Cu-NHC Complex for Chan-Evans-Lam Cross-Coupling Reactions of N-Heterocyclic Compounds and Arylboronic Acids

An efficient copper(II) N-heterocyclic carbene (NHC) complex with an NCN coordination mode was optimized to catalyze the Chan-Evans-Lam (CEL) cross-coupling reaction of imidazole and other N-heterocyclic nucleophiles with arylboronic acid. This air-stable copper catalyst shows robust catalytic performance and tolerates a diverse array of functional groups on both the N-nucleophile and arylboronic acid coupling partners in C-N bond forming reactions with up to 95% yield. Formation of the Cu-NHC complex in situ generated similar catalytic performance for CEL coupling. Alternative metal ions (Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺, Ru²⁺, and Pd²⁺) were also screened in the presence of the NHC precursor as CEL catalysts. An efficient copper(II) N-heterocyclic carbene (NHC) complex catalyzing the Chan-Evans-Lam cross-coupling reaction of N-heterocyclic nucleophiles with arylboronic acid has been explored. This air-stable copper catalyst shows practical robustness that tolerates a diverse array of functional groups on both the N-nucleophile and arylboronic acid coupling partners in C-N bond forming reactions through the CEL reaction.