Reductive Cleavage of Isoxazolo[3,4-d]pyridazinones: A Synthetic Approach to Various 4,5-Functionalized 3(2H)-Pyridazinones

Abstract

4-Aminopyridazin-3(2H)-ones substituted at position 5 with a variety of oxygenated carbon chains were obtained in good yields by reductive opening of the pentatomic ring of isoxazolo[3,4-d]pyridazinones (1). Starting from ethyl 4-acylisoxazole-3-carboxylates, several 4,5-functionalized 3(2H)pyridazinones (3) are obtained in a one step by treatment with the appropriate hydrazine and Pd/C