Methoxylamine

A mixture of 3 -hydroxypregna-5,l6-dien-20-one acetate (10 g), 70 ml of ethanol and 2 ml of methoxylamine is refluxed for 12 hr (Note methoxyl-amine hydrochloride leads to oxime formation). After cooling, another 1.75 ml of methoxylamine is added and the reaction is refluxed for another 12 hr. The solvent is removed in vacuo and the residue is dissolved in ether. Hydrogen chloride gas is passed into the ether solution and the white crystalline salt (113) is filtered off and washed with ether (85% yield crude mp 228-229°). 

The methoxylamine derivative is converted to the aziridine (115) in 94% yield by heating with a solution of 2 N sodium methoxide for 2 hr. The product is isolated by extraction after dilution with water. 

A synthesis for the enantiomerically pure 535 was developed starting with D-phenylalanine which upon reaction with methyl chloroformate gave 528 whose reaction with methoxylamine afforded 529. Cyclization with bis(trifluoroacetoxy)iodobenzene in presence of trifluoroacetic acid gave the tetrahydroquinoline derivative 530 which was demethoxylated to give 531. Treatment of 531 with either benzyl chloroformate or... 

Nucleophilic attack of substituted alkylamines including benzylamines to 6,7-dihydro-imidazo[l,2- ]imidazole-2,5-diones 34, cleaved the imidazolidinone ring to generate the acetamide derivatives 81 (Equation 34) <1998APH389, 2001JST73>. Reaction of the tricyclic thiazolium salt 45 with methoxylamine gave the oxime 82 (Equation 35) <1999JME2828>. 

If polyribonucleotides are treated simultaneously with methoxylamine and bisulphite, cytidine residues are converted into 5,6-dihydro-7V4-methoxycytidine-6-sulphonate,154 and uridine into 5,6-dihydrouridine-6-sulphonate.155 Treatment with dilute ammonia regenerates the uridine residues, leaving the dihydrocytidine derivatives unaffected. When only the cytidine residues have been derivatized, pancreatic ribonuclease becomes uridyl ribonuclease, since it is unable to cleave the chain on the 3 -side of the modified cytidine.154 This allows the isolation of blocks of modified cytidine residues. T2 ribonuclease may also be used. Alternatively, a ribonuclease from Physarum polycephalum has been found to hydrolyse CpX links very slowly, allowing the isolation of cytidine blocks.156 If both uridine and cytidine residues are modified, T2 ribonuclease acts as puryl ribonuclease, allowing the isolation of cumulative blocks of pyrimidines.155 This ability to alter the specificity of nuclease cleavage is a useful tool in sequence analysis. 

The first manufacturing route of the GEM side-chain relied on a-cyanoketone 125 however, the number of chemical steps from 125 to the final side-chain was reduced by one step (Noh et ah, 2004a). The sequence began with a selective hydrogenation with Raney nickel followed by double bond migration to enamine 131 (Scheme 4.25). The amino functionality of 131 was then monoprotected, and the double bond was reduced under hydrogenation conditions to afford pyrrolidine-3-one 133. Treatment of 133 with methoxylamine yielded methoxyoxime 129. Deprotection of the carbamate functionality was achieved with methanesulfonic acid to afford the C7-side-chain as the bis-methansulfonate salt. 

The conjugate addition of hydrazine, hydroxylamine, methoxylamine and alkylamines with various alkyl and halegenofumaric acids to give N-substituted aspartic acids can be carried out enantioselectively in the presence of the enzyme 3-methylaspartase91. 

Other less common but highly effective trapping techniques include cyanide trapping via iminium ion formation and methoxylamine or semicarbazide for reactive... 

Niphatynes A (418) and B (419) are pyridine derivatives with alkyne and methoxylamine functionalities isolated from the Fijian sponge Niphates sp. (344). Niphatyne A (418) exhibits cytotoxic activity. Theonelladins A-D (420-423) are other pyridine alkaloids obtained from the Okinawan sponge Theonella swinhoei and exhibit antineoplastic activity (345). These... 

Treatment of all-trans-retinal with methoxylamine hydrochloride in pyridine gave two products which were identified as the anti- and syn-isomers of retinal methoxime (86) from n.m.r. data, especially the signal of the C-15 proton.47 The formation of retinoylhydroxamic acid (87) and NO-diretinoylhydroxylamine (103)... 

Oxidation of methoxylamine and some other O-substituted hydroxylamines by lead tetraacetate in the presence of alkenes can also lead to the formation of aziridines. The oxidation of 2,4-dinitrobenzenesul-fenamide is analogous.In view of the results reported widi aminolactams, these reactions do not necessarily establish the intomediacy of nitrenes in the oxidations. 

Very recently it has been discovered that / -methylaspartase also catalyzes the conjugate addition of hydrazine, hydroxylamine, methoxylamine, methylamine, and dimethylamine to various substituted fumaric acids136. 

Hydroxylamine acts as a reducing agent when absorbed systemically, producing methemoglobin and the formulation of Heinz bodies in the blood. It can induce hemolytic anemia. It inhibits platelet aggregation and is a nitric oxide vasodilator. Oxy-Imines such as hydroxylamine and methoxylamine disturb DNA replication and act as potent mutagens, causing nucleotide transition from one purine to another or one pyrimidine to another. 

Carbamoyl chlorides. A direct preparation of carbamoyl chlorides from tertiary benzylamines (debenzylation) is by reaction with triphosgene. A-Methoxy-N-methyl-carbamoyl chloride, which is useful for coupling with various unsaturated organostannanes, is obtained from chloroformylation of the methoxylamine in the presence of pyridine. ... 

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