A Chiral Pentafluorinated Isopropyl Group via Iodine(I)/(III) Catalysis.

An I(I)/(III) catalysis strategy to construct an enantioenriched fluorinated isostere of the i Pr group is reported. The difluorination of readily accessible α-CF3 -styrenes is enabled by the in situ generation of a chiral ArIF2 species to forge a stereocentre with the substituents F, CH2 F and CF3 (up to 95 %, >20:1 vicinal:geminal difluorination). The replacement of the metabolically labile benzylic proton results in a highly preorganised scaffold as was determined by X-ray crystallography (π→σ* and stereoelectronic gauche σ→σ* interactions). A process of catalyst editing is disclosed in which preliminary validation of enantioselectivity is placed on a structural foundation.