- From Pyridine- N-oxides to 2-Functionalized Pyridines through Pyridyl Phosphonium Salts: An Umpolung Strategy
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The reactions of pyridine-N-oxides with Ph3P under the developed conditions provide an unprecedented route to (pyridine-2-yl)phosphonium salts. Upon activation with DABCO, these salts readily serve as functionalized 2-pyridyl nucleophile equivalents. This umpolung strategy allows for the selective C2 functionalization of the pyridine ring with electrophiles, avoiding the generation and use of unstable organometallic reagents. The protocol operates at ambient temperature and tolerates sensitive functional groups, enabling the synthesis of otherwise challenging compounds.
- Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
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supporting information
p. 6099 - 6104
(2021/08/03)
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- Recyclable anhydride catalyst for H2O2 oxidation:: N -oxidation of pyridine derivatives
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The catalytic efficiency and recyclability of poly(maleic anhydride-alt-1-octadecene) (Od-MA) and poly(maleic anhydride-alt-1-isobutylene) (Bu-MA) were evaluated for use in the development of a metal-free, reusable catalyst for the oxidation of pyridines to pyridine N-oxides in the presence of H2O2. The Od-MA catalyst was easily recovered via filtration with recovery yields exceeding 99.8%. The catalyst retained its activity after multiple uses and did not require any treatment for reuse. The Od-MA and H2O2 catalytic system described herein is eco-friendly, operationally simple, and cost-effective; thus, it is industrially applicable. Od-MA and H2O2 could potentially be used in place of percarboxylic acid as an oxidant in a wide range of oxidation reactions.
- Gajeles, Ghellyn,Kim, Se Mi,Lee, Kyung-Koo,Lee, Sang Hee,Yoo, Jong-Cheol
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p. 9165 - 9171
(2020/03/13)
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- ANTIBACTERIAL THERAPEUTICS AND PROPHYLACTICS
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The present disclosure relates generally to novel molecules, compositions, and formulations for treatment of bacterial infections in general and more specifically to bacterial infections with antibiotic resistant pathogens.
- -
-
Paragraph 00332; 00369; 00373; 00387
(2017/02/24)
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- Catalyst-free and selective oxidation of pyridine derivatives and tertiary amines to corresponding N-oxides with 1,2-diphenyl-1,1,2,2-tetrahydroperoxyethane
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The catalyst-free oxidation of various pyridine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields. Graphical abstract: The catalyst-free oxidation of various pyridine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields.
- Azarifar, Davood,Mahmoudi, Boshra
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p. 645 - 651
(2016/02/19)
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- Copper powder-catalyzed N-arylation of imidazoles in water using 2-(hydrazinecarbonyl)pyridine N-oxides as the new ligands
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2-(2-Hydrazinecarbonyl)pyridine N-oxides, which were derived from pyrrole-2-carbohydrazides and pyridine N-oxides, were synthesized and utilized as the ligands for copper powder-catalyzed N-arylation of imidazoles with aryl halides in water. Imidazoles could be arylated smoothly with various aryl halides to provide the title products in preferable yields without the need of an inert atmosphere.
- Wu, Feng-Tian,Yan, Nan-Nan,Liu, Ping,Xie, Jian-Wei,Liu, Yan,Dai, Bin
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supporting information
p. 3249 - 3251
(2014/06/09)
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- Co(ii), a catalyst for selective conversion of phenyl rings to carboxylic acid groups
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An inexpensive protocol for the conversion of -C6H4R into -COOH groups using Co(ii)-Oxone mixture as the catalytic system is described. A series of substrates containing substituted and non-substituted phenyl groups could be selectively converted into carboxylic acids. Initial mechanistic data have been provided.
- Sinha, Shashi Bhushan,Campos, Jess,Brudvig, Gary W.,Crabtree, Robert H.
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p. 49395 - 49399
(2014/12/10)
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- Structural designs and property characterizations for second-harmonic generation materials
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Second-harmonic generation (SHG) materials only exist in solids that have no inversion center space groups, and they are constructed by the building blocks or chromophores of noncentrosymmetricity (NCS). In this chapter, we employed one or multiple chromophores that result from the coordination structure distortions of a d0 cation, polar displacement of d 10 cation center, a stereochemically active lone pair (SCALP) of cations, and asymmetrical delocalization π-charge systems, as building blocks to obtain some new compounds with NCS space group. The single-crystal structures were characterized, and physical properties, in particular SHG responses, were measured for these compounds. The electronic structures and density of states were calculated by DFT method, and the SHG properties are simulated to gain an insight into the relations between structure and NLO properties for the materials. The electronic origination of large SHG responses was assigned in terms of the calculated results.
