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.