1003-67-4Relevant articles and documents
Visible-Light-Induced ortho-Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes
Jeon, Jinwon,He, Yu-Tao,Shin, Sanghoon,Hong, Sungwoo
, p. 281 - 285 (2020)
The photocatalyzed ortho-selective migration on a pyridyl ring has been achieved for the site-selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by the selective addition of a CF3 radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically valuable C2-fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P-centered radicals. The utility of this transformation was further demonstrated by the late-stage functionalization of complex bioactive molecules.
A simple and efficient method for the preparation of pyridine-N-oxides II
Coperet, Christophe,Adolfsson, Hans,Chiang, Jay P.,Yudin, Andrei K.,Sharpless, K. Barry
, p. 761 - 764 (1998)
Oxidation of pyridines with bis(trimethylsilyl)peroxide in the presence of catalytic amounts of inorganic rhenium derivatives gives high yields of their analytically pure N-oxides by simple work-ups, typically a filtration or a Kugelrohr distillation.
Rational design, synthesis, and characterization of deep blue phosphorescent Ir(III) complexes containing (4′-Substituted-2′- pyridyl)-1,2,4-triazole ancillary ligands
Park, Hea Jung,Kim, Ji Na,Yoo, Hyun-Ji,Wee, Kyung-Ryang,Kang, Sang Ook,Cho, Dae Won,Yoon, Ung Chan
, p. 8054 - 8064 (2013)
On the basis of the results of frontier orbital considerations, 4-substituted-2′-pyridyltriazoles were designed to serve as ancillary ligands in 2-phenylpyridine main ligand containing heteroleptic iridium(III) complexes that display deep blue phosphorescence emission. The iridium(III) complexes, Ir1-Ir7, prepared using the new ancillary ligands, were found to display structured, highly quantum efficient (Φp = 0.20-0.42) phosphorescence with emission maxima in the blue to deep blue 448-456 nm at room temperature. In accord with predictions based on frontier orbital considerations, the complexes were observed to have emission properties that are dependent on the electronic nature of substituents at the C-4 position of the pyridine moiety of the ancillary ligand. Importantly, placement of an electron-donating methyl group at C-4′ of the pyridine ring of the 5-(pyridine-2′-yl)-3-trifluoromethyl-1,2,4-triazole ancillary ligand leads to an iridium(III) complex that displays a deep blue phosphorescence emission maximum at 448 nm in both the liquid and film states at room temperature. Finally, an OLED device, constructed using an Ir-complex containing the optimized ancillary ligand as the dopant, was found to emit deep blue color with a CIE of 0.15, 0.18, which is close to the perfect goal of 0.15, 0.15.
Reaction of Pyridine-N-Oxides with Tertiary sp2-N-Nucleophiles: An Efficient Synthesis of Precursors for N-(Pyrid-2-yl)-Substituted N-Heterocyclic Carbenes
Bugaenko, Dmitry I.,Karchava, Alexander V.,Yurovskaya, Marina A.
, p. 5777 - 5782 (2020)
N-(Pyrid-2-yl)-substituted azolium and pyridinium salts, precursors for hybrid NHC-containing ligands, were obtained with excellent regioselectivity, employing a deoxygenative CH-functionalization of pyridine-N-oxides with substituted imidazoles, thiazoles, and pyridine. Unlike the traditional SNAr-based methods, this approach provides high yields for substrates bearing substituents of different electronic nature. The utility of azolium and pyridinium salts thus prepared was also highlighted by the synthesis of pyridyl-substituted imidazolyl-2-thione, benzodiazepine as well as 2-aminopyridines.
Bromamine-T/RuCl3 as an efficient system for the oxidation of tertiary amines to N-oxides
Sharma, Vishal B.,Jain, Suman L.,Sain, Bir
, p. 4281 - 4283 (2004)
A variety of tertiary amines were efficiently and selectively oxidized to the corresponding N-oxides by bromamine-T using ruthenium trichloride as catalyst in alkaline (pH8.4) acetonitrile/water (1:1) at 80°C.
The M?CPbA?NH3(G) system: A safe and scalable alternative for the manufacture of (substituted) pyridine and quinoline N?oxides?
Palav, Amey,Misal, Balu,Ernolla, Anilkumar,Parab, Vinod,Waske, Prashant,Khandekar, Dileep,Chaudhary, Vinay,Chaturbhuj, Ganesh
, p. 244 - 251 (2019)
An improved, safe, and scalable isolation process for (substituted) pyridine and quinoline N-oxides in quantitative yields along with high purities using the m-CPBA?NH3(g) system is described. The safety was assessed by reaction calorimetry and differential scanning calorimetry studies for possible hazards during the conversion and isolation steps. Careful interpretation of the data substantiated the safety and scalability. The process flow is simplified to meet the industrial requirements of safety, cost-effectiveness, and utility minimization. The reaction was safely demonstrated at a 2.5 kg scale.
