Enantioselective Synthesis of Axially Chiral Tetrasubstituted Alkenes by Copper-Catalyzed C(sp2)–H Functionalization of Arenes with Vinyl Cations

Abstract

Axially chiral tetrasubstituted alkenes are of increasing value and interest in chemistry-related areas. However, their catalytic asymmetric synthesis remains elusive, due to the high steric repulsion and relatively low conformational stability. Herein, we disclose the straightforward construction of atropisomeric tetrasubstituted alkenes via an effective enantiocontrol of vinyl cations. This copper-catalyzed enantioselective C(sp2)–H functionalization of sterically hindered (hetero)arenes with vinyl cations enables the efficient and atom-economical preparation of axially chiral acyclic tetrasubstituted styrenes and pyrrolyl ethylenes with high atroposelectivities. Importantly, this reaction represents the first example for the assembly of axially chiral alkenes through vinyl cation approach. Computational mechanistic studies reveal the reaction mechanism, origin of regioselectivity, Z/E selectivity and enantioselectivity. The synthetic utility has been demonstrated by diverse product derivatizations, chiral organocatalyst synthesis, as well as further applications in asymmetric catalysis.