Construction Of C-S And C-Se Bonds Under Green Conditions

The C-S/C-Se bond is widely present in molecular structures such as biologically active compounds,pharmaceutical agrochemicals,and functional materials.In recent years,the construction of C-S/C-Se bond reaction has been well developed,and many important research results have been obtained.As one of the research hotspots in the field of chemistry,Green Chemistry advocates the use of less polluting reagents,efficient and low-energy reaction methods,and the use of environmentally friendly solvents.Therefore,it is still very urgent to explore the construction method of efficient green C-S/C-Se bond.The research content revolves the selective functionalization of alkyne to construct C-S /C-Se bonds.According to the principle of green chemistry,non-metal catalysis,ultrasonic radiation instead of traditional heating and the use of ionic liquids,etc.,selective functionalization of alkyne with thiocyanate or selenocyanate is achieved,and various important olefin derivatives containing C-S bond/C-Se bond are obtained.The following is a brief introduction to the research content of this paper:(1)A general method for the free radical addition reaction of sodium thiocyanate or potassium selenocyanate with an alkyne molecule to obtain a(E)-1,2-dithiocyano/dis-selenyl olefin derivative was studied.The reaction mechanism includes oxidizing sodium thiocyanate or potassium selenate,forming a thiocyano radical or a selenocyano radical intermediate,and further undergoing a bimolecular radical addition reaction with the alkyne molecule.The method has wide application range and high selectivity,and is a novel method for synthesizing dithiocyano/selenium cyano olefin derivatives.(2)A multi-component reaction of alkyne,potassium thiocyanate and elemental iodine under ultrasonic irradiation conditions was investigated to obtain the corresponding(Z)-1-thiocyano-2-iodoolefin compound.The reaction replaces the traditional stirring heating method with ultrasonic radiation,which significantly reduces the amount of catalyst/solvent added,shortens the reaction time,and improves the stereoselectivity of the reaction.The reaction substrate has good adaptability,simple reaction operation and mild reaction conditions.In addition,a multi-component reaction of potassium selenate,elemental iodine and alkyne under ultrasonic irradiation was further developed,and a series of(Z)-1-selenocyan-2-iodene compounds were synthesized.(3)A high stereoselective Michael addition reaction of acidic ionic liquid-promoted thiocyanate with electron-poor propionate was developed under ultrasonic irradiation conditions.A series of(Z)-3-thiocyanate was synthesized.A general method for acrylate based compounds.The reaction mechanism includes an intermolecular hydrogen bond between an acidic ionic liquid and an electron-poor alkyne,and the thiocyano group is added in a direction from a small steric hindrance.The reaction has the following advantages: the ionic liquid is used in a small amount and can be recycled;the reaction conditions are mild and the time is short,and the functional group compatibility is good.Based on the above work,we further expanded the highly stereoselective Michael addition reaction of selenocyanate and propiolate with the environmentally friendly natural biomass acid lactic acid instead of ionic liquid.