Synthesis of Pyrazolo [4,3-c]Pyridazine and Isoxazolo [3,4-d]Pyridazine Derivatives

Arylhydrazones of diethyl acetonedicarboxylate 3 was treated with fomaldehyde to 1-aryl-1, 4, 5, 6-tetrahyeheypyridazine derivatives 4a-f Cyclization of compound 4a-f by hydroxy-lamine afforded [3, 4-d] 1, 4, 5, 6-tetrahydropyridazine derivative 5a-f. Also, cyclization of compound 4c with semicarbazide gave pyrazolote [4, 3-c] pyridazine 6. On the other hand compound 3 reacted with ethylothofomate to give diethyl-1, 4-dihydro-1-arypyridazine-4-one-3, 5 dicaboxylate 7, which on treatment with hydrazine, semicarbazide and thiosemicarbazide gave pyridazine, amido and thioamido derivatives. The spectrl and antimicrobial data of these compounds 1-8 were studied.