Synthesis of new thieno- and pyrazolo- pyridazine derivatives

5,6-Di(pyridin-2-yl)-3-thioxo-2,3-dihydropyridazine-4-carbonitrile 2 has been reacted with ahalocompounds, such as chloroacetone, chloroacetamide, ethyl chloroacetate and chloroacetic acid gave the corresponding 2-S-alkylated pyridazine derivatives 3, 6, 10 and 13 which have been cyclised to give the corresponding thienopyridazine derivatives 4, 7, 11, and 14 respectively. Reaction of 15 with hydrazine hydrate gave the corresponding pyrazolopyridazine 16.