Electrochemical, EPR, and quantum chemical study of reductive cleavage of <i>cone</i>‐Calix[4]arene nosylates – New electrosynthetic approach

Abstract The mechanism of electrochemical reduction a series six cone ‐calix[4]arene‐bis‐nosylates (4‐nitrophenylsulfonate aryl esters) was investigated on mercury electrodes using DC‐polarography and cyclic voltammetry (CV) combined with in situ electron paramagnetic resonance (EPR)‐spectroelectrochemistry aprotic dimethylformamide. Model compounds – expected fragments products ‐ were studied for comparison. experimental results are supported by quantum chemical calculations. All calix[4]arene‐bis‐nosylates reduced first reversible step to bis‐(radical anion) two simultaneous one‐electron transfers. Each the electrons is unpaired separately localized nosylate groups. In second next 2×2 transferred both sulfonate ester groups cleaved 4‐nitro‐benzenesulfinate ions calixarene bis‐phenolate (95%). This electroreductive generation arylsulfinate anions significant finding from electrosynthetic point view. Activated arylsulfinates, synthesis which generally difficult, can be easily prepared nosyl esters.