Electrochemical Properties and Reactions of Oxygen‐Containing Organotrifluoroborates and Their Boronic Acid Esters

Abstract

AbstractElectrochemical analyses of anisole, phenoxymethylboronic acid pinacol ester, tetra‐n‐butylammonium phenoxymethyltrifluoroborate, and their benzyloxy analogues were comparatively studied by using cyclic voltammetry measurements, and a marked β‐effect for organotrifluoroborates was found, which was indicated by experimental and theoretical aspects. Organotrifluoroborates were found to have much lower oxidation potentials than the corresponding boronic acid pinacol esters. The oxidation potentials of boronic acid pinacol esters were also significantly decreased in the presence of fluoride ions. This β‐effect is more pronounced than that of the corresponding organosulfur compounds reported previously. Anodic substitution reactions of organotrifluoroborates were successfully carried out in the presence of oxygen nucleophiles to provide regioselectively substituted products in moderate yields. Supporting‐electrolyte‐free electrolysis was also demonstrated.