Metal-Free Electrochemical Oxidative Difluoroethylation/Cyclization of Olefinic Amides To Construct Difluoroethylated Azaheterocycles

A new strategy of electrochemical oxidative difluoroethylation to generate difluoroethyl radical with sodium difluoroethylsulfinate (DFES-Na) has been reported for the first time. The method allows quick access to a variety of valuable difluoroethylated azaheterocycles including oxindoles and isoquinoline-1,3-diones via radical tandem difluoroethylation/cyclization in moderate to good yields. The electrochemical cyclopropyldifluoromethylation of N-arylacrylamides also works well using this strategy. Moreover, radical capture and cyclic voltammetry (CV) experiments are also carried out to determine the proposed mechanism.

Automated summary

A new strategy of electrochemical oxidative difluoroethylation using sodium difluoroethylsulfinate (DFES-Na) has been reported for generating difluoroethyl radical. This method provides a quick access to valuable difluoroethylated azaheterocycles including oxindoles and isoquinoline-1,3-diones via radical tandem difluoroethylation/cyclization with moderate to good yields. The electrochemical cyclopropyldifluoromethylation of N-arylacrylamides also showed good results using this strategy. Furthermore, radical capture and cyclic voltammetry (CV) experiments were conducted to determine the proposed mechanism.