Base-Free SuFEx Reaction Promoted by Silica Gel for the Synthesis of β-Sultams

β-Sultams are recognized as potential antibacterial agents and crucial building blocks in chemical synthesis. Herein, a "SuFEx on silica gel" approach has been developed for one-step synthesis of β-sultams utilizing readily available amines and ethenesulfonyl fluoride (ESF). This process involves a sequential Michael addition of amines to ESF, followed by an intramolecular SuFEx reaction promoted by silica gel. Silica gel facilitates the activation of sulfonyl fluoride through hydrogen bonding between SVI–F and the surface hydroxyl groups on the silica gel and eliminates HF formed during the reaction. Notably, the use of a base, which is typically required in nearly all known SuFEx reactions, was rendered unnecessary. The β-sultam moiety was successfully incorporated into 26 tested primary amines, including pharmaceuticals and natural products, in high yields, showcasing the broad potential applications of this method.