- Visible-Light-Mediated C-H Alkylation of Pyridine Derivatives
-
We report herein a visible-light-mediated C-H alkylation of pyridine derivatives that proceeds by simple combination of a large variety of N-alkoxypyridinium ions with alkanes in the presence of 2 mol % of fac-Ir(ppy)3 under blue illumination. The mild reaction conditions together with the high group functional tolerance make of this process a useful synthetic platform for the construction of structurally strained heterocycles. Detailed mechanistic investigations, including density functional theory calculations and quantum yield measurement, allowed us to understand factors controlling the reactivity and the selectivity of the reaction.
- Rammal, Fatima,Gao, Di,Boujnah, Sondes,Gaumont, Annie-Claude,Hussein, Aqeel A.,Lakhdar, Sami
-
supporting information
p. 7671 - 7675
(2020/10/09)
-
- A Biocatalytic Synthesis of Heteroaromatic N-Oxides by Whole Cells of Escherichia coli Expressing the Multicomponent, Soluble Di-Iron Monooxygenase (SDIMO) PmlABCDEF
-
Aromatic N-oxides (ArN?OX) are desirable biologically active compounds with a potential for application in pharmacy and agriculture industries. As biocatalysis is making a great impact in organic synthesis, there is still a lack of efficient and convenient enzyme-based techniques for the production of aromatic N-oxides. In this study, a recombinant soluble di-iron monooxygenase (SDIMO) PmlABCDEF overexpressed in Escherichia coli was showed to produce various aromatic N-oxides. Out of 98 tested N-heterocycles, seventy were converted to the corresponding N-oxides without any side oxidation products. This whole-cell biocatalyst showed a high activity towards pyridines, pyrazines, and pyrimidines. It was also capable of oxidizing bulky N-heterocycles with two or even three aromatic rings. Being entirely biocatalytic, our approach provides an environmentally friendly and mild method for the production of aromatic N-oxides avoiding the use of strong oxidants, organometallic catalysts, undesirable solvents, or other environment unfriendly reagents. (Figure presented.).
- Petkevi?ius, Vytautas,Vaitekūnas, Justas,Taurait?, Daiva,Stankevi?iūt?, Jonita,?arlauskas, Jonas,??nas, Narimantas,Me?kys, Rolandas
-
supporting information
p. 2456 - 2465
(2019/01/25)
-
- Electrochemical Deoxygenation of N-Heteroaromatic N -Oxides
-
An electrochemical method for the deoxygenation of N-heteroaromatic N -oxide to give the corresponding N-heteroaromatics has been developed. Several classes of N-heterocycles such as pyridine, quinoline, isoquinoline, and phenanthridine are tolerated. The electrochemical reactions proceed efficiently in aqueous solution without the need for transition-metal catalysts and waste-generating reducing reagents.
- Xu, H.-C.,Xu, P.
-
supporting information
p. 1219 - 1221
(2019/06/08)
-
- Synthesis method of topiroxostat
-
The invention belongs to the field of medicine and chemical industry and discloses a synthesis method of topiroxostat. The method comprises that 4-cyanopyridine as a starting raw material is oxidized by hydrogen peroxide to form an intermediate 1, the intermediate 1, sodium methoxide and ammonium chloride undergo a reaction to produce an intermediate 2, the intermediate 2 and 4-cyanopyridine undergo an annulation reaction under action of cuprous bromide and sodium carbonate to produce an intermediate 3, and the intermediate 3 and trimethylsilyl cyanide undergo a cyanation reaction to produce topiroxostat. The method utilizes low-price 4-cyanopyridine as a starting raw material, and in the first reaction step, methanol is used as a solvent and 4-cyanopyridine nitrogen oxide as the intermediate 1 is prepared. The method has a high yield and produces a high-purity product. The whole route is easy to operate and is conducive to industrial mass production.
- -
-
Paragraph 0028; 0029; 0033; 0034; 0035; 0036; 0037-0044
(2017/11/08)
-
- Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C-H functionalization of pyridine: N -oxides
-
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.
- Rassadin, Valentin A.,Zimin, Dmitry P.,Raskil'dina, Gulnara Z.,Ivanov, Alexander Yu.,Boyarskiy, Vadim P.,Zlotskii, Semen S.,Kukushkin, Vadim Yu.