Brown, D. H.,Kenyon, D.,Sharp, D. W. A.
, (1969)
REACTION OF PYRIDINE N-OXIDES WITH TRIFLIC ANHYDRIDE: FORMATION OF N-SULFONYLOXY AND DIPYRIDINIUM ETHER SALTS
Chen, Zhen-Chu,Stang, Peter J.
, p. 3923 - 3926 (1984)
Pyridine and picoline-N-oxides react with (CF3SO2)2O to give N-sulfonyloxy and dipyridinium ether triflate salts.
Reactivity of perfluoro-(cis-2,3-dialkyloxaziridines) with heteroaromatic nitrogen compounds
Bernardi, Rosanna,Novo, Barbara,Resnati, Giuseppe
, p. 2517 - 2521 (1996)
Pyridine N-oxides 3 are exclusively formed under particularly mild conditions when perfluorinated dialkyloxaziridines 1 are reacted with pyridine derivatives 2 bearing a substituent at the 2-position. Starting from pyridines substituted at the 3- and 4-positions, the previously unreported N-perfluoroacylpyridiniumaminides 4 are also produced and isolated as solid, stable compounds. Bis(pyridinium-N-aminides) 9, which have been prepared starting from bis-pyridine substrates and pyridazine and quinoxaline starting materials, also show the same reactivity. This behaviour reveals how oxaziridines 1 can work as both animating and oxygenating agents.
Enthalpies of combustion of the pyridine N-oxide derivatives: 4-methyl-, 3-cyano-, 4-cyano-, 3-hydroxy-, 2-carboxy-, 4-carboxy-, and 3-methyl-4-nitro, and of the pyridine derivatives: 2-carboxy-, and 4-carboxy-. The dissociation enthalpies of the N-O bonds
Ribeiro da Silva, Maria D. M. C.,Agostinha,Matos,Vaz, M. Claudia,Santos, Luis M.N.B.F.,Pilcher,Acree Jr.,Powell, Joyce R.
, p. 869 - 878 (1998)
The standard (po = 0.1 MPa) molar enthalpies of formation ΔfHom(cr) at T = 298.15 K were determined using static-bomb calorimetry for crystalline 4-methylpyridine N-oxide (4MePyNO), 3-cyanopyridine N-oxide (3CNPyNO), 4-cyanopyridine N-oxide (4CNPyNO), 3-hydroxypyridine N-oxide (3OHPyNO), 2-pyridinecarboxylic acid N-oxide (2CO2HPyNO), 4-pyridinecarboxylic acid N-oxide (4CO2HPyNO), 3-methyl-4-nitropyridine N-oxide (3Me4NO2PyNO), 2-pyridinecarboxylic acid (2CO2HPy), and 4-pyridinecarboxylic acid (4CO2HPy). The standard molar enthalpies of sublimation ΔgcrHom at T = 298.15 K were measured by microcalorimetry, or by a mass-loss effusion technique, and from the enthalpies of formation of the gaseous compounds the dissociation enthalpies Dom of the (N+-O-) dative covalent bonds were derived. ΔfHom(cr)/(kJ · mol-1) ΔgcrHom/(kJ · mol-1) Dom(N-O)/(kJ · mol-1) 4-MePyNO 5.6 ± 2.1 85.3 ± 2.6 262.4 ± 3.4 3-CNPyNO 170.9 ± 1.4 101.9 ± 2.0 254.3 ± 3.1 4-CNPyNO 162.8 ± 1.4 104.4 ± 4.3 265.5 ± 4.6 3-OHPyNO -171.3 ± 1.0 121.8 ± 4.4 255.0 ± 4.8 2-CO2HPyNO -364.1 ± 1.8 94.4 ± 4.0 275.9 ± 5.1 4-CO2HPyNO -381.2 ± 1.3 136.1 ± 1.2 259.5 ± 5.0 3-Me4NO2PyNO -19.5 ± 3.4 106.7 ± 2.0 263.4 ± 7.1 2-CO2HPy -341.0 ± 1.2 98.0 ± 2.3 4-CO2HPy -348.7 ± 1.6 113.9 ± 4.4 Comparison has been made with Dom(N-O) values in pyridine N-oxide derivatives.
