- Thermodynamic favorable CO2 conversion via vicinal diols and propargylic alcohols: A metal-free catalytic method
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Organocatalysis represents a promising field in chemical fixation of CO2. Herein, a facile metal-free strategy was reported for the one-pot preparation of cyclic carbonates and α-hydroxy ketones from vicinal diols, propargylic alcohols and CO2. Wide scope of vicinal diols and propargylic alcohols was demonstrated to be efficient under the DBU-catalyzed conditions. A plausible mechanism was proposed, which included detailed main and side reactions under the metal-free conditions.
- Han, Li-Hua,Li, Jing-Yuan,Song, Qing-Wen,Zhang, Kan,Zhang, Qian-Xia,Sun, Xiao-Fang,Liu, Ping
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supporting information
p. 341 - 344
(2019/07/04)
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- Selective Synthesis of Unsymmetrical Aliphatic Acyloins through Oxidation of Iridium Enolates
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The first method to access unsymmetrical aliphatic acyloins is presented. The method relies on a fast 1,3-hydride shift mediated by an IrIII complex in allylic alcohols followed by oxidation with TEMPO+. The direct conversion of allylic alcohols into acyloins is achieved in a one-pot procedure. Further functionalization of the Cα′ of the α-amino-oxylated ketone products gives access to highly functionalized unsymmetrical aliphatic ketones, which further highlights the utility of this transformation.
- Sanz-Marco, Amparo,Martinez-Erro, Samuel,Martín-Matute, Belén
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supporting information
p. 11564 - 11567
(2018/07/31)
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- The gold-catalyzed formal hydration, decarboxylation, and [4+2] cycloaddition of alkyne derivatives featuring L2/Z-type diphosphinoborane ligands
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The catalytic formal hydration of alkynes and decarbox-ylation of alkynoic acid were developed using a Au catalyst featuring a Z-ligand. Furthermore, the intramolecular [4+2] cycloaddition of the alkynoic acid-alkene derivative for the formation of the oxabicyclo[4.4.0] skeleton also proceeded.
- Matsumoto, Chiaki,Yamada, Masayuki,Dong, Xun,Mukai, Chisato,Inagaki, Fuyuhiko
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supporting information
p. 1321 - 1323
(2018/10/15)
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- Synthesis and Characterization of Urofuranoic Acids: In Vivo Metabolism of 2-(2-Carboxyethyl)-4-methyl-5-propylfuran-3-carboxylic Acid (CMPF) and Effects on in Vitro Insulin Secretion
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CMPF (2-(2-carboxyethyl)-4-methyl-5-propylfuran-3-carboxylic acid) is a metabolite that circulates at high concentrations in type 2 and gestational diabetes patients. Further, human clinical studies suggest it might have a causal role in these diseases. CMPF inhibits insulin secretion in mouse and human islets in vitro and in vivo in rodents. However, the metabolic fate of CMPF and the relationship of structure to effects on insulin secretion have not been significantly studied. The syntheses of CMPF and analogues are described. These include isotopically labeled molecules. Study of these materials in vivo has led to the first observation of a metabolite of CMPF. In addition, a wide range of CMPF analogues have been prepared and characterized in insulin secretion assays using both mouse and human islets. Several molecules that influence insulin secretion in vitro were identified. The molecules described should serve as interesting probes to further study the biology of CMPF.
- Nagy, Edith,Liu, Ying,Prentice, Kacey J.,Sloop, Kyle W.,Sanders, Phillip E.,Batchuluun, Battsetseg,Hammond, Craig D.,Wheeler, Michael B.,Durham, Timothy B.
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p. 1860 - 1875
(2017/03/17)
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- Α - hydroxy ketone compound low priced high-efficient synthetic method
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The invention discloses a cheap and efficient synthesis method of an alpha-hydroxyketone compound. The synthesis method is characterized in that a carbonyl compound undergoes an oxidation hydroxylation reaction at 10-120DEG C under normal pressure with iodine simple substance, N-bromosuccimide, copper bromide, bromine simple substance, hydrogen bromide, N-iodosuccimide or hydrogen iodide as a catalyst, sulfoxide as an oxidant, water or sulfoxide as a hydroxy source and sulfoxide, ethyl acetate, N,N-dimethyl formamide, acetonitrile, toluene, 1,4-dioxane, 1,2-dichloroethane, tetrahydrofuran or H2O as a solvent, and converts into the alpha-hydroxyketone compound in a high selectivity manner. Compared with traditional synthesis methods, the method disclosed in the invention has the advantages of simple operation, high yield, simple conditions, easy purification, small waste discharge amount, simple reaction apparatus, and easy industrial production. The method has wide applicability and can be used for synthesizing various alpha-hydroxyketone compounds.
