Rhodium-Catalyzed Asymmetric Allylic Dearomatization of β-Naphthols with gem-Difluorinated Cyclopropanes

Abstract

Transition-metal-catalyzed allylation reactions using gem-difluorinated cyclopropanes have drawn considerable interest in recent years. However, linear-selective and enantioselective 2-fluoroallylic substitution reaction is underexplored. Herein, we report a rhodium-catalyzed asymmetric allylic dearomatization of β-naphthols with gem-difluorinated cyclopropanes. In the presence of a rhodium catalyst consisting of commercially available rhodium precursor and chiral bisphosphine ligand, linear-selective 2-fluoroallylic β-naphthalenones bearing quaternary carbon centers were obtained in good yields and enantioselectivity (up to 86% yield and 95% ee). Mechanistic studies disclosed that the NaBAr^F additive in this reaction is critical, and a kinetic resolution is operated for the C–C cleavage of the gem-difluorinated cyclopropane.