Chiral Imidazoline–Phosphine Ligands for Palladium-Catalyzed Asymmetric Allylic Substitutions

Abstract

Chiral imidazoline–phosphine ligands with a 1,1′-binaphthalene framework have been developed as new types of N,P ligands. The chiral ligand L1 prepared from (R)-(−)-2-(diphenylphosphino)-1,1′-binaphthyl-2′-acid efficiently affects the palladium-catalyzed enantioselective allylic alkylation of 1,3-diarylpropenyl acetate with dimethyl malonate to give the corresponding adducts in excellent yields and enantioselectivities (up to 96% ee), and chiral ligand L9 can be used for the palladium-catalyzed asymmetric allylic monofluoromethylation of 1,3-diphenylpropenyl acetate with 1-fluorobis(phenylsulfonyl)methane to afford the corresponding product in excellent enantioselectivities (up to 98% ee) and moderate yields under mild conditions. The bidentate N,P-coordination pattern to the Pd atom with ligand L1 has been unambiguously confirmed by X-ray diffraction.