Rhodium-Catalyzed Atroposelective C-H Arylation: Efficient Synthesis of Axially Chiral Heterobiaryls.

Rhodium(I)-catalyzed atroposelective C-H arylation of heterobiaryls was presented. In the presence of a Rh catalyst derived from [Rh(C2H4)2Cl]2 and a TADDOL-derived monodentate phosphonite, with 2-pyridine, 2-isoquinoline and their analogs as directing groups, a series of axially chiral heterobiaryls were obtained in excellent yields and enantioselectivities (up to 99% yield, 97% ee) via C-H direct functionalization reaction. The products obtained from this method provide a platform for the synthesis of axially chiral biaryl ligands and catalysts. As a demonstration, a chiral N-oxide synthesized from the product in one step could act as an efficient catalyst for asymmetric allylation of benzaldehyde with allyltrichlorosilane, leading to homoallyl alcohol with excellent enantiocontrol.