Hydroxyl amines, Rearrangement

Finally, an acid catalyzed rearrangement of an o-(2-arylphenyl)-hydroxyl-amine followed by a ring enlargement to yield some unsaturated 7-aryl-azepinones should be mentioned (not shown). Until now, scope and limitations of that process are not known [52]. 

An irreversible dyotropic rearrangement of fluoro-substituted tris(silyl)hydroxyl-amines (127) (128) has been reported and ab initio and density functional calculations for model compounds have confirmed the dyotropic course of this rearrangement. ... 

To explore the dyotropic rearrangement of silyl hydroxylamines, Schmatz, Klinge-biel and colleagues studied the behaviour of 0-lithium-Af,Af-bis(f-butyldimethylsilyl) hydroxylamine 207 in the presence of chlorotrimethylstannane (equation 62). They found that the primarily formed Af,Af-bis(f-butyldimethylsilyl)-0-(trimethylstannyl)hydroxyl-amine 208 underwent a dyotropic rearrangement to form 209. This reaction mechanism is corroborated by quantum chemical calculations partly employing an effective core potential for tin. 

Starting from nitrobenzene, p-aminophenol can be generated at lead cathodes via the intermediate hydroxyl amine, which rearranges under the reaction conditions. This reaction is also unprecedented by other methods [19] ... 

If primary or secondary amines are used, AT-substituted amides are formed. This reaction is called aminolysis. Hydrazines yield the corresponding hydrazides, which can then be treated with nitrous acid to form the azides used in the Curtius rearrangement. Hydroxyl amines give hydroxamic acids. 

Oxidation of the <5-dibenzylamino-a,/J-unsaturated esters 4, prepared in enantiomerically pure form from the corresponding amino acids, with 3-chloroperbenzoic acid gave the hydroxyl-amines 6 in 70-80% yields63. The optical purity of the a-hydroxy esters 7, obtained from 6 by reduction with H2/Pd(OH)2, was determined to be higher than 95% by the Mosher procedure. Thus, the sigmatropic rearrangement of the intermediate amine oxides 5 proceeds with essentially complete transfer of chirality. 

Reductions of aromatic nitro compounds often proceed to generate mixtures of nitroso and hydroxyl-amine products which then condense to form azoxy and, eventually, azo compounds. This bimolecular reduction is practical only for the generation of symmetrically substituted azo compounds. The situation can be further complicated if the reduction continues such that aromatic amines are formed the amines may then condense with the intermediate nitroso compounds to generate hydrazo compounds which can then undergo a benzidine rearrangement. 

Molecular Rearrangement to para-Amino Phenol.— Phenyl hydroxyl amine undergoes an important molecular rearrangement. When boiled with mineral acids it is converted into para-amino phenol. 

The rearrangement occurs also when nitro benzene is electrolytically reduced by immersing the cathode in nitro benzene and sulphuric acid and the anode in sulphuric acid. Phenyl hydroxyl amine is first produced and by the above rearrangement is converted into para amino phenol. This rearrangement is analogous to the one occurring when phenyl methyl nitrosamine goes over to para-nitroso methyl aniline (P- S59)-... 

Rearrangement.—Like nitroso methyl aniline and phenyl hydroxyl amine it undergoes molecular rearrangement as above. 

Molecular Rearrangement of Hydroxyl Amines.—An important synthesis of amino phenols is by. -molecular rearrangement of hydroxyl... 

Quinone Oximes.—The most interesting of the derivatives of quinones are the oximes. As stated in the discussion of the ketone structure for quinones one of the proofs for this constitution is the fact that benzoquinone forms both a mono-and a di-oxime when treated with hydroxyl-amine. The mono- oxime of benzoquinone would have the structure as written below and as given on page 638. Now as previously mentioned, (p. 628), para-nitroso phenol, which is made by the action of nitrous acid upon phenol and the constitution of which is established by other methods of synthesis, (p. 627), proves to be one and the same compound with this mono-oxine of para-benzoquinone, the constitution of which is likewise established by the above reaction of hydroxyl amine upon quinone. This is explained by a rearrangement as shown in the following ,... 

Some interesting transformations were described for N-substituted A-ary I hydroxyl -amines. The a-aminohydroxamic acids 180 rearranged in the presence of amines to give A - acy lo x y ary I am i n es 181 (N O transacylation)273 (equation 71). 

Tiemann rearrangement. Rearrangement of amide oximes (available from nitriles and hydroxyl-amine) to monosubstituted ureas by treatment with benzenesulfonyl chloride and water. 

Hydroboration of (-f)-verbenone (202 X = 0) and treatment with hydroxyl-amine-O-sulphonic acid results in a 65% yield of (-l-)-cw-S-pinene (213) by elimination, with no resultant amine. Dehydrated neutral alumina may be used for the room-temperature concerted 1,2-elimination from 10-pinanyl tosylate to yield /3-pinene (70%) and some a-pinene (14%) with little rearrangement to camphene/ The addition of diethyl N,7V-dichlorophosphoroamidate to (-)-a-pinene yields (-t-)-(214) and the structure of the adduct (-)-(13) from MePCl2-AICI3 addition to (-)-a-pinene has been confirmed by X-ray analysis. The addition of HCNO to a- and / -pinene was reported earlier. 

The amide can be easily prepared in high yield and high purity by the reaction of 2,3-dichloro-4-hydroxy-aniline and 1-methylcyclohexane-carboxylic acid chloride, e.g., in toluene with sodium hydroxide as a base (Scheme 17.24). The starting aniline can be made by a Bamberger rearrangement of the intermediate hydroxyl-amine obtained by partial reduction of the corresponding nitro aromatic [109]. 

Noyes and Clement, on the reduction of nitrobenzene in a concentrated sulphuric acid solution, obtained p-amido-phenol-sulphonic acid. Gatter-mann, starting with a similar solution, by varying the conditions of the experiment obtained directly p-amido-phenol. He explains the reaction by assuming the intermediate formation of phenyl-hydroxyl-amine, which on further reduction changes by molecular rearrangement into the final product. By similar treatment were formed ... 

Scheme 14.11 Preparation of a-oxygenated ketones and aldehydes by the condeasation and rearrangement of jV-methyl-O-protected hydroxyl amines and carbonyl compounds.

Rearrangements of 0-Vinyl-A/-Aryl hydroxyl amines to Indoles, 2-Amino-2 -Hydroxy-l,rBiaryls, and a-Arylated Carbonyl Compounds... 

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