- Highly diastereoselective aldol reactions of 3-Fluorooxindoles promoted by MgBr2?OEt2/iPr2NEt
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A highly diastereoselective aldol reaction between 3-fluorooxindoles and aromatic aldehydes has been developed. Commercially available, cheap Lewis acid MgBr2[rad]OEt2 was used to promote the reaction. The reaction has a broad substrate scope with respect to both 3-fluorooxindoles and aromatic aldehydes, giving a series of α-fluoro-β-hydroxyoxindoles in good yields with high diastereoselectivities (63–94 percent yield, up to 99:1 anti/syn).
- Qiu, Zi-Bin,Chen, Ling-Yan,Ji, Jian,Ren, Xinfeng,Li, Ya
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- Highly selective catalytic cross-aldol reactions of chloral with aliphatic aldehydes
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An efficient synthetic method for β-trichloromethyl-β-hydroxy aldehydes is described. Using piperidine or L-prolinamide as the catalyst, direct cross-aldol reactions of chloral with aliphatic aldehydes occur smoothly at room temperature. The cross-aldol condensation products are isolated in high yields (up to 95%), and a moderate to high enantioselectivity (up to 88% ee) is observed in the case of L-prolinamide. Georg Thieme Verlag Stuttgart.
- Zhang, Fanglin,Su, Ning,Gong, Yuefa
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- Aldol Addition of Butyraldehyde over Solid Base Catalysts
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Aldol addition of butyraldehyde was investigated on alkaline earth oxides, zirconium oxide, and lanthanum oxide to compare the active site and mechanism with those for aldol addition of acetone.It is found that the active site is the surface O2(1-) and th
- Zhang, Geng,Hattori, Hideshi,Tanabe, Kozo
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Read Online
- Development of an azanoradamantane-type nitroxyl radical catalyst for class-selective oxidation of alcohols
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The development of 1,5-dimethyl-9-azanoradamantane N-oxyl (DMN-AZADO; 1,5-dimethyl-Nor-AZADO, 2) as an efficient catalyst for the selective oxidation of primary alcohols in the presence of secondary alcohols is described. The compact and rigid structure of the azanoradamantane nucleus confers potent catalytic ability to DMN-AZADO (2). A variety of hindered primary alcohols such as neopentyl primary alcohols were efficiently oxidized by DMN-AZADO (2) to the corresponding aldehydes, whereas secondary alcohols remained intact. DMN-AZADO (2) also has high catalytic efficiency for one-pot oxidation from primary alcohols to the corresponding carboxylic acids in the presence of secondary alcohols and for oxidative lactonization from diols.
- Doi, Ryusuke,Shibuya, Masatoshi,Murayama, Tsukasa,Yamamoto, Yoshihiko,Iwabuchi, Yoshiharu
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p. 401 - 413
(2016/10/12)
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- 9-azanoradamantane N—oxyl compound and method for producing same, and organic oxidation catalyst and method for oxidizing alcohols using 9-azanoradamantane N—oxyl compound
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An organocatalyst for oxidizing alcohols in which a primary alcohol is selectively oxidized in a polyol substrate having a plurality of alcohols under environmentally-friendly conditions. The organic oxidation catalyst has an oxygen atom bonded to a nitrogen atom of an azanoradamantane skeleton and at least one alkyl group at positions 1 and 5. The oxidation catalyst has higher activity than TEMPO, which is an existing oxidation catalyst, in the selective oxidation reaction of primary alcohols, and better selectivity than AZADO and 1-Me-AZADO. This DMN-AZADO can be applied to the selective oxidation reaction of primary alcohols that contributes to shortening the synthesizing process for pharmaceuticals, pharmaceutical raw materials, agricultural chemicals, cosmetics, organic materials, and other such high value-added organic compounds.