- -
-
Paragraph 0149-0152
(2017/08/25)
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- I2- or NBS-catalyzed highly efficient α-hydroxylation of ketones with dimethyl sulfoxide
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An efficient method for the direct preparation of high synthetic valuable α-hydroxycarbonyls is described. The simple and readily available I2 or NBS was used as catalyst. DMSO acts as the oxidant, oxygen source, and solvent. A diverse range of tertiary Csp3-H bonds as well as more challenging secondary Csp3-H bonds could be hydroxylated in this transformation. The reaction is mild, less toxic and easy to perform.
- Liang, Yu-Feng,Wu, Kai,Song, Song,Li, Xinyao,Huang, Xiaoqiang,Jiao, Ning
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supporting information
p. 876 - 879
(2015/04/14)
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- Palladium-catalyzed selective anti-markovnikov oxidation of allylic esters
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An aldol alternative: The palladium(II)-catalyzed anti-Markovnikov oxidation of allylic esters to aldehydes at room temperature provides a viable alternative to valuable cross aldol products. High regioselectivity towards the aldehyde product was achieved using the ester protecting group for the allylic alcohol. Rapid isomerization and the much higher rate of oxidation of the branched isomer result in the same product forming from both linear and branched allylic esters. Copyright
- Dong, Jia Jia,Fananas-Mastral, Martin,Alsters, Paul L.,Browne, Wesley R.,Feringa, Ben L.
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p. 5561 - 5565
(2013/06/27)
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- Revealing substrate promiscuity of 1-deoxy-D-xylulose 5-phosphate synthase
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A study of DXP synthase has revealed flexibility In the acceptor substrate binding pocket for nonpolar substrates and has uncovered new details of the catalytic mechanism to show that pyruvate can act as both donor and acceptor substrate.
- Brammer, Leighanne A.,Meyers, Caren Freel
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supporting information; experimental part
p. 4748 - 4751
(2010/02/28)
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- Isolable gold(I) complexes having one low-coordinating ligand as catalysts for the selective hydration of substituted alkynes at room temperature without acidic promoters
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Hydration of a wide range of alkynes to the corresponding ketones has been afforded in high yields at room temperature by using gold(I)-phosphine complexes as catalyst, with no acidic cocatalysts required. Suitable substrates covering alkyl and aryl terminal alkynes, enynes, internal alkynes, and propargylic alcohols, including enantiopure forms, are cleanly transformed to the corresponding ketones in nearly quantitative yields. Acid-labile groups present in the substrates are preserved. The catalytic activity strongly depends on both the nature of the phosphine coordinated to the gold (I) center and the softness of the counteranion, the complex AuSPhOsNTf2 showing the better activity. A plausible mechanism for the hydration of alkynes through ketal intermediates is proposed on the basis of kinetic studies. The described catalytic system should provide an efficient alternative to mercury-based methodologies and be useful in synthetic programs.
- Leyva, Antonio,Corma, Avelino
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scheme or table
p. 2067 - 2074
(2009/08/07)
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- Direct amino acid catalyzed asymmetric α oxidation of ketones with molecular oxygen
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(Chemical equation presented). A possible prebiotic pathway for the asymmetric incorporation of molecular oxygen into organic compounds involves the amino acid catalyzed reaction of molecular singlet oxygen with ketones. Amino acids and their derivatives mediate the reaction between oxygen and ketones with high efficiency to produce α-hydroxyketones (see scheme).
