Mechanistic Studies on the Anodic Functionalization of Alkenes Catalyzed by Diselenides

Herein, we present a detailed kinetic and thermodynamic analysis of the anodic allylic esterification of alkenes as well as the bulk application of the anodic amination and esterification of nonactivated alkenes catalyzed by diselenides. The electrochemical study led to a comprehensive picture of the coupled electrochemical and chemical reaction steps. Cyclic voltammetry measurements are consistent with a bimolecular step after initial electrochemical 1e– oxidation of the diphenyl diselenide catalyst, 1a, and therefore we postulate a dimerization of the cation, which reacts very rapidly with the alkene, forming the addition product, i.e. the selenolactone 2a. Subsequent electrochemical oxidation of 2a occurs at a slightly higher potential than initial oxidation of 1a. The second oxidation is also followed by a bimolecular process and we hypothesize a dimerization of the cation, which finally eliminates 1a and protons in the rate-determining step, forming the product. Electrochemical analysis of various catalysts, i.e. nonsterically demanding diaryl diselenides with electron withdrawing and donating substituents, revealed that the oxidation potential of the catalyst and the intermediate can be readily tuned by the substituents, thus, prospectively allowing for a wide application of olefinic and nucleophilic substrates. The substituent pattern at the alkene has a smaller influence on the redox potential of the adduct. Controlled potential electrolysis experiments employing different nucleophiles proved that the reaction can be run electrochemically. The functionalization of unactivated alkenes with N- and O-nucleophiles was successfully demonstrated in several bulk electrolysis experiments, and the products were isolated in good yields