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Page/Page column 27
(2015/09/23)
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- Amino functionalized chitosan as a catalyst for selective solvent-free self-condensation of linear aldehydes
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An aminopropyltrimethoxysilane functionalized chitosan was found to be an efficient solid base catalyst for the self-aldol condensation of linear aldehydes under solvent-free conditions. The modified catalyst was characterized using physical techniques, elemental analysis, FT-IR, and TGA. The modified chitosan was evaluated for the aldol condensation of C3-C7 linear aldehydes in which the selective formation was obtained for α,β-unsaturated aldehydes. A decreasing trend in the conversion from propanal to heptanal was observed. Propanal and pentanal were subjected for detail investigations to study the effect of parameters like amount of catalyst and aldehyde, and temperature on the conversion and selectivity. Kinetic performance of the modified chitosan investigated for a representative aldehyde, pentanal showed that the rate was increased with the catalyst amount, pentanal and temperature. The catalyst was reused up to six cycles without significant loss in its activity and selectivity.
- Jose, Tharun,Sudheesh,Shukla, Ram S.
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experimental part
p. 158 - 166
(2011/02/23)
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- The continuous self aldol condensation of propionaldehyde in supercritical carbon dioxide: A highly selective catalytic route to 2-methylpentenal
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The aldol reactions of propionaldehyde and butyraldehyde have been explored in supercritical CO2, scCO2, using an automated continuous flow reactor. The reaction was found to proceed over a variety of heterogeneous acidic and basic catalysts and with increased selectivity compared to using neat reactants.
- Stevens, James G.,Bourne, Richard A.,Poliakoff, Martyn
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scheme or table
p. 409 - 416
(2010/04/22)
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- Processes for preparing beta-hydroxy-ketones and alpha,beta-unsaturated ketones
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Processes for producing β-hydroxy-ketones and α,β-unsaturated ketones are disclosed which comprise the crossed condensation of an aldehyde with a ketone in the presence of a hydroxide or alkoxide of alkali metal or an alkaline earth metal as catalyst. The products of the process, β-hydroxy-ketones and α,β-unsaturated ketones, are useful for the preparation of many commercially important products in the chemical process industries including solvents, drug intermediates, flavors and fragrances, other specialty chemical intermediates.
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Page 11-15; 17; 18
(2008/06/13)
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- InBr3-Et3N promoted alkynylation of aldehydes and N,O-acetals under mild conditions: Facile and simple preparation of propargylic alcohols and amines
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The use of a novel InBr3-Et3N reagent system to promote addition reactions of 1-alkynes not only with a variety of aromatic or bulky aliphatic aldehydes but also with N,O-acetals is described. The corresponding propargylic alcohols or amines are produced in good to excellent yields.
- Sakai, Norio,Hirasawa, Maki,Konakahara, Takeo
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p. 4171 - 4174
(2007/10/03)
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- COMPOUNDS FOR THE CONTROLLED RELEASE OF ACTIVE ALDEHYDES
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The present invention relates to the field of perfumery. More particularly, it concerns an aldoxane derivative of Formula (I) capable of protecting an active aldehyde R1CHO, for example a perfumery or flavor aldehyde, from a chemically aggressive medium into which they have to be added, and then of releasing said active aldehyde at the desired moment. The present invention concerns also the use of said compound in perfumery or in the flavor industry as well as the compositions or articles associated with said aldoxanes.
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Page/Page column 20
(2008/06/13)
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- Catalytic Conversions in Water. Part 21: Mechanistic Investigations on the Palladium-Catalysed Aerobic Oxidation of Alcohols in Water
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Water-soluble complexes of palladium(II) with phenanthroline-derivatives are stable, recyclable catalysts for the selective aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic liquid-liquid system. The active catalyst is a dihydroxy-bridged palladium dimer. Kinetics of the reaction, ligand and anion effects are discussed.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Sheldon, Roger A.
