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 for electrochemical oxidative difluoroethylation using sodium difluoroethylsulfinate (DFES-Na) has been reported, which successfully generates difluoroethyl radical for the first time. This method allows the quick synthesis of valuable difluoroethylated azaheterocycles, including oxindoles and isoquinoline-1,3-diones, in moderate to good yields. The electrochemical cyclopropyldifluoromethylation of N-arylacrylamides also shows good results using this strategy. Furthermore, radical capture and cyclic voltammetry (CV) experiments were carried out to confirm the proposed mechanism.