Water-accelerated single-electron transfer aquaphotocatalysis for open-chain SuFEx hubs

Sulfur(VI)-fluoride exchange (SuFEx) has emerged as a strategy to capitalize on intermolecular conjugation possible using sulfonyl fluorides. The facile synthesis of alkylated sulfur(VI) species is crucial, and their water-compatible nature unlocks a myriad of potential applications. Here, we report an aquaphotocatalysis approach for efficiently synthesizing open-chain sulfonyl fluorides facilitated by bulk water. A range of amines and carboxylic acids is efficiently converted to alkyl sulfonyl fluoride products under mild aqueous conditions, using 0.1–1 mol% of cyanoarene organic photocatalyst (1,3-dicyano-2,4,5,6-tetrakis(diphenylamino)-benzene, 4DP-IPN). Detailed mechanistic investigations suggest a single-electron transfer photochemical pathway. Sulfonyl fluoride products are used in SuFEx click chemistry for intermolecular conjugation with diverse small molecules and a DNA scaffold. This water-accelerated single-electron transfer aquaphotocatalytic strategy provides a platform for accessing alkyl sulfonyl fluoride libraries for potential drug discovery.