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Hydroperoxide Oxidation of Different Organic Compounds Catalyzed by Silica-Supported Selenenamide

Giurg M., Brząszcz M., Młochowski J.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 3

417-428

EN

The recoverable heterogeneous silica-supported catalyst selenenamide 2 was prepared by the coupling of 3-aminopropylsilicate (4)with 2-chloroselenobenzoyl chloride (6). Its catalytic activity was demonstrated in tert-butyl hydroperoxide oxidation of aldehydes 8 to carboxylic acids 9 and benzylamines 17 to nitriles 18. Moreover, it was employed for hydrogen peroxide oxidation of azomethine compounds such as tosylhydrazones 10, oximes 13 and N,N-dimethylhydrazones 16 to parent ketones 12, arenecarboxylic acids 11 and 15, their methyl esters 14 and nitriles 18 depending on the substrate used and the reaction conditions. The catalystwas simply recovered by filtration and could be reused.

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Hydroperoxide Oxidation of Benzylamines Catalyzed by Selenium Compounds

Brząszcz M., Kloc K., Młochowski J.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 11

1579-1586

EN

Selenium(IV) oxide, poly(bis-1,2-phenylene) diselenide, bis[2-(N-benzisoselenazol- 3(2H)-onyl]diselenide and particularly 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen), were employed as the catalysts for hydrogen peroxide and t-butyl hydroperoxide oxidation of benzylamines. A reaction of primary amines proceeded via hydroxylamine and oxime, and the nitriles accompanied by imines, carboxylic acids and aldehydes were the final products. The secondary amines produced mainly the nitrones, while tetrahydroisoquinoline was dehydrogenated to isoquinoline.

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Związki selenu jako odczynniki i katalizatory w reakcjach utleniania związków organicznych

Młochowski J., Brząszcz M., Giurg M., Wójtowicz H.

Wiadomości Chemiczne

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2001

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[Z] 55, 1-2

9-44

EN

Oxidation reactions are fundamental processes widely applied in organic synthesis. Among many reagents used in these reactions, elemental selenium and particularly some of its compounds have been reported as effective and selective oxidants and catalysts for the oxidation of various organic substrates. One of them is selenium(IV) oxide, easily available regent for hydroxylation of activated a-positions particularly at allylic and propargylic sites. It also can introduce carbonyl functionality at activated positions. Used in combination with hydrogen peroxide or t-butylhydroperoxide it acts as oxygen-transfer agent. Both of these hydroperoxides can be used in the presence of seleniumu(IV) oxide for epoxidation, 1,2-dihydroxylation and a-carbonylation of alkenes, for oxidation of aldehydes into carboxylic acids, sulfides to sulfoxides or sulfones, secondary amines to nitrones and for other reactions. Benzeneseleninic acid, other areneseleninic acids and their anhydrides are known as stoichiometric oxidants or activators of other oxygen donors. They have been successfully applied for oxidation of many organic compouns, among them alkenes, alcohols, phenols, amines, hydrazones, sulfides, 1,3-dithiolanes and azines. Organic diselenides, the precursors of seleninic acids, have been used as oxygen-transfer catalysts for oxidation of various functional groups with hydrogen peroxide, t-butylhydroperoxide and other oxygen donors , while dimethyl and diphenyl selenoxides are efficient stoichiometric oxidants (e.g. for conversion of halomethyl or hydroxymethyl group into formyl group]. Most recently, selenenamides, particularly 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen) and its analogous were found as efficient catalysts for hydrogen peroxide and tbutylhydroperoxide oxofunctionalization of olefins, oxidation of azomethine compounds and sulfides.