- Cheng, Wen-Dan,Lin, Chen-Sheng,Zhang, Wei-Long,Zhang, Hao
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experimental part
p. 1 - 41
(2012/08/08)
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- Ligands for copper-catalyzed C-N bond forming reactions with 1 Mol% CuBr as catalyst
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Several new ligands were designed to promote copper-catalyzed Ullman C-N coupling reactions. In this group, 8-hydroxyquinolin-N-oxide was found to serve as a superior ligand for CuBr-catalyzed coupling reactions of aryl iodides, bromides, and chlorides with aliphatic amines and N-heterocycles under a low catalyst loading (1% [Cu] mol). Reactions with the inexpensive catalytic system display a high functional group tolerance as well as excellent chemoselectivity.
- Yang, Kai,Qiu, Yatao,Li, Zheng,Wang, Zhaoyang,Jiang, Sheng
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experimental part
p. 3151 - 3159
(2011/06/23)
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- Influence of a reaction medium on the oxidation of aromatic nitrogen-containing compounds by peroxyacids
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The influence of different solvents on the oxidation reaction rate of pyridine (Py), quinoline (QN), acridine (AN), α-oxyquinoline (OQN) and a-picolinic acid (APA) by peroxydecanoic acid (PDA) was studied. It was found that the oxidation rate grows in the series Py eq) and its decomposition constant (k2) in acetone and benzene were calculated. It was shown that the nature of the solvent influences the numerical values of both Kp and k2. It was established that introduction of acetic acid (which is able to form compounds with Py) into the reaction medium slows the rate of the oxidation process drastically. Correlation equations linking the polarity, polarizability, electrophilicity, and basicity of solvents with the constant of the PDA oxidation reaction rate for Py were found. It was concluded that the basicity and polarity of the solvent have a decisive influence on the oxidation reaction rate, while the polarizability and electrophilicity of the reaction medium do not influence the oxidation reaction rate. Pleiades Publishing, Ltd., 2011.
- Dutka,Matsyuk,Dutka
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scheme or table
p. 45 - 50
(2011/06/18)
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- COMPOSITION FOR OXIDATION OF ORGANIC SUBSTRATES
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The invention relates to a composition comprising a soluble source of manganese, a ligand, a base, hydrogen peroxide and a ketone or an aldehyde, wherein the ligand is a pyridine heterocycle containing carboxylic acid or a precursor thereof, wherein the nitrogen atom of the pyridine ring is capable of coordinating to the carboxylate bonded manganese center, wherein the 2-position relative to the nitrogen atom is part of the N(pyridine)-Mn-O(carboxylate) containing chelate ring and the second 2-position relative to the nitrogen atom in the ring is not a carboxylic acid group. Furthermore, the invention relates to a process for oxidation of an organic substrate using the composition of the invention.
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Page/Page column 10
(2011/09/30)
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- Manganese catalyzed cis-dihydroxylation of electron deficient alkenes with H2O2
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A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H2O2 is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from a manganese salt, pyridine-2-carboxylic acid, a ketone and a base, under ambient conditions. Under optimized conditions, for diethyl fumarate at least 1000 turnovers could be achieved with only 1.5 equiv. of H2O2 with d/l-diethyl tartrate (cis-diol product) as the sole product. For electron rich alkenes, such as cis-cyclooctene, this catalyst provides for efficient epoxidation.
- Saisaha, Pattama,Pijper, Dirk,Van Summeren, Ruben P.,Hoen, Rob,Smit, Christian,De Boer, Johannes W.,Hage, Ronald,Alsters, Paul L.,Feringa, Ben L.,Browne, Wesley R.
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supporting information; experimental part
p. 4444 - 4450
(2010/11/05)
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- Recyclable polyisobutylene-supported pyridyl N-oxide allylation catalysts
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Polyisobutylene (PIB) is a useful soluble polymer support that facilitates catalyst recovery and recycling in liquid-liquid biphasic systems because the long polyisobutylene chain confers high phase selective solubility in the nonpolar phase of polar-nonpolar liquid-liquid biphasic systems on groups attached to the polymer's terminus. This work shows that PIB-supports that are effective with metal catalysts can also facilitate synthesis and use of organocatalysts. This is demonstrated by the use of a PIB-supported pyridyl N-oxide to promote the allylation of several aromatic aldehydes with allyltrichlorosilane. These studies show that a PIB-supported pyridyl N-oxide is a very active recyclable catalyst that promotes the allylation of aromatic aldehydes in yields of up to 99% yield. These PIB-supported pyridyl N-oxide catalysts were recovered in the hexane phase of a hexane/90% EtOH-H2O solvent system and were successfully recycled through 5 cycles with little effect on catalyst efficiency.
