Pd(II)-Catalyzed Enantioselective Alkynylation of Unbiased Methylene C(sp3)-H Bonds Using 3,3'-Fluorinated-BINOL as a Chiral Ligand.

Abstract

The first Pd(II)-catalyzed enantioselective alkynylation of unbiased methylene β-C(sp3)-H bonds is reported. The readily accessible and tunable BINOL derivatives are used as chiral ligands in C-H activation for the first time. 3,3'-Fluorinated-BINOL proved crucial in determining both the reactivity and enantioselectivity. A wide range of carboxylic acid derivatives are well tolerated with high enantioselectivities (up to 96% ee). Mechanistic studies suggest that multiple ligands may participate in the stereodetermining C-H palladation step, and a chiral amplification effect is observed.