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

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