Oxidation of sulfides by 3-hydroperoxy-4,4,5,5-tetramethyl-3-phenyl-1,2-dioxolane: Effect of solvent and sulfide substituent

Abstract

The reaction of 3-hydroperoxy-4,4,5,5-tetramethyl-3-phenyl-1,2-dioxolane, 1, with a series of sulfides (2a = thioanisole, 2b = ethyl phenyl sulfide, 2c = 2-chloroethyl phenyl sulfide, and 2d = 2-chloroethyl methyl sulfide) at 34°C in various solvents yielded the corresponding sulfoxides and 3-hydroxy-1,2-dioxolane 3 in quantitative yields. The oxidations showed excellent second-order kinetic behavior overall. In CDCl3, the reactivity order was 2d > 2b > 2a > 2c. For 2a, the relative rate in various solvents was CDCl3 (17); CD3OD (7); C6D6 (∼3); CD3CN (1); CD3C(O)CD3 (∼0.3). Addition of ∼1 equivalent of acetic acid to reactions of 1 and 2a in CDCl3 and C6D6 resulted in small increases in the values of k2. The results are consistent with an electrophilic oxygen-atom transfer mechanism similar to that proposed for oxidations by α-azohydroperoxides. Since the precursor to 1, 3-hydroxy-1,2-dioxolane 3, is regenerated during the oxidation, the system has the potential to be developed as a cyclic process. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:75–78, 1998