Reaction Of N-oxide Research Articles

The Participation of Oleic Acid and its Esters in [3+2] Cycloaddition Reactions: A Mini-Review

This mini review presents the state of knowledge on the [3+2] cycloaddition reactions involving fatty acids and their esters with triatomic components (TAC). In general, the literature reports are quite sparse and relatively old. The reaction yield was in the range of 12-85%. The best result of 32CA was obtained from the reaction of butylonitrile N-oxide (4) and methyl oleate (2). Other tested TAC as components of title reactions were nitrylimines and ozone.

Facile Installation of β-Hydroxyarylethylamino Motifs at the C2-Position of Quinoline Moiety via Copper-Catalyzed [3+3]-Cycloaddition Reaction of N-Oxide with N-Ts Aziridine

AbstractA general and atom-efficient synthesis of quinoline-C2-substituted β-hydroxyarylethylamino derivatives was achieved by copper-catalyzed [3+3]-cycloaddition reaction of N-oxide with N-Ts aziridines. Notably, temperature has a huge impact on this transformation as evidenced by the fact that, at 80 °C, exclusively the [3+3] cycloadduct was isolated whereas, at elevated temperature (140 °C), it has been converted into the aminated product with good yield. Notably, there is no byproduct in the overall process. The use of base-free conditions, excellent site selectivity, and good functional group tolerance are the important features of the process.

Bilirubin Quantification in Human Blood Serum by Deoxygenation Reaction Switch-Triggered Fluorescent Probe.

A coumarin-based fluorescent compound, bilirubin fluorescent probe N-oxide (BFPNox), was successfully designed and synthesized for highly selective and sensitive detection of free bilirubin with short response time. The fluorescence "turn-on" response of the probe is based on the in situ generated Fe2+-mediated deoxygenation reaction of N-oxide from the diethylarylamine group of the probe, where the group attached to the coumarin π-conjugated system is responsible for the fluorescence quenching state of the probe, BFPNox. Here, the reaction of the added Fe3+ ions with bilirubin produces Fe2+ ions in situ in aqueous buffer. Fluorescence enhancement of BFPNox was achieved by more than 12-fold when a double equivalent of bilirubin solution was added in reaction buffer at pH 7.2 (50 mM HEPES, 5% DMSO) at 25 °C under excitation at 400 nm. It detected free bilirubin as low as 76 nM in an aqueous system without any interference of metal ions, anions, and other important biomolecules with a linear concentration range of 0-10 μM (R2 = 0.991). The probe was also employed in the estimation of free bilirubin in human serum specimens to verify the efficacy of this probe. With these, it is revealed that this probe is a good candidate to be used as a powerful diagnostic tool for the assessment of free bilirubin with significant accuracy and reliability.

Metal-Free Synthesis of 3-(Iso)quinolinyl 4-Chromenones and 3-(Iso)quinolinyl 4-Quinolones from (Iso)quinoline N-Oxides and Ynones.

A general approach for the synthesis of 3-(iso)quinolinyl 4-chromenones and 3-(iso)quinolinyl 4-quinolones from (iso)quinoline N-oxides and ynones under metal-free conditions was developed. The reaction of (iso)quinoline N-oxide with the electron-deficient alkyne first generated an (iso)quinolinyl β-diketone intermediate, which then underwent an intramolecular dehydration, affording 3-(iso)quinolinyl 4-chromenones and 3-(iso)quinolinyl 4-quinolones.

A Room Temperature Curing Agent for Hydroxyl-Terminated Polybutadiene: Synthesis of a Novel Nitrile N-Oxide and Curing Properties of the Polymer Network

2,5-Diethyl-1,4-benzenedinitrile N-oxide was designed and synthesized to achieve room temperature curing of hydroxyl-terminated polybutadiene binders. The structures and properties of the four cured elastomers having different content of curing agent were investigated. The results showed that the isoxazoline rings from the reaction of nitrile N-oxide with cis-alkene are observed in the four cured elastomers. The results also revealed that the hydroxyl-terminated polybutadiene with the lowest content of curing agent showed the lowest cross-linking density and stress at break. The proper activity and steric hindrance of 2,5‑diethyl-1,4-benzenedinitrile N-oxide gave better mechanical properties and hydrophobic properties of the cured elastomers than nitrile N-oxide prepared by our previous work.

Asymmetric Henry Reaction of 2-Acylpyridine N-Oxides Catalyzed by a Ni-Aminophenol Sulfonamide Complex: An Unexpected Mononuclear Catalyst.

The asymmetric Henry reaction of 2-acylpyridine N-oxide remains a challenge as N-oxides generally act as competitive catalyst inhibitors or displace activating ligands. A novel variable yield (up to 99%) asymmetric Henry reaction of 2-acypyridine N-oxides catalyzed by a Ni-aminophenol sulfonamide complex with good to excellent enantioselectivity (up to 99%) has been developed. Mechanistic studies suggest that the unique properties of the electron-pairs of N-oxides for complexation with Ni makes the unexpected mononuclear complex, rather than the previously reported dinuclear complex, the active species.

