Catalytic asymmetric sulfonimidoyl transfer to access chiral sulfonimidoyl fluorides and related derivatives.

Sulfur fluoride exchange (SuFEx) click chemistry is a powerful tool for constructing functional molecules. However, catalytic asymmetric methods for constructing chiral sulfur(VI)-centred sulfonimidoyl fluorides are rare, resulting in the limited application of SuFEx. Owing to the crowded three-dimensional environment, chiral sulfonimidoyl transfer is challenging. Here we show a catalytic enantioselective Cl-F exchange reaction to realize the asymmetric sulfonimidoyl transfer reaction with racemic sulfonimidoyl chlorides as reactants, constructing chiral SuFEx connecting arms. This strategy enables chiral sulfonimidoyl azides, sulfonimidamides and sulfonimidoyl esters by reacting with corresponding nucleophiles. Mechanistic studies revealed that the reaction is a dynamic kinetic asymmetric transformation process, and a two-catalyst-bound pentacoordinate sulfur is responsible for the sulfur-configurational epimerization. The key steps involve the formation of O-sulfonimidoyl ester pyridinium cation intermediates via covalent organocatalysis. The resulting optically active sulfonimidoyl fluorides enable a further stereospecific SuFEx with C-, N- and O-centred nucleophiles, thereby establishing a modular platform for the asymmetric SuFEx ligation.