The Chemistry of 5-Oxodihydroisoxazoles. XV. Reaction of Derived Ketenimines With Enamines and Enolates

Abstract

Reaction of 2-heterocyclisoxazol-5(2H)-ones with bases leads to the formation of ketenimines, which react with nucleophiles in competition with intramolecular reactions. Such reactions in the presence of enamines, enamine anions or enolates are reported. Enamines undergo addition through carbon and nitrogen to the ketenimine in competition with direct addition-elimination to the isoxazolone. Enolates of imines or ketones add to the ketenimine to give a mixture of products: only the reaction with the enolate of cyclohexanone is sufficiently specific to provide a useful new synthetic procedure.