Synthesis and Biological Activity of New [1,3]Thiazolo[4,5-d]pyridazin-4(5H)-ones.

A series of novel 2-(N-pyrrolidino, N-piperidino or N-morpholino)-7-phenyl(α-furoyl or α-thienyl)-[1,3]thiazolo[4,5-d]pyridazinones 10a-c, 14-16a,b was synthesized in 78-87% yields via the reaction of methyl 5-benzoyl(α-furoyl or α-thienyl)-2-aminosubstituted-thiazol-4-carboxylates 9a-c, 13a-e with hydrazine. These new compounds have been tested for their in vivo analgesic and anti-inflammatory activities. All compounds have been characterized by (1)H-NMR, (13)C-NMR spectroscopy, and liquid chromatography-mass spectrometry.