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.