Hydroxylamine derivatives compounds

CHR) , formed, e g. from the reaction of diazomethane and alcohols or hydroxylamine derivatives in the presence of boron compounds or with metal compounds. Poly-methylene is formally the same as polyethene and the properties of the various polymers depend upon the degree of polymerization and the stereochemistry. 

Polarographic reduction of l-methyl-5-nitroimidazole (97 R = Me, R2 = H) has been shown to proceed in two distinct steps, probably via the hydroxylamine derivative (102), to give the amino compound (96 R = Me, R2 = H) (62CR2603). 

Acyl nitroso compounds (3, Scheme 7.2) contain a nitroso group (-N=0) directly attached to a carbonyl carbon. Oxidation of an N-acyl hydroxylamine derivative provides the most direct method for the preparation of acyl C-nitroso compounds [10]. Treatment of hydroxamic acids, N-hydroxy carbamates or N-hydroxyureas with sodium periodate or tetra-alkyl ammonium periodate salts results in the formation of the corresponding acyl nitroso species (Scheme 7.2) [11-14]. Other oxidants including the Dess-Martin periodinane and both ruthenium (II) and iridium (I) based species efficiently convert N-acyl hydroxylamines to the corresponding acyl nitroso compounds [15-18]. The Swern oxidation also provides a useful alternative procedure for the oxidative preparation of acyl nitroso species [19]. Horseradish peroxidase (HRP) catalyzed oxidation of N-hydroxyurea with hydrogen peroxide forms an acyl nitroso species, which can be trapped with 1, 3-cyclohexanone, giving evidence of the formation of these species with enzymatic oxidants [20]. 

Compound 59a reacted with arylhydrazines to give complex mixtures as shown in Scheme 53 (70G745). The reaction presumably goes via an electron transfer process in which the diazo compound serves as electron acceptor. Similar reactions leading to even more complex mixtures were also observed with hydroxylamine, hydrazo compounds, and conjugate indole derivatives (70G757). 

The most frequent rearrangement of substituted hydroxylamines is the thermal [3,3]-sigmatropic rearrangement, the 3-aza-4-oxa-Cope rearrangement also called 3-aza-4-oxy-Cope rearrangement, that proceeds by a cyclic six-membered transition state (equation 1). Albeit the difficulty to prepare hydroxylamine derivatives, this rearrangement proceeds in mild conditions and is useful in the synthesis of several heterocyclic compounds. 

Many N-hydroxylamine derivatives are known. They appear to be non-explosive, stable compounds eg CH,HNOH (Ref 1) or HOOCCH2-NHOH (Ref 2)... 

Hydroxylamine Derivatives.—Several derivatives of cupric sulphate containing hydroxylamine in place of ammonia are known. Thus, cupric sulphate unites with hydroxylamine, giving a mono-hydroxylamino-compound Cu[NH20H]S04, a dihydroxylamino-salt, [Cu(NH20H)2]S04, and a pentahydroxylamino-salt, [Cu(NH2OIT) ]SO.j. The latter is unstable, but the two former compounds are stable in the dry state and even in solution up to 0° C. Above that temperature reduction of the salts occurs. 

Substituted nitrobenzenes gave similar results on reduction of less than stoichiometric quantities in the absence of added alkali, hydrogen atom-substrate ratios of 3.0 to 4.1 being obtained while cessation of hydrogen absorption occurred at H/Co = 2.0 in all cases. Azoxy and azo compounds were isolated from o-nitrotoluene (H/substrate = 3.9) p-nitrotoluene (H/substrate = 3.2) yielded a mixture of azoxy and hydroxylamine derivatives, the latter believed to be the immediate precursor of the bimolecular product. Reduction of o-nitro-anisole in the presence of added alkali (NaOH, 3.3X cobalt concentration)... 

The capability of hydroxylamine derivatives to be either 0- or N-nucleophiles in the reactions with acetylenic compounds depends on the structure of the latter. For example, ALferf-butylhydroxylamine can add to acetylenic sulfones either by the nitrogen atom or by the oxygen atom, depending on the character of the substituent at the triple bond (Scheme 80) (74JOC2641). 

Hydroxylamines play a significant role in modern industrial chemistry. Their most important chemical properties include differential reactivity of the N and O termini, changes in reactivity with pH and solubility in both aqueous and organic solvents. Hence the study of reactions of hydroxylamine derivatives, especially their oxidation to nitroso compounds, constitutes an important area of investigation. 

