Hydroperoxides, from alkenes, with hydrogen peroxide

Sulfides react faster with hydrogen peroxide and alkyl hydroperoxides than do alkenes. For this reason, transition metal catalysts are rarely necessary, but these reactions are acid catalyzed and first order in both sulfide and peroxide. The acid (HX) can be as weak as alcohol or water but the "effectiveness (of the oxidation) is determined by the pXa of the acid. Sulfides also react faster with peroxides than do ketones (see the Baeyer-Villiger reaction, sec. 3.6). Formation of the sulfone in these reactions is straightforward, but requires more vigorous reaction conditions. It is usually easy to isolate the sulfoxide from oxidation of a sulfide. Direct conversion of a sulfide to a sulfone requires excess peroxide and vigorous reaction conditions (heating, long reaction times, more concentrated peroxide). 

Literature procedures for the synthesis of hydroperoxides include the preparation from hydrogen peroxide (via reaction with alkyl halides, -phosphites, -suEonates, alkenes. 

Oxirans.— Epoxides are readily available from the catalytic oxidation of alkenes with 2-hydroperoxyhexafluoropropan-2-ol (HPHI) (1), which itself is easily prepared from hexafluoroacetone hydrate (2) and hydrogen peroxide (Scheme 1). HPHI is claimed to have similarities to the natural flavin hydroperoxides which are implicated in epoxidations and hydroxylations by external flavoprotein mono-oxygenases. Yields are typically in the range 77—92%. 

Oxirans.—A simple four-stage preparation of (5)-propylene oxide from ethyl L-( —)-maleate has been described (Scheme 2). This work is of importance for the synthesis of nonactin carboxylic acid. Another synthesis of optically-active propylene oxide involves the cyclization of OL-propylene chlorohydrin with a variety of bases in the presence of a cobalt complex the highest optical purity was 27%. Wynberg and co-workers have shown that the base-catalysed epoxidation of electron-poor alkenes is subject to catalytic asymmetric induction hydrogen peroxide and t-butyl hydroperoxide were used as oxidants in the presence of quaternary... 

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