- Biocatalytic cascade for the synthesis of enantiopure β-azidoalcohols and β-hydroxynitriles
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A three-step, two-enzyme, one-pot reaction sequence starting from prochiral a-chloroketones leading to enantiopure (3- azidoalcohols and (3-hydroxynitriles is described. Asymmetric bioreduction of a-chloroketones by hydrogen transfer catalysed by an alcohol dehydrogenase (ADH) established the stereogenic centre in the first step to furnish enantiopure chlorohydrin intermediates. Subsequent biocatalysed ring closure to the epoxide and nucleophilic ring opening with azide, N3-, or cyanide, CN-, both catalysed by a nonselective halohydrin dehalogenase (Hhe) proceeded with full retention of configuration to give enantiopure (-azidoalcohols and (3-hydroxynitriles, respectively. Both enantiomers of various optically pure (-azidoalcohols and (-hydroxynitriles were synthesised.
- Schrittwieser, Joerg H.,Lavandera, Ivan,Seisser, Birgit,Mautner, Barbara,Kroutil, Wolfgang
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supporting information; experimental part
p. 2293 - 2298
(2009/08/17)
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- Asymmetric reduction of α-thiocyanatoketones by Saccharomyces cerevisiae and Mortierella isabellina-a new route to optically active thiiranes
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A simple method for the preparation of optically active 1-aryloxy- and 1-arylsulphanyl-3-thiocyanatopropan-2-oles from racemic 1-chloro-3-aryloxy- and 1-chloro-3-arylsulphanyl-2-propanols via 1-aryloxy- and 1-arylsulphanyl-3-thiocyanatopropan-2-ones has been developed. The enantiomerically enriched β-hydroxythiocyanates were obtained by a microbiological reduction of the thiocyanatoketones with Saccharomyces cerevisiae or Mortierella isabellina and subsequently converted into optically active thiiranes on treatment with a lithium hydroxide solution.
- Lukowska, Edyta,Plenkiewicz, Jan
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p. 1202 - 1209
(2008/02/05)
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- Non-racemic halohydrins via biocatalytic hydrogen-transfer reduction of halo-ketones and one-pot cascade reaction to enantiopure epoxides
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Biocatalytic hydrogen-transfer reduction of α-chloro-ketones furnished non-racemic chlorohydrins by employing either Rhodococcus ruber as lyophilized cell catalyst or an alcohol dehydrogenase preparation from Pseudomonas fluorescens DSM 50106 (PF-ADH). Fo
- Poessl, Tina M.,Kosjek, Birgit,Ellmer, Ursula,Gruber, Christian C.,Edegger, Klaus,Faber, Kurt,Hildebrandt, Petra,Bornscheuer, Uwe T.,Kroutil, Wolfgang
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p. 1827 - 1834
(2007/10/03)
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- PROCESS FOR THE PREPARATION OF ALPHA-CHLOROKETONES FROM ALKYL ESTERS
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The present invention relates to a process for the preparation of α-chloroketones from readily available alkyl esters by the reaction of a sulfoxonium ylide on said alkyl esters to generate a keto sulfoxonium ylide that is in turn treated with anhydrous HCl.
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Page/Page column 7
(2010/02/11)
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- One-Carbon Chain Extension of Esters to α-Chloroketones: A Safer Route without Diazomethane
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The reaction of a variety of methyl esters with dimethylsulfoxonium methylide at 0-25 °C affords the chain-extended β-keto dimethylsulfoxonium ylides. Subsequent treatment with hydrogen chloride in THF proceeds with loss of DMSO to afford the corresponding α-chloroketones. This sequence has been utilized to convert the methyl esters of CBZ-protected alanine and valine to the anti N-protected α-amino epoxides, which are important pharmaceutical intermediates. When the same protocol is applied to BOC-protected phenylalanine methyl ester, epimerization occurs so that the use of a more reactive aryl ester is required. This chemistry provides a practical route to α-chloroketones that avoids the use of toxic and explosive diazomethane.
