- Simple preparation and application of TEMPO-coated Fe3O 4 superparamagnetic nanoparticles for selective oxidation of alcohols
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The organic oxidant TEMPO (2,2,4,4-tetramethylpiperdine-1-oxyl) was immobilized on iron oxide (Fe3O4) superparamagnetic nanoparticles by employing strong metal-oxide chelating phosphonates and azide/alkyne "click" chemistry. This simple preparation yields recyclable TEMPO-coated nanoparticles with good TEMPO loadings. They have excellent magnetic response and efficiently catalyze the oxidation of a wide range of primary and secondary alcohols to aldehydes, ketones, and lactones under either aerobic acidic MnII/CuII oxidizing Minisci conditions, or basic NaOCl Anelli conditions. The nanoparticles could be recycled more than 20 times under the Minisci conditions and up to eight times under the Anelli conditions with good to excellent substrate conversions and product selectivities. Immobilization of the catalyst through a phosphonate linkage allows the particles to withstand acidic oxidizing environments with minimal catalyst leaching. Clicking TEMPO to the phosphonate prior to phosphonate immobilization, rather than after, ensures the clicked catalyst is the only species on the particle surface. This facilitates quantification of the catalyst loading. The stability of the phosphonate linker and simplicity of this catalyst immobilization method make this an attractive approach for tethering catalysts to oxide supports, creating magnetically separable catalysts that can be used under neutral or acidic conditions. Recycling to a different TEMPO: An extremely simple and economic synthesis of a recyclable 2,2,4,4-tetramethylpiperdine-1-oxyl(TEMPO)-coated superparamagnetic catalyst is described. The catalyst shows excellent performance in the rapid oxidation of primary and secondary benzylic and aliphatic alcohols by using oxygen and MnII/CuII or biphasic NaOCl/KBr conditions.
- Tucker-Schwartz, Alexander K.,Garrell, Robin L.
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- Samarium-promoted coupling of pyridine-based heteroaryl analogues of benzylic acetates with carbonyl compounds
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(Chemical Equation Presented) 2-Substituted pyridine, quinoline, isoquinoline, bipyridine, and 1,10-phenanthroline analogues of benzylic acetates undergo Sml2-promoted coupling with aldehydes and ketones to afford (2-hydroxyalkyl)heteroaromatics.
- Weitgenant, Jeremy A.,Mortison, Jonathan D.,Helquist, Paul
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- Oxidative "reverse-esterification" of ethanol with benzyl/alkyl alcohols or aldehydes catalyzed by supported rhodium nanoparticles
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A very unusual role of polystyrene stabilized rhodium (Rh@PS) nanoparticles as a supported catalyst is described for "reverse-esterification" of ethanol with benzyl/alkyl alcohols or aldehydes. Faster and selective oxidation of ethanol to acetaldehyde and H2 under Rh@PS catalyzed conditions which restricted further oxidation of benzyl/alkyl alcohols and their in situ reaction gave the corresponding acetate esters following the dehydrogenative-coupling approach. A hitherto redox dehydrogenative-coupling of ethanol and aldehydes has also been explored for the same acetate ester synthesis under Rh@PS catalyzed conditions.
- Guha, Nitul Ranjan,Sharma, Saurabh,Bhattacherjee, Dhananjay,Thakur, Vandna,Bharti, Richa,Reddy, C. Bal,Das, Pralay
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- The Reactions of 1,2,3-Triazolopyridine with Electrophiles
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On treatment with chlorine, bromine, or mercuric acetate triazolopyridine (1) gives dichloromethyl-, dibromomethyl-, and alkoxy(alkoxymercurio)methyl-pyridines (3), (4), (5), and (8) with loss of nitrogen.Nitration gives 3-nitrotriazolopyridine (9), which on reduction gives 3-(2-pyridyl)imidazopyridine (11).The mechanism of formation of these compounds is discussed.
- Jones, Gurnos,Sliskovic, D. Robert,Foster, Beverley,Rogers, John,Smith, Anthony K.,et al.
