Oxymetallation. Part 10. Synthesis of β-mercurioalkyl hydroperoxides and bis-β-mercurioalkyl peroxides from hydrogen peroxide

Abstract

Terminal alkenes react with mercury(II) trifluoroacetate and hydrogen peroxide in dichloromethane to provide mixtures of β-mercurioalkyl hydroperoxides (CF₃·CO₂·Hg·CH₂·CR¹R²·O·OH) and bis-β-mercurioalkyl peroxides [(CF₃·CO₂·Hg·CH₂·CR¹R²·O)₂]. Product ratios have been determined for reactions with amounts of hydrogen peroxide varying from 0.5 to 3 mol. equiv.

Representative peroxymercurials have been isolated, sometimes as the organomercury chloride, and characterised both spectroscopically and by their chemical reactivity. Under acidic conditions suitable hydroperoxides undergo a Criegee-type rearrangement to yield mercuriated ketones, whereas peroxides derived from monosubstituted ethenes undergo carbonyl-forming eliminations under basic conditions. Peroxides have also been characterised by bromodemercuriation, and hydroperoxides by participation in further peroxymercuriations; the latter process has afforded the mixed peroxide CF₃·CO₂·Hg·CH₂·CMe₂·O·OCHPh·CH₂·Hg·O₂C·CF₃.

¹³ C N.m.r. spectroscopy has been shown to be particularly suitable for analysing mixtures of hydroperoxides and related peroxides, and has been used to distinguish diastereoisomeric peroxides in which the asymmetric centres are separated by the peroxide linkage.