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p. 355 - 369
(2007/10/03)
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- Process for obtaining β-hydroxy and/or α,β-unsaturated carbonyl compounds
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The present invention relates to a process for obtaining β-hydroxy carbonyl compounds and/or α,β-unsaturated carbonyl compounds, characterized in that at least one aldehyde or one ketone is brought into contact with a solid catalyst of general formula (I): with 0.20≤x≤0.33 and n1.
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- Transformations of butyraldehyde in the presence of catalysts based on large-pore molecular sieves VPI-5 and AlPO4-8
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It was found that zeolite-like ctystalline aluminophosphates VPI-5, Si-VPI-5, and Mn-VPI-5 as well as those derived from them, AlPO4-8, SAPO4-8, and MnAPO4-8, are capable of catalyzing aldol condensation and crotonization of butyraldehyde (BA).Pd/AlPO4-8 is catalytically active in hydrocondensation of BA with H2 at atmospheric pressure.The activities in BA conversion to 2-ethylhexane-3-ol-1-al increase in following order: Mn-VPI-5 +NaX (CsNaX), but they are much more stable.Pd/AlPO4-8 catalyzes BA conversion to 2-ethylhexanal even in the absence of H2 feed to the reaction zone.The influence of catalyst pretreatments and experimental conditions on the catalyst structures and catalytic activities is discussed. - Key words: butyraldehyde; condendation; crystalline aluminophosphates; molecular sieves; VPI-5; AlPO4-8; catalysis.
- Isakov, Ya. I.,Minachev, Kh. M.,Tome, R.,Tissler, A.,Oehlmann, G.,et al.
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p. 2004 - 2010
(2007/10/02)
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- Self-Condensation of n-Butyraldehyde over Solid Base Catalysts
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The catalytic properties of various solid bases for self-condensation of n-butyraldehyde in liquid phase were studied to elucidation the factors governing the activity and selectivity.For alkaline earth oxide catalysts and γ-alumina catalyst, aldol condensation ocurred, followed by Tishchenko-type cross-esterification of n-butyraldehyde with the dimer produced by the aldol condensation to form trimeric glycol ester.Alkali ion-modified alumina catalysts exhibited a high selectivity for the aldol condensation dimer, the trimeric glycol ester being formed little.Both basic and acidic sites on the surfaces of the alkaline earth oxides and γ-alumina were assumed to contribute to Tishchenko-type cross-esterification.The suppression of Tischenko-type cross-esterification.The suppression of Tischenko-type cross-esterification for alkali ion-modified alumina catalysts is due to the absence of acidic sites on the surfaces.The catalytic performances of alumina-supported magnesium oxide exhibited lower activity but higher selectivity to trimeric glycol ester than MgO.This catalytic feature was caused by the lower basicity and higher acidity on the surface of alumina-supported magnesium oxide as compared with MgO.The activity of alkali ion-exchanged zeolites was lowest among the catalysts examined in this study.The modification of zeolites with excess alkali ions improved the activity.
- Tsuji, Hideto,Yagi, Fuyuki,Hattori, Hideshi,Kita, Hideaki
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p. 759 - 770
(2007/10/02)
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- Indirect Electrooxidation of Alcohols by a Double Mediatory System with Two Redox Couples of +=O>/R2NO. and . or Br+>/Br- in an Organic-Aqueous Two-Phase Solution
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An indirect electrooxidation method for alcohol to aldehyde or ketone conversion has been developed.This method, applicable to chemoselective oxidation, employs two redox couples, consisting of 2,2,6,6-tetramethylpiperidine-1-oxyl derivatives 6 and active bromine species.The former is required for the chemical process and recycled, whereas the latter is to be involved in the electrochemical process.Three chemical events play an important role in this system: (1) the formation of . or Br+> from bromide ion by discharge on the anode in an aqueous solution, (2) the reaction of N-oxyl compounds 6 with active bromine species to generate N-oxoammonium ion 7, and (3) the oxidation of alcohols with 7 in an organic phase.Optimum conditions were established as follows: an aqueous 25percent NaBr solution buffered at pH 8.6 in a binary system, the use of 1-10 mol percent of 4-(benzoyloxy)piperidine derivatives 6, and adjustment of an electric current at 10-100 mA/cm2.The successful applications of the present method to the oxidation of a variety of primary and secondary alcohols including 1,n-diols, giving the corresponding carbonyl compounds, have delineated its synthetic utility.The chemoselective oxidation of a primary hydroxy group in the presence of secondary one has been achieved with a high selectivity by the present procedure.