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- Supramolecular Catalysis of Acyl Transfer within Zinc Porphyrin-Based Metal-Organic Cages
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To illustrate the supramolecular catalysis process in molecular containers, two porphyrinatozinc(II)-faced cubic cages with different sizes were synthesized and used to catalyze acyl-transfer reactions between N-acetylimidazole (NAI) and various pyridylcarbinol (PC) regioisomers (2-PC, 3-PC, and 4-PC). A systemic investigation of the supramolecular catalysis occurring within these two hosts was performed, in combination with a host-guest binding study and density functional theory calculations. Compared to the reaction in a bulk solvent, the results that the reaction of 2-PC was found to be highly efficient with high rate enhancements (kcat/kuncat = 283 for Zn-1 and 442 for Zn-2), as well as the different efficiencies of the reactions with various ortho-substituted 2-PC substrates and NAI derivates should be attributed to the cages having preconcentrated and preoriented substrates. The same cage displayed different catalytic activities toward different PC regioisomers, which should be mainly attributed to different binding affinities between the respective reactant and product with the cages. Furthermore, control experiments were carried out to learn the effect of varying reactant concentrations and product inhibition. The results all suggested that, besides the confinement effect caused by the inner microenvironment, substrate transfer, including the encapsulation of the reactant and the release of products, should be considered to be a quite important factor in supramolecular catalysis within a molecular container.
- Li, Lili,Yang, Linlin,Li, Xuezhao,Wang, Jing,Liu, Xin,He, Cheng
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supporting information
p. 8802 - 8810
(2021/06/28)
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- Proton-exchanged montmorillonite-mediated reactions of hetero-benzyl acetates: Application to the synthesis of Zafirlukast
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Proton-exchanged montmorillonite (H-mont) with outstanding surface characteristics can provide abundant acidic sites in the mesopores, and serve as an efficient heterogeneous catalyst for the synthesis of heterocycle-containing diarylmethanes via Friedel-Crafts-like alkylation of (hetero)arenes by heterobenzyl acetates under mild reaction conditions without requiring any additives or an inert atmosphere. Using this strategy, the gram-scale synthesis of indole-containing diarylmethane 13 has been accomplished in good yield for the preparation of Zafirlukast. In addition, H-mont can be applied to the nucleophilic substitution reactions of heterobenzyl acetate 5p with a variety of alcohols and 1,3-dicarbonyl compounds.
- Yang, Lei,Chen, Xuan,Ni, Kaidong,Li, Yuansheng,Wu, Jianhong,Chen, Weilin,Ji, Yin,Feng, Lili,Li, Fei,Chen, Dongyin
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supporting information
(2020/06/28)
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- Formyloxyacetoxyphenylmethane and 1,1-diacylals as versatile O-formylating and O-acylating reagents for alcohols
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Formyloxyacetoxyphenylmethane, symmetric 1,1-diacylals and mixed 1-pivaloxy-1-acyloxy-1-phenylmethanes have been used as moisture stable O-formylating and O-acylating reagents for primary and secondary alcohols, allylic alcohols and phenols under solvent/catalyst free conditions to afford their corresponding esters in good yield.
- Chapman, Robert S.L.,Francis, Molly,Lawrence, Ruth,Tibbetts, Joshua D.,Bull, Steven D.
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p. 6442 - 6452
(2018/10/02)
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- Preparation method for preparing 2-pyridylaldehyde by catalytic oxidation of 2-methylpyridine
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The invention discloses a preparation method for preparing 2-pyridylaldehyde by catalytic oxidation of 2-methylpyridine. The preparation method comprises the following steps of firstly adopting ammonium molybdate, sodium citrate, manganese acetate and sodium hydroxide as raw materials, preparing a composite catalyst, then adopting the 2-methylpyridine and glacial acetic acid, adding hydrogen peroxide for catalytic oxidation, dropwise adding acetic anhydride for reaction, and preparing acetic acid 2-pyridine methyl ester; then dropwise adding a sodium hydroxide solution into the acetic acid 2-pyridine methyl ester to carry out hydrolysis so as to prepare 2-pyridinemethanol; finally mixing and stirring the 2-pyridinemethanol and dichloromethane uniformly, transferring into a three-mouth flask, then adding the prepared composite catalyst and hydrogen peroxide, stirring to react for 1-3 hours at the temperature of 30-40 DEG C after the adding step is finished, cooling to room temperature after the reaction is ended, filtering, collecting filtrate, distilling at normal pressure to remove dichloromethane, then carrying out vacuum reduced-pressure distillation on residues, and collecting63-65 DEG C/1.73kPa of fractions to prepare the 2-pyridylaldehyde. The method provided by the invention is simple and environment-friendly, and the target-product yield is high.
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Paragraph 0029; 0037; 0045; 0048; 0053; 0061
(2018/04/28)
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- Synthesis method for 2-pyridylaldehyde
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The invention belongs to the field of organic chemistry and particularly relates to a synthesis method for 2-pyridylaldehyde. The method comprises the following steps of (1) adopting 2-methylpyridine as a raw material and obtaining 2-pyridine n-oxide through oxidation reaction under an acid condition; (2) synthesizing acetic acid-2-piperidinecarbonitrile by using the 2-pyridine n-oxide through acetic anhydride acylation rearrangement; (3) hydrolyzing the acetic acid-2-piperidinecarbonitrile to obtain 2-pyridinemethanol; and (4) carrying out oxidation reaction on the 2-pyridinemethanol to obtain the 2-pyridylaldehyde. The synthesis method has the advantages of being high in total yield, low in raw material price, short in reaction time, mild in condition and simple in technological operation.