-
supporting information
p. 6630 - 6636
(2018/03/01)
-
- Metal-Free, Phosphonium Salt-Mediated Sulfoximination of Azine N-Oxides: Approach for the Synthesis of N-Azine Sulfoximines
-
Herein, we report a simple and metal-free method for the synthesis of N-azine sulfoximines by the nucleophilic substitution of azine N-oxides with NH-sulfoximines. The present method works at room temperature with wide functional group compatibility and gives several unprecedented N-azine sulfoximines. The reaction conditions were also found suitable with enantiopure substrates and furnished products without any racemization. It also finds an application in the sulfoximination of azine-based functional molecules such as 2,2′-bipyridine, 1,10-phenanthroline, and quinine.
- Aithagani, Sravan Kumar,Kumar, Mukesh,Yadav, Mahipal,Vishwakarma, Ram A.,Singh, Parvinder Pal
-
p. 5886 - 5894
(2016/07/23)
-
- Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles
-
A Mo/P catalytic system for an efficient gram-scale oxidation of a variety of nitrogen heterocycles to N-oxides with hydrogen peroxide as terminal oxidant has been investigated. Combined spectroscopic and crystallographic studies point to the tetranuclear Mo4P peroxo complex as one of the active catalytic species present in the solution. Based on this finding an optimized catalytic system has been developed. The utility and chemoselectivity of the catalytic system has been demonstrated by the synthesis of over 20 heterocyclic N-oxides.
- Larionov, Oleg V.,Stephens, David,Mfuh, Adelphe M.,Arman, Hadi D.,Naumova, Anastasia S.,Chavez, Gabriel,Skenderi, Behije
-
p. 3026 - 3036
(2014/05/06)
-
- PROCESS FOR MAKING AND USING HOF.RCN
-
The invention relates to a process for making HOF.RCN and using it to oxidise organic substrates in a quick and safe way. The process comprises passing diluted fluorine through a conduit and RCN in water through another conduit into a microreactor to form HOF.RCN and reacting this with an organic substrates.
- -
-
Page/Page column 7
(2011/04/14)
-
- Oxidation of organic compounds by sulfonated porous carbon and hydrogen peroxide
-
The oxidation of organic compounds by sulfonated porous carbon and H 2O2 was studied at room temperature. Alkyl and aryl sulfides were oxidized to the corresponding sulfoxides or sulfones in excellent yields. Secondary alcohols were also converted to the corresponding esters/lactones and aldehydes to methyl esters in good yields. Moreover, aliphatic tertiary amines and substituted pyridines were oxidized to N-oxides.
- Shokrolahi, Arash,Zali, Abbas,Keshavarz, Mohammad Hossein
-
experimental part
p. 1427 - 1432
(2012/04/18)
-
- Synthesis and structure-activity relationship of Huprine derivatives as human acetylcholinesterase inhibitors
-
New series of Huprine (12-amino-6,7,10,11-tetrahydro-7,11-methanocycloocta[b]quinolines) derivatives have been synthesized and their inhibiting activities toward recombinant human acetylcholinesterase (rh-AChE) are reported. We have synthesized two series of Huprine analogues; in the first one, the benzene ring of the quinoline moiety has been replaced by different heterocycles or electron-withdrawing or electron-donating substituted phenyl group. The second one has been designed in order to evaluate the influence of modification at position 12 where different short linkers have been introduced on the Huprine X, Y skeletons. All these molecules have been prepared from ethyl- or methyl-bicyclo[3.3.1]non-6-en-3-one via Friedlaender reaction involving selected o-aminocyano aromatic compounds. The synthesis of two heterodimers based on these Huprines has been also reported. Activities from moderate to same range than the most active Huprines X and Y taken as references have been obtained, the most potent analogue being about three times less active than parent Huprines X and Y. Topologic data have been inferred from molecular dockings and variations of activity between the different linkers suggest future structural modifications for activity improvement.
