Three‐Component Radical Cross‐Coupling: Asymmetric Vicinal Sulfonyl‐Esterification of Alkenes Involving Sulfur Dioxide

Abstract A novel catalytic system for radical cross‐coupling reactions based on copper and chiral Pyridyl‐bis(imidazole) (PyBim) ligands is described. It overcomes the challenges of chemoselectivity and enantioselectivity, achieving a highly enantioselective vicinal sulfonyl‐esterification reaction of alkenes involving sulfur dioxide. This strategy involves the use of earth‐abundant metal catalyst, mild reaction conditions, a broad range of substrates (84 examples), high yields (up to 97% yield), and exceptional control over enantioselectivity. The reaction system is compatible with different types of radical precursors, including O ‐acylhydroxylamines, cycloketone oxime esters, aryldiazonium salts, and drug molecules. Chiral ligand PyBim is identified as particularly effective in achieving the desired high enantioselectivity. Mechanistic studies reveal that copper/PyBim system plays a vital role in C─O coupling, employing an outer‐sphere model. In addition, the side arm effect of ligand is observed.