Showing papers on "Nitroso published in 2006"
TL;DR: In this article, a chromogenic oxazine compound for the colorimetric detection of cyanide was designed and the [1,3]oxazine ring of the compound opens to form a phenolate chromophore in response to cyanide.
218 citations
TL;DR: In this paper, a microreview outlines recent advances in the area of asymmetric NDA reaction following the review by Streith and Defoin in 1994, and a number of important compounds have been synthesized using this method.
157 citations
TL;DR: Hydrolysis of acyloxy nitroso compounds produces nitrous oxide, the dimerization and dehydration product of HNO, and provides evidence for the intermediacy of H NO, andKinetic analysis shows that the rate of hydrolysis depends on pH and the structure of the acyl group of theAcyloxy Nitroso compound relax pre-constricted rat aortic rings similar to known HNO donors.
Abstract: Nitroxyl (HNO/NO-), the reduced form of nitric oxide, has gained attention based on its separate chemistry and biology from nitric oxide. The inherent reactivity of HNO requires new and mechanistically unique donors for the detailed study of HNO chemistry and biology. Oxidation of cyclohexanone oxime with lead tetraacetate yields 1-nitrosocyclohexyl acetate, whereas oxidation of oximes in the presence of excess carboxylic acid gives various acyloxy nitroso compounds. These bright blue compounds exist as monomers as indicated by their infrared, proton, and carbon NMR spectra, and X-ray crystallographic analysis reveals the nitroso groups possess a “nitroxyl-like” bent configuration. Hydrolysis of these compounds produces nitrous oxide, the dimerization and dehydration product of HNO, and provides evidence for the intermediacy of HNO. Both thiols and oxidative metal complexes inhibit nitrous oxide formation. Hydrolysis of these compounds in the presence of ferric heme complexes forms ferrous nitrosyl comple...
119 citations
TL;DR: The ability of monomeric and dimeric flavanols to scavenge reactive nitrogen species derived from nitrous acid to highlight multiple routes in which dietary derived Flavanols may exert beneficial effects in the gastrointestinal tract.
77 citations
TL;DR: The first direct enantioselective N-nitroso aldol reaction of aldehyde with nitrosobenzene catalyzed by an L-prolinamide derivative is presented, furnishing the -hydroxyamino carbonyl compounds, the otherwise disfavored products, in good yields.
75 citations
TL;DR: The structure and bonding as well as N,N rotational barriers are discussed on the basis of theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis) and a detailed discussion of the molecular structures will be presented.
Abstract: N-Nitroso- (5a,c) and N-nitraminotetrazoles (6a−c) were synthesized from the corresponding aminotetrazoles (3a−c) either by the direct nitration with acetic anhydride/HNO3 or by dehydration of the corresponding nitrates (4a−c) with concentrated sulfuric acid. The conversion of the N-nitrosoaminotetrazoles (5a,c) with peroxytrifluoroacetic acid (CF3CO3H) yielded the corresponding nitramines in high yield (6a (82%), 6c (80%)). The N-nitroso- (5a,c) and N-nitraminotetrazoles (6a−c) have been fully characterized by vibrational (IR, Raman) and multinuclear NMR spectroscopy (14N/15N, 1H, 13C), mass spectrometry, and elemental analysis. A detailed discussion of the 15N chemical shifts and 1H−15N coupling constants is given. The molecular structures in the solid state were determined by single-crystal X-ray diffraction (3a,c; 5a,c; 6a−c) and a detailed discussion of the molecular structures will be presented. Furthermore, the structure and bonding as well as N,N rotational barriers are discussed on the basis of t...
62 citations
TL;DR: The HOF.CH3CN complex, readily prepared by passing F2 through aqueous acetonitrile, is an exceptionally efficient oxygen transfer agent in its capacity to oxidize various azides into the corresponding nitro derivatives.
