1,3-Dipolar cycloaddition of nitrosonaphthols to 3-aroylazindines. Novel syntheses of substituted naphtho[1,2-d]oxazoles and naphtho[2,1-d]oxazoles

Abstract

A series of 3-aroyl-2-arylaziridines underwent 1,3-dipolar cycloadditions in both orientations to the nitrogen–oxygen bond of 1-nitroso-2-naphthol. Spontaneous 1,3-cleavage of the intermediate oxadiazolidines to nitrones and cyclodehydration of the latter afforded both 2-aryl- and 2-aroylnaphtho-[1,2-d]oxazoles in good yields. The interpretation of the reaction received confirmation by independent, unambiguous synthesis of several 2-aroylnaphtho[1,2-d]oxazoles.