Selective electrochemical oxidation of heteroatom compounds having both silicon and tin on the same carbon as electroauxiliaries

The selective electrochemical oxidation of heteroatom compounds having two different electroauxiliaries, i.e. silicon and tin, on the same α-carbon was examined. The oxidation potentials of such compounds were found to be similar to those of the corresponding compounds having only tin, indicating the predominant role of tin over that of silicon. The HOMO levels obtained by the molecular orbital calculations were consistent with the experimental results. The molecular orbital calculation of the cation radical suggests the selective cleavage of the C-Sn bond by the oxidation. Preparative electrochemical oxidation gave rise to selective cleavage of the C-Sn bond and the introduction of a nucleophile to the carbon. The C-Si bond was not affected at all. The product can also be further oxidized using the silyl group as an electroauxiliary. The second oxidation proceeded smoothly to cleave the C-Si bond and a second nucleophile was introduced on the same carbon. The present study indicates the feasibility of the redox potential based selective sequential transformation using electroauxiliaries.