• Title/Summary/Keyword: chiral intermediates

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Lipase Mediated Chiral Resoulution of 4-Arylthio-2-Butanol as an Intermediate for $\beta-Lactam$ Antibiotics

  • Hwang, Kwang-Jin;Lee, Jinkue;Chin, Sung-Min;Moon, Chi-Jang;Lee, Won-Jae;Baek, Chae-Sun;Kim, Hyung-Jin
    • Archives of Pharmacal Research
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    • v.26 no.12
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    • pp.997-1001
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    • 2003
  • This paper deals with chiral enzymatic resolution of 4-arylthio-2-butanols by lipase to prepare potential intermediates of $\beta$-lactam antibiotics. Among several lipases employed, lipase P type enzyme gave the highest ee value to prepare (R)-4-arylthio-2-butyl acetate. The enzymatic resolution of phenyl substituted alcohol (6a) using lipase P showed the highest ee value (99.7%) among those of 4-arylthio-2-butanol derivatives. Lipase P mediated hydrolysis of acylester 7a gave also (R)-alcohol 6a selectively. For determination of enantiomeric purity of these enzymatic resolved analytes, liquid chromatographic analysis was performed using two coupled Chiralcel OD and (R,R)-WhelkO chiral column.

Biocatalytic Production of Chiral Epoxides (생촉매를 이용한 광학활성 에폭사이드 생산)

  • 이은열;최원재;윤성준;김희숙;최차용
    • KSBB Journal
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    • v.14 no.3
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    • pp.291-296
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    • 1999
  • Chiral epoxides are key intermediates for the production of chiral pharmaceuticals, agrochemicals, and functional food additives. Chiral epoxides can be produced by either chemical or biological method. In biocatalytic production routes, chiral epoxides can be produced via epoxidations of prochiral alkenes by monooxygenase or peroxidase. Kinetic resolution of racemic epoxides using whole cells of bacteria or fungi might be commercially useful, since it is possible to obtain chiral epoxides with high optical purities from relatively cheap and readily avaiable racemic epoxides. Some bioprocesses already are commercially developed: the biocatalytic production of chiral epichlorohydrin via microbial stereospecific dehalogenation, and lipase-catalyzed enantioselective hydrolysis in a hollow fiber membrane bioreactor for the production of chiral methyl trans-3-(4-methoxyphenyl)glycidate. the intermediate for calcium antagonist diltiazem. The importance of biocatalytic production of chiral epoxides with several examples from literature are presented.

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Epoxide Hydrolase-catalyzed Hydrolytic Kinetic Resolution for the Production of Chiral Epoxides (에폭사이드 가수분해효소에 의한 동력학적 가수분해반응을 이용한 광학활성 에폭사이드 생산)

  • 이은열
    • KSBB Journal
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    • v.17 no.4
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    • pp.321-325
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    • 2002
  • Chiral epoxides are valuable intermediates for the asymmetric synthesis of enantiopure bioactive compounds. Microbial epoxide hydrolases (EHs) are newly discovered enzymes and versatile biocatalysts for the preparation of chiral epoxides by enantioselective hydrolysis of cheap and easily available racemic epoxide substrates. EHs are commercially potential biocatalysts due to their characteristics such as high enantioselectivity, cofactor-independent catalysis, and easy-to-Prepare catalysts. In this Paper, recent progresses in biochemistry and molecular biology of EH and developments of novel reaction systems are reviewed to evaluate the commercial feasibility of EH-catalyzed hydrolytic kinetic resolution for the production of chiral epoxides.

Synthesis of Enantiopure Epoxide Compounds Using Dimeric Chiral Salen Catalyst (이량체구조를 갖는 키랄 살렌 촉매를 이용한 고 광학순도의 에폭사이드 화합물 합성)

  • Kim, Geon-Joong;Kim, Seong-Jin;Li, Wenji;Chen, Shu-Wei;Shin, Chang-Kyo;Thakur, Santosh S.
    