- Continuous enzymatic stirred tank reactor cascade with unconventional medium yielding high concentrations of (S)-2-hydroxyphenyl propanone and its derivatives
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The implementation of biocatalysis in flow chemistry offers synergistic synthesis advantages in line with green chemistry principles. Yet, the conversion of high substrate concentrations is in many cases hindered by insolubility issues or substrate toxicity. Here, the continuous synthesis of (S)-2-hydroxyphenyl propanone (2-HPP) from inexpensive benzaldehyde and acetaldehyde in a methyltert-butyl ether based organic reaction environment, namely micro-aqueous reaction system, has been established. Kinetic parameters of the applied whole cell catalyst were identified to design a continuous process for (S)-2-HPP synthesis. This revealed a necessity to distribute acetaldehyde over a spatial coordinate to remain below a toxic concentration threshold. Hence, three continuous stirred tank reactors (cSTR) were conjugated in a technical cascade with an additional influx of acetaldehyde into each unit. The catalytic behaviour of this reaction setup was described based on mass balances and a kinetic model. Enzyme deactivation was described by a novel staged model and compared to a simple generic model. The optimized continuous setup yielded 190 mM (S)-HPP with an ee > 98% over 8 h. The product was easily recovered from the organic reaction environment by crystallization with an isolated yield of 68% and a purity of >99%. Further, the substrate range of the applied catalystPseudomonas putidabenzoylformate decarboxylase variant L461A was analysed. This revealed numerous halogenated, methoxylated and nitro-derivatives inortho,meta, andparaposition, which can in principle be gained by the established process. As an example, the applied cSTR concept was transferred top-methoxy benzaldehyde with good results even without further optimization.
- Glaser, Juliane,Oeggl, Reinhard,Rother, D?rte,von Lieres, Eric
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p. 7886 - 7897
(2021/12/27)
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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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- Azole compounds, their production and use
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PCT No. PCT/JP96/00325 Sec. 371 Date Oct. 17, 1996 Sec. 102(e) Date Oct. 17, 1996 PCT Filed Feb. 15, 1996 PCT Pub. No. WO96/25410 PCT Pub. Date Aug. 20, 1996The present invention provides an azole compound represented by the formula (I): wherein Ar is an
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- Optically active antifungal azoles. IX. An alternative synthetic route for 2-[(1R,2R)-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol- 1-yl)propyl]-4-[4-(2,2,3,3-tetrafluoropropoxy)phenyl]-3(2H,4H)1,2,4- triazolone and its analogs
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A new route for the synthesis of the optically active antifungal azole TAK-187, 2-[(1R,2R)-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4- triazol-1-yl)propyl]-4-[4-(2,2,3,3-tetrafluoroptopoxy)phenyl]3(2H,4H)-1,2,4- triazolone, was established. The key synthetic intermediate, 2-[(1R)-2-(2,4- difluorophenyl)-2-oxo-1-methylethyl]-4-[4-(2,2,3,3- tetrafluoropropoxy)phenyl]-3(2H,4H)-1,2,4-triazolone (8), was prepared starting from the esters (11a, b) of (S)-lactic acid in a stereocontrolled manner. This optically active propiophenone derivative 8 was converted to the one carbon-elongated (1R,2S)-diol 7, which was then reacted with 1H-1,2,4- triazole to yield TAK-187. This newly developed route was applied to the synthesis of the analogs (25a, b - 28a, b) containing an imidazolone or imidazolidinone nucleus.
- Kitazaki, Tomoyuki,Tasaka, Akihiro,Hosono, Hiroshi,Matsushita, Yoshihiro,Itoh, Katsumi
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p. 360 - 368
(2007/10/03)
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- Production of optically active triazole compounds and their intermediates
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A compound of the formula (V): STR1 wherein Ar' is a halogenated phenyl group, R is a hydrocarbon residue having a functional group at the α-carbon, R3' is an optionally substituted aliphatic or aromatic hydrocarbon residue or an optionally substituted aromatic heterocyclic group, Y and Z are, the same or different, a nitrogen atom or a methine group optionally substituted with a lower alkyl group, and (R) and (S) represent configurations, which is an optically active intermediate for production of optically active triazole compounds (I): STR2 wherein the symbols have the same meanings as defined above, and methods of preparing the compounds (V) and (I).
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