Stereoselective Copper-Catalyzed Cross-Coupling of Aziridines with Benzimidazoles via Nucleophilic Ring Opening and C(sp²)–H Functionalization

A copper-catalyzed cross-coupling of 2-alkyl-/2-arylaziridines with benzimidazoles is reported. The reactions involve a regiospecific ring opening of aziridines with benzimidazoles to give benzoimidazolylethylamine derivatives that lead to dehydrogenative cross-coupling between C­(sp²)-H and N–H bonds to produce dihydroimidazobenzimidazoles. Optically active 2-arylaziridines can be stereoinvertivebly cross-coupled with high enantiomeric purities (77–97% ee). These aerobic catalytic systems comprise an inexpensive Cu­(II) salt and PCy₃ ligand at moderate temperature.