Organocatalytic Asymmetric [3 + 3] Annulation Reaction Between 5-Aminopyrazoles and Enynones: Synthesis of Pyrazolo[3,4-b]pyridines

Abstract

An organocatalytic asymmetric [3 + 3] annulation reaction between 1,3-aryl-1H-pyrazol-5-amines and enynones has been developed. This study is the first to describe an organocatalytic enantioselective synthesis of pyrazolo[3,4-b]pyridines. The reaction's scope is broad, and with 20 mol% of a chiral phosphoric acid catalyst, pyrazolo[3,4-b]pyridines were produced in moderate to good yields with high enantioselectivities.