Construction of β-Quaternary α,α-Difluoroketones via Catalytic Nucleophilic Substitution of Tertiary Alcohols with Difluoroenoxysilanes.

An efficient Fe(OTf)3-catalyzed nucleophilic substitution of cyclic or acyclic tertiary alcohols with difluoroenoxysilanes is developed, which provides a facile protocol for assembling structurally diverse α,α-gem-difluoroketones featuring a quaternary carbon center in good to excellent yields under mild conditions. Moreover, the diverse product elaborations highlight the utility of this protocol, as exemplified by the preparation of valuable difluorinated tricyclic indolines.