Elektrosynthese von N‐substituierten DL‐Arylglycinestern und 1,2‐Diarylamino‐1,2‐diarylethanen durch Kathodische Reduktion von Azomethinen in Gegenwart von CO2

Electosynthesis of N‐Substituted DL‐Arylglycineesters and 1,2‐Diarylamino‐1,2‐diarylethanes by Cathodic Reduction of Azomethines in the Presence of Carbon Dioxide The electroreduction of the N‐arylidene‐arylamines 1–12 in CO2‐saturated solvents of low proton availability as DMF at markedly more positive potentials than carbon dioxide end up in carboxylating the C‐atom and hydrogenating the nitrogen of the double bond. The resulting N‐arylsubstituted DL‐arylglycines and traces of carbamates may be isolated as esters, adding ethylchloride during the electrolysis. A competing pathway of the electrocarboxylation is the CC‐hydrodimerisation and the hydrogenation of the double bond, whose importance increases with the water content of the solvent. Based on cyclic‐voltametric evidence and product analysis the mechanism of the reductive electrocarboxylation reaction is discussed in terms of nucleophilic attack of the azomethine anion radical on a proton or CO2.