Abstract: The HOF.CH3CN complex, readily prepared by passing F2 through aqueous acetonitrile, is an exceptionally efficient oxygen transfer agent. It is unique in its capacity to oxidize various azides into the corresponding nitro derivatives. This method requires short reactions times and room temperature or below, and the desired nitro compounds were usually isolated in very good yields. The respective nitroso derivatives are believed to be the intermediates in this reaction. Functional groups such as aromatic rings, ketones, nitriles, halides, alcohols, and esters are tolerated. Sulfides react with HOF.CH3CN usually at the same rate as azides. Amines and olefins, however, react faster, so they have to be protected first. Nitro derivatives with various oxygen isotopes can be made using the labeled H18OF.CH3CN. In the case of chiral azides the stereochemistry around the nitrogen-bonded carbons is retained.
38 citations
TL;DR: The photochemistry of p-azidoaniline was studied in argon matrices in the absence and presence of oxygen and quantum chemical calculations turned up no evidence for the claimed diradical character of these compounds.
Abstract: The photochemistry of p-azidoaniline was studied in argon matrices in the absence and presence of oxygen. With the help of quantum chemical calculations we were able to characterize the triplet p-aminophenylnitrene as well as the cis- and trans-p-aminophenylnitroso oxides. It was found that the latter two isomers can be interconverted by selective irradiation and that they are ultimately converted into p-nitroaniline. Although restricted wavefunctions of the nitroso oxides are unstable, CASSCF calculations turned up no evidence for the claimed diradical character of these compounds. Also we found no evidence for dioxaziridines as intermediates of the conversion of the nitroso oxides to p-nitroaniline.
36 citations
Patent•
19 Jul 2006TL;DR: A functionalized polymer as mentioned in this paper is a polymer chain and, bonded thereto, a functional group having the general formula NQOR 1 where R 1 is a hydrogen atom or CH 2 Z where Z is either a substituted or unsubstituted aryl or aralkyl group.
Abstract: A functionalized polymer includes a polymer chain and, bonded thereto, a functional group having the general formula —NQOR 1 where R 1 is a hydrogen atom or —CH 2 Z where Z is a hydrogen atom or a substituted or unsubstituted aryl, alkyl, alkenyl, alkenaryl, aralkenyl, alkaryl, or aralkyl group and where Q is a moiety connected to the nitrogen atom of the functional group through a C, N, O, or S atom. The material can be the reaction product of a living polymer and a compound that includes nitroso functionality. The functional group can interact with particulate filler such as, e.g., carbon black.
32 citations
TL;DR: In this paper, the visible spectra of a series of various nitroso dyes have been evaluated by using time-dependent density functional theory approach and explicitly taking into account bulk solvent effects.
32 citations
TL;DR: In this paper, the electronic spectra were measured and the kinetics of unimolecular decomposition of the isomeric forms (cis and trans) of phenylnitroso oxide, (4-methylphenyl)nitropenyl) and 4-methoxyphenyl) nitroso oxides in acetonitrile, benzene, and n-hexane was studied using flash photolysis.
Abstract: The electronic spectra were measured and the kinetics of unimolecular decomposition of the isomeric forms (cis and trans) of phenylnitroso oxide, (4-methylphenyl)nitroso oxide, (4-nitropenyl)nitroso oxide, (4-bromophenyl)nitroso oxide, 4-(N,N-dimethylamino)phenylnitroso oxide, and (4-methoxyphenyl)nitroso oxide in acetonitrile, benzene, and n-hexane was studied using flash photolysis. In all of the nitroso oxides except for 4-(N,N-dimethylamino)phenylnitroso oxide, the cis form absorbed in a shorter wavelength region and was more labile than the trans form. The difference between the reactivity of the two species increased on going from n-hexane to acetonitrile. The temperature dependence of reaction rate constants was studied for both of the isomeric forms. Unlike the trans isomer, the cis isomer almost did not react with tetramethylethylene.
TL;DR: A combination of 1,3-dihalo-5,5-dimethylhydantoin (X = Br, Cl) and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of N,N-dialkyl amines to their corresponding nitroso derivatives under mild and heterogeneous conditions in good to excellent yields as mentioned in this paper.
Abstract: A combination of 1,3-dihalo-5,5-dimethylhydantoin (X = Br, Cl) and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of N,N-dialkyl amines to their corresponding nitroso derivatives under mild and heterogeneous conditions in good to excellent yields.
