Recent Advances in the Direct N–C(sp2) Nitrone Synthesis from Oxime

Nitrones are pivotal in organic chemistry, especially for the synthesis of natural and biologically active compounds via 1,3-dipolar cycloadditions and Kinugasa reactions. Although numerous methods have been reported for the synthesis of nitrones with an sp3 carbon connected to a nitrogen atom, the development of nitrones with an sp2 carbon linkage, including N-vinyl, N-aryl, and N-alkoxycarbonyl nitrones, remains relatively underexplored. This review summarizes the current research trends and methodologies for the direct synthesis of nitrones, in which an sp2 carbon is directly bonded to a nitrogen atom, beginning with oximes.