Screening chiral fluorinated binaphthyl ketone catalysts for asymmetric epoxidation

A series of five chiral binaphthyl ketone catalysts 4–8 with variable distributions of fluorine atoms alpha to the carbonyl have been synthesized. These catalysts were screened in the asymmetric epoxidation of trans-β-methylstyrene. The best catalyst was α,α′-difluoroketone 6 which catalyzed the epoxidation to trans-β-methylstyrene oxide with 100% conversion and 86% e.e. at 10 mol% catalyst loading.