Remote Electronic Tuning for High-performance N-Heterocyclic Carbene Catalysis

One of the privileged motifs of chiral N-heterocyclic carbene (NHC) catalyst is an aminoindanol-derived structure, and many researchers achieved an improvement of this type of catalyst by introducing various substitutions at the triazolium nitrogen, which is located at the proximal site of the reactive carbene. Recently, we found that the introduction of substituents at the benzene ring of the indane moiety, which is far from the carbene carbon, could efficiently tune the catalytic activity of NHC catalysts in the enantioselective acylation of racemic alcohols, asymmetric intramolecular Stetter reactions, and intermolecular benzoin condensation of benzaldehyde derivatives. Herein, we report the development of novel high-performance NHC catalysts by remote substituent effects.