Light-Mediated Chiral Phosphate Catalysis for Asymmetric Dicarbofunctionalization of Enamides

Abstract

A light-mediated asymmetric dicarbofunctionalization of enamides with carboxylic-acid-derived redox-active esters (RAEs) and indoles has been established by using chiral lithium phosphate catalysis in the presence or absence of photoredox catalyst. This reaction features mild reaction conditions and broad substrate scopes, delivering a wide range of highly functionalized chiral amine derivatives. Mechanistic studies suggest that chiral lithium phosphate can serve as a pocket to accelerate the aggregation of enamide and RAE through hydrogen-bonding and coordination interaction, enabling the formation of a charge-transfer complex (CTC). Either enamide or CTC can be excited by direct irradiation or Ru(II)-mediated photosensitization to furnish chiral iminium intermediates for the asymmetric Friedel–Crafts reaction of indole.