Enantioselective Synthesis of Biaryl Atropisomers by Pd-Catalyzed C-H Olefination using Chiral Spiro Phosphoric Acid Ligands

Abstract

The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C-H activation. Herein, we reported the synthesis of axially chiral biaryls by Pd-catalyzed atroposelective C-H olefination. A novel chiral spiro phosphoric acid, STRIP, was identified as a superior ligand for this transformation. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee). Density functional theory was used to gain a theoretical understanding of the enantioselectivities in this reaction.

Keywords: C−H olefination; atroposelectivity; chiral spiro phosphoric acids; palladium; quinoline biaryls.