- Wang, Dengjin,Schwinden, Mark D.,Radesca, Lilian,Patel, Bharat,Kronenthal, David,Huang, Ming-Hsing,Nugent, William A.
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p. 1629 - 1633
(2007/10/03)
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- CHLOROHYDROXYACETONE DERIVATIVE AND PROCESS FOR PRODUCING OPTICALLY ACTIVE CHLOROPROPANEDIOL DERIVATIVE FROM THE SAME
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A process for efficiently preparing an optically active chloropropanediol derivative, especially (S)-1-benzyloxy-3-chloro-2-propanol, which has a high optical purity and is useful as an intermediate for medicines. The process comprises treating an inexpen
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- Preparation of halohydrin β-blocker precursors using yeast-catalysed reduction
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The preparation of halohydrin β-blocker precursors using yeast-catalysed reduction of α-haloketones was performed. The influence in the yield and e.e. of several process variables was analysed. The (S)-enantioselectivity observed with Saccharomyces cerevisiae can be changed to (R)-enantioselectivity using methyl vinyl ketone as selective inhibitor (25 mM). Using resting fresh cells better yields and e.e.s are observed than using growing cells. Yarrowia lipolytica 1240 resting cells gave 87% yield of (S)-1-chloro-3(1-naphthyloxy)propan-2-ol (99% e.e.). Pichia mexicana 11105 resting cells gave 85% yield of (R)-1-chloro-3(1-naphthyloxy)propan-2-ol (precursor of propranolol) (95% e.e). The reduction process is applied to other α-haloketones, a lower e.e. being obtained the closer the size of the ketone substituents.
- Martinez, Fernando,Del Campo, Carmen,Sinisterra,Llama, Emilio F.
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p. 4651 - 4660
(2007/10/03)
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- NUCLEOPHILIC SUBSTITUTION OF α-HALO-KETONES-XXII ACETOLYSIS OF α'-PHENOXY-α-CHLORO-KETONES. A COMPARISON OF THEIR REACTIVITY WITH THAT OF THE CORRESPONDING THIOETHERS
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The results obtained in the acetolysis of α-chloro-ketones 1 a-e are compared with those previously reported for the acetolysis of the corresponding α'-phenylthio-α-chloro-ketones 15a-e and discussed in terms of the enolization-solvolysis mechanisms.
- Pusino, A.,Rosnati, V.,Saba, A.
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p. 1893 - 1900
(2007/10/02)
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- Carbon and oxygen analogs of penicillin
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In accordance with this invention, it has been found that carbon and oxygen analogs of 6β-aminopenicillanic acid and biologically active derivatives thereof can be formed from esters of 6-oxopenicillanic acid. For example, 6β-phenoxyacetoxypenicillanic ac
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- Cyclopentanone derivatives
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Cyclopentane derivatives of the formula: STR1 wherein R1 represents hydrogen or a carboxylic acyl group, and either (I) R2 represents a group of the formula: (wherein R3 and R4 represent hydrogen or alkyl, and R5 represents hydrogen, or alkyl, alkoxy, cycloalkyl or adamantyl, or R5 represents alkyl substituted by alkoxy, or by cycloalkyl or by adamantyl, or the group --CR3 R4 R5 together forms a cycloalkyl or adamantyl group), X represents trans-vinylene or ethylene and Y represents carbonyl or a group of the formula: STR2 wherein R6 represents hydrogen or alkyl, and R7 represents hydrogen or a carboxylic acyl group, or else (ii) R2 represents a group of the formula: (wherein A represents alkylene, Z represents a direct bond or oxygen or sulphur, and R8 represents an aryl or heterocyclyl group which may be substituted by one or more of halogen, alkyl, alkoxy and trihalomethyl), X in formula I represents ethylene or trans-vinylene and Y in formula I represents carbonyl or a group of formula III, or else (iii) R2 represents a group R8 and X and Y in formula I represent simultaneously ethylene and carbonyl, trans-vinylene and carbonyl, or ethylene and --CH(OR7)-- groups respectively. The compounds are new and possess pharmacological properties similar to those of prostaglandins.
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