Electronic Effects on Chiral NHC-Transition-Metal Catalysis

Though the properties of N-heterocyclic carbenes (NHCs) are generally dominated by the very strong sigma donating character, electronic activation has emerged as an effective method to cooperate with typical carbon-framework steric optimization for highly enantioselective chiral NHC-transition-metal catalysis in recent years. NHC electronic changes associated with structural variations are now better understood by quantitative analysis using various methods. Here we highlighted and correlated some interesting chiral induction improvement methods, which were brought by electronic and steric cooperation on chiral NHC-transition-metal catalysis.