondensation of chalcones 1a-d with either thiosemicarbazide or thiourea, respectively. Dehydrative cyclization of chalcones 1a-d with thiosemicarbazide in refluxing dioxane containing few drops of acetic acid gave the corresponding 4,5-dihydropyrazoles 2a-d which were subsequently oxidized with sodium hypochlorite in dioxane to give pyrazole-1-carbothioamides 4a-d. N-acetyl derivatives of pyrazole-1-carbothioamides were obtained by two routes. Treat- ment of either hydrazones 3a-d or pyrazole-1-carbothioamides 4a-d with acetic anhydride gave the desired N-acetyl deriva- tives of pyrazole-1-carbothioamides 5a-d. Finally, cyclocondensation of chalcones 1a-d with thiourea in ethanolic potas- sium hydroxide gave the corresponding pyrimidine-2-(1H)-thiones 6a-d. The structural identification of products is re- ported and also the heterocyclic compounds were screened for their antimicrobial activity.