Metal-free Synthesis Of Vinyl Sulfides Under Continuous-flow Conditions

Vinyl sulfides are key structural motifs found in bioactive compounds,natural products and polymers.Different synthetic methods have been developed to construct such structures.However,many of them could demand harsh reaction conditions and/or the employment of metallic reagents or catalysts.Flow chemistry also known as continuous-flow chemistry,refers to the completion of a series of reactions in a continuous-flow liquid.Compared to traditional batch chemistry,flow chemistry has better process safety,especially in gas production and high temperature reactions.At the same time,it can increase production capacity,save space and facilitate the expansion of the reaction scale.In this paper,the following work is carried out around the metal-free synthesis of vinyl sulfides in a continuous-flow conditions:we demonstrated a metal-free two-step continuous-flow approach to access vinyl sulfides.Through a series of condition screening,the optimal conditions are obtained.That is using DCM as a solvent,various terminal alkenes and thiol compounds,and sulfonyl chloride as raw materials,a two-step continuous-flow reaction under 0°C is used for rapid synthesis to access vinyl sulfides.35 compounds were synthesized by this method(?)This method can rapidly access vinyl sulfides with easily accessible terminal alkenes and thiol compounds under mild conditions.In comparison to reactions conducted under batch conditions,the flow syntheses Flow synthesis does not require intermediate separation or low temperature equipment,which not only effectively simplifies the synthesis of alkenyl sulfides,but also significantly improves the yield of the target product.This protocol represents a successful example of handling unstable sulfenyl chloride intermediates by using a simple yet efficient continuous-flow protocol.and has certain reference value for the synthesis of related structural types of products.Moreover,the obtained vinyl sulfides have been successfully transformed into various compounds by post-synthetic modifications on the sulfur atom or the carbon-carbon double bond,the obtained alkenyl sulfides have been successfully converted into a variety of compounds with certain application prospects.The structures of above compounds were characterized by ¹H NMR,¹³C NMR and HRMS,and the characteristic structure was confirmed by X-Ray single crystal diffraction.