Enantioselective Palladium-Catalyzed Hydrofluorination of Alkenylarenes

Hydrofluorination of simple alkenes is an attractive strategy to prepare fluorine containing molecules. However, the catalytic asymmetric hydrofluorination remains an ongoing challenge. We describe here a palladium(II)-catalyzed enantioselective hydro-fluorination of alkenylarenes, by employing sulfoxide phosphine (SOP) as chiral ligand, triarylphosphine as secondary ligand, Selectfluor® as fluorine source and trihexylsilane as hydride source. Under the optimal reaction conditions, a range of chiral ben-zyl fluorides bearing different functional groups are obtained in good yields (up to 80%) with high enantiopurity (up to 94:6 e.r.). Some mechanistic insight of this reaction is obtained using in situ 1- and 2-dimensional 1H-31P HMBC nuclear magnetic resonance (NMR) spectroscopy and a catalytic cycle is proposed.