Hydroxyamines nitro compounds

The syntheses of N-hydroxy-N-nitrosamines are usually carried out by the nitrosation of the corresponding N-hydroxyamines (Scheme 3.8) [123, 124]. N-Hydroxyamines are readily obtained by the reduction of the corresponding nitro-compounds. The most efficient methods are neutral or basic reactions. Recent applications of this method have resulted in the preparation of a variety of cupferron derivatives (Scheme 3.8) via nitrosation of phenylhydroxylamine with amyl nitrite/ammonia [125] or methyl nitrite/ammonia [126]. Behrend and Konig have shown that the organic... 

Today, many stable radicals are known, as shown in Figures 1.11 and 1.12. However, most of them are nitroxyl radicals like NO or N02. Standard generation methods of nitroxyl radicals are as follows. One is the oxidation of amines or hydroxyamines by Pb02, or by less toxic oxidants such as oxone, Cu(OAc)2, mCPBA (eqs. 1.13 and 1.14). Another one is the reaction of nitro compounds with Grignard reagents (eq. 1.15) [9-14]. 

Use is made of the facile hydrogenation of nitro groups to prepare a-hydroxy primary amines from nitromethane-ketone addition products (Eqn. 19.22). The addition of a little acetic acid to the reaction medium can sometimes improve the yield. The p-hydroxyamines are more easily prepared in this way than by the hydrogenation of the corresponding cyanohydrin. a-Chloro nitro compounds are selectively hydrogenated to the oxime over palladium under... 

A similar compound with a bipyridyl central core was sought according to Scheme 3.42. In this manner, a greater degree of planarity could be achieved due to reduced interactions in the absence of 2- and 2 -steric interactions. To that end, 2-chloro-3-nitropyridine was homocoupled in the presence of copper/bronze and dimethylformamide. The bipyridine ring system was brominated at the 5-and 5 -position under harsh conditions (due to its electrophilicity) to afford intermediate 98 that was then coupled with two equivalents of TMSA. These coupling conditions unfortunately afforded the hydroxyamine and a very small amount of the dinitro-coupled product. The electron deficient 98 presumably underwent nitro loss and Pd-catalyzed reduction by the hydridopalladium species that are present in the coupling catalytic cycle to afford the undesired 99 (Scheme 3.42). ... 

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