Iridium-Catalyzed Asymmetric Hydrogenation of Fluorinated Olefins

The authors report the first successful asymmetric hydrogenation of vinyl fluorides. The current method provides access to compounds bearing CHF stereocenters adjacent to functionalities amenable to synthetic transformation. A major difficulty encountered was the undesired defluorination of substrate under the reaction conditions. Of the two possible pathways, formation of 4 from 2 was ruled out experimentally, indicating that the vinylic fluorine undergoes cleavage.