An efficient one-step synthesis of heterobiaryl pyrazolo[3,4-b]pyridines via indole ring opening.

A mild one-step synthetic method to access privileged heterobiaryl pyrazolo[3,4-b]pyridines from indole-3-carboxaldehyde derivatives and a variety of aminopyrazoles has been developed. This novel method constructs heterobiaryls with the wide scope of substrate generality and excellent regioselectivity via indole ring opening.