Oxone reaction with aldehydes

Oxone has also been recently more thoroughly studied as reagent for the oxidation of aldehydes. Aryl- and aliphatic aldehydes can be efficiently converted directly to acids or esters depending on the choice of solvent (eq 34). They can also be converted to nitriles in one pot by reaction with hydroxylamine on alumina with microwave irradiation (eq 35). ... 

Recently, Borhan and coworkers reported the facile oxidation of aliphatic and aromatic aldehydes to acids and esters in DMF or methanol with Oxone (equation 53) . These reactions are considered to be valuable alternatives to traditional metal-mediated oxidations. 

When a variety of aldehydes and Af,Af-dimethylhydrazones are treated with Oxone on wet AI2O3 under microwave irradiation in the absence of a solvent, the corresponding nitriles are obtained in good yields. Under these reaction conditions high selectivity... 

Oxidative Cleavage of Alkenes. An alternative to the oxidative cleavage of alkenes using ozone or the Lemieux-Johnson protocol has been reported recently. Under the action of catalytic osmium tetroxide, with oxone as a reoxidant, a variety of substituted alkenes were cleaved efficiently to furnish carbonyl compounds (eq 37). Any of the aldehydes that are produced via this sequence are immediately oxidized in situ to give the corresponding acid clearly this does not happen for any ketones so produced. Even electron deficient alkenes such as o , -unsaturated carbonyl compounds could be conveniently oxidized, although the products then underwent a decarboxylation reaction to produce the corresponding diacid. 

Interestingly, the reaction of a solid slurry of Oxone and wet Alumina with solutions of cyclic ketones in CH2CI2 provokes Baeyer-Villiger oxidation to give the corresponding lactones (eq 2). The same wet alumina-Oxone reagent can be used to oxidize secondary alcohols to ketones (eq 3). Aldehydes are oxidized to acids by aqueous Oxone. ... 

Ketones, Aldehydes, and Alcohols. The well-known Baeyer-Villiger oxidation of ketones by Oxone (eq 2) has been exploited in a variety of reactions. This protocol has been used with KHSO5 for cleavage of a- and /3-dicarbonyl compounds to esters or acids (eqs 30 and 31). This process is sirr5>ler, cheaper, and milder than the commonly used haloform reaction. 

Polystyrene-supported iodosylbenzene (22) (loading of -lO groups up to 1.50 mmol g" ) has been prepared by a solvent-free reaction of poly[(diacetoxyiodo)styrene] (4) with sodium hydroxide (Scheme 5.11) [22]. Elemental analysis of polymer 22 indicates that the -lO groups are partially hydrated as shown in structure 23. This resin has been successfully used for efficient oxidation of a diverse collection of alcohols to aldehydes and ketones in the presence of BF3-Et20. Reagent 22 can also be employed as efficient co-catalyst in combination with RuCls in the catalytic oxidation of alcohols and aromatic hydrocarbons, respectively, to the corresponding carboxylic acids and ketones using Oxone as the stoichiometric oxidant [22]. 

This reaction has been improved by addition of 2,6-lutidine to suppress the side reactions and increase the yields of aldehydes. In addition, this oxidation has been modified by using osmium tetraoxide and oxone as oxidants, which directly convert 1,2-disubstituted olefins into two individual carboxylic acids. On the basis of this modification, osmium tetraoxide has been made to be a three-dimensional networked nanomaterial that, in combination with oxone, forms a superior heterogeneous catalyst, which even oxidizes alkynes into carboxylic acids7... 

Hydrazones stemming from aldehydes are easily converted into nitriles. For example, when treated with alkylating agents hydrazones form hydrazonium salts [232], which upon ehmination give nitriles as the formally oxidized products. Alternatively, hydrazones can be oxidized directly, and for this reaction oxidants such as peracids [233], oxone [234] and dioxirane [235] were found to be effective. Finally, catalytic systems based on combinations of hydrogen peroxide with metal catalysts [236] or selenium compounds [237] have been developed for this process. Other reactions along these lines include oxidations of monohydrazones giving diazo compounds [238] or nitrilimines [239] and conversions of vicinal dihydrazones into alkynes [240]. 

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