Synthesis and molluscicidal activity of some new thiophene, thiadiazole and pyrazole derivatives

Abstract The base-catalyzed reaction of benzoyl acetone 1 with phenyl isothiocyanate yields the non-isolable intermediate 2 . Treatment of 2 with dilute HCl afforded the corresponding thiocarbamoyl derivative 3 . Reaction of the intermediate 2 with phenacyl bromide, ethyl bromoacetate, chloroacetonitrile, chloroacetyl chloride, bromodiethyl malonate and chloroacetone afforded the corresponding thiophene derivatives 5 , 8 , 15 and 17 . The thiocarbamoyl derivative 3 reacts with arylazophenacyl bromide and/or hydrazine hydrate to afford the corresponding thiadiazole and pyrazole derivatives 20a – c and 22 , respectively. These new synthesized compounds show generally a moderate molluscicidal activity to Biomphalaria alexandrina snails.