Some further work on the tryptoquivaline-related metabolites of Aspergillus fumigatus has been reported, but some features of their chemistry still remain to be elucidated.25 On the basis of its n.m.r. spectrum, tryptoquivaline D (FTD) is now regarded as a secondary acetate, and is formulated as (25), i.e. the structure attributed to nortryptoquivaline direct comparison of specimens subsequently confirmed this conclusion. Similar arguments led to the conclusion that tryptoquivaline C (FTC) is also a secondary acetate, rather than an O-acetyl-hydroxylamine derivative, and should be identical with Buchi s tryptoquivaline (26) however, direct comparison of specimens failed to support this conclusion, and the relationship between these two compounds is still not clear. 

A variety of different metal complexes have been screened as catalysts for allylic amination using phenyl hydroxylamine 108 as the nitrogen fragment donor, and it was found that iron-complexes have better redox capacity compared to molybdenum [64]. With the iron compounds, higher yields and a lower amount of hydroxylamine-derived byproducts are obtained. These byproducts constitute one of the problems in this type of allylic amination reactions in general, as their formation is difficult to suppress. The allylic amination reaction of a-methyl styrene 112 with 108 can, e.g., be catalyzed by the molybdenum dioxo complex 107, iron phthalocyanine 114, or by the combination of the iron chlorides 115 [64,65]. It appears from the results in... 

Titov and Laptev also suggest the possibility of conversions with the aid of the hydrogen ion, causing the reduction of nitroso compounds to hydroxylamine derivatives followed by an oxidation ... 

In general, the chemical properties of nareline are those expected of a compound containing the complex functionality of (173), including the unusual hemiacetal unit formed from an aldehyde and a hydroxylamine derivative. However, the oxidation by chromic acid in acetic acid takes a course that would have been difficult to predict, and affords a product, oxonareline (175), which is presumably formed from (173) by oxidative fission of the 2, 3, Nb system to give an oxindole function (176), followed by internal acetal formation between oxygen attached to C-5 and a carbinolamine equivalent at C-3.98... 

Dibenzoyl peroxide oxidizes morpholine, piperidine and other simple secondary amines in good yield to the corresponding benzoyloxyamines these compounds can then be hydrolyzed in basic conditions to the free hydroxylamines. An analogous reaction t es place between secondary amines and bis(diphe-nylphosphinyl) peroxide for example, diethylamine is converted into the hydroxylamine derivative Et2NOFOPh2 (97%) by this reagent. The products are easily hydrolyzed to the free hydroxylamines, and they can also be used as aminating agents. 

A number of compounds containing the NH residue may behave as either substrates or amine reagents in the Mannich reaction, depending on the nature of the co-reagent. Among them, NH-heteroaromatic compounds and hydrazine or hydroxylamine " derivatives may be considered as amine reagents when allowed to react with more acidic substrates, such as alkylthiols affording S-Mannich bases 26. 

Catalytic hydrogenation is a heterogeneous reaction which occurs at the surface of the catalyst. The mechanism is complex and proceeds through the nitroso and hydroxylamine derivatives minor by-products such as the azo and azoxy compounds occasionally appear. 

Functionalization of rubbers with nitroso compounds (174) involves two reaction steps [233] formation of a hydroxylamine derivative 175 and its... 

Oxaziridines can be regarded as a special category of cyclic hydroxylamines. Activated compounds of this type, such as the IV-benzenesulfonyl derivative (46) and the salt (47), are very easily reduced. They are proving to be useful in synthesis as oxygen-transfer reagents to alkenes, thiols and other nucleophiles. 

Methods for preparation of hydroxylamine derivatives have been reviewed in detail recently. Here, mainly new developments concerning the synthesis of hydroxylamines by substitution processes with heterobond formation are presented. Reduction of nitro, nitroso, oxime and nitrone derivatives as well as direct oxidation of amines leading to hydroxylamine compounds will not be considered. 

Figure 1.19 Mass spectra of acetaldehyde PFB-oxime (a), diacetyl mono PFB-oxime (b), acetoin PFB-oxime derivative (c), and o-chlorobenzaldehyde PFB-oxime (d) recorded in the GC/MS analysis of standard solution performed in positive ion chemical ionization mode using methane as reagent gas (reagent gas flow 1 mL/min ion source temperature 200 °C). Flamini et al., (2005) Monitoring of the principal carbonyl compounds involved in malolactic fermentation of wine by synthesis of 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine derivatives and solid-phase-microextraction positive-ion-chemical-ionization mass spectrometry analysis, Journal of Mass Spectrometry, 40, p. 1561. Copyright John Wiley Sons, Ltd. Reproduced with permission...

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