(3+2) Cycloaddition reactions with the participation of hetarene N-oxides: A review

This review presents the current state of knowledge on the (3+2) cycloaddition (32CA) reactions involving heteroarene N-oxides. While aromatic amine oxides behave similarly to nitrones, their participation in cycloaddition processes is chemically distinct due to the thermodynamic stability of the aromatic ring system. The manuscript critically examines these reactions, focusing on the competition between the formation of stable fused isoxazolidines and the tendency toward rearomatization. The latter often leads to spontaneous ring opening, elimination, or complex rearrangements rather than the isolation of the primary cycloadduct.