Synthesis Of S-alkyl Dithiocarbamates And S-aryl Xanthates Based On Electron Donor–Acceptor Complex Photoactivation

Elemental sulfur is prevalent in a wide range of bioactive natural products and pharmaceuticals,and sulfur-containing compounds are of increasing importance in polymer and materials chemistry,biomedical chemistry,etc.Therefore,construction of sulfur-containing organic compounds is of great importance.As the number of approved sulfur-containing pharmaceuticals has increased,researches have been conducted to construct C-S bonds in organic molecules.Dithiocarbamate compounds have been a focus of research in medicinal chemistry since the 20 th century and are well known for their wide range of applications in agriculture,polymer chemistry,coordination chemistry,etc.In recent years,dithiocarbamates act as a versatile intermediate in organic synthesis for the construction of various bioactive compounds.Many organic compounds containing dithiocarbamate groups exhibit unique chemical and medicinal versatility,and these compounds have been widely used as anti-tumor,anti-bacterium,antioxidation,and insecticidal agents.Xanthate esters,similar to dithiocarbamates,are also widely used in fungicides,pesticides and organic materials and have important design value in materials science and pharmaceutical science.In recent years,visible light-induced organic synthesis has been developed as an attractive alternative to traditional method of generating synthetically useful radical intermediates in complex settings,providing new pathways for the energy transfer and electron transfer of compounds.The introduction of visible light into organic synthesis by photocatalysis is undoubtedly a major breakthrough in terms of energy efficiency and environmental protection.Electron donor-acceptor(EDA)complex-mediated photoredox reactions have become a research hotspot for photocatalytic organic synthesis in recent years because of the ease of operation,the unique ability to use visible light to activate colorless substances,and the possibility of generating radicals without expensive metal complexes or organic dyes as catalysts.Based on the research achievements of our research group in visible light-induced organic synthesis and C-S bond construction,the synthesis strategies of S-alkyl dithiocarbamate and S-aryl xanthate compounds induced by visible light were explored in this paper,and the following new synthesis methods were developed:(1)An efficient and environmentally friendly visible-light promoted method for the synthesis of S-alkyl dithiocarbamates with a broad substrate scope and good functional group tolerance in water has been developed.Most appealingly,the reaction can proceed smoothly without any external photocatalyst being added.This method opens a new avenue towards S-alkyl dithiocarbamates,thus promising their broad applications in pharmaceutical chemistry and sulfur chemistry.(2)A method for the preparation of S-aryl xanthate by intermolecular charge transfer using functional sulfonium salts through the formation of EDA complex promoted by visible light is established.This mild,metal-free method provides a new synthesis method for the synthesis of S-aryl xanthate compounds and has wide applications in pharmaceutical chemistry.