TL;DR: A method for a concise assembly of oxazine rings based on a Lewis acid-promoted hetero-Cope rearrangement featuring the first examples of the [3,3]-sigmatropic transpositions involving the nitroso group is described.
Abstract: A method for a concise assembly of oxazine rings based on a Lewis acid-promoted hetero-Cope rearrangement is described. The hetero-Cope rearrangement features the first examples of the [3,3]-sigmatropic transpositions involving the nitroso group. A variety of functionalized substrates have been subjected to the reaction. The described method has a strong potential for the synthesis of marine natural products containing oxazine rings.
TL;DR: In vivo experiments demonstrated that Angeli's salt exhibits a unique nitrosation signature which differs from that of DEA/NO inasmuch as substantial amounts of a mercury-resistant nitroso species are generated in the heart, whereas S-nitrosothiols are the major reaction products in plasma.
Abstract: While nitroxyl (HNO) has been shown to engage in oxidation and hydroxylation reactions, little is known about its nitrosating potential. We therefore sought to investigate the kinetics of formation and identity of the reaction products of the classical nitroxyl donor Angeli's salt (AS) with three representative tryptophan derivates (melatonin, indol-3-acetic acid, and N-acetyl-l-tryptophan) in vitro. In the presence of oxygen and at physiological pH, we find that the major products generated are the corresponding N-nitrosoindoles with negligible formation of oxidation and nitration products. A direct comparison of the effects of AS, nitrite, peroxynitrite, aqueous NO* solution, and the NO-donor DEA/NO toward melatonin revealed that nitrite does not participate in the reaction and that peroxynitrite is not an intermediate. Rather, N-nitrosoindole formation appears to proceed via a mechanism that involves electrophilic attack of HNO on the indole nitrogen, followed by a reaction of the intermediary hydroxylamine derivative with oxygen. Further in vivo experiments demonstrated that AS exhibits a unique nitrosation signature which differs from that of DEA/NO inasmuch as substantial amounts of a mercury-resistant nitroso species are generated in the heart, whereas S-nitrosothiols are the major reaction products in plasma. These data are consistent with the notion that the generation of nitroxyl in vivo gives rise to formation of nitrosative post-translational protein modifications in the form of either S- or N-nitroso products, depending on the redox environment. It is intriguing to speculate that the particular efficiency of nitroxyl to form N-nitroso species in the heart may account for the positive inotropic effects observed with AS earlier.
Patent•
17 Feb 2006
TL;DR: In this article, a thermoplastic urethane with the superior performance characteristics of a cross-linked polyurethane was used for the processing of a sports equipment with the advantages of a polyamide.
Abstract: Sports equipment incorporate thermoplastic compositions including urethane and a nitroso reaction product of a nitroso compound and a diisocyanate or polyisocyanate. The invention on allows for the processing advantages of a thermoplastic urethane with the superior performance characteristics of a cross-linked polyurethane.
TL;DR: Acyl nitroso cycloadducts of the alkaloid thebaine undergo an unexpected cleavage of the C5-C6 bond when treated with 2 equiv of samarium(II) iodide in THF to give novel hexahydrobenzazocine products.
Abstract: [reaction: see text] Acyl nitroso cycloadducts of the alkaloid thebaine undergo an unexpected cleavage of the C5-C6 bond when treated with 2 equiv of samarium(II) iodide in THF to give novel hexahydrobenzazocine products A proposed mechanism for the transformation involves rearrangement of the initial radical anion
TL;DR: In this paper, the linear nitroso group and a water molecule are coordinated in the trans positions, three nitrogen atoms from NO and NH3 ligands occupy the coordination octahedron face.
Abstract: The reaction between [RuNO(NH3)2(NO2)2OH] and an excess of 3 M HCl leads to denitration of the starting complex and precipitation of [Ru(NO)(NH3)2Cl3]. Crystals of the tittle complex have been obtained by evaporation of the mother liquor at ambient temperature. The crystal structure of the product has been determined. The linear nitroso group and a water molecule are coordinated in the trans positions, three nitrogen atoms from NO and NH3 ligands occupy the coordination octahedron face.