- Ronco, Cyril,Sorin, Geoffroy,Nachon, Florian,Foucault, Richard,Jean, Ludovic,Romieu, Anthony,Renard, Pierre-Yves
-
supporting information; experimental part
p. 4523 - 4536
(2009/12/04)
-
- Rhenium-catalyzed highly efficient oxidations of tertiary nitrogen compounds to N-oxides using sodium percarbonate as oxygen source
-
Sodium percarbonate was found to be an ideal and efficient oxygen source for the oxidation of tertiary nitrogen compounds to N-oxides in excellent yields in presence of various rhenium-based catalysts under mild reaction conditions. Georg Thieme Verlag Stuttgart.
- Jain, Suman L.,Joseph, Jomy K.,Sain, Bir
-
p. 2661 - 2663
(2008/09/16)
-
- Bromamine-T/RuCl3 as an efficient system for the oxidation of tertiary amines to N-oxides
-
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.
- Sharma, Vishal B.,Jain, Suman L.,Sain, Bir
-
p. 4281 - 4283
(2007/10/03)
-
- Oxidation of substituted pyridines by dimethyldioxirane: Kinetics and solvent effects
-
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.
- Winkeljohn, W. Rucks,Vasquez, Pedro C.,Strekowski, Lucjan,Baumstark, Alfons L.
-
p. 8295 - 8297
(2007/10/03)
-
- Methyltrioxorhenium catalyzed aerobic oxidation of organonitrogen compounds
-
A variety of tertiary, secondary and primary organonitrogen compounds have been efficiently and selectivity oxidized to their corresponding N-oxides, nitrones, and nitro compounds with molecular oxygen using methyltrioxorhenium as catalyst.
- Sharma, Vishal B.,Jain, Suman L.,Sain, Bir
-
p. 3235 - 3237
(2007/10/03)
-
- An unconventional cobalt-catalyzed aerobic oxidation of tertiary nitrogen compounds to N-oxides
-
A simple system, simple workup, and excellent yields make the new method for the oxidation of tertiary nitrogen compounds described in Equation (1) an attractive, environmentally acceptable synthetic tool. Molecular oxygen serves as the oxygen source and no sacrificial agents are required.
- Jain, Suman L.,Sain, Bir
-
p. 1265 - 1267
(2007/10/03)
-
- Ruthenium catalyzed oxidation of tertiary nitrogen compounds with molecular oxygen: An easy access to N-oxides under mild conditions
-
A variety of tertiary nitrogen compounds have been efficiently oxidized to their corresponding N-oxides in excellent yields with molecular oxygen as a sole oxidant and ruthenium trichloride as catalyst.
- Jain, Suman L.,Sain, Bir
-
p. 1040 - 1041
(2007/10/03)
-
- An efficient synthesis of heterocyclic N-oxides over molecular sieve catalyst
-
Heterocyclic N-oxides have been synthesized in very high yields over redox molecular sieve catalysts in the presence of H2O2.
- Prasad, M. Ramakrishna,Kamalakar, G.,Madhavi, G.,Kulkarni, S. J.,Raghavan, K. V.
-
p. 1577 - 1578
(2007/10/03)
-
- A simple and efficient method for the preparation of N- heteroaromatic N-oxides
-
Urea-hydrogen peroxide/formic acid system has shown utility for mild and safe N-oxidation of N-heteroaromatic compounds.
- Balicki, Roman,Golinski, Jerzy
-
p. 1529 - 1534
(2007/10/03)
-
- Crystalline organization and bonding of N-perfluoroacylpyridiniumaminides
-
N-Perfluoroacylpyridiniumaminides are stable crystalline solids characterized by a potentially useful set of properties. The molecular geometries resulting from the determination of the crystal structures of three members of the series suggest that, due to the presence of the perfluoroalky chains, the electron density on the formally negatively charged nitrogen of the ylide system is reduced. The N-N and the OC-N bonds in the systems are shortened and the whole molecules are stabilized as compared to non-fluorinated N-alkanoylpyridiniumaminides. The packing in the crystals can be qualitatively understood as a compromise between two distinct effects: the tendency to segregate, of the fluorocarbon groups on one hand and the bipyridinium blocks on the other, as in the case of 4b or c, the formation of weak interactions involving the pyridinium hydrogens and the most effective hydrogen bond accepting atoms (i.e. O and N).The latter effect leads to disorder of the perfluoroalkyl chains in 4a. In 4b and c, even at room temperature, a surprisingly ordered arrangement of the segregated perfluoropropyl chains is observed, showing a clear tendency to helicoidal conformation related to fluorine-fluorine repulsion.
