- Enantio- and regioselective reduction of α-diketones by baker's yeast
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Although yeast reduction of α-diketones 1 affords a mixture of two α-hydroxy ketones and a vic-diol, the use of methyl vinyl ketone as an enzyme inhibitor prevents the production of the diol. Regioselectivity in the reduction to afford α-hydroxy ketones i
- Nakamura, Kaoru,Kondo, Shin-Ichi,Kawai, Yasushi,Hida, Kouichi,Kitano, Kazutada,Ohno, Atsuyoshi
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- α-Hydroxylation of α,α-Disubstituted N-tert-Butanesulfinyl Ketimines with Molecular Oxygen: Stereoselective Synthesis of α-Tertiary Hydroxyimines
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α-Tertiary hydroxyimines were stereoselectively synthesized from enantioenriched N-tert-butanesulfinyl ketimines using potassium tert-butoxide, molecular oxygen, and trimethyl phosphite. The stereoselective hydroxylation of acyclic ketimines bearing two sterically similar α-substituents was achieved by controlling the geometry of the metalloenamine intermediates and the facial selectivity of hydroxylation. The synthetic utility of the resulting α-tertiary hydroxyimines was demonstrated through the successful diastereoselective synthesis of highly substituted β-amino alcohols.
- Liu, Hui,Lu, Chong-Dao,Yao, Yun,Yisimayili, Nuermaimaiti
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supporting information
(2022/01/20)
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- Biocatalytic route to chiral acyloins: P450-catalyzed regio- and enantioselective α-hydroxylation of ketones
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P450-BM3 and mutants of this monooxygenase generated by directed evolution are excellent catalysts for the oxidative α-hydroxylation of ketones with formation of chiral acyloins with high regioselectivity (up to 99%) and enantioselectivity (up to 99% ee). This constitutes a new route to a class of chiral compounds that are useful intermediates in the synthesis of many kinds of biologically active compounds.
- Agudo, Rubén,Roiban, Gheorghe-Doru,Lonsdale, Richard,Ilie, Adriana,Reetz, Manfred T.
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p. 950 - 956
(2015/01/30)
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- Benzoylformate decarboxylase from Pseudomonas putida as stable catalyst for the synthesis of chiral 2-hydroxy ketones
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The thiamin diphosphate-and Mg2+-dependent enzyme benzoylformate decarboxylase (BFD) from Pseudomonas putida was characterized with respect to its suitability to catalyze the formation of chiral 2-hydroxy ketones in a benzoin-condensation type reaction. Carboligation constitutes a side reaction of BFD, whereas the predominant physiological task of the enzyme is the non-oxidative decarboxylation of benzoylformate. For this purpose the enzyme was obtained in sufficient purity from Pseudomonas putida cells in a one-step purification using anion-exchange chromatography. To facilitate the access to pure BFD for kinetical studies, stability investigations, and synthetical applications, the coding gene was cloned into a vector allowing the expression of a hexahistidine fusion protein. The recombinant enzyme shows distinct activity maxima for the decarboxylation and the carboligation beside a pronounced stability in a broad pH and temperature range. The enzyme accepts a wide range of donor aldehyde substrates which are ligated to acetaldehyde as an acceptor in mostly high optical purities. The enantioselectivity of the carboligation was found to be a function of the reaction temperature, the substitution pattern of the donor aldehyde and, most significantly, of the concentration of the donor aldehyde substrate. Our data are consistent with a mechanistical model based on the X-ray crystallographic data of BFD. Furthermore we present a simple way to increase the enantiomeric excess of (S)-2-hydroxy-1-phenyl-propanone from 90% to 95% by skillful choice of the reaction parameters. Enzymatic synthesis with BFD are performed best in a continuously operated enzyme membrane reactor. Thus, we have established a new enzyme tool comprising a vast applicability for stereoselective synthesis.
- Iding, Hans,Duennwald, Thomas,Greiner, Lasse,Liese, Andreas,Mueller, Michael,Siegert, Petra,Groetzinger, Joachim,Demir, Ayhan S.,Pohl, Martina
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p. 1483 - 1495
(2007/10/03)
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- Asymmetric reduction of α-keto esters and α-diketones with a bakers' yeast keto ester reductase
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Optically pure α-hydroxy esters and α-hydroxy ketones have been synthesized by the reduction of the corresponding ketones with a keto ester reductase isolated from bakers' yeast (YKER-I). The reduction of α-keto esters affords the corresponding (S)- or (R)-hydroxy esters selectively, where the stereochemical course depends on the chain length of the alkyl substituent on the carbonyl group. An α-keto short alkanoic ester affords the corresponding (S)-hydroxy ester, whereas a long alkanoate yields the corresponding (R)-hydroxy ester. The reduction of α-diketones affords the corresponding (S)-2-hydroxy ketones regio- and stereoselectively.
- Kawai, Yasushi,Hida, Kouichi,Tsujimoto, Munekazu,Kondo, Shin-Ichi,Kitano, Kazutada,Nakamura, Kaoru,Ohno, Atsuyoshi
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- A General Synthetic Method of Chiral 2-Arylalkanoic Esters via Thermal 1,2-Rearrangement
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(S)-1-Aryl-2-sulfonyloxy-1-alkanone acetals, prepared from natural ethyl (S)-lactate or (S)-valine (chiral sources) by the use of a Grignard reaction, were rearranged under hydrolytic conditions in the presence of a base to give (S)-2-arylalkanoic esters which in general, showed much higher pharmacological activities than their antipodes.
- Honda, Yutaka,Ori, Aiichiro,Tsuchihashi, Gen-ichi
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p. 1027 - 1036
(2007/10/02)
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