ELECTROCHEMICAL SYNTHESIS AND X-RAY MOLECULAR-STRUCTURE OF 2-ARYLIMINO-4,5-DIARYL-1,3-DIOXOLES

Selective cathodic reduction of diaryl-1,2-diketones in the presence o f N-arylcarbonimidoyl dichlorides leads to 2-arylimino-4,5-diaryl-1,3- dioxoles, a little known class of heterocycle, in almost quantitative yields. NMR spectra of these compounds show a remarkable dependence up on temperature associated with a low configurational stability around the carbon-nitrogen double bond. An x-ray crystallographic analysis ha s been performed showing an unusually short carbon-nitrogen double bon d, which might be expected to be longer to explain the mechanism of th e facile thermal isomerization through a polar transition state in whi ch the double bond character is lost.