- Inokuchi, Tsutomu,Matsumoto, Sigeaki,Torii, Sigeru
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p. 2416 - 2421
(2007/10/02)
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- A Selective and Efficient Method for Alcohol Oxidations Mediated by N-Oxoammonium Salts in Combination with Sodium Bromite
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The oxidation of primary and secondary alcohols leading to aldehydes, carboxylic acids, and ketones has been carried out in a N-oxoammonium salts-NaBrO2 system.Sodium bromite as a stoichiometric oxidizing reagent activates N-oxyl compounds (recycling catalysts) to their N-oxoammonium salts in a weakly basic medium, which oxidize primary hydroxyl groups preferentially rather than secondary ones to the corresponding aldehydes.Calcium hypochlorite is used as an alternative terminal oxidant in the same media.The procedure, applicable to the selective formation of γ- and δ-lactones, β-hydroxy aldehydes, and 2-acetoxy ketones, is advantageous in terms of reagent cost, safety, and ease of operation.
- Inokuchi, Tsutomo,Matsumoto, Sigeaki,Nishiyama, Tokio,Torii, Sigeru
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p. 462 - 466
(2007/10/02)
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- 2-Allylisourea as an Effective Agent for Direct α-Allylation of Ketone and Aldehyde Assisted by Palladium(0) under Neutral Conditions
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Direct α-allylation of a variety of ketones and aldehydes with 2-allylisourea took place in the presence of a catalytic amount of a palladium(0) complex under neutral and mild conditions.Scope and limitations of this novel method have been investigated.
- Inoue, Yoshio,Toyofuku, Masanori,Taguchi, Masaaki,Okada, Shin-ichi,Hashimoto, Harukichi
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p. 885 - 892
(2007/10/02)
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- MECHANISM OF THE ALDOL CONDENSATION OF ALDEHYDES, CATALYZED BY THE SALTS OF METALS AND HIGHER ORGANIC ACIDS
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The salts of transition metals are the most active catalysts for the aldol condensation of aliphatic aldehydes.By IR spectroscopy it was found that an intermediate complex between the aldehyde and the catalyst is formed at the initial stage of the reaction.A chelate mechanism of catalysis is proposed for the aldol condensation and satisfactorily explains the order of formation of the intermediate and final products.
- Katsnel'son, M. G.,Kagna, S. Sh.,Nikitina, L. I.,Oranskaya, O. M.,Semenskaya, I. V.
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p. 1437 - 1441
(2007/10/02)
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- Chemoselective Oxidation of the Primary Alcohol Function of Diols Catalyzed by Zirconocene Complexes
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Zirconocene complexes, Cp2ZrH2 and Cp2Zr2, catalyze the Oppenauer-type oxidation of alcohol functions to the corresponding carbonyl compounds in the presence of an appropriate hydrogen acceptor such as benzophenone.In the oxidation of primary α,ω-diols and of diols containing two secondary alcohol functions, one of the alcohol functions is selectively oxidized to form hydroxy aldehydes and hydroxy ketones, respectively, in substantial yields.The chemoselective oxidation of the primary alcohol function can be achieved in the oxidation of diols containing both the primary and secondary alcohol functions.
- Nakano, Tatsuya,Terada, Takanobu,Ishii, Yasutaka,Ogawa, Masaya
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p. 774 - 776
(2007/10/02)
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