Aldehydes amides from, with hydroxylamine

Nitrones resulting from the condensation of aldehydes and ketones with N-monosubstituted hydroxylamines were used in a four component Ugi reaction in a one-pot synthesis of a-acyloxyamino-amides (260). 

Palladium(ii) acetate (Pd(OAc)2) exhibits catalytic behaviour for this transformation when used in conjunction with hydroxylamine hydrochloride in a DMSO-H2O mixture (Scheme 17.19). This reaction is most favourable under elevated temperatures of 100 °C and for some substrates can also require lengthy reaction times of 20 hours. In addition to these metals, Sc(OTf)3 has exhibited catalytic activity, forming primary amides from aldehydes and hydroxylamine hydrochloride. ... 

Copper(II) acetate has been reported as a versatile catalyst for the transformation of aldehydes into primary amides with hydroxylamine. A route to dibenzoxazepinones from 2-iodobenzamides and 2-bromophenols has been reported to involve a copper-catalysed Ullmann coupling followed by a base-mediated Smiles rearrangement and ring-closing process (Scheme 104). " ... 

Deprotonation of Al,<9-bis(trimethylsilyl)hydroxylamine with n-butyllithium or potassium hydride at low temperature yields the nitrogen centered anion Al,<9-bis(trimethylsilyl)hydroxyl-amide. At higher temperatures the oxyanion Al,A -bis(tri-methylsilyl)hydroxylamide is formed by rearrangement. Each reacts with acyl chlorides chemospecifically by M-acylation and 0-acylation, respectively. The oxyanion also reacts with silyl halides, methyl iodide, and sulfonyl chlorides chemospecifically on oxygen. In a Peterson-type one-pot reaction, oximes and oxime derivatives can be prepared effectively from the N-anion of iV,0-bis(trimethylsilyl)hydroxylamine and an aldehyde or ketone (eq 5). Oximes of sterically hindered ketones can be formed in high yields by this procedure. 

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