- Bergbreiter, David E.,Ortiz-Acosta, Denisse
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p. 5608 - 5610
(2008/12/22)
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- An efficient synthesis of heterocyclic N-oxides over molecular sieve catalyst
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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.
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p. 1577 - 1578
(2007/10/03)
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- Novel chiral pyridine N-oxide ligands and their application in the enantioselective catalytic reduction of ketones and the addition of diethylzinc to aldehydes
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Starting from picolinic acids 3 and 4, the amino acid-derived 2- aminoacylpyridine N-oxides 1a,c-e and 2,6-bis(aminoacyl)pyridine N-oxides 2b- e can be prepared in two steps by the coupling of picolinic acid N-oxides 5 and 6 under Appel conditions with the corresponding L-amino acid ester or (1R,2S)-norephedrine. Compounds 1 and 2 were used as chiral ligands in two different asymmetric catalyses. In the catalytic addition of diethylzinc to benzaldehyde 11, low enantioselectivities (2-29percent ee) were obtained regardless of the amino acid moiety. However, the corresponding 2,6- bis(aminoacyl)pyridines 7 and 8 led to increased ee values (55percent ee). In the catalytic reduction of ketones 9a-c to alcohols 10a-c low enantioselectivities were observed for alanine-, valine-, and leucine-derived N-oxides 1a,c and 2b,c. An increase of selectivity was observed for bismethionine ligand 2d (32-38percent ee) relative to that of monomethionine ligand 1d (7-16percent ee). However, mononorephedrine ligand 1e (≤ 64percent ee) and the corresponding bis-norephedrine ligand 2e (≤ 51percent ee) displayed the highest selectivities. The influence of the N-oxide moiety on the enantioselectivity was demonstrated by the observation that 2,6-bis(aminoacyl)pyridines 7 and 8 gave much lower selectivities than the corresponding pyridine N-oxides 2d and e.
- Derdau, Volker,Laschat, Sabine,Hupe, Eike,Ko?nig, Wilfried A.,Dix, Ina,Jones, Peter G.
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p. 1001 - 1007
(2007/10/03)
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- Chemoselective N-oxidation of picolinaldehydes with dimethyldioxirane
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The N-oxidation of picolinaldehydes with dimethyldioxirane proceeds with remarkable selectivity. Especially the N-oxides of 3- and of 4- picolinaldehyde are isolated in high yields. The aldehyde-hydrate 3- dihydoxymethylpyridin-N-oxide was fully characterized.
- Dyker, Gerald,Hoelzer, Bettina
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p. 12557 - 12562
(2007/10/03)
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- Syntheses and Fe(II)/Fe(III) equilibria of the new multidentate ligands pyridine-2-phosphonic-6-carboxylic acid and 2,6-pyridinediphosphonic acid for the use of their iron chelates as catalysts for the oxidation of H2S to S8 by air
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The syntheses of two terdentate chelating agents, pyridine-2-phosphonic-6-carboxylic acid (2PP6C) and 2,6-pyridinediphosphonic acid (2,6PDPA), are described. The stepwise stability constants for the ferric complexes at 25.0°C and μ = 0.100 M (KNO3) are log KML = 15.97 and log KML2 = 9.50 for 2PP6C, and log KML = 20.87 and log KML2 = 7.81 for 2,6PDPA. Under the same conditions the stepwise formation constants for the ferrous chelates are log KML = 8.70 and log KML2 = 5.10 for 2PP6C, and log KML = 10.12 and log KML2 = 5.33 for 2,6PDPA. The stabilities of the Fe(III) and Fe(II) chelates are high enough to prevent precipitation of Fe(OH)3 and FeS, respectively, from solutions having pH as high as 10.0. The rates of oxidative degradation of these ligands are very slow when the iron chelates are used as redox catalysts for the oxidation of H2S to S8 by air. The rates of oxidative degradation are immeasurably slow when the iron chelates are used with sodium thiosulfate as a radical scavenger.
