NHC-Catalyzed Enantioselective Access to Pyrazoles with a Nitrile-Containing All-Carbon Quaternary Center.

Chiral nitriles are valuable structural motifs found in numerous pharmaceuticals and natural products. This study presents an efficient method for synthesizing chiral nitriles via a cycloaddition reaction between β-cyano-substituted α,β-unsaturated aldehydes and 3-methyl-1-phenyl-1H-pyrazole-5-amine. The transformation is catalyzed by N-heterocyclic carbene (NHC) at low loadings, affording the corresponding chiral nitriles in good to excellent yields with excellent enantioselectivities.