Transition-metal-free C–S bond cleavage and transformation of organosulfur compounds

The activation and transformation of organic chemical bonds is a fundamental scientific problem. In the past several decades, C-S bond cleavage for the construction of C-C and C-heteroatom bonds has received tremendous attention in organic chemistry. Although significant progress has been made in the field of transition metal strategies, a variety of novel transition-metal-free strategies have also been developed using halogenated reagents, oxidants, acids, and bases. Moreover, organic photochemical and electrochemical methods have also been developed to achieve transition-metal-free C-S bond cleavage of organosulfur compounds. To date, however, no comprehensive review of transition-metal-free strategies has been reported. Therefore, we herein provide a comprehensive review of the major advances in the field of the transition-metal-free C-S bond cleavage and transformation of organosulfur compounds, including thioethers, sulfoxides, sulfones, thioacetals, sulfonium salts, and sulfur ylides.