Enantioselective Synthesis of Chiral 1,4-Dicarbonyls Bearing All-Carbon Quaternary Stereocenters via Photoredox/Nickel Dual Catalyzed Tandem Radical Addition/Oxidation.

Abstract

The asymmetric synthesis of 1,4-dicarbonyl compounds bearing all-carbon quaternary stereocenters remains a significant challenge in organic synthesis. Herein, we report a photoredox/nickel dual-catalyzed tandem radical addition and oxidation protocol that directly converts β-keto esters and styrenes into enantioenriched 1,4-dicarbonyl products in a single operation. This approach harnesses the synergistic cooperation of a photocatalyst and a chiral nickel catalyst to generate α-carbonyl radicals chelated to the chiral catalyst, via single-electron oxidation of in situ-formed Ni-enolate complexes. The resulting radical intermediates are stereoselectively trapped by alkenes, and the ensuing benzyl radicals are subsequently oxidized by molecular oxygen to furnish the desired scaffolds. This catalytic system operates under mild conditions using molecular oxygen as the terminal oxidant, thereby obviating the need for prefunctionalized coupling partners while offering excellent functional group compatibility and broad substrate scope.