SYNTHESIS OF PYRIDINE N-OXIDE-SbCl5 COMPLEXES AND THEIR INTRAMOLECULAR AND OXYGEN-TRANSFER REACTION
Yamamoto, Jiro,Imagawa, Masahiro,Yamauchi, Sigeyuki,Nakazava, Osamu,Umezu, Masahiro,et al.
, p. 1871 - 1873 (1981)
Mixing with equimolar solutions of pyridine N-oxide or its homologs and SbCl5 in CCl4 deposited 1:1 complexes as colorless crystals in high yield.On thermolysis, these complexes underwent intramolecular oxygen transfer to give selectively the corresponding 2-pyridone derivatives.N,N-Dimethylaniline N-oxide and SbCl5 also gave a crystalline 1:1 complex which on termolysis yield o-dimethylaminophenol in good yield.
Oxidation of alcohols and pyridines by a water-soluble polyoxometalate with hydrogen peroxide
Zhang, Zhenxin,Zhu, Qianqian,Ding, Yong
, p. 1211 - 1218 (2013)
A water-soluble catalyst based on a silicotungstate polyoxometalate, K 8[β-SiW11O39] · 14H2O, was developed for the oxidation of pyridines and alcohols with hydrogen peroxide. The reactions were carried out in water, and good yields of the corresponding heterocyclic N-oxides and ketones were obtained under relatively mild conditions. The catalyst could be easily recovered by extraction with ethyl acetate and reused several times. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
Selective oxidation of pyridine to pyridine-N-oxide with hydrogen peroxide over Ti-MWW catalyst
Xie, Wei,Zheng, Yuting,Zhao, Song,Yang, Junxia,Liu, Yueming,Wu, Peng
, p. 114 - 118 (2010)
The oxidation of pyridine to pyridine-N-oxide (PNO) with hydrogen peroxide has been investigated on various titanosilicate catalysts. Superior to other titanosilicates like TS-1, Ti-Beta and Ti-MOR, Ti-MWW showed a higher catalytic activity and product se
The oxidation of pyridine and alcohol using the Keggin-type lacunary polytungstophosphate as a temperature-controlled phase transfer catalyst
Ding, Yong,Zhao, Wei
, p. 45 - 51 (2011)
A novel temperature-controlled phase transfer catalyst of [(C 18H37)2(CH3)2N] 7[PW11O39] has been developed for the oxidation of pyridines and alcohols with hydrogen peroxide. The reactions were conducted in 1,4-dioxane, and high yields of the corresponding heterocyclic N-oxides and ketones were obtained under relative mild conditions. The catalyst could be easily recovered and reused after reaction with cooling. There was no discernable loss in activity and selectivity after several reaction cycles.
Green and reusable synthetic procedure for pyridine N-oxides catalyzed by a lacunary polyoxometalate
Zhao, Wei,Wang, Xing,Yang, Chunxia
, p. 150 - 160 (2014)
A lacunary Keggin polyoxometalate of K8[BW11O39H] · 13H2O was used as an effective and reusable catalyst for pyridine oxidation. Good yields of pyridine N-oxides were obtained in this catalytic system with hydrogen peroxide in water under mild conditions. Taylor and Francis Group, LLC.
Drtil, A.,Meux, Jay,Meux, J. W.,Williams, R. J.,Rogers, J. W.
, p. 479 - 484 (1983)
A lipase-glucose oxidase system for the efficient oxidation of: N -heteroaromatic compounds and tertiary amines
Yang, Fengjuan,Zhang, Xiaowen,Li, Fengxi,Wang, Zhi,Wang, Lei
, p. 3518 - 3521 (2016)
In this work, a lipase-glucose oxidase system has been designed and proven to be an efficient system for the oxidation of N-heteroaromatic compounds and tertiary amines. This dual-enzyme system not only displays environmental friendliness, but also demonstrates its huge potential in industrial applications.
Metal-free methylation of a pyridine N-oxide C-H bond by using peroxides
Li, Gang,Yang, Suling,Lv, Bingjie,Han, Qingqing,Ma, Xingxing,Sun, Kai,Wang, Zhiyong,Zhao, Feng,Lv, Yunhe,Wu, Hankui
, p. 11184 - 11188 (2015)
Metal-free methylation of a pyridine N-oxide C-H bond was developed using peroxide as a methyl reagent under neat conditions. Pyridine N-oxide derivatives with various groups (e.g., Cl, NO2, and OCH3) were all suitable substrates, and the desired products were obtained in moderate to excellent yields under standard conditions. Moreover, the methylation can be performed with a good yield on the gram-scale experiment. Tentative mechanistic studies show that the methylation is a classical radical process.
Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C-H functionalization of pyridine: N -oxides
Rassadin, Valentin A.,Zimin, Dmitry P.,Raskil'dina, Gulnara Z.,Ivanov, Alexander Yu.,Boyarskiy, Vadim P.,Zlotskii, Semen S.,Kukushkin, Vadim Yu.
, p. 6630 - 6636 (2016)
A novel solvent- and halide-free atom-economical synthesis of practically useful pyridine-2-yl substituted ureas utilizes easily accessible or commercially available pyridine N-oxides (PyO) and dialkylcyanamides. The observed C-H functionalization of PyO is suitable for the good-to-high yielding synthesis of a wide range of pyridine-2-yl substituted ureas featuring electron donating and electron withdrawing, sensitive, or even fugitive functional groups at any position of the pyridine ring (63-92%; 19 examples). In the cases of 3-substituted PyO, the C-H functionalization occurs regioselectively providing a route for facile generation of ureas bearing a 5-substituted pyridine-2-yl moiety.
Oxidation of substituted pyridines by dimethyldioxirane: Kinetics and solvent effects
Winkeljohn, W. Rucks,Vasquez, Pedro C.,Strekowski, Lucjan,Baumstark, Alfons L.
, p. 8295 - 8297 (2004)
The second order rate constants for the oxidation of substituted pyridines by dimethyldioxirane at 23°C in dried acetone were found to correlate with sigma values (ρ = -2.91). The reaction was shown to be very sensitive to protic, polar solvents. The oxidation of a series of substituted pyridines by dimethyldioxirane (1) produced the expected N-oxides in quantitative yields. The second order rate constants (k2) for the oxidation of a series of substituted pyridines (2a-g) by dimethyldioxirane were determined in dried acetone at 23°C. An excellent correlation with Hammett sigma values was found (ρ = -2.91, r = 0.995). Kinetic studies for the oxidation of 4-trifluoromethylpyridine by 1 were carried out in the following dried solvent systems: acetone (k2 = 0.017 M-1 s-1), carbon tetrachloride/acetone (7:3; k2 = 0.014 M-1 s -1), acetonitrile/acetone (7:3; k2 = 0.047 M-1 s-1), and methanol/acetone (7:3; k2 = 0.68 M-1 s-1). Kinetic studies of the oxidation of pyridine by 1 versus mole fraction of water in acetone [k2 = 0.78 M-1 s-1 (χ = 0) to k2 = 11.1 M-1 s-1 (χ = 0.52)] were carried out. The results showed the reaction to be very sensitive to protic, polar solvents.
A Simple and Efficient Method for the Preparation of Heterocyclic N-Oxide
Zhong, Ping,Guo, Sheng-Rong,Song, Cai-Sheng
, p. 247 - 253 (2004)
Pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, quinoline, isoquinoline and 2-chloropyridine are readily oxidized to their N-oxides with a solution of trichloroisocyanuric acid, acetic acid, sodium acetate and water in acetonitrile and methylene dichloride in 78%-90% yields.
Oxidation of N-heterocycles by H2O2 catalyzed by a Mn-porphyrin: An easy access to N-oxides under mild conditions
Thellend,Battioni,Sanderson,Mansuy
, p. 1387 - 1388 (1997)
A variety of N-heteroaromatic compounds were converted into their corresponding N-oxides with good yields and with high chemoselectivity in tile presence of hydrogen peroxide as oxygen donor and a catalytic amount of Mn-porphyrin. The scope and limitation of this method are discussed.
Method for synthesizing pyridine-N-oxide through catalytic oxidation by continuous non-solvent method
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Paragraph 0044-0050, (2020/08/06)
The invention discloses a method for synthesizing pyridine-N-oxide through catalytic oxidation by a continuous non-solvent method, and belongs to the field of chemical synthesis. The method is characterized by comprising the following steps: mixing metered pyridine or alkyl pyridine with an oxidizing agent in proportion, carrying out a reaction in a continuous tubular reactor filled with an immobilized catalyst, and distilling off excess water after the reaction is finished to obtain a pyridine-N-oxide or alkyl pyridine-N-oxide product, wherein the catalyst is cross-linked polystyrene resin immobilized with active substance anions and has a quaternary ammonium salt group. Compared with the prior art, the method for synthesizing the pyridine-N-oxide through catalytic oxidation by the continuous non-solvent method can realize continuous production of the pyridine-N-oxide, is environment-friendly, energy-saving and high in conversion rate, and has very good promotion and application values.
