Metal-catalyzed N–H insertions of carbenes have enabled a number of transformations to form C–C, C–N, and C–O bonds. 1 It has been proved as a powerful strategy to construct many important pharmaceutical compounds as well as natural products during the past twenty years. Enantioselective versions of this reaction were developed using chiral ligands, and high enantioselectivities were achieved. 2 In addition, organocatalysis has attracted more attention due to its ...
