THE CHEMISTRY OF 5-OXODIHYDROISOXAZOLES .15. REACTION OF DERIVED KETENIMINES WITH ENAMINES AND ENOLATES

Reaction of 2-heterocyclisoxazol-5(2H)-ones with bases leads to the fo rmation of ketenimines, which react with nucleophiles in competition w ith intramolecular reactions. Such reactions in the presence of enamin es, enamine anions or enolates are reported. Enamines undergo addition through carbon and nitrogen to the ketenimine in competition with dir ect addition-elimination to the isoxazolone. Enolates of imines or ket ones add to the ketenimine to give a mixture of products: only the rea ction with the enolate of cyclohexanone is sufficiently specific to pr ovide a useful new synthetic procedure.