- PROCESS FOR PREPARATION OF OPTICALLY ACTIVE PROPOXYANILINE DERIVATIVES
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Treatment of a lactic acid ester derivative with an enzyme or the like, which has asymmetric ester-hydrolyzing ability, can specifically hydrolyze the ester moiety of an isomer existing as the pair to the racemic derivative. Use of the compound obtained by this hydrolysis makes it possible to produce an optically active propoxyaniline derivative by a shorter process than the conventional art.
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- Stereochemistry and fate of hydrogen atoms in the diol-dehydratase- catalyzed dehydration of meso-butane-2,3-diol
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The transformation of meso-butane-2,3-diol into butan-2-ol by a strain of Lactobacillus brevis occurs through a diol-dehydratase-catalyzed conversion of the diol into butan-2-one, which is then reduced to the secondary alcohol by dehydrogenases. Experiments performed with deuterated meso-butane-2,3-diols showed that the dehydration reaction brings about an inversion of configuration at the (R)-configured C-atom of mesobutane-2,3- diol as a consequence of the substitution of the OH group by a H-atom; at the same time, the H-atom already bound to the (R) C-atom is retained in the resulting methylene group. The H-atom replacing the OH group was assessed to come from the medium since the H-atom at the (S)-configured C-atom was completely lost. By contrast, in the case of the conversion of (RS)-propane- 1,2-diol into propan-1-ol under the same fermentation conditions, an extensive H-transfer (ca. 80%) from the primary-alcohol function to the adjacent C-atom was observed. This fact is taken as an indication of different modes in which the two substrates are processed by the enzyme (despite the same stereochemical outcome). A speculative hypothesis is presented to interpret such a dissimilarity.
- Manitto, Paolo,Speranza, Giovanna,Fontana, Gabriele,Galli, Antonietta
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p. 2005 - 2016
(2007/10/03)
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