Concurrent Anodic Cyanation and Methoxylation of Methylated Furans. Oxidation Potential and Reactivity, and Stereochemical Control of Addition

Article abstract of DOI:10.1246/bcsj.60.229

The potentiostatic electrooxidation of a series of methyl-substituted furans was performed in MeOH that contains NaCN at a Pt anode in a divided cell.In all instances, the 1,4-additions of cyano and/or methoxyl group(s) across the furan ring were achieved.Replacement of an aromatic hydrogen by a cyano group occured concurrently in some cases.The relative rates of cation radicals toward two different nucleophiles (CN^- ion and the solvent MeOH) (or the MeO^- ion as a result of the equilibrium between CN^- ion and the solvent MeOH) at the electrode surface were determined from the yields of products by using the rate expressions of competitive reactions.There is a linear correlation between the relative reactivity of the furans (on a log scale) and their oxidation potential.The ratio of stereoisomers formed in an electrooxidation of 2,5-dimethylfuran (2,5-DMF) changes with addition of adsorbable compound as well as substrate concentration and this is thought to be due to the influence of concentration (or coadsorbate) on substrate orientation in the adsorption layer.