Organocatalytic asymmetric [3+3] annulation reaction between 5-aminopyrazoles and enynones: synthesis of pyrazolo[3,4- b ]pyridines

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.