Abstract
Carbon fiber (CF) was anodically oxidized and the resulting oxidized CF was modified with several organic compounds such as butyl bromide, benzoic anhydride, and β-cyclodextrin (CD) under electroreductive conditions. By using the resulting modified CFs as cathodes, the electroreduction of methyl cinnamate (1) was carried out in MeCN affording methyl 3,4-diphenylcyclopentanone-2-carboxylate (3), methyl 3-phenylpropionate (4), and trace amount of dimethyl 3,4-diphenyladipate (2), and the electrode effects on the reduction efficiency and the products selectivity were investigated. The use of the oxidized CF gave relatively high products selectivity (the products ratio 3/4=29.0) and slight increase of the reduction efficiency (62%) in comparison with the use of the untreated CF or the alkylated CF (the products ratio 3/4=9.4–9.6, the reduction efficiency=57–58%). In the electroreduction by using the modified CF having benzoate groups (Ph-modified CF) the yield of 3 and the reduction efficiency also increased (3/4=11.2, the reduction efficiency=67%). The use of the CD-modified CF afforded the highest yield of the hydromonomer 4 (15%) in MeCN–H2O mixed solvent. These electrode effects were explained by the interaction between the functional groups on the modified CFs and the substrate 1.
