Mechanistic aspects of the reaction of dimedone derivatives with sulfenic acids and other sulfur compounds-a computational study

Dimedone derivatives are used as highly selective test reagents for the detection of biogenic sulfenic acids. DFT-calculations have been applied to elucidate the reaction mechanism and the factors triggering the selectivity towards sulfenic acids, in the presence of other sulfur compounds, such as sulfinic acids, sulfonic acids and disulfides. The SN2-like substitution of the sulfenic OH by dimedone requires the active participation of water molecules for pre-orientation of the reactants, as a proton shuttle and depository, as well as a buttressing agent. Alternative reaction pathways could be excluded because of their unfavourable energy profiles.