Studies Using (E)-6-Oxo-1-aryl-4-(2-N-piperidinyl)vinyl-1,6-dihydropyridazine-5-carbonitrile

Abstract

Condensing 1-aryl-4-methyl-1,6-dihydropyridazine-5carbonitrile with triethyl orthoformate and piperidine afforded the transenamine 2. This could be converted into pyrido [3,4-d]pyridazine 3 upon treatment with primary aromatic amines.Reacting 2 with hydrazonoyl chlorides 5 afforded 7 rather than 6.Compound 2 gives also pyrido [3,4d]pyridazine 10 upon treatment with acetic acid and ammonium acetate.Compound 2 afforded N-aminopyrido [3,4-d]pyridazine 11 upon treatment with hydrazine hydrate.Compound 11 reacted with triethyl orthoformate to give [1,2,4]triazolo[2',3':1,2]pyrido[4,3-d]pyridazin-10-one 12 and can be acetylated to 13. Compound 2 could be coupled with pchlorobenzenediazonium chloride to give the pyridazino[4,5-d]pyridazine 17.