Asymmetric Addition of Pyrazolones to Allenamides Catalyzed by a Chiral Phosphoric Acid

Abstract

We describe a new asymmetric allylic alkylation of pyrazolones, in which an all‐carbon quaternary stereocenter with broad substrate scope and good enantioselectivity was generated. The asymmetric addition of pyrazolones to allenamides could be carried out under mild conditions in excellent yields with a relatively low catalyst loading. The allylic products with an enamide structure can be easily transformed to the pyrazolones with other functional groups, which provides a new approach for the asymmetric introduction of new functional groups into the pyrazolone skeleton.