alpha-(2-Thienylidene)-gamma-aryl-delta beta,gamma-butenolides 1 are prepared by condensing thiophene-2-aldehyde with beta-aroylpropionic acids in sodium acetate-acetic anhydride mixture. The butenolides react with ammonia in ethanol to give the corresponding 5-oxo-2-pyrrolines 2. Hydrazine hydrate reacts with the butenolides 1 with the formation of the corresponding acrylic acid hydrazides 3. Ring closure of the latter hydrazides with hydrochloric/acetic acid mixture gives the pyridazinones 4. The biological activity of the synthesized compounds is tested against bacterial and yeast strains. The butenolides 1 and the oxopyrrolines 2 inhibit the growth of yeast and gram-negative strain. The hydrazides 3 and the pyridazinones 4 are effective on gram-positive strains.