- Caronna, Tullio,Corradi, Eleonora,Valdo Meille, Stefano,Novo, Barbara,Resnati, Giuseppe,Sidoti, Giancarlo
-
p. 183 - 190
(2007/10/03)
-
- A simple and efficient method for the preparation of pyridine-N-oxides II
-
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.
- Coperet, Christophe,Adolfsson, Hans,Chiang, Jay P.,Yudin, Andrei K.,Sharpless, K. Barry
-
p. 761 - 764
(2007/10/03)
-
- Reactivity of perfluoro-(cis-2,3-dialkyloxaziridines) with heteroaromatic nitrogen compounds
-
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.
- Bernardi, Rosanna,Novo, Barbara,Resnati, Giuseppe
-
p. 2517 - 2521
(2007/10/03)
-
- ELUCIDATION OF THE REACTION PATH FOR THE NITROSATION OF 2- AND 4-METHYLPYRIDINE 1-OXIDES WITH ALKYL NITRITE IN LIQUID AMMONIA
-
The reaction path for the nitrosation of 2- and 4-methylpyridine 1-oxides with alkyl nitrite in the presence of NaNH2 in liquid NH3 was elucidated experimentally, and theoretically by the use of a semiempirical molecular orbital method (PM3 method).In the case of the nitrosation of 4-methylpyridine 1-oxide at room temperature, only 4-pyridinecarboxamide 1-oxide was obtained, while at -33 deg C a thermodynamically unstable aldoxime, (Z)-4-pyridinecarbaldehyde 1-oxide oxime, which was easily transformed into E-form by heating, was obtained.On the other hand, the nitrosation of 2-methylpyridine 1-oxide gave only a thermodynamically stable aldoxime, (E)-2-pyridinecarbaldehyde 1-oxide oxime, both at room temperature and at -33 deg C.These results were reasonably explained by PM3 method.
- Tagawa, Yoshinobu,Togashi, Hideo,Goto, Yoshinobu
-
p. 327 - 336
(2007/10/02)
-
- An Excellent Method for the Mild and Safe Oxidation of N-Heteroaromatic Compounds and Tertiary Amines
-
Selective, mild and safe N-oxidation of N-heteroaromatic compounds and tertiary amines affording high product yields was achieved by using the H2O2-urea/phthalic anhydride system. Key Words: N-Oxidation / Hydrogen peroxide / Urea / Phthalic anhydride
- Kaczmarek, Lukasz,Balicki, Roman,Nantka-Namirski, Pawel
-
p. 1965 - 1966
(2007/10/02)
-
- FURTHER FUNCTIONAL GROUP OXIDATIONS USING SODIUM PERBORATE
-
Sodium perborate in acetic acid is an effective reagent for the oxidation of aromatic aldehydes to carboxylic acids, iodoarenes to (diacetoxyiodo)arenes, azines to N-oxides, and various types of sulfur heterocycles to S,S-dioxides.Nitriles are unaffected by the reagent in acetic acid, but undergo smooth hydration to amides when aqueous methanol is employed as solvent.
- McKillop, Alexander,Kemp, Duncan
-
p. 3299 - 3306
(2007/10/02)
-
- An Electron Spin Resonance and Voltametric Investigation of Some 2-Mono- and 2,4-Di-substitued Pyridinyl Radicals
-
The chemical reduction of some 2-monosubstitued and 2,4-disubstitued pyridinium ions has been investigated by means of e.s.r. spectroscopy and the result compared with those of an electrochemical study on the same species.By combining the electrochemical and e.s.r. data, a scale of stability has been determined for the investigated pyridinyl radicals.N-Methyl-2-cyanopyridinyl, wich was found to be too unstable to be observed, eventually evolved to the 2,4-dicyano-substitued radical.E.s.r. studies have also been carried out on the structurally similar, although more persistent, N-germylpyridinyls.
- Greci, Lucedio,Alberti, Angelo,Carelli, Italo,Trazza, Antonio,Casini, Antonio
-
p. 2013 - 2018
(2007/10/02)
-
