Electrochemical Synthesis of α-Fluoroalkylated Ketones using Sodium Fluoroalkylsulfinate
The fluorine-containing group has a significant effect on properties such as lipophilicity,permeability,and meta-bolic stability of compounds.Therefore,the efficient introduction of fluorine-containing groups into pharmaceutical and ag-rochemical compounds,as well as functional organic materials,has become an important research field of chemistry.Un-doubtedly,new methodologies for the efficient and highly selective incorporation of fluorinated substituents into diverse mo-lecular structures continue to be in strong demand.During the past few years,electrosynthesis has been considered to be a practical and environmentally friendly synthetic tool.The application of electrochemical anodic oxidation in synthetic organ-ic chemistry has drawn increasing attention.Electrochemistry utilizes direct interaction of electrons from the anode and cathode with the nucleus,avoids using strong oxidants,and minimizes byproduct formation.Herein we describe an electro-chemical synthesis of α-trifluoromethylated ketones from alkenes based on sodium trifluoromethanesulfinate.Sodium tri-fluorometh anesulfinate generates trifluoromethyl radicals through anodic oxidation to attack the carbon-carbon double bonds of alkenes,and then oxidized in air atmosphere to obtain the target compounds.The optimized reaction conditions of electro-chemical synthesis of α-trifluoromethylated ketones are as follows:1 equiv.of alkenes,2 equiv.of sodium trifluoro-methanesulfinate,a mixture of CH3CN/H2O(V∶V=2∶1)as the solvent,2 equiv.of lithium perchlorate as electrolyte,CF3COOH as the sacrificial oxidant,graphite as the anode and platinum as the cathode,react at room temperature for 6 h under a constant current of 20 mA and air atmosphere,giving the corresponding α-trifluoromethyl-substituted ketones in 66％～84％yields.The reaction substrate has good applicability,and the reaction conditions are mild.Compared with the traditional methods,the electrocatalytic process avoids the use of peroxidants or expensive photocatalysts.In addition,this reaction can be applied to the synthesis of α-difluoromethylated ketones when using sodium difluoromethanesulfinate instead of sodium trifluoromethanesulfinate.
NETL
NSTL
万方数据