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- Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification
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A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid-base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.
- Zeng, Ruijie,Sheng, Hongting,Zhang, Yongcang,Feng, Yan,Chen, Zhi,Wang, Junfeng,Chen, Man,Zhu, Manzhou,Guo, Qingxiang
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p. 9246 - 9252
(2014/12/11)
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- Base-catalyzed retro-Claisen condensation: A convenient esterification of alcohols via C-C bond cleavage of ketones to afford acylating sources
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The base-catalyzed esterification of alcohols via retro-Claisen condensation has been demonstrated for the first time. A variety of alcohols including aryl- and heteroaryl methanols as well as aliphatic ones underwent efficient acylation to give the ester products in reasonable to good yields upon isolation. Not only conventional 1,3-diketones but also strong electron-withdrawing group containing acetophenones could serve as the acylating suppliers. The synthetic protocol is operationally simple and adaptable to a broad substrate scope. It complements the existed esterification via the retro-Claisen condensation, and enlarges this benign synthetic methodology.
- Xie, Feng,Yan, Fengxia,Chen, Mengmeng,Zhang, Min
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p. 29502 - 29508
(2014/08/05)
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- Cp*Rh-based heterometallic metallarectangles: Size-dependent borromean link structures and catalytic acyl transfer
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A series of CpRh-based functional metallarectangles have been synthesized from metallaligands. Enlargement of one linker leads to the isolation of two novel Borromean link architectures. All these complexes are intact in solution, as evident from ESI-MS spectroscopic analysis. Arising from the combination of open Cu centers and favorable cavity space, {(CpRh)4(bpe) 2[Cu(opba)·2MeOH]2}4(OTf)·6MeOH shows extraordinary catalytic abilities with high efficiency and wide substrate selectivity in the acyl-transfer reaction.
- Huang, Sheng-Li,Lin, Yue-Jian,Hor, T. S. Andy,Jin, Guo-Xin
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supporting information
p. 8125 - 8128
(2013/07/19)
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- Palladium-catalyzed acetoxylation of sp3 C-H bonds using molecular oxygen
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Molecular oxygen as oxidant to promote palladium-catalyzed acetoxylation of sp3 C-H bonds to afford α-oxygenated products is reported.
- Jiang, Huanfeng,Chen, Huoji,Wang, Azhong,Liu, Xiaohang
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supporting information; experimental part
p. 7259 - 7261
(2011/01/07)
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- Thallium(III) chloride: A mild and efficient catalyst for acylation of alcohols, phenols and thiols, and for geminal diacylation of aldehydes under solvent-free conditions
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Thallium(III) chloride is a simple and efficient catalyst for acylation of alcohols, phenols and thiols. It is also very effective for geminal diacylation of aldehydes. The acylation reaction using acetic anhydride proceeds in excellent yield in the presence of catalytic amounts of thallium(III) chloride (1 mol%) at room temperature within relatively short reaction times (20 min). Structurally diverse alcohols, phenols, thiols and aldehydes undergo acylation under solvent-free conditions.
- Kadam, Santosh T.,Kim, Sung Soo
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experimental part
p. 3307 - 3313
(2009/05/07)
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- Synthesis of alkyl heteryl ethers from acetates under interphase catalysis conditions in a liquid/solid system
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The reaction of acetates of heterocyclic alcohols with alkyl halides in the two-phase catalytic system of solid KOH/C6H6/18-crown-6 at room temperature leads selectively to the formation of the corresponding heterocyclic ethers in 32-93% yield. 1998 Plenum Publishing Corporation.
