Catalytic Construction of Axially Chiral Cyclohexylidenes through Symmetry-Breaking Asymmetric Elimination

Abstract

A symmetry-breaking asymmetric β-elimination for the catalytic construction of axially chiral cyclohexylidenes is described. Using a chiral BINOL-derived bis(hydroxy) polyether/KF catalytic system, the asymmetric elimination of prochiral β-sulfonyl ketones directly converts molecular symmetry into axial chirality through stereogenic C=C bond formation. A broad range of axially chiral cyclohexylidenes were obtained in moderate to excellent yields with high to excellent enantioselectivities. The synthetic utility of the resulting axially chiral cyclohexylidenes was further demonstrated through reduction, epoxidation, and bromination. This work provides a complementary catalytic approach to nonatropisomeric axial chirality and expands the synthetic potential of asymmetric β-elimination toward the construction of diverse stereogenic elements.