Enantioselective Copper-Catalyzed N-H Insertion Reaction of Pyrazoles and α-Diazo Phosphates.

Asymmetric N-H insertion reaction provides a streamlined process for accessing N-alkylated pyrazoles and their derivatives. However, the enantioselective N-H insertion reaction of aromatic heterocycles with diazo compounds represents a long-standing challenge. Herein, we report a copper-catalyzed asymmetric N-H insertion reaction for the generation of chiral pyrazolyl phosphates in high yields with excellent regioselectivities and moderate to high enantioselectivities. Salient features of this reaction include synthetic convenience, mild reaction conditions, and excellent functional group tolerance.