Light-induced phosphine-catalyzed asymmetric functionalization of benzylic C–H bonds

Despite rapid development in the past two decades,there are still some unsolved synthetic challenges in the field of phosphine catalysis.In this report,through photo-induced activation of ortho-alkyl aromatic ketones,we achieved highly enantioselective functionalization of substrates bearing a benzylic C–H bond.In the presence of amino acid-derived bifunctional phosphine catalysts,a range of benzylic allylation products were obtained in good yields and with excellent enantioselectivities.The strategy disclosed herein offers new insight into the activation and functionalization of pronucleophiles containing less acidic C–H bonds in the domain of phosphine catalysis and beyond.