Patent•
24 May 2006TL;DR: In this article, a method for inhibiting the premature polymerization of unsaturated monomers was proposed, which adds to the monomers an effective amount of at least one nitroso inhibitor of the structure.
Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one nitroso inhibitor of the structure: Formula (I) wherein R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, nitro, nitroso, halogen, COOR wherein R is hydrogen or alkyl, alkyl, and heteroatom- substituted alkyl; or adjacent groups R1, R2, R3, and R4 can be taken together to form a substituted or unsubstituted fused six-membered ring. Also disclosed is a composition of matter comprising: A) an ethylenically unsaturated monomer and B) at least one nitroso compound of the above-described structure.
TL;DR: A tetradentate NOOO-donor ligand, N-(salicylidene)nitrosophenylglycine (H2snpg) has been designed, synthesized and structurally characterized as discussed by the authors.
Abstract: A new tetradentate NOOO-donor ligand, N-(salicylidene)nitrosophenylglycine (H2snpg) has been designed, synthesized and structurally characterized. Copper(II), nickel(II), cobalt(II), manganese(II) and zinc(II) complexes of H2snpg have been prepared for the first time. The authenticities of the ligand and its metal complexes have been established on the basis of elemental analyses, molar conductance measurements, magnetic properties, spectral (i.r., 1H-n.m.r., u.v.–vis. and mass) studies. The i.r. spectral studies of all the complexes exhibit a similar feature about the ligating nature of the ligand to the metal ions and revealed that the ligand has coordinated through the carbonyl oxygen, azomethine nitrogen, nitroso oxygen and deprotonated hydroxyl oxygen. The molar conductance data suggest them to be non-electrolytes. The antimicrobial activity of all the compounds was studied against Escherichia coli, Bacillus cirroflagellosus, Aspergillus niger and Candida albicans. All the complexes have shown a moderate to high fungal activity compared to the ligand.
TL;DR: Density functional theory studies of the hetero-Cope reactions of 4-nitroso-1-butenes and nitrosobicyclo-hexenes are reported, finding Lewis acids such as SbF5 and TiCl4 accelerate the reactions, as has been found experimentally by Zakarian and Lu.
TL;DR: In this article, a microreview outlines recent advances in the area of asymmetric NDA reaction following the review by Streith and Defoin in 1994, and a number of important compounds have been synthesized using this method.
Abstract: During the past decade, the nitroso Diels–Alder (NDA) reaction has become more practical tool for organic synthesis, and a numbers of important compounds have been synthesized using this method. Until recently, no reports on a catalytic asymmetric version of this reaction had been reported; the major issues were the high reactivity of nitroso compounds and their chemical properties. This microreview outlines recent advances in the area of asymmetric NDA reaction following the review by Streith and Defoin in 1994. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
TL;DR: In this paper, the influence of micellar media upon the transnitrosation reaction between N-methyl-N-nitroso-p-toluensulfonamide (MNTS) and three linear alkylamines was studied.
Abstract: The influence of micellar media upon the transnitrosation reaction between N-methyl-N-nitroso-p-toluensulfonamide (MNTS) and three linear alkylamines (n-octylamine (OA), N-methyl-n-octylamine (MOA) and N,N-dimethyl-n-octylamine (DMOA)) in micelles of Cetyltrimethylammonium Chloride (CTACl) has been studied. The rate constants were obtained and the pseudophase model allowed us to obtain the intrinsic reactivity constants in the aqueous pseudophase and in the micellar pseudophase (k2i and k2w) and the binding constant of the amines to the micellar phase (Ka). © 2006 Science Reviews.
TL;DR: An intramolecular hetero-Diels-Alder cycloadduct of an acyl nitroso compound and a 9,10-dimethyl anthracene derivative was prepared as a potential nitroxyl (HNO) donor, resulting in the formation of a nitrone, whose structure was confirmed by X-ray crystallography.
