Construction of Planar Chiral Ferrocenes by Cobalt-Catalyzed Enantioselective C–H Acyloxylation Enabled by Dual Ligands

Oxy-substituted planar chiral ferrocenes are of great importance in asymmetric synthesis and pharmaceuticals.However,enantioselective C–H activation of ferrocenes that form C–O bonds remains a huge challenge and has not yet been reported.Herein,the asymmetric synthesis of oxy-substituted planar chiral ferrocenes is achieved by cobalt-catalyzed enantioselective dehydrogenative C–H acyloxylation.The use of a dual-ligand system consisting of a chiral salicyloxazoline(Salox)ligand and a neutral phosphine oxide ligand,which is oxidized in situ from the corresponding phosphine,resulted in good yield(up to 83%)and excellent enantioselectivity(90–99%ee).The utility of this unprecedented protocol is highlighted by its versatile synthetic transformations.