Study of tert-amino effect: The role of substituents in isomerization of 5-amino-4-vinyl-3(2H)-pyridazinones

Abstract

The thermal isomerization reaction of ortho-vinyl tert-anilines and their heterocyclic analogues via tert-amino effect affords tetrahydropyrido-fused heterocyclic ring systems with a new C-C bond formation between the vinyl and tert-amino groups. A novel series of 5-amino-4-vinyl-3(2H)-pyridazinone derivatives were prepared to study the role of substituents of the pyridazinone ring and the vinyl group in their isomerization reaction to tetrahydropyrido[2, 3-d]pyridazines. In particular, 6-phenyl and 5-trioxopyrimidinediylmethylene substituents were found to significantly increase the rate of isomerization. Compounds possessing benzyl and methyl groups as amino substituents isomerized with the involvement of the benzyl group. On the basis of experiments with deuterated compounds, an intramolecular pathway was confirmed for the isomerization. ©ARKAT USA, Inc.