- Sunden, Henrik,Engqvist, Magnus,Casas, Jesus,Ibrahem, Ismail,Cordova, Armando
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p. 6532 - 6535
(2007/10/03)
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- A new route to protected acyloins and their enzymatic resolution with lipases
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A series of 16 different 3-acyloxy methyl ketones, the acyloin acetates and butyrates (±)-5, was synthesised by a straight-forward new method through alkylation of tert-butyl 2-acyloxyacetoacetates 3, followed by chemoselective dealkoxy-carbonylation of the tert-butyloxycarbonyl group in the presence of other ester groups. Subsequent hydrolysis of (±)-5 can be achieved with base to give racemic acyloins 6, or with lipase catalysis to afford the corresponding non-racemic acyloins (S)-6. The remaining (R)-acyloin esters 5 can be racemised and resubjected to the procedure, or hydrolysed chemically. The kinetic resolution with two of the six tested enzymes, CAL-B and BCL (PS) lipase, proceeded selectively [enantiomeric ratio (E) values between 50 and > 200] and most of the acyloins (S)-6 were obtained in very high enantiomeric excesses (up to > 99% ee). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Scheid, Guenther,Kuit, Wouter,Ruijter, Eelco,Orru, Romano V. A.,Henke, Erik,Bornscheuer, Uwe,Wessjohann, Ludger A.
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p. 1063 - 1074
(2007/10/03)
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- Chemoenzymatic synthesis of aroma active 5,6-dihydro- and tetrahydropyrazines from aliphatic acyloins produced by baker's yeast
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Twenty-five acyloins were generated by biotransformation of aliphatic aldehydes and 2-ketocarboxylic acids using whole cells of baker's yeast as catalyst. Six of these acyloins were synthesized and tentatively characterized for the first time. Subsequent chemical reaction with 1,2-propanediamine under mild conditions resulted in the formation of thirteen 5,6-dihydropyrazines and six tetrahydropyrazines. Their odor qualities were evaluated, and their odor thresholds were estimated. Among these pyrazine derivatives, 2-ethyl-3,5-dimethyl-5,6-dihydropyrazine (roasted, nutty, 0.002 ng/L air), 2,3-diethyl-5-methyl-5,6-dihydropyrazine (roasted, 0.004 ng/L air), and 2-ethyl-3,5-dimethyltetrahy-dropyrazine (bread crustlike, 1.9 ng/L air) were the most intensive-smelling aroma active compounds.
- Kurniadi, Toshinari,Bel Rhlid, Rachid,Fay, Laurent-Bernard,Juillerat, Marcel-Alexandre,Berger, Ralf Guenter
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p. 3103 - 3107
(2007/10/03)
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- Hydration of terminal alkynes to aldehydes in aqueous micellar solutions by ruthenium(II) catalysis; first anti-Markovnikov addition of water to propargylic alcohols
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The hydration of terminal alkynes and of propargylic alcohols to the corresponding aldehyde derivatives is conveniently carried out at 60°C in an aqueous micellar environment, in the presence of 5 mol% of the indenyl ruthenium(II) complex [Ru(η5-C9H7)Cl(PPh3) 2]. Higher yields and improved regioselectivity of aldehyde versus ketone as well as reaction conditions, in particular temperature and catalyst load, are found with respect to a solvent mixture 2-propanol-water, due to the aggregating conditions of the micellar solution. The reactions of the propargylic alcohols indicate the tolerance of the hydroxy functionality by the ruthenium complex.
- Alvarez, Patricia,Bassetti, Mauro,Gimeno, José,Mancini, Giovanna
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p. 8467 - 8470
(2007/10/03)
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- Generation of odorous acyloins by yeast pyruvate decarboxylases and their occurrence in sherry and soy sauce
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Volatile acyloins (α-hydroxy ketones) were obtained by condensing either aldehydes with pyruvate or 2-keto acids with acetaldehyde in a reaction catalyzed by yeast pyruvate decarboxylases (EC 4.1.1.1). Odor qualities and threshold values of 34 acyloins were evaluated, and 23 of them possessed distinct flavor properties. Sherry and soy sauce flavors were analyzed: 2-hydroxy-3-pentanone and 3-hydroxy-2-pentanone were identified in soy sauce for the first time; these and 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-1-phenyl-2-butanone were isolated from sherry for the first time. The biocatalytic efficiencies of crude pyruvate decarboxylase preparations from Zygosaccharomyces bisporus, Saccharomyces cerevisiae, Kluyveromyces lactis, and Kluyveromyces marxianus were compared. Product yields comparable to those of conversions with purified pyruvate decarboxylase demonstrated the suitability of crude enzyme extracts as cost-effective biocatalysts in acyloin formation. Conversion rates of >50% showed that the potential of this type of enzyme to catalyze the formation of aliphatic acyloins has been underestimated before.
- Neuser, Frauke,Zorn, Holger,Berger, Ralf G.
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p. 6191 - 6195
(2007/10/03)
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- Ruthenium Tetroxide Oxidation of Alkenes. A More Complete Picture
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The ruthenium tetroxide oxidation of some linear and cyclic alkenes, representatives of five substitution patterns, has been performed in acetone-water (5:1) solution at -70 deg C using stoichiometric ammounts of the oxidant.The main reaction products are 1,2-diols and/or α-ketols depending on the nature of the substrate little amounts of scission products, aldehydes and/or carboxylic acids, are also obtained.Generally 1,2-diols predominate over α-ketols except in the oxidation of (-)-α-pinene that afforded the α-ketol in 51percent yield while no trace of the corresponding 1,2-diol was detected.All reactions prceeded through the formation of unstable brownish precipitates, presumably the intermediate ruthenium (VI) esters, which easily decomposed during the work-up step.Results from oxidation of trans-7-tetradecene and cis and trans-11-tetradecenyl acetate indicated that the reaction was syn stereospecific.In some cases, 1,3-dioxolane products, formed by condensation of the 1,2-diol and the aldehyde materials, were also obtained among the reaction products.Their possible origin is briefly discussed.
- Albarella, Laura,Piccialli, Vincenzo,Sica, Donato,Smaldone, Dina
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p. 2442 - 2456
(2007/10/03)
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- A direct conversion of vic-diols into 1,2-diketones with aqueous hydrogen peroxide catalyzed by peroxotungstophosphate (PCWP)
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α-Hydroxy ketones and vic-diols were successfully oxidized to the corresponding diketones with acqueous hydrogen peroxide in the presence of a catalytic amount of peroxotungstophosphate (PCWP). This method provides a straightforward route of 1,2-diketones which are difficult to prepare by conventional oxidation of vic-diols.
- Iwahama, Takahiro,Sakaguchi, Satoshi,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 1523 - 1526
(2007/10/02)
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- Origin of α-Hydroxy Ketones in the Osmium Tetroxide-Catalyzed Asymmetric Dihydroxylation of Alkenes
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The origin and the mechanism of formation of α-hydroxy ketones in the osmium tetroxide-catalyzed asymmetric cis-dihydroxylation (ADH) of alkenes in the presence of tert-butyl hydroperoxide is described.The formation of α-hydroxy ketones has been established to proceed through either the hydration of monooxobisglycolate ester 2 followed by oxidation with tert-butyl hydroperoxide (TBHP) or by acid-catalyzed addition of TBHP on the intermediate bisglycolate ester 2.On the basis of the mechanistic insight, it has been possible to shut down the formation of α-hydroxy ketones and other side products in the ADH reaction, even when TBHP is used as an oxygen source.It is possible to prepare α-hydroxy ketones in good yields but the optical purity of ketols has been found to be very low, which not only shed significant light on the mechanism of their formation, but also delineated the improbability of syntesizing them in optically active forms by ADH reaction of alkenes.
- Lohray, Braj B.,Bhushan, Vidya,Kumar, R. Krishna
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p. 1375 - 1380
(2007/10/02)
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- The acyloin reaction using tethered diesters
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A study of the intramolecular acyloin condensation using diesters tethered by their alkoxide groups was undertaken.The goal was to provide a method for optimizing the yield of mixed acyloin products from the reaction of two different esters by utilizing tethered dissimilar esters as substrates.The results of the study show that the yield of the acyloin condensation is dependant on the tether length.Tethers of 8 and 14 carbons in length give yields comparable to those obtained from an intermolecular control reaction while shorter tethers give reduced yields of product.However, the use of mixed tethered diesters and a crossover experiment between two different tethered substrates provides a statistical distribution of products.These observations have been interpreted as resulting from a fragmentation of the initially formed radical anion intermediate that destroys the tethered nature of the substrate(s).
- Daynard, Tim S.,Eby, Paul S.,Hutchinson, John H.
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p. 1022 - 1028
(2007/10/02)
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- Direct Catalytic Transformation of Olefins into α-Hydroxy Ketones with Hydrogen Peroxide Catalyzed by Peroxotungstophosphate
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Aliphatic olefins were directly converted into α-hydroxy ketones with acidic aqueous hydrogen peroxide in the presence of catalytic amount of peroxytungstophosphate (PCWP) under the biphasic system using chloroform as a solvent.The acidic medium was necessary to open the resulting epoxide to vic-diol which was subsequently oxidized to α-hydroxy ketones.
- Sakata, Yasuyuki,Katayama, Yuji,Ishii, Yasutaka
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p. 671 - 674
(2007/10/02)
-
- Metalation of Alkynes. Part 2. Behaviour of Alkynes with Mercury(II)Acetate in Methanol: a Systematic Reinvestigation
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The reaction of a series of alkynes with mercury(II)acetate, both in equimolar and catalytic amounts, were investigated in methanol.Hex-1-yne, oct-1-yne, oct-4-yne, 1,4-diacetoxybut-2-yne, methyl oct-2-ynoate, methyl 3-phenylpropynoate, oct-2-ynoic acid, phenylpropynoic acid, oct-1-yn-3-ol, 1-ethynylcyclohexanol, 1-ethynylcyclohexamine, phenylethyne, diphenylethyne, and ethynylferrocene were the examined substrates.The non-mercuriated products from the reaction were the corresponding vinyl ether, dialkoxyalkane, and ketone, isolated under preparative conditions.The presence of 0.1percent toluene-p-sulphonic acid increased the reactivity.The reactions of oct-1-yne and oct-4-yne were studied in detail by following with time the formation of the products under a variety of conditions, and a mechanistic scheme was drawn.For comparison, styrene, trans-oct-4-ene, and trans-β-methylstyrene were treated with 5 molpercent mercury(II) acetate.The reaction of alkenes was found to be non-catalytic.
- Bassetti, Mauro,Floris, Barbara
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p. 227 - 234
(2007/10/02)
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- Selectivity in the Oxidation of Aliphatic Ketones by Thallic Sulphate in Aqueous Medium
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The effects of temperature, structure and sulphuric acid concentration on the selectivity of the oxidation of aliphatic ketones (R1COR2) (1a-g) by thallic sulphate have been investigated.With increasing temperature the quantity of internal α-hydroxyketone (3a-d) decreases and the quantity of 1-hydroxyketone (2a-d) increases in the oxidation of methyl alkyl ketone (R2>CH3) (1a-d).The same concerns to the oxidation products of hexan-3-one (1e): 2-hydroxy-hexan-3-one (2e) and 4-hydroxy-hexan-3-one (3e), respectively. "The inverse selectivity temperature" (IST) for oxidation of linear methyl alkyl ketones (1a-c) and hexan-3-one (1e) has been found.With the use of the linear free-energy relationship it has been found that the selectivity of the reaction decreases with increasing the polar and steric effects of substituents R1,R2.With increasing the sulphuric acid concentration the selctivity of the oxidation of methyl alkyl ketones (1a, 1d) increases.
- Pechal, Miroslav,Strasak, Milan
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p. 374 - 380
(2007/10/02)
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- Urofuranic Acids - a Hitherto Unknown Class of Metabolic Compounds
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By a combination of chromatographic methods 1 mg of pentylurofuranic acid, a dicarboxylic acid C14H20O5, was isolated from 10 l urine.According to spectroscopic measurements in combination with reactions in microscale its structure is 3-carboxy-4-methyl-5-pentyl-2-furanpropanoic acid (1a).This was confirmed by synthesis.Pentylurofuranic acid does not only occur in urine, but also in blood.Accompanying compounds differ only in the construction of the side chain in position 5.
- Spiteller, Michael,Spiteller, Gerhard,Hoyer, Georg-Alexander
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p. 699 - 709
(2007/10/02)
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- α-DIALKYLAMINONITRILES: PRACTICAL REAGENTS FOR NUCLEOPHILIC ACYLATION
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An efficient synthesis of α-hydroxyketones from the reaction of carbonyl compounds and lithio α-dialkylaminonitriles is described.
- Reutrakul, Vichai,Ratananukul, Piniti,Nimgirawath, Surachai
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