1007-49-4Relevant articles and documents
Simple preparation and application of TEMPO-coated Fe3O 4 superparamagnetic nanoparticles for selective oxidation of alcohols
Tucker-Schwartz, Alexander K.,Garrell, Robin L.
, p. 12718 - 12726 (2010)
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.
Samarium-promoted coupling of pyridine-based heteroaryl analogues of benzylic acetates with carbonyl compounds
Weitgenant, Jeremy A.,Mortison, Jonathan D.,Helquist, Paul
, p. 3609 - 3612 (2005)
(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.
Oxidative "reverse-esterification" of ethanol with benzyl/alkyl alcohols or aldehydes catalyzed by supported rhodium nanoparticles
Guha, Nitul Ranjan,Sharma, Saurabh,Bhattacherjee, Dhananjay,Thakur, Vandna,Bharti, Richa,Reddy, C. Bal,Das, Pralay
, p. 1206 - 1211 (2016)
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.
The Reactions of 1,2,3-Triazolopyridine with Electrophiles
Jones, Gurnos,Sliskovic, D. Robert,Foster, Beverley,Rogers, John,Smith, Anthony K.,et al.
, p. 78 - 81 (1981)
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.
Supramolecular Catalysis of Acyl Transfer within Zinc Porphyrin-Based Metal-Organic Cages
Li, Lili,Yang, Linlin,Li, Xuezhao,Wang, Jing,Liu, Xin,He, Cheng
supporting information, p. 8802 - 8810 (2021/06/28)
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.
Proton-exchanged montmorillonite-mediated reactions of hetero-benzyl acetates: Application to the synthesis of Zafirlukast
Yang, Lei,Chen, Xuan,Ni, Kaidong,Li, Yuansheng,Wu, Jianhong,Chen, Weilin,Ji, Yin,Feng, Lili,Li, Fei,Chen, Dongyin
supporting information, (2020/06/28)
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.
Formyloxyacetoxyphenylmethane and 1,1-diacylals as versatile O-formylating and O-acylating reagents for alcohols
Chapman, Robert S.L.,Francis, Molly,Lawrence, Ruth,Tibbetts, Joshua D.,Bull, Steven D.
, p. 6442 - 6452 (2018/10/02)
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.
Preparation method for preparing 2-pyridylaldehyde by catalytic oxidation of 2-methylpyridine
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Paragraph 0029; 0037; 0045; 0048; 0053; 0061, (2018/04/28)
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.
Synthesis method for 2-pyridylaldehyde
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Paragraph 0034; 0038; 0041; 0047; 0051, (2017/11/04)
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.
Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification
Zeng, Ruijie,Sheng, Hongting,Zhang, Yongcang,Feng, Yan,Chen, Zhi,Wang, Junfeng,Chen, Man,Zhu, Manzhou,Guo, Qingxiang
, p. 9246 - 9252 (2014/12/11)
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.
