Electrogeneration of (Z)-α-aroyloxy-β-aroylthiostilbenes and (Z)-4,5-diaryl-2-arylimino-1,3-oxathioles by cathodic reduction of monothiobenzils in the presence of electrophilic reagents. Computational B3LYP and RI-MP2 study on the relative stability of oxathiole compounds

Abstract

Electrochemical reductions of monothiobenzils in the presence of either aroyl or carbonimidoyl dichlorides were carried out, yielding products with sulfur retention. Electrolyses in the presence of aroyl chlorides led to previously unknown (Z)-α-aroyloxy-β-aroylthiostilbenes in high to quantitative yields, whereas reactions in the presence of arylcarbonimidoyl dichlorides provided novel 4,5-diaryl-2-arylimino-1,3-oxathioles in fair to high yields. The molecular structures of (Z)-α-benzoyloxy-β-benzoylthio-4,4′-dimethylstilbene and (Z)-2-(2,4-dichlorophenylimino)-4,5-diphenyl-1,3-oxathiole were determined by X-ray crystallography. Also, ab initio HF, density functional B3LYP, and Moller–Plesset RI-MP2 procedures were applied to oxathiole compounds revealing that (Z)-isomers are more stable than (E)-isomers and that both isomers are separated by a relatively low activation barrier.