Synthesis Of Nitrones Research Articles

Protein Modification by Strain‐Promoted Alkyne–Nitrone Cycloaddition

Protein Modification by Strain‐Promoted Alkyne–Nitrone Cycloaddition

ChemInform Abstract: Rapid, Efficient, and Room Temperature Synthesis of Nitrones in Excellent Yields over MgO under Solvent‐Free Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Nafion supported molybdenum oxychloride: Recyclable catalyst for one-pot synthesis of nitrones via direct condensation/oxidation of primary amines and aldehydes using UHP as oxidant

Immobilization of molybdenum(VI) oxychloride to the surface of perfluorinated ion-exchange polymer “Nafion”via an ion exchange method was carried out for the first time. The prepared Nafion immobilized molybdenum(VI) oxychloride catalyst was used for the direct synthesis of nitrones via one-pot condensation/oxidation of primary amines with aldehydes using solid urea-hydrogen peroxide (UHP) as oxidant under very mild reaction conditions. The developed polymer immobilized catalyst showed better activity than its analogous homogeneous catalyst with the added benefits of facile recovery and recyclability of the catalyst without leaching and loss in catalytic activity.

Rapid, efficient, and room temperature synthesis of nitrones in excellent yields over MgO under solvent‐free conditions

AbstractA large variety of C‐aryl and C‐alkyl nitrones were synthesized within 0.5–15 min via the condensation of aldehydes with N‐(methyl, phenyl, or t‐butyl)hydroxylamines over MgO by hand‐grinding with an agate mortar. These reactions were investigated under different conditions and over different solid supports including basic alumina, montemorillonite, MgO, and molecular sieves (pore size 3 Å). In the more interesting cases, nitrones were prepared over MgO without heating and any catalyst. In this procedure, nitrones were prepared in a very short time, excellent yields, and good purity without using harmful solvents in the workup. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:177–181, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20527

One‐Pot Synthesis of Nitrones from Primary Amines and Aldehydes Catalyzed by Methyltrioxorhenium

One-pot condensation/oxidation of primary amines and aldehydes using urea-hydrogen peroxide (UHP) as the stoichiometric oxidant in the presence of methyltrioxorhenium (MTO) as catalyst affords nitrones in a simple and regioselective manner. UHP is a practical and safe source of H2O2, and its use here instead of aqueous H2O2 solutions also simplifies greatly the workup procedure as extractions with organic solvents can be avoided. Typically, at the end of the reaction the solid urea is simply filtered off. From a sustainability point of view, this one-pot synthesis is simple to perform, takes place under mild conditions, has a high atom economy, and releases water as the only by-product.

Solvent-free synthesis of nitrones in a ball-mill

Various C-aryl and C-alkyl-nitrones were synthesized within 0.5–2 h via condensation of an equimolar amount of aldehydes and N-substituted-hydroxylamines under solvent-free conditions in a ball-mill apparatus. Reactions can be performed without the need of excluding air and moisture and yields the expected products with no need for further purification. The study has been complemented by Differential Scanning Calorimetry (DSC) and solid-state 13C MAS nuclear magnetic resonance experiments. We have also studied the temperature profile during the reaction. A comparative study with the corresponding solvent-free microwave activated reaction showed the superiority of the ball-milling method; 31 examples are described, including the synthesis of the anti-aging agent C-phenyl- N- tert-butyl nitrone (PBN) and one of its analogues C-2-pyridyl- N- tert-butylnitrone (2-PyBN).

A convenient method for the synthesis of nitrones by oxidation of N,N-disubstituted hydroxylamines with N-tert-butylphenylsulfinimidoyl chloride

A convenient method for the synthesis of nitrones by oxidation of N,N-disubstituted hydroxylamines with N-tert-butylphenylsulfinimidoyl chloride

Regioselective Synthesis of Nitrones by Decarboxylative Oxidation of N-Alkyl-α-amino Acids and Application to the Synthesis of 1-Azabicyclic Alkaloids

Abstract Tungstate-catalyzed oxidation of N-alkyl-α-amino acids with 30% H2O2 solution under phase-transfer conditions gives nitrones regioselectively in good yields. Using this method, stereodivergent synthesis of (R)- and (S)-4-(t-butyldimethylsilyloxy)-1-pyrroline N-oxides ((R)-17a and (S)-17a) was achieved. In addition, (R)- and (S)-3-(t-butyldimethylsilyloxy)-1-pyrroline N-oxides ((R)-45 and (S)-45) were prepared by catalytic oxidation of the corresponding chiral pyrrolidines in a regioselective manner. These chiral cyclic nitrones, 17 and 45 are versatile intermediates for the synthesis of optically active nitrogen heterocycles, since stereoselective additions of carbon nucleophiles to these chiral nitrones can be readily performed. Typically, ZnI2-mediated addition of ketene t-butyldimethylsilyl methyl acetal (29a) to (R)-17a gave the cis-adduct, methyl (2R,4R)-[1,4-bis(t-butyldimethylsilyloxy)pyrrolidin-2-yl]acetate (cis-30). In contrast, the addition of lithium acetylides 34 to the nitrone (R)-17a gave the trans-adducts, (2S,4R)-2-(1-alkynyl)-4-(t-butyldimethylsilyloxy)-1-hydroxypyrrolidines trans-35. These adducts are useful intermediates for syntheses of the nitrogen heterocycles (3R,5R)-1-aza-3-hydroxybicyclo[3.3.0]octane (37) and (6R,8R)-1-aza-8-hydroxybicyclo[4.3.0]nonane (38), respectively. The ZnI2-mediated addition of ketene silyl acetal 29a to the nitrone (R)-45 gave methyl (2S,3R)-[1,3-bis(t-butyldimethylsilyloxy)pyrrolidin-2-yl]acetate (trans-50a), which was used for asymmetric synthesis of the Geissman–Waiss lactone ((−)-49).

