[3 + 2] Cycloadditions with Azirine Radical Cations: A New Synthesis of <i>N</i>‐Substituted Imidazoles

Abstract

Photoinduced electron-transfer conditions (the photoexcitation of the electron acceptor naphthalenedicarbonitrile (DCN)) are required for [3 + 2] cycloadditions of azirines (1) with imines, which afford N-substituted imidazoles (3). Probable intermediates are the radical cations 2, which were detected by the trapping reaction with trifluoroethanol.