Electrochemical study of two tris-O-substituted calix[4]arenes:: 25,27-dipropoxy-26-hydroxy-28-benzoyloxycalix[4]arene(partial cone) and 25,27-dibenzyl-26-hydroxy-28-benzoyloxy-calix[4]-arene (partial cone).: Electro synthesis of the corresponding calix[4]arene-monoquinones

The anodic oxidation of 25,27-dipropoxy-26-hydroxy-28-benzoyloxycalix[4]arene 1 and 25,27-dibenzyl-26-hydroxy-28-benzoyloxycalix[4]arene 2 in dichloromethane was investigated by electrochemical and spectroclectrochemical techniques. For both, the overall reaction is a two-electron oxidation of the phenolic group according to an ECE mechanism resulting in the ultimate formation of an observable phenoxylium cation. After reaction of the latter with traces of water and subsequent internal electron transfer, the corresponding calix[4]-monoquinones are formed. (c) 2006 Elsevier B.V. All rights reserved.