ChemInform Abstract: Synthesis of Nitrones from 3,4‐Dihydroisoquinoline Derivatives by Oxidation with m‐Chloroperoxybenzoic Acid.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Synthesis of Nitrones by Methyltrioxorhenium‐Catalyzed Direct Oxidation of Secondary Amines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: A New General Method for the Synthesis of Nitrones by Reaction of Nitroso Compounds with Anions of Aliphatic Nitro Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of nitrones by methyltrioxorhenium catalyzed direct oxidation of secondary amines

Oxidation of secondary amines catalyzed by methyltrioxorhenium (MTO) with H2O2 or urea-hydrogen peroxide complex (UHP) at room temperature gives the corresponding nitrones in good yields.

A novel general method for the synthesis of nitrones by reaction of nitroso compounds with anions of aliphatic nitro compounds

Anions of aliphatic nitro compounds R1R2C=NO2− react with nitroso compounds RNO to give nitrones R1R2C=N(O)R. Salts of nitro compounds with metals and Et3N, as well as trimethylsilyl nitronates in the presence of F−, can serve as the sources of the anions. The structure of the nitrones was established by NMR spectroscopy. 1,3-Dipolar cycloaddition of a series of the nitrones obtained to olefins was investigated.

1,3-Dipolar cycloaddition reactions of homochiral cyclic nitrones derived from 1-deoxynojirimycin

The synthesis of nitrones 12, 19 and 20, derived from 1-deoxynojirimycin (1, dNM), using 2,2-dimethyldioxirane, is reported. In subsequent 1,3-dipolar cycloaddition reactions of nitrones 12 and 19 with phenyl isocyanate and trichloro acetonitrile the cycloadducts 13 and 15, ring-closed to C-1, and 14, 16, 21 and 22, which are ring-closed to C-5 of the dNM ring, were obtained. Cycloaddition reaction of 19 and 20 with methyl vinylacetate at 15 kbar pressure, provided the cycloadducts 23, 24 and 25, which are highly functionalized dNM derivatives with various possibilities for further synthesis.

ChemInform Abstract: Highly Efficient and Mild Synthesis of Nitrones by Catalytic Oxidation of Hydroxylamines with Tetra‐n‐propylammonium Perruthenate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Highly efficient and mild synthesis of nitrones by catalytic oxidation of hydroxylamines with tetra- n-propylammonium perruthenate

Oxidation of N,N-disubstituted hydroxylamines by N-methylmorpholine N-oxide (NMO) and catalytic amounts of tetra-n-propylammonium perruthenate (TPAP) at room temperature occurs very rapidly to give the corresponding nitrones, which can be trapped by dipolarophiles present in the reaction mixture, in excellent yields. A competitive experiment in the presence of a primary alcohol gave a > 50:1 nitrone to aldehyde ratio.

Imines and derivatives. Part 24. Nitrone synthesis by imine oxidation using either a peroxyacid or dimethyldioxirane

The oxidation of N-alkyl imines by m-chloroperoxybenzoic acid to yield nitrones was facilitated by (i) the presence of C-aryl substituents, (ii) steric inhibition of attack at the imino C-atom, (iii) electron donating para-substituents on the C-aryl substituent, (iv) non-hydroxylic solvents, (v) optimal conjugation between C-aryl substituents and the imino group, and (vi) less bulky N-alkyl groups.The oxidation of N-alkyl imines by dimethyldioxirane (DMD) in dichloromethane–acetone solution yielded nitrones without evidence of oxaziridine formation. The yields of isolated nitrones were higher for C,C-diaryl imines and for imines bearing less bulky N-alkyl substituents. N–H substituted ketimines were found to yield oximes after reaction with dimethyldioxirane.

ChemInform Abstract: Selenium Dioxide Catalyzed Oxidation of Secondary Amines with Hydrogen Peroxide. Simple Synthesis of Nitrones from Secondary Amines.

AbstractThe secondary amines (I) are oxidized with hydrogen peroxide in the presence of selenium dioxide to give the nitrones (II).

Selenium dioxide catalyzed oxidation of secondary amines with hydrogen peroxide. Simple synthesis of nitrones from secondary amines

Oxidation of secondary amines with hydrogen peroxide in the presence of selenium dioxide catalyst at room temperature gives nitrones, which are versatile synthetic intermediates, highly efficiently.

A new approach to cyclic nitrones: Application to the synthesis of α,α′-disubstituted piperidines and pyrrolidines

A new synthesis of nitrones is described. This involves the Ag(I)-catalysed cyclisation of allenic oximes, the resulting nitrones being trapped by various 1,3-dipolarophiles.