Oxydifluoromethylation of Alkenes by Photoredox Catalysis: Simple Synthesis of CF2H-Containing Alcohols

Abstract

We have developed a novel and simple protocol for the direct incorporation of a difluoromethyl (CF2H) group into alkenes by visible-light-driven photoredox catalysis. The use of fac-[Ir(ppy)3] (ppy=2-pyridylphenyl) photocatalyst and shelf-stable Hu's reagent, N-tosyl-S-difluoromethyl-S-phenylsulfoximine, as a CF2H source is the key to success. The well-designed photoredox system achieves synthesis of not only β-CF2H-substituted alcohols but also ethers and an ester from alkenes through solvolytic processes. The present method allows a single-step and regioselective formation of C(sp3)-CF2H and C(sp3)-O bonds from C=C moiety in alkenes, such as hydroxydifluoromethylation, regardless of terminal or internal alkenes. Moreover, this methodology tolerates a variety of functional groups. Light up the bulb! A novel and simple protocol for the direct incorporation of a difluoromethyl (CF2H) group into alkenes by visible-light-driven photoredox catalysis has been developed (see scheme). An Ir photocatalyst is useful for the generation of a CF2H radical through one-electron reduction of Hu's reagent. The present reaction system produces not only various β-CF2H-substituted alcohols, but also ethers and esters in regiospecific manners under mild conditions.