O-Acyl hydroxylamines

Silberring, J., Demuth, H. U., Brostedt, P., and Nyberg, F. (1993). Inhibition of dynorphin converting enzymes from human spinal cord by TV -peptidyl-O-acyl hydroxylamines. J. Biockem. 114, 648-651. 

Die Synthese N-unsubstituierter O-Acyl-hydroxylamine ist mit Hilfe von Schutzgruppen-techniken moglich1 bei der direkten Einwirkung von Acylierungsreagentien auf Hydroxyl-amine wird im ersten Reaktionsschritt am N-Atom, im zweiten am O-Atom und im dritten wieder am N-Atom acyliert. 

O-Acyl-hydroxylamine allgemeine Arbeitsvorschrift (C arpino-Methode)5 6 ... 

O-Acyl-hydroxylamine reagieren mit Carbonyl-Verbindungen zu O-Acyl-oximen (s. S. 780), die durch katalytische Hydrierung Oder durch Behandlung mit Natriumamalgam zu den O-Acyl-N-alkyl-hydroxylaminen reduziert werden konnen z.B. 4 ... 

N,N-Disubstituierte O-Acyl-hydroxylamine allgemeine Arbeitsvorschrift2 Zu aquimolaren Mengen Hy-droxylamin und Triethylamin in THF wird bei 0° die in THF geloste aquimolare Menge Acylchlorid ge-... 

Typische Vertreter fur cyclische O-Acyl-hydroxylamine sind die 5-Oxo-2,5-dihydro-1,2-oxazole und -1,2-oxazolidine, die nach folgenden Methoden erhalten werden ... 

An XD, Yu S (2015) Visible-light-promoted and one-pot synthesis of phenanthridines and quinolines from aldehydes and o-acyl hydroxylamine. Org Lett 17(ll) 2692-2695 Tang C, Yuan Y, Jiao N (2015) Metal-free nitrogenation of 2-acetylbiphenyls expeditious synthesis of phenanthridines. Org Lett 17(9) 2206-2209... 

A diaryIprolinol silyl ether induces ee < 99% for aldehyde a-alkylation on 1,4-addition to acridinium salts. Computational chemistry has been used to explain stereoinduction by a family of iodooxazoline catalysts developed for enantioselective a-tosyloxylation of ketones by m-CPBA/TsOH. a-Benzoyloxylation of ketones (cyclohexanones and 1-indanones) by dibenzoyl peroxide occurs enantioselectively in the presence of a mixture of 9-amino-(9-deoxy)epi-dihydroquinidine and salicylic acid. ° The scope and limitations of asymmetric a-oxyacylation of cyclic ketones by chiral Ai-alkyl-O-acyl hydroxylamines have also been reported. ... 

O-Alkyl-7 und O-Aryl-hydroxylamine8 lassen sich mit Lithiumalanat in die Komponenten spalten bzw. re-duktivumlagern , O-Acyl-10bzw. N-Sulfonyl-hydroxylamine11 imerstenSchritt zum Hydroxylamin und Al-kohol bzw. Sulfonamid reduzieren. 

The acylation product of hydroxylamine, /-butyl N-hydroxy-carbamate,6 is a valuable intermediate in the synthesis of O-sub-stituted hydroxylamines such as O-acyl- and O-sulfonylhydroxyl-amines, many of which are valuable aminating agents and have not been obtained in any other way.8-9... 

Preparation of hydroxamic acids through acylation of hydroxylamines is a common and straightforward reaction. However, acylation of iV-alkylhydroxylamines is known to proceed on both the oxygen and nitrogen atoms and can result in mixtures of N- and 0-acylation products . In iV-alkylhydroxylamines possessing a bulky " or an electron-poor substituent on nitrogen atom, O-acylation is predominant. 

Intramolecular addition of hydroxylamines and hydroxamic acids to the non-activated double bonds is possible through oxidative cyclization. Reaction of O-Acyl fi,y-unsaturated hydroxamates (e.g. 56, equation 38) with bromine provides 3,4-substituted iV-hydroxy -lactams such as 57 with high diastereoselectivity. Analogous reaction of O-benzyl hydroxylamine 58 (equation 39) with iodine results in five-membered cyclization with 2 1 ratio of diastereomers. ... 

Multicomponent reactions have recently become one of the favored methods to prepare pharmacologically important compounds. Ugi condensations with O-protected hydroxylamines have been successfully performed in THE using ZnCl2 as activating agent (Scheme 56). This synthetic strategy opens up the route to a very convergent assembly of internal hydroxamic acid derivatives (A-acyl-A-hydroxypeptides 109)" . 

The direct solution-phase hydroxyamination of esters is commonly accomplished by a two-step preparation of the potassium salt of hydroxylamine followed by the addition of the ester in alcohol". Alternatively, the stepwise saponification of the ester to the acid is followed by activation of the acid as acyl chloride or mixed anhydride and then by quenching with an O-protected hydroxylamine analogue". In special cases, the hydrox-yamination of ester substrates has been achieved via enzymatic methods" or, for more reactive esters, by treatment with excess hydroxylamine in alcohol". ... 

Often, the use of expensive O-substituted hydroxylamines and the azodicarboxylates could be avoided by direct hydroxaminolysis of protected amino acid esters 151 with hydroxylamine itself, followed by in situ acylation and finally substitution of Ph3P/CCl4/ EtsN for PhsP/DEAD during the cyclization step from 152 to 153 (Scheme 70) . 

The intermediate generated in pyrolysis of IV-acylacetyl-iV-phenylhydroxylamines 48 can form a 3-aza-4-oxa-l,5-diene system (50) (equation 16). A homolytic cleavage of the O—H bond with subsequent rearrangement to the aniline radical, followed by recombination with the hydrogen radical to give the corresponding 0-acyl hydroxylamine 49,... 

Tan-No, K., Taira, A., Nakagawasai, O., Niijima, F., Demuth, H. U., Silberring, J., Terenius, F., and Tadano, T. (2005a). Differential effects of A-peptidyl-0-acyl hydroxylamines on dynorphin-induced antinociception in the mouse capsaicin test. Neuropeptides 39, 569—573. 

Isatin and 1-alkylisatins react with hydroxylamine or O-methyl hydroxylamine hydrochloride under aqueous alkaline conditions to furnish the corresponding 3-oximes, which have been studied as monoamine oxidase inhibitors . Isatin oximes can be acylated... 

Table 12 Reduction of O-Alkyl, O-Aryl and O-Acyl Oximes to O-Substituted Hydroxylamines... 

---