One-step synthesis of 3,5-dihydro-2H-pyrrolo[3,4-d]oxazoles by reaction of p-nitrosophenols with 2-aroylaziridines

Abstract

Reaction of 1-alkyl-2-aroyl-3-arylaziridines, bearing electron-releasing substituents in the 2- or 3-positions, with substituted p-nitrosophenols give 3,5-dihydro-2H-pyrrolo[3,4-d]oxazoles. The isolation of nitrones and aryl and aroyl imines as secondary products supports the interpretation of the reaction in terms of two consecutive 1,3-dipolar additions, in which the second regiospecific addition is autocatalytic and is followed by a Paal–Knorr condensation.

Separate regiospecific addition of ketoaldehydes to 2-aroylaziridines followed by Paal–Knorr condensation with primary amines confirms the proposed reaction scheme and gives excellent yields of 3,5-dihydro-2H-pyrrolo[3,4-d]-oxazoles and related compounds.