Abstract: An intramolecular hetero-Diels−Alder cycloadduct of an acyl nitroso compound and a 9,10-dimethyl anthracene derivative was prepared as a potential nitroxyl (HNO) donor. This compound did not release HNO under any of the conditions tested. Treatment of this cycloadduct with excess MeMgCl resulted in the formation of a nitrone, whose structure was confirmed by X-ray crystallography. A mechanism where MeMgCl acts as a nucleophile, strong base, and Lewis acid possibly explains the formation of this product.
Journal Article•
TL;DR: In this paper, the effect of A 1,3 -strain introduced by N-NO group in N-nitroso-r--2,c-6-diphenylpiperidin-4-ones on the selectivity in the formation of oximes 14-18 and semicarbazones 19-22 has been studied.
Abstract: The effect of A 1,3 -strain introduced by N-NO group in N-nitroso-r--2,c-6-diphenylpiperidin-4-ones on the selectivity in the formation of oximes 14-18 and semicarbazones 19-22 has been studied. In general, the oximes and semicarbazones formed are the E isomers, exclusively, except in the cases of the oximation of 3-methyl-N-nitrosopiperidin-4-one and 3,5-dimethyl-N-nitrosopiperidin-4-one which have produced a mixture of E and Z isomeric oximes. Oximation of 3,5-dimethyl-N-nitrosopiperidin-4-one yields a mixture of two isomers 17 and 18 differing in the relative configurations of methyl group due to epimerization at C5. The configurations and preferred conformations of the oximes 14-18 and semicarbazones 19-22 of N-nitroso-r-2,c-6-diphenylpiperidin-4-ones have been determined using NMR spectral experiments and are found to prefer twist-boat conformations with an equilibrium between two rotameric states due to restricted rotation around N-NO bond. The semiempirical MO calculations performed on the nitrosamines 14-22 have also shown the preference of twist-boat conformations.
TL;DR: In this paper, a ring-opening product of the nitrosonium, a nitroso compound, was proposed as an active species for the decomposition of a hydroperoxide by hindered amine light stabilizers.
Abstract: Hydroperoxide decomposition by hindered amine light stabilizers (HALSs) is an important process producing active HALS derivatives and has been studied energetically. The decisive active species of the decomposition, however, has not been proposed yet. In this article, HALS nitrosonium that forms in the decomposition of a hydroperoxide by HALSs and a ring-opening product of the nitrosonium, a nitroso compound, are proposed as active species for hydroperoxide decomposition. Furthermore, the reactivity of the nitrosonium with phenols is discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1310–1317, 2006
TL;DR: In this paper, three different reactions of O-nitroso aldol products promoted by metal ions are described, and three different types of catalysts are used for α-aminooxy ketones.
Abstract: Lewis acid catalysts play an important role in the transformation of α-aminooxy ketones (O-nitroso aldol products). Three different reactions of O-nitroso aldol products promoted by metal ions are described.
TL;DR: In this paper, the synthesis of tert-alkyl nitroso compounds from commercially available tertalkyl amines RCH 2 CMe 2 NH 2 proceed cleanly via the intermediacy of the benzoyl derivatives and the corresponding hydroxylamines, and are suitable for scale-up and were successfully performed on up to 500mmol scale.
Abstract: The syntheses of tert-alkyl nitroso compounds RCH 2 CMe 2 N=O from commercially available tert-alkyl amines RCH 2 CMe 2 NH 2 proceed cleanly via the intermediacy of the benzoyl derivatives RCH 2 CMe 2 NHOC(O)Ph and the corresponding hydroxylamines RCH 2 CMe 2 NHOH. Since the intermediates require no purification in the course of the transformations, the overall yields of the isolated crystalline nitroso dimers (75-80% for R = H, 75% for R = Me and 66% for R = Me 3 C) are based on the corresponding amine precursors. In the latter case (R = Me 3 C), significant steric demands and hydrophobicity of Me 3 CCH 2 CMe 2 group necessitate the application of more efficient reagents and conditions on the debenzoylation and oxidation steps. The syntheses are perfectly suitable for scale-up and were successfully performed on up to 500-mmol scale.
TL;DR: In this article, the influence of 4-hydroxy- l -proline (Hyp) nitrosation on the conformation of the synthesized N-nitroso-compound was analyzed.