Regioselective Ring Opening Reactions of Pyridine N-Oxide Analogues by Magnesium Hydride Complexes

The stoichiometric reactions of phosphinimino-amino (PIA)-supported magnesium hydride complex 1, [L1MgH]2 (L1 = (2,6-iPr2-C6H3)NC(Me)CHP(Cy2)N(2,6-Me2-C6H3)), with pyridine N-oxide and 2-phenylpyridine N-oxide afforded 2,4-pentadiene-1-oximate complex 2 and 5-phenyl-2,4-pentadiene-1-oximate complex 3, respectively. The reaction of 1 with 2-methylpyridine N-oxide showed a unique regioselectivity to produce 2,4-hexadiene-1-oximate 4a in toluene and 3,5-hexadiene-2-oximate 4b in THF, respectively. Treatment of β-diketiminato (BDI)-supported magnesium hydride complex 5, [L2MgH]2 (L2 = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3)), with quinoline N-oxide gave 1,2-dihydroquinoline type product 6, while treatment of complex 5 with 2-methylpyridine N-oxide either in toluene or THF afforded 1-methyl-2,4-pentadiene-1-oximate complex 7 as the only product. All these complexes were fully characterized by NMR spectroscopy and X-ray diffraction analyses, and mechanism researches were conducted to understand the ring-opening reaction of pyridine N-oxide.

New complexes of triethanolamine N-oxide with metal salts

New potentially pharmacologically active complexes of general formula n[(HOCH2CH2)3N—O]·MX2 (M = Zn, Co, Ni, Cu; X = Cl, MeCO2, ArOCH2CO2; n = 1, 2) were synthesized by the reaction of triethanolamine N-oxide with essential metal salts.

ChemInform Abstract: Cobalt(III) Catalyzed C‐8 Selective C—H and C—O Coupling of Quinoline N‐Oxide with Internal Alkynes via C—H Activation and Oxygen Atom Transfer.

An efficient, scalable, atom-economical, regio-selective air stable Cp*Co(III) catalyzed C–H and C–O coupling via a C–H activation/oxygen atom transfer reaction of quinoline N-oxide and an internal alkyne is reported. Such a catalytic transformation is witnessed for the first time with a cobalt catalyst and using N-oxide as a traceless directing group, in contrast to the existing literature. The developed synthetic methodology is straightforward and possesses various functional group tolerances, including heterocycles.

New biologically active arylchalcogenylacetates based on triethanolamine N-oxide

New potentially pharmacologically active tris(2-hydroxyethyl)hydroxyammonium salts were synthesized by the reaction of triethanolamine N-oxide with biologically active acetic acid derivatives RYCH2CO2H (R = Ar, 3-indolyl; Y = O, S, SO2).

Probing the metal complexing ability of bis-quinolizidine N-oxides: Synthesis, spectroscopy and crystal structures

New ZnX 2 (X = Cl, Br) complexes with sparteine N1-oxide, sparteine epi- N16-oxide, lupanine (2-oxosparteine) N-oxide and α-isosparteine N-oxide were obtained and characterized by spectroscopic and crystallographic methods. Complexation with N1-oxides involves inversion of the configuration at the N16 atom of sparteine, converting its C ring from a boat into a chair form, whereas the structure of sparteine epi- N16-oxide, typified by the trans boat/chair C/D quinolizidine moiety, remains unchanged upon complexation. Coordination of zinc salts in the above compounds is realized solely through the oxygen atom of the N-O group and is accompanied by protonation of the “not- N-oxide” nitrogen atom. At variance lupanine N-oxide forms bis-monodentate complexes with ZnX 2 utilizing both the N-oxide and the lactam carbonyl oxygen atoms to bridge the neighboring ZnX 2 units, while reaction of α-isosparteine N-oxide with ZnX 2 leads to formation of complex salts of the general formula [H(−)α-Sp( N-oxide)][(ZnX 3)(H 2O)].

Synthesis, X-ray analysis and DFT study of 2-amino-3-(N-oxipiridin-4-ilsulfanil)-propionic acid dihydrate

The title compound, C8H14N2O5S 2(H2O), 2-amino-3-(N-oxipiridin-4-ilsulfanil)-propionic acid dihydrate, is obtained by the reaction of cysteine and 4-nitropyridine N-oxide in dimethylformamide, removing the NO2 group from the benzene ring and releasing nitrous acid into the solution. The molecule exists as a Zwitterion. Hydrogen bond interactions involving the title molecule and water molecules allow the formation of R55 (23) edge fused rings parallel to (010). Water molecules are connected independently, forming infinite chains (wires), in square wave form, along the b-axis. The chirality of the cysteine molecule used in the synthesis is retained in the title molecule. A density functional theory (DFT) optimized structure at the B3LYP/6-311G(3df,2p) level allows comparison of calculated and experimental IR spectra.