- Chen, Dian,Martell, Arthur E.,Motekaitis, Ramunas J.,McManus, Derek
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p. 445 - 451
(2007/10/03)
-
- The crystal structures of
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The new heteropolyperoxometalate compounds [NMe4][(Me2AsO2){MoO(O2) 2}2] 1, [NMe4][(Ph2PO2){MoO(O2) 2}2] 2, [NBun4][(Ph2PO2){WO(O 2)2}2] 3 and [NH4][(Ph2PO2){MoO(O2) 2(H2O)}] 4 have been isolated and their crystal structures determined. Compounds 1-3 are dinuclear, whilst compound 4 is mononuclear; in all four structures the metal centre(s) have essentially identical pentagonal-bipyramidal co-ordination geometries with a weak axial ligand trans to an oxo group. The utility of 3 as a catalyst for the oxidation of alkenes, alcohols and tertiary amines with hydrogen peroxide as cooxidant has been studied.
- Gresley, N. Melanie,Griffith, William P.,Parkin, Bernardeta C.,White, Andrew J. P.,Williams, David J.
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p. 2039 - 2045
(2007/10/03)
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- Heteropolyperoxo- and Isopolyperoxo-tungstates and -molybdates as Catalysts for the Oxidation of Tertiary Amines, Alkenes and Alcohols
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The catalytic oxidation of tertiary amines to the corresponding N-oxides by 4>(3-) (X = P or As, M = Mo or W) and by (2-) with H2O2 as co-oxidant has been studied.Epoxidation of alkenes and oxidation of alcohols by (2-) with H2O2 as co-oxidant has also been examined and compared with that effected by 4>(3-).A possible structure for (2-) is suggested.
- Bailey, Alan J.,Griffith, William P.,Parkin, Bernardeta C.
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p. 1833 - 1838
(2007/10/02)
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- The oxidation of aromatic aldehydes to carboxylic acids using hydrogen peroxide in formic acid
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Aromatic aldehydes and particularly heteroaromatic aldehydes 1 are efficiently and conveniently oxidized to their corresponding carboxylic acids 2 by hydrogen peroxide in formic acid at 4°C.
- Dodd,Le Hyaric
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p. 295 - 297
(2007/10/02)
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- APPLICATION OF ORGANOLITHIUM AND RELATED REAGENTS IN SYNTHESIS. PART 7. SYNTHESIS AND METALLATION OF 4-METHOXYPICOLIN- AND 2-METHOXYISONICOTIN-ANILIDES. A USEFUL METHOD FOR PREPARATION OF 2,3,4-TRISUBSTITUTED PYRIDINES
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The synthesis and metallation of 4-methoxypicolin- and 2-methoxyisonicotin-anilides as a way of regiospecific transformation of picolinic and isonicotinic acids into 2,3,4-trisubstituted pyridines, is described.The resulted C-alkylated derivatives underwent smooth acid - catalysed conversion into the corresponding pyridones.
- Epsztajn, Jan,Bieniek, Adam,Plotka, Mieczyslaw W.,Suwald, Krzysztof
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p. 7469 - 7476
(2007/10/02)
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- THE REACTION OF INDOLIZINES AND ACETYLINDOLIZINES WITH TRIFLUOROMETHYLSULFENYL CHLORIDE
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Two trifluoromethylsulfenyl groups were introduced into the 1,3 positions of indolizines by the reaction of trifluoromethylsulfenyl chloride with indolizine and its 2-methyl, 2-phenyl. 2-methyl-3-acetyl and 2-phenyl-3-acetyl derivatives.
- Mirek, Julian,Haas, Alois
-
-
- Studies on Tertiary Amine Oxides. LXVII. Reactions of Aromatic N-Oxides with 3-Arylrhodanines in the Presence of Acetic Anhydride
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Quinoline 1-oxides 1 readily react with 3-arylrhodanines 2 in the presence of acetic anhydride to afford 3-aryl-5-(2-quinolyl)rhodanines 3 in high yields.These products resist hydrolysis under both alkaline and acidic conditions, but are oxidized to quinaldinic acid 1-oxide 4 with 30percent hydrogen peroxide in hot acetic acid.Besides isoquinoline 2-oxide 5, pyridine 1-oxide 7a also react in the same way to give 3-aryl-5-(2-pyridyl)rhodanines 8, although the reactivity of γ-picoline 1-oxide 7b is considerably lower.Contrary to 3, 3-phenyl-5-(2-pyridyl)rhodanine 8a is successfully hydrolyzed with boiling 48percent hydrobromic acid to 2-pyridinemethanethiol 10 in 57percent yield.
- Yousif, Mohammed M.,Saeki, S.,Hamana, M.
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p. 305 - 309
(2007/10/02)
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