Cage-Shaped Phosphites Having C3 -Symmetric Chiral Environment: Steric Control of Lewis Basicity and Application as Chiral Ligands in Rhodium-Catalyzed Conjugate Additions

Abstract

Designing chiral ligands with an axial symmetry higher than C₂ -rotational symmetry is one of the most crucial approaches to improving enantioselectivity in asymmetric synthesis. Herein, C₃ -symmetric chiral cage-shaped phosphites are reported. Their Lewis basicity and chiral environment are precisely controlled by the tethered group. The cage-shaped phosphites successfully worked as chiral ligands in Rh-catalyzed asymmetric conjugate additions, realizing acceptable yields with excellent enantioselectivity, and were used to synthesize a pharmacologically important molecule.

Keywords: 1,4-addition; C3-symmetric ligand; cage-shaped phosphite; chiral Lewis base; rhodium catalyst.