Hydroxylamines aliphatic nitro groups

Alternatively, if such azides bear a l°-benzylic group they can be converted to A-methylanilines by reaction with EtsSiH and SnCl4. Wilkinson s catalyst and Et3SiH reduce aromatic nitro groups to their amines in moderate to good yields, while the combination of Pd(OAc)2 and EtsSiH in a THF-water mixture reduces aliphatic nitro groups to the A-hydroxylamines (eq 25). ... 

The reduction of aliphatic nitrocompounds in acid solution proceeds in two steps. First the nitrosocompound is formed. A low steady state concen ation of 2-methyl-2-nitrosopropane has been detected during the reduction of 2-methyl-2-nitropropane [13]. At the cathode potential necessary to attach the first electron to a nitro group, the nitroso intermediate undergoes further reduction to the hydroxyla-mine. When the nitrocompound has one a-hydrogen substituent, tautomerism of the nitroso intermediate to an oxime is in competition with further reduction. Both temperature and proton availability affect the rate of this isomerisation. Reduction of aliphatic nitrocompounds to the hydroxylamine is usually carried out in acid solution at 0-5° C to minimise oxime formation [14, 15], The hydroxylamine is stable towards further reduction in acid solution. Oximes in acid solution are reduced... 

Nitro compounds are versatile synthetic intermediates which have found widespread utility in industrial applications. Aromatic nitro compounds are the usual starting materials for commercial applications, but aliphatic compounds exhibit a greater diversity of chemical behavior under reducing conditions. " Nitroso compounds, hydroxylamines, oximes, amines, nitrones, ketones and silyl nitronates are frequently encountered during the reduction of nitro compounds. Several specialized reviews have appeared which highlight the versatility of the nitro group in organic chemistry. ... 

Aliphatic and aromatic nitro compounds are reduced at relatively positive potentials via the hydroxylamines to the corresponding amines. The carcinogenic 4-nitroquinoline-/V-oxide is determined by DPP in the presence of 4-hydroxyam-inoquinoline-/V-oxide and 4-aminoquinoline-/V-oxide via the reduction of the nitro group [79]. Nitrazepam, parathion, nitrofurantoin, and the ni-troimidazoles in blood plasma or urine are also determined via the reduction of the respective nitro groups. 

Samarium(II) iodide smoothly reduces primary, secondaryand tertiary aliphatic as well as aromatic nitro compounds to hydroxylamines (equation 52). This reaction was found to be highly versatile although with limited scalability, since at least four equivalents of Sml2 are necessary. Most functional groups, except aldehydes and sulfones, are compatible with Sml2 reduction (equation 53). 

As with aliphatic amines, oxidation by peroxidic reagents proceeds through the hydroxylamine intermediate (see below), but this rapidly reacts further to a nitroso compound and cannot be isolated. Under slightly more vigorous conditions, the nitroso group is oxidised to nitro (equation 77) . 

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