On the diastereoselective electrogeneration of (2SR,3SR)-1,5-diaryl-2-(2,2-dichlorovinyl)-3-(trichloromethyl)pentane-1,5-diones from 2,2,2-trichloroethylideneacetophenones. A combined experimental and density functional computational study

Abstract

Electrochemical reductions of 2,2,2-trichloroethylideneacetophenones under constant cathodic potential in anhydrous acetonitrile–lithium perchlorate followed by addition of water led to previously unknown (2SR,3SR)-1,5-diaryl-2-(2,2-dichlorovinyl)-3-(trichloromethyl)pentane-1,5-diones in high to near quantitative yields. The molecular structure of a member of this family of compounds, (2SR,3SR)-(2,2-dichlorovinyl)-1,5-bis(4-nitrophenyl)-3-(trichloromethyl)pentane-1,5-dione, was determined by X-ray crystallography. The formation mechanism of these products has been studied on the basis of chemical, voltammetric and HF and B3LYP computational methods. It corresponds to electrogeneration of dienolate anions, which attack starting material molecules by a Michael addition reaction type.