Probing the Origin of Solvent Dependent Oxidation Behavior of Water-Soluble Hypervalent Iodine Reagents.

摘要

Recently synthesized and reported water-soluble derivatives of o-iodoxybenzoic acid (IBX) have exhibited solvent dependent oxidation behavior of alcohols. While the ease and selectivity of oxidation of alcohols using the new IBX derivatives parallel that of IBX in polar aprotic solvents. The selectivities observed in the oxidation of substrates carrying benzylic, non-benzylic and homobenzylic alcohol moieties in aqueous solvent mixtures allude to an alternate oxidation mechanism. The observed selectivities are explained both using an alternate H-atom abstraction mechanism and correlated to the bond dissociation energies of the benzylic, homobenzylic and non-benzylic alpha C-H bonds involved in the initial H-atom abstraction step. Progress towards the synthesis, 85 and 86, of two substrates, that carry combinations of benzylic, non-benzylic and homobenzylic alcohol moieties to further probe the observed selectivities will be discussed.