Synthesis and Some Reactions of Thieno(2,3-c)pyridazine Derivatives and Their Antibacterial Activity.

Abstract The title compounds (4a-f) were prepared by S-alkylation of 4-cyano-5,6-difur-2′-yl-2H-pyridazine-3-thione (2) and subsequent cyclization in ethanol in the presence of potassium carbonate. Reaction of o-disubstituted thienopyridazines (4a-d) with different reagents afforded tricyclic compounds namely, imidazothienopyridazine (5), pyridazinothienooxazine (6) and pyridazinothienopyrimidines (7–9). Most of the prepared compounds exhibited pronounced antibacterial activity.