Oxidation of nitriles and amines

The transformation of nitriles into amides is a well-known and well-studied reaction that can be carried out under a variety of conditions and generally requires heating, a long reaction time and metal catalysts [40], A simple, mild and efficient method uses urea-hydrogen peroxide adduct (UHP H2NC0NH2 H202) in the presence of a catalytic amount of K2CO3 in water-acetone at room temperature [40, 41]. Some results are reported in Table 6.5. The procedure is efficient for both aromatic and aliphatic nitriles, and other hydrolyzable functionalities are preserved. 

Nitriles are not affected by SPB in acetic acid, but undergo oxidative hydration to form amides in aqueous media such as H20-Me0H [42]  

H20-acetone [43] and H20-dioxan [44]. When the reaction is performed on o-amidobenzonitriles, the oxidation is followed by cyclization to give quinozalin-4-(3fr)-ones, which are suitable systems to build pharmaceutical compounds [45]  

Anilines containing a carboxylic or alcoholic functionality are oxidized to nitro compounds by oxone in 20-50% aqueous acetone at 18 C in 73-84% yields [46]. When the reactions are performed in the absence of acetone, lower yields are obtained, suggesting the generation of dimethyldioxirane, which competes with oxone. 

The synthesis of aminopyridine A-oxides usually occurs under acidic conditions in organic media and generally requires protection of the amino group by acylation reaction and then a final deprotection [47]. By using oxone in water under neutral or basic conditions at room temperature, the reaction can be carried out directly on aminopyridine and the A-oxide is isolated in good yield [48]. The chemoselectivity depends on the position of the amino group in the pyridine ring. 

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