Chiral Phosphoric Acid-Catalyzed Asymmetric Synthesis of Axially Chiral Arylpyrazole.

A chiral phosphoric acid-catalyzed efficient, operationally simple, general method for straightforward syntheses of axially chiral arylpyrazole employing -alkyl of 3-aryl-5-aminopyrazoles reacting with azonaphthalenes was achieved. A wide variety of axially chiral heterobiaryl diamines in generally good yields with excellent enantioselectivities were obtained under mild conditions. In addition, a scaled-up experiment and postmodification of the chiral product further highlighted the synthetic utility.