Facile C−N Bond Cleavage Promoted by Cuprous Oxide: Formation of C−C-Coupled Biimidazole from Its Methylene-Bridged Congener

The methylenebis(N-alkylimidazolium) halides are converted to dialkylbiimidazoles by cuprous oxide with concurrent C−N bond cleavage and C−C bond formation. This unusual C−N bond cleavage is proposed to involve a Cu(I)−NHC (N-heterocyclic carbene) complex. The reaction is unique, as it involves C−H bond activation, C−N bond cleavage, and C−C bond formation.