Cu(II)-NHC CatalyzedInsertion of Quinoid Carbenesinto <i>cis</i>-Epoxides: Stereoselective Synthesis of <i>trans</i>-Dihydronaphthodioxine

A straightforward synthesis of <i>trans</i>-dihydronaphthodioxine has been efficiently accomplished through Cu­(II)-NHC catalysis, involving the stereoselective ring opening of <i>cis</i>-epoxides with quinoid-carbene. Intramolecular S_N2-like substitution facilitates the inversion of stereochemistry during <i>cis</i>-epoxide ring opening. This reaction has been developed under simple conditions, demonstrating a broad substrate scope with a wide chemoselective profile. Additionally, late-stage functionalization of complex bioactive molecules has been successfully achieved.