Crystallographic characterization of the intermediate in the synthesis of tetrazole from nitrile and azide in water

The intermediate [Zn(4-PTZ)2(H2O)4] (4-PTZ=5-(4-pyridyl N-oxide)tetrazolate) (1) in the synthesis of 4-H-PTZ (2) from cycloaddition reaction of 4-cyanopyridine N-oxide with NaN3 in water catalyzed by ZnCl2 was structurally characterized. The catalysis role of Zn2+ in the synthesis of tetrazole stems from the formation of tetrazolate zinc complex 1.

Enantio‐ and Diastereoselectivity in 1,3‐Dipolar Cycloaddition Reactions of Nitrones with 3‐Crotonoyl‐2‐oxazolidinone Catalyzed by Ni(II)‐Binaphthyldiimine Complexes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Reaction of 4‐Azidoquinoline N‐Oxide with Dimethyl Acetylenedicarboxylate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Enantio- and Diastereoselectivity in 1,3-Dipolar Cycloaddition Reactions of Nitrones with 3-Crotonoyl-2-oxazolidinone Catalyzed by Ni(II)- Binaphthyldiimine Complexes

Abstract Chiral Ni(II)-1,1′-binaphthyl-2,2′-diimine complexes were found to be effective Lewis-acid catalysts for an asymmetric 1,3-dipolar cycloaddition reaction of N-benzylideneaniline N-oxide with 3-crotonoyl-2-oxazolidinone. In the presence of molecular sieves (4 Å), when the chiral N,N′-bis(2,6-dichlorobenzylidene)-1,1′-binaphthyl-2,2′-diamine (BINIM-DC) and Ni(ClO4)2·6H2O were used to prepare the catalyst, up to 81% ee of the corresponding endo-cycloadduct was obtained with endo-selectivity (87 : 13, and up to 96 : 4). The use of N,N′-bis(3-chloro-substituted 2-hydroxybenzylidene) derivatives as ligands under similar conditions showed high exo-selectivity (up to 95 : 5) with moderate enantioselectivity. Although almost no diastereoselectivity was observed, endo- and exo-cycloadducts were obtained with promising levels of enantioselectivity (up to > 98%) in the presence of catalysts, which were prepared from chiral BINIM-DC, NiBr2, and AgBF4, AgSbF6, or AgPF6.

Rapid Microwave‐Promoted Solvent‐Free Oxidation of α‐Methylene Ketones to α‐Diketones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Rapid microwave-promoted solvent-free oxidation of α-methylene ketones to α-diketones

A convenient and rapid method for the oxidation of α-methylene ketones to α-diketones has been described involving the reaction of pyridine N-oxide with α-nosyloxy ketone intermediates.

Reactivity of a triamidoamine complex of trivalent uranium

Reduction of [U(NN′3)I] [NN′3 = N(CH2CH2NSiMe2But)3] with potassium in pentane gives the purple trivalent monomer [U(NN′3)] in good yield, this compound having previously been synthesised via fractional vacuum sublimation of mixed-valent [{U(NN′3)}2(μ-Cl)]. The magnetic susceptibility of this compound is consistent with the presence of U(III) centres, and this is confirmed by a characteristic near IR spectrum. Its reactions with Lewis bases to give e.g. [U(NN′3)(Py)] and [U(NN′3)(HMPA)] are reported, along with the molecular structure of the latter. The complex [U(NN′3)] is readily oxidised, imido and hydrazido complexes being formed readily by reaction with trimethylsilyl-azide and -diazomethane, respectively. The reaction with methylene trimethylphosproane however led to the formation of an addition compound [U(NN′3)(CH2PMe3)]. Reaction of this latter complex with air gave a few crystals of the unusual hydroxo complex [U(NN′3)(OH)(CH2PMe3)] which was structurally characterised. Reaction of [U(NN′3)(CH2PMe3)] with trimethylamine N-oxide gave pentavalent [U(NN′3)(O)], or perhaps a dimer thereof. The latter complex reacted with [U(NN′3)] to give the bridging oxo complex [{U(NN′3)}2(μ-O)] which could also be prepared directly by reaction of trimethylamine N-oxide with [U(NN′3)].

Reaction of 4-Azidoquinoline N-Oxide with Dimethyl Acetylenedicarboxylate

The reaction of 4-azidoquinoline N-oxide with dimethyl acetylenedicarboxylate occurs via a 1,3-dipolar cycloaddition mechanism at the N-oxide and not at the azide group.