Sulfuric acid hydroxylamine derivatives

Aromatic amines 4 are metabolised in vivo by cytochrome P450 mediated oxidation to phenolic and hydroxylamine derivatives 5 and 6. Phase II conjugation of the latter with PAPS or acyl transferase results in formation of the sulfuric or acetic acid esters 7. Nitrogen conjugation to give the A-acetyl analogues is also possible (Scheme l).54 65... 

Dihydrooxazoles are readily prepared from (V-acyl derivatives of /3-hydroxylamines by heating or by the action of thionyl chloride, sulfuric acid or phosphorus pentoxide (equation 167) (79JCS(P1)539>. The direct condensation of carboxylic acids with 13-hydroxylamines succeeds best with substituted compounds, such as norephedrine (equation 168). There are many variations of this general method, such as the use of imino ether hydrochlorides (equation 169) (78ACR375) and of cyanides (equation 170) (74LA996). 

The direct amination of (1) and (2) by hydroxylamine in concentrated sulfuric acid in the presence of vanadium pentoxide (71CHE561, 72CHE297) gives equal amounts of the 4-and 5-amino derivatives, indicating a probable radical mechanism. Similar results were obtained on amination of the 4- and 5-methyl derivatives of (1) and (2). 

Saccharin (I) combines with hydroxylamine to give derivative 3-hydroxy-3-hydroxylamino (87) and not 3-oximino-2,3-dihydrobenz-[djisothiazole (88) which was obtained from 2 under similar conditions.227, 258 The addition is reversed and 87 converted to 1 by heating or treatment with concentrated sulfuric acid.227... 

Among the azomethine derivatives of hydroxylamine, the ordinary oximes are the most important, and many polarographic and electrolytic investigations of oximes have been made [1,85,86]. Most oximes are reducible in acid solution, and only few in alkaline solution polarographic data prove that it is the protonated oxime that is the reducible species in acid and neutral solutions. Classic reductions in sulfuric acid at lead cathodes or controlled potential reductions in acid solution at mercury cathodes yield the amine in a four-electron reduction. As the hydroxylamine corresponding to the oxime is not reducible under the conditions employed, it has been suggested [1] that the reduction proceeds as in ... 

When reduced with lithium aluminum hydride, both lycorenine and homolycorine yield tetrahydrohomolycorine (LXXXVa). When warmed with dilute acid, LXXXVa formed the cyclic ether (LXXXVI) which was identical with deoxylycorenine, the product of the electrolytic reduction of lycorenine. Acetylation of LXXXVI with acetic anhydride and sulfuric acid gave the so-called acetyldeoxylycorenine of Kondo and Ikeda which was identical with tetrahydrohomolycorine diacetate. Acetylation of homolycorine was reported by Kondo and Tomimura (120a) to yield a diacetyl derivative, m.p. 173°. In view of the absence of OH or NH groups in homolycorine, it must be presumed that these workers had merely recovered homolycorine, m.p. 175°. Acetylation of lycorenine produced only one acetyl derivative, m.p. 179-180°. Upon further purification (116), the so-called monoacetyl (m.p. 185-187°) and diacetyl (m.p. 175-176°) derivatives (120b) of lycorenine were found to be identical with it. Acetyllycorenine gave lycorenine on saponification and an oxime hydrochloride with hydroxylamine hydrochloride. Because the ultraviolet spectrum of acetyllycorenine resembled that of veratraldehyde, it was represented as LXXXVII rather than as the acetyl derivative of the hemiacetal form (LXXXIV). 

An efficient procedure for the synthesis of isoxazoles suitable for a multi-kilogram scale is shown in Scheme 1. An imine 1 is converted into its lithium derivative 2 by the action of lithium diisopropylamide, and an ester is added, The product 3 is treated with aqueous or methanolic hydroxylamine and the resulting oxime 4 (which exists largely as the hemiacetal 4a) is dehydrated to the isoxazole 5 with concentrated sulfuric acid. <97S439>. 5-Alkoxyisoxazoles and /VTV-disubstituted 5-isoxazolamines 6 (R = OMe, NMe2 or NMePh) rearrange to the azirines 7 in the presence of iron(II) chloride <97710911>. 

A positive reaction is obtained, however, with a series of nonphenolic compounds aromatic amines, ends or hydroxymethylene compounds, tautomeric jS-diketones, j -ketoesters, derivatives of malonic acid esters or of cyanoacetate with a negative substituent at the -- CH2 group, some isonitrites, hydroxylamine derivatives, oximes, hydroxamic acids, and certain derivatives of sulfur. 

Pentamethyleneoxaziridine (459) has been used to 5-aminate thiouracils <91S327>. Similarly, either 3,3-pentamethylenoxaziridine or hydroxylamine-O-sulfonic acid reacts with 1-acylamino, with 1-phenylureido-, or with l-arylaminopyrimidine-2-thiones (458) to form 5-aminated derivatives (461). A postulated intermediate (460) is arrived at by nucleophilic attack by the sulfur at the nitrogen of the oxaziridine ring. The structure of the A-ylide (461 Ar = p-tolyl, R = Ph) in the solid was verified by x-ray analysis <93T3767>. 

Other methods, among which thermolysis or photolysis of tetrazene [59], photolysis of nitrosoamines in acidic solution [60], photolysis of nitrosoamides in neutral medium [61], anodic oxidation of lithium amides [62], tributylstannane-mediated homolysis of O-benzoyl hydroxamic derivatives [63, 64], and spontaneous homolysis of a transient hydroxamic acid sulfinate ester [65] could have specific advantages. The redox reaction of hydroxylamine with titanium trichloride in aqueous acidic solution results in the formation of the simplest protonated aminyl radical [66] similarly, oxaziridines react with various metals, notably iron and copper, to generate a nitrogen-centered radical/oxygen-centered anion pair [67, 68]. The development of thiocarbazone derivatives by Zard [5, 69] has provided complementary useful method able to sustain, under favorable conditions, a chain reaction where stannyl radicals act simply as initiators and allow transfer of a sulfur-containing... 

In these studies, the nitrogen was introduced in the already activated carbons. Another way to prepare such active carbons is to start from coals enriched in nitrogen before the step of pyrolysis or activation [36,37], Two coals were selected a Polish subbituminous coal, preoxidized with performic acid, and a Russian lignite. Ammonia and its derivatives (ammonium carbonate, hydrazine, hydroxylamine, and urea) were applied as N-reagents [36,37], The N-rich-acti-vated carbons showed good oxidative removal activity for traces of hydrogen sulfide and for its oxidized by-products (elemental sulfur and sulfur dioxide) [36],... 

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