Highly Stereoselective Dimerization of 3-Alkoxyimino-2-aryl-alkylnitriles via Oxidative Carbon-Carbon Bond Formation

The MnO2-mediated oxidative dimerization of a series of 3-alkoxyimino-2-aryl-alkylnitriles was investigated. The developed method stereospecifically afforded solely the corresponding C2-symmetric dl-dimers, with the trans-configuration of the C=N double bonds, in good to excellent yields under mild conditions. The alkoxyimino substituents in the substrates and a thermodynamically controlled mechanism are proposed to be essential for the stereo­selectivity of this radical dimerization process.