Stereoselective vicinal C(sp³)-C bond formation via metallaphotoredox 1,2-difunctionalization of internal alkenes.

Abstract

Achieving precise stereocontrol when forging two vicinal C(sp³)-C bonds on unsymmetrical internal alkenes remains a formidable challenge. The comparable reactivity of alkyl radicals often compromises chemo- and regioselectivity, while the concurrent induction of diastereo- and enantioselectivity has proven elusive. Here, we show a unified metallaphotoredox strategy that addresses these challenges through two complementary multicomponent difunctionalization protocols. First, a Ni/terpyridine catalyst system enables anti-selective 1,2-dialkylation of both cyclic and acyclic internal alkenes, delivering vicinal C(sp³)-C(sp³) linkages with high levels of chemo-, regio-, and diastereoselectivity. A switch to a chiral biimidazole ligand and replacement of the alkyl halide with a (hetero)aryl bromide unlocks enantioselective 1,2-alkylarylation of cyclic internal alkenes. This transformation affords β-aryl-α-alkylated lactones and related scaffolds bearing two contiguous stereocenters with excellent diastereo- and enantioselective control. This dual strategy offers a rapid and efficient access to drug-like molecular architectures.