Hydrogen peroxide oxidation systems

Paillard H, Brunet R, Dore M (1988) Optimal Conditions for Applying an Ozone/Hydrogen Peroxide Oxidizing System, Water Research 22 91-103. 

Imines 337 were converted to oxaziridines 338 in good to excellent yields (60-90%) using a benzonitrile-hydrogen peroxide oxidizing system (Table 27) <2001SC263>. Commercial aqueous hydrogen peroxide (35%) can be used successfully in this reaction. Nonracemic oxaziridines were obtained when chiral imines were used. 

In the presence of metal catalysts, hydrogen peroxide oxidations proceed in improved yields. The most common catalyst is an iron(II) salt which produces the well-known Fenton system or reagent. Dimethyl sulphoxide is oxidized to the sulphone using this system although a range of unwanted side-products such as methanol and methane are produced Diphenyl sulphoxide does not react using this reagent due to its insolubility and in all cases some iron(III) is formed by other side-reactions. 

This gives tautomeric mixtures119 when the tert-butyl group is removed. The methyl ether has been used to obtain 3-hydroxy-2-carbonyl derivatives in the selenophene series.120 The unsubstituted 2-hydroxyselenophene system has been prepared by hydrogen peroxide oxidation of 2-selenophene-boronic acid.121 However, in the 5-methyl-substituted system deboronation became such an important side reaction that 5-methyl-2-hydroxyselenophene had to be prepared by acid-catalyzed dealkylation of 5-methyl-2-fert-butoxy-selenophene. Both 2-hydroxy- and 5-methyl-2-hydroxyselenophene exist mainly as 3-selenolene-2-ones (93) and for the 5-methyl derivative it was possible to isolate the / ,y-unsaturated form (92) and follow the tautomeric isomerization. The activation parameters thus obtained were compared with those for the corresponding furan and thiophene systems. 

The formation of chloramines is an initial step of another mechanism of oxidative modification of LDL. It has been shown that the MPO-hydrogen peroxide-chloride system reacts with L-tyrosine to form p-hydroxyphenylacetaldehyde [163], As activated neutrophils release both MPO and hydrogen peroxide, it was suggested that neutrophils can stimulate the formation of p-hydroxyphenylacetaldehyde by producing chloramines as intermediates during the oxidation of LDL [164],... 

HOC1 is probably not a single active MPO oxidant able to chlorinate LDL. Hazen et al. [166] have shown that such a powerful oxidant as molecular chlorine is formed under in vitro conditions during the reaction of MPO-hydrogen peroxide-chloride system of phagocytes with LDL. They pointed out that there is an equilibrium between HOC1 and Cl2, which is shifted to the right under acidic conditions ... 

Heinecke JW, Li W, Mueller DM, Bohrer A, Turk J (1994) Cholesterol Chlorohydrin Synthesis by the Myeloperoxidase-Hydrogen Peroxide-Chloride System Potential Markers for Lipoproteins Oxidatively Damaged by Phagocytes. Biochemistry 33 10127... 

Hazen SL, d Avignon A, Anderson MM, Hsu FF, Heinecke JW (1998) Human Neutrophils Employ the Myeloperoxidase-Hydrogen Peroxide-Chloride System to Oxidize a-Amino Acids to a Family of Reactive Aldehydes. J Biol Chem 273 4997... 

H12. Hazen, S. L., d Avignon, A., Anderson, M. M., Hsu, F. F., and Heinecke, J. W., Human neutrophils employ the myeloperoxidase-hydrogen peroxide-chloride system to oxidize alpha-amino acids to a family of reactive aldehydes. Mechanistic studies identifying labile intermediates along the reaction pathway. J. Biol. Chem, 273, 4997-5005 (1998). 

Figure 3.39 Oxidation of alcohols using a hydrogen peroxide I hydrogen bromide oxidation system.

Figure 3.77 Use of the photolytic hydrogen peroxide/HBr system for the side-chain oxidation of mildly activated alky (benzenes.

When hydroboration of an olefin is carried out with the intention of oxidizing an initially formed secondary alcohol to a ketone, hydrogen peroxide oxidation can be dispensed with and the alkylborane oxidized directly with chromic acid. Thus Pappo converted a hydroxyl-free A -steroid into a mixture of stereoisomeric alkyl-boranes comparable to (1) and (2), oxidized the mixture with chromic acid, and obtained the 6-keto-5a-steroid in good yield the initially formed 6-keto-5i3-steroid underwent isomerism in the process. H. C. Brown developed an efficient two-phase system for oxidation of either alkylboranes or free alcohols to the ketones using aqueous chromic acid and ether. 

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