Photocatalytic Direct C-S Bond Formation:Facile Access To Organosulfur Compounds Based On Thiolyl Radicals

Carbon-sulfur bonds play an important role in the organic compounds.The functionalization of thiol groups through C-S bond formation not only has served as a crucial synthetic strategy in medicinal chemistry and chemical biology,but also was playing a prominent approach in advanced functional materials,structural frameworks of natural products and pharmaceuticals.In addition,thiols as a synthetic precursor are also widely used in the field of organic synthesis.Photocatalysis features low cost,easy access and environmental friendliness,which has been widely used in organic synthesis in recent years.Therefore,photocatalysis has become one of the most active research fields in recent years.In our research,we presented a protocol for direct functionaliztion of thiols to access3-thioindole/thiocyanate derivatives via visible-light induced using Rose bengal as the photocatalyst.Furthermore,we also discussed the substrate adaptability of the two photocatalytic synthesis strategies and studied their respective reaction mechanisms.The main research work is as follows:1.Direct thiocyanation strategy,we reported a novel C-S bond cleavage and reconstruction strategy for the synthesis of thiocyanates through direct photocatalytic S-H bond cyanation from thiols and inorganic thiocyanate salts.In our strategy,the unprecedented example of cutting off C-S bond of SCN~-to deliver the green?CN?sources is demonstrated.This transformation features nontoxic and inexpensive?CN?sources,available starting materials,metal-/base-/ligand-/peroxide-free,high step economy and mild conditions.It leads to the construction of various thiocyanates and some medicinally and biologically active thiocyanate-containing molecules.2.Combined with the concept of photocatalytic direct functionalization of thiol compounds,we developed an efficient and convenient protocol for the construction of 3-sulfenylations via photocatalytic direct C-3 sulfenylation of indoles with thiophenols.This protocol employs thiophenols as the sulfenylating agents,inexpensive rose bengal as the photocatalyst,and shows high atom and step atom economy,and environmental advantages.The representative method provides a straightforward approach for C-S bond formation,and has potential applications in the chemical and pharmaceutical industries.