- Abele,Abele,Gaukhman,Lukevics
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- Structure-activity relationship of 2-[[(2-Pyridyl)methyl]thio]-1H- benzimidazoles as anti Helicobacter pylori agents in vitro and evaluation of their in vivo efficacy
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A relationship between the structure of 21 2-[[(2-pyridyl)methyl]thio]- 1H-benzimidazoles (6) and their anti Helicobacter pylori activity expressed as minimum bactericidal concentration (MBC) values is described. Observed MBCs ranged from 256 to 1 μg/mL. The structure - activity relationship (SAR) showed that larger and more lipophilic compounds, especially compounds with such substituents in the 4-position of the pyridyl moiety, generally had lower MBC values. Four new compounds 'that were predicted to be potent by the established SAR model were synthesized and tested. One such compound, i.e., 2-[[(4-[(cyclopropylmethyl)oxy]3-methyl-2-pyridyl)methyl]thio]-1H- benzimidazole (18), was tested for in vivo efficacy in a mouse Helicobacter felis model (125 μmol/kg bid given orally for 4 days, n = 4). Unfortunately, antibacterial activity could not be clearly demonstrated in this model. Instead a potent acid secretion inhibition was observed. This finding was attributed to the methylthio compound being oxidized to the corresponding methyl sulfinyl derivative, i.e., a proton pump inhibitor, in vivo. Although the antibacterial activity had the potential of decreasing H. felis cell counts in vivo the proton pump inhibitory effect became dominant and actually promoted H. felis cell growth. Hence, we conclude that the antibacterial utility of the 2-[[(2-pyridyl)methyl]thio]1H-benzimidazoles (6) as a compound class is compromised by their propensity to become proton pump inhibitors upon metabolic oxidation in vivo.
- Kühler, Thomas C.,Swanson, Marianne,Shcherbuchin, Vladimir,Larsson, H?kan,Mellg?rd, Bj?rn,Sj?str?m, Jan-Eric
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p. 1777 - 1788
(2007/10/03)
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- Oxidation of substituted pyridines PyrCHRSiMe3 (R=H, Me, Ph) and substituted quinolines QnCH2SiMe3 with hypervalent iodine reagents
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Oxidation of a variety of substituted pyridines, PyrCHRSiMe3 (R = H, Me, Ph) and quinolines, QnCH2SiMe3 with hypervalent iodine reagents PIDA, (PhI(OCOCH3)2) and PIFA, (PhI(OCOCF3)2) has been studied. Oxy-desilylation with PIDA/TBAF gives low to moderate yields of PyrCHROR1 and QnCH2OR1 (R1 = H, Ac), while good yields of PyrCHROH and QnCH2OH are obtained when PIFA is used.
- Andrews, Ian P.,Lewis, Norman J.,McKillop, Alexander,Wells, Andrew S.
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p. 1151 - 1158
(2007/10/03)
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- 2--1H-thienoimidazoles. A Novel Class of Gastric H+/K+-ATPase Inhibitors
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2-thienoimidazoles were synthesized and investigated as potential inhibitors of gastric H+/K+-ATPase.The isomers of the two possible thienoimidazole series were found to be potent inhibitors of gastric acid secretion in vitro and in vivo.Structure-activity relationships indicate that especially lipophilic alkoxy, benzyloxy, and phenoxy substituents with additional electron-demanding properties in the 4-position of the pyridine moiety combined with an unsubstituted thienoimidazole lead to highly active compounds with a favorable chemical stability.Various substitution patterns in the thienoimidazole moiety result in lower biological activity.The heptafluorobutyloxy derivative saviprazole (HOE 731, 5d) was selected for further development and is currently undergoing clinical evaluation.Comprehensive pharmacological studies indicate a pharmacodynamic profile different to omeprazole, the first H+/K+-ATPase blocker introduced on the market.
- Weidmann, Klaus,Herling, Andreas W.,Lang, Hans-Jochen,Scheunemann, Karl-Heinz,Rippel, Robert,et al.
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p. 438 - 450
(2007/10/02)
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- Triazolopyridines. Part 6. Ring Opening Reactions of Triazolopyridines
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The triazole ring in 1,2,3-triazolo-pyridines and -quinolines, and in 1,2,3-triazoloisoquinolines can be opened with loss of nitrogen.The reagents described are bromine, aqueous sulphuric acid, glacial acetic acid, and selenium dioxide; the products from the triazolopyridines are dibromomethyl, hydroxymethyl, acetoxymethyl, and acyl derivatives of pyridine.The generality of the reactions is discussed.The first reported reaction in which the six-membered ring of a 1,2,3-triazolopyridine is opened, by hydride reduction, gives a triazolylbutadiene.
- Jones, Gurnos,Mouat, Deborah J.,Tonkinson, Daryl J.
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p. 2719 - 2724
(2007/10/02)
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- THE KATADA REACTION: A STUDY OF EXPERIMENTAL CONDITIONS
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Experimental conditions for the Katada reaction have been studied using 2-picoline N-oxide as model substrate.Using a mixture of acetyl chloride and acetic anhydride, the reaction takes place rapidly at room temperature to give an excellent yield of 2-acetoxymethylpyridine.
- McKillop, Alexander,Bhagrath, Manjeet K.
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p. 1697 - 1701
(2007/10/02)
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