- Biocatalytical production of (5S)-hydroxy-2-hexanone
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Biocatalytical approaches have been investigated in order to improve accessibility of the bifunctional chiral building block (5S)-hydroxy-2-hexanone ((S)-2). As a result, a new synthetic route starting from 2,5-hexanedione (1) was developed for (S)-2, whi
- Katzberg, Michael,Wechler, Kerstin,Mueller, Marion,Duenkelmann, Pascal,Stohrer, Juergen,Hummel, Werner,Bertau, Martin
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experimental part
p. 304 - 314
(2009/03/11)
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- Highly efficient synthesis of enantiopure diacetylated C 2-symmetric diols by ruthenium- and enzyme-catalyzed dynamic kinetic asymmetric transformation (DYKAT)
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Highly efficient synthesis of enantiopure diacetates of 2,4-pentanediol and 2,5-hexanediol starting from commercially available mixtures of the diols (dl/ meso ≈1:1) has been realized by combining a fast ruthenium-catalyzed epimerization with an enzymatic transesterification. The in situ coupling of these two processes produces the diacetates in high yield in > 99 % enantiomeric excess.
- Martin-Matute, Belen,Edin, Michaela,Baeckvall, Jan-E.
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p. 6053 - 6061
(2007/10/03)
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- Regio- and stereoselective reduction of diketones and oxidation of diols by biocatalytic hydrogen transfer
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The asymmetric reduction of symmetrical and nonsymmetrical diketones as well as the stereoselective oxidation of various diols by biocatalytic hydrogen transfer was investigated by employing lyophilized cells of Rhodococcus ruber DSM 44541 containing alcohol dehydrogense ADH-'A'. Symmetrical and nonsymmetrical diketones at the (ω-1)- and (ω-2)-positions are reduced to the Prelog product with high stereopreference, while sterically more demanding ketone moieties, for example those at the (ω-3)-position, remain unchanged. For the oxidation mode, differentiation between primary and secondary alcohols is achieved, and the (S)-configured secondary alcohols at the (ω-1)- and (ω-2)-positions are oxidized preferentially. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Edegger, Klaus,Stampfer, Wolfgang,Seisser, Birgit,Faber, Kurt,Mayer, Sandra F.,Oehrlein, Reinhold,Hafner, Andreas,Kroutil, Wolfgang
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p. 1904 - 1909
(2007/10/03)
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- New continuous production process for enantiopure (2R,5R)-hexanediol
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A new continuous production process has been developed for optically active pure (2R,5R)-hexanediol. The process uses resting whole cells of Lactobacillus kefir DSM 20587 as a biocatalyst. The reduction of (2,5)-hexanedione to (2R,5R)-hexanediol was carried out in a 2-L continuously operated membrane reactor. Conversion of (2,5)-hexanedione was nearly quantitative and the selectivity between product and intermediate was 78% for the product. Enantioselectivity and diastereoselectivity were >99% for the whole period. The productivity of L. kefir could be increased by factor 30. (2R,5R)-Hexanediol was continuously produced over 5 days with a space-time yield of 64 g·L-1·d-1.
- Haberland, Juergen,Hummel, Werner,Daussmann, Thomas,Liese, Andreas
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p. 458 - 462
(2013/09/06)
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- Yeast-mediated synthesis of optically active diols with C2-symmetry and (R)-4-pentanolide
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Reduction of some diketones and a keteacid with yeast, Pichia farinosa IAM 4682 was examined. The reduction of carbonyl groups proceeded highly selectively with an anti-Prelog fashion to give (R)-alcohols. (2R,5R)2,5- Hexanediol (83% yd., >99% e.e., 95% d.e.), (2R,4R)-2,4-pentanediol (94% yd., >99% e.e., 98% d.e.), and (R)-4-pentanolide (67% yd., >99% e.e.) were highly efficiently obtained from the corresponding ketones. Effect of the structure of substrate on the stereochemical course as well as the selectivity were discussed.
- Ikeda,Sato,Sugai,Ohta
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p. 8113 - 8122
(2007/10/03)
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- Clemmensen reduction. Part 5. Chiral γ-hydroxy-ketones
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The reduction of some chiral γ-hydroxy-ketones by amalgamated zinc-hydrochloric acid (Clemmensen reduction) has been studied. Reduction of the carbonyl group occurs rapidly with retention of configuration at the carbinol carbon atom. This result invalidates part of an earlier hypothesis.
- Davis, Brian R.,Rewcastle,Stevenson, Ralph J.,Woodgate, Paul D.
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p. 2148 - 2154
(2007/10/05)
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