First Enantioselective Chalcogen Bonding Catalysis Controlled Solely by σ-Hole Interactions

We report the first enantioselective organocatalysis driven exclusively by chalcogen bonding. A new class of chiral chalcogen-bond donors promotes the asymmetric aza-Henry reaction, governed solely by σ-hole interactions, to deliver drug-relevant β-nitroamines in high yields and enantioselectivities of up to 99:1 er. Mechanistic studies and controlled experiments corroborate the essential role of σ-hole directionality during the enantioselective nucleophilic addition. Despite their perceived weakness, σ-hole interactions proved sufficiently strong to enable substrate binding in competition with the triflate anion bound in the catalyst’s σ-hole. Until now, chalcogen bonding has served only as a supporting interaction alongside more prominent stereodetermining tools; however, this work pioneers its use as an independent stereodetermining tool in asymmetric synthesis, offering a conceptual alternative to more established hydrogen-bonding or metal-based strategies.