Photo-induced Desulfurative Processes for Carbon Radical Generation

Thiols constitute an important family among sulfur-containing compounds, with well-established applications in various fields ranging from medicine to material science. For instance, thiol residues are good hydrogen donors which reduce radical species in biological or chemical processes. However, even though the S-H bond activation of thiols for providing access to thiyl radicals has been largely studied, desulfurative processes affording carbon-based radicals by C-S bond activation have been less explored. In recent years, photoredox catalysis has become the prevalent method for the generation of radicals under soft reaction conditions from readily available starting materials under visible light. In this context, recent studies have been devoted to the development of photocatalytic procedures aiming at the desulfurization of thiol derivatives leading to new C-H, C-C or C-Het bond formation reactions. This review will cover the synthetic methodologies and strategies for photo-mediated desulfurization of native thiols, thioethers, sulfonium salts and xanthates to access new organic compounds. This emerging field is especially interesting for new transformations of cysteine and peptide derivatives.