From symmetrical tetrasulfides to trisulfide dioxides: Via photocatalysis

A straightforward strategy involving photocatalysis has been established for accessing trisulfide dioxides from readily achieved symmetrical tetrasulfides. Stern-Volmer analysis and radical quenching experiments demonstrated the occurrence of a single electron transfer between the photocatalyst and sulfinic acid. Bioactive molecules such as the antihypertensive drug captopril, allicin derivatives, amino acids and terpenes were efficiently and reversibly linked through sulfur-sulfur covalent bonds. Furthermore, flow-setup syntheses of trisulfide dioxides were successfully achieved on the gram scale, indicating the great potential of the developed protocol for practical industrial applications.