Organocatalytic Silicon-Free SuFEx reactions for modular synthesis of sulfonate esters and sulfonamides

Sulfur(VI) fluoride exchange (SuFEx) click chemistry provides a powerful tool for rapid construction of modular connections. Here, we report a novel catalytic silicon-free SuFEx reaction with sulfonyl fluorides. Under the catalysis of 10 mol% N-heterocyclic carbene (NHC), a range of phenols and alcohols react with different sulfonyl fluorides to afford sulfonate esters in 49-99% yields. In addition, Under the relay catalysis of 10 mol% N-heterocyclic carbene and 10 mol% 1-hydroxybenzotriazole (HOBt), a variety of primary and secondary amines react with different sulfonyl fluorides to produce sulfonamides in 58%-99% yields. More than 140 sulfonylated products, including 17 natural product derivatives have been prepared through this method. Mechanism study showed that NHCs might act as a carbon-centered Brønsted base to catalyse the SuFEx click reactions via the formation of hydrogen bonding with phenols or alcohols.