Phosphate‐Modulated Asymmetric Copper Catalysis for Photochemical Enantioselective S ‐Benzylation of Sulfenamides

ABSTRACT S ‐stereogenic sulfilimines constitute valuable S(IV)‐based scaffolds widely encountered in chiral ligands, pharmaceuticals, and bioactive molecules, yet their catalytic enantioselective construction remains a formidable challenge. Herein, we report a versatile copper catalytic platform assembled from a chiral pyridine‐oxazoline (PyOx) ligand, a bulky phosphate, and a Cu(I) salt to generate the active catalyst. This chiral copper/PyOx/phosphate system accommodates three mechanistically distinct radical‐generation pathways upon light irradiation, encompassing single‐electron transfer reduction of Katritzky salts, proton‐coupled electron transfer decarboxylation of carboxylic acids, and hydrogen atom transfer activation of toluene derivatives. Such flexibility enables efficient asymmetric radical benzylation of readily accessible sulfenamides under mild conditions. Mechanistic investigations reveal that the phosphate anion serves a multifunctional role, modulating the copper coordination sphere and stabilizing key copper–sulfur intermediates, which collectively boost both reactivity and enantioselectivity. The methodology delivers enantioenriched sulfilimines with broad substrate scope and operational simplicity. This work establishes a general blueprint for integrating multiple radical‐generation modes into a single stereocontrolled catalytic framework, demonstrating that rational modulation of the secondary coordination sphere can unlock new possibilities in stereoselective radical chemistry.