- METHOD FOR PREPARING A ?-HYDROXYKETONE
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Method for preparing a β-hydroxyketone having 4 to 8 carbon atoms by reacting formaldehyde with a branched or unbranched dialkyl ketone having 3 to 7 carbon atoms in the liquid phase in a reactor in the presence of a basic component at a temperature of 50 to 150° C. and a pressure of 0.2 to 10 MPa abs, in which (a) a trialkylamine having 1 to 4 carbon atoms per alkyl group is used as basic component and the reaction (b) is carried out in the presence of 1 to 25% by weight water, based on the liquid phase, and (c) at a molar ratio of trialkylamine to formaldehyde in the liquid phase of from 1 to 5.
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Paragraph 0119-0134
(2020/01/24)
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- METHOD FOR PREPARING 1-HYDROXY-2-METHYL-3-PENTANONE
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Method for preparing 1-hydroxy-2-methyl-3-pentanone (I) by reacting formaldehyde with diethyl ketone in a reactor in the presence of water and a basic component at a temperature of 50 to 150° C. and a pressure of 0.2 to 10 MPa abs, in which the basic component used is a trialkylamine from the group comprising trimethylamine, N,N-dimethylethylamine, N,N-diethylmethylamine, triethylamine, N,N-dimethyl-n-propylamine, N-ethyl-N-methyl-n-propylamine, N,N-dimethylisopropylamine, N-ethyl-N-methylisopropylamine, N,N-dimethyl-n-butylamine, N,N-dimethylisobutylamine and N,N-dimethyl-sec-butylamine, and from the reaction mixture obtained, trialkylamine as low boiler and a bottom product comprising 1-hydroxy-2-methyl-3-pentanone (I) as high boiler are separated in a distillation apparatus, wherein the distillation apparatus is operated at a top pressure of 0.2 to 1 MPa abs.
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Paragraph 0156-0166; 0167-0180; 0181-0195
(2020/01/24)
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- Finding the Selectivity Switch - A Rational Approach towards Stereocomplementary Variants of the Ene Reductase YqjM
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Ene reductases from the Old Yellow Enzyme family are versatile biocatalysts useful for the synthesis of optically active compounds. One disadvantage of biocatalysts when compared to competing catalysts in chemical syntheses is that often only one stereoisomer of the product is available. Another drawback can be the lack of activity in certain enzyme-substrate combinations. We were able to approach both of these challenges rationally in the case of the enzymatic synthesis of methyl 3-hydroxy-2-methylpropanoate (commonly denoted as the Roche ester) and derivatives thereof using the ene reductase YqjM. By a highly efficient, concept-based approach of designing mutant variants of YqjM and engineering substrates we could alter both the rate constant and the enantioselectivity of the reaction. Preparative scale reactions have been performed with successful mutants. In addition, the iterative modification of the substrate gave experiment-based insights into the binding mode of the Roche ester precursor and its derivatives.
- Rüthlein, Elisabeth,Classen, Thomas,Dobnikar, Lina,Sch?lzel, Melanie,Pietruszka, J?rg
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p. 1775 - 1786
(2015/06/02)
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- Catalytic, Asymmetric Synthesis and Diastereoselective Aldol Reactions of Dipropionate Equivalents
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The dimer of methylketene can be conveniently prepared in one step and high enantiomeric excess from propionyl chloride, using a catalytic amount of a silylated cinchona alkaloid as a source of chirality. Opening of the dimer with a lithiated sulfonamide
- Calter, Michael A.,Song, Wei,Zhou, Jianguang
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p. 1270 - 1275
(2007/10/03)
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- The baker's yeast reduction of the β-keto aldehydes in the presence of a sulfur compound
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Improved enantio- and diastereoselectivity was achieved in the baker's yeast reduction of β-keto aldehyde derivatives using a sulfur compound as an additive. The resulting enantiomerically pure diol was transformed into serricornin, a sex pheromone of the cigarette beetle.
- Hayakawa, Ryuuichirou,Shimizu, Makoto
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p. 1298 - 1300
(2007/10/03)
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- Process for the selective trihalogenation of ketones useful as intermediates in the synthesis of thiophenes
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The present invention concerns a novel process for the selective trihalogenation of ketones employing organic halogen salts.
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- Rare Earth Metal Complexes as Water-Tolerant Lewis Acid Catalysts in Organic Synthesis
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Rare earth metal triflates are stable in aqueous media and can act as Lewis acid catalysts in several carbon-carbon bond forming reactions. This article describes some of these reactions; aldol and Mannich-type reactions in aqueous solution, and Friedel-Crafts acylations and Fries rearrangement in organic solvents. The reactions proceeded smoothly in the presence of a catalytic amount of the triflate under mild conditions. Moreover, the catalysts could be recovered after the reactions were completed and could be reused.
- Kobayashi,Hashiya,Ishitani,Moriwaki,Nagayama
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p. 193 - 202
(2007/10/03)
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- Lanthanide Triflates as Water-Tolerant Lewis Acids. Activation of Commercial Formaldehyde Solution and Use in the Aldol Reaction of Silyl Enol Ethers with Aldehydes in Aqueous Media
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Lanthanide trifluoromethanesulfonates (triflates), especially ytterbium triflate (Yb(OTf)3), were found to be stable Lewis acids in water.In the presence of a catalytic amount of lanthanide triflate, formaldehyde in water solution (commercial formaldehyde
- Kobayashi, Shu,Hachiya, Iwao
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p. 3590 - 3596
(2007/10/02)
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- ASYMMETRIC ALDOL REACTIONS USING CHIRAL BORON REAGENTS: APPLICATION TO THE SYNTHESIS OF TIRANDAMYCIN A
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The bicyclic acetal 1, a key intermediate in previous synthetic studies on tirandamycin A, has been prepared in enantiomerically pure form starting from the (R)-ethylketone 2 and the aldehyde 3.A reagent controlled aldol reaction using (-)-(Ipc)2BOTf sele
- Paterson, Ian,Lister, M. Anne,Ryan, Glen R.
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p. 1749 - 1752
(2007/10/02)
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- Lanthanide Trifluoromethanesulfonates as Stable Lewis Acids in Aqueous Media. Yb(OTf)3 Catalyzed Hydroxymethylation Reaction of Silyl Enol Ethers with Commercial Formaldehyde Solution
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Silyl enol ethers smoothly react with commercial formaldehyde solution to give the corresponding hydroxymethylated adducts in high yields by the promotion of a catalytic amount of ytterbium(III) triflate (Yb(OTf)3), which is a stable Lewis acid in aqueous
- Kobayashi, Shu
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p. 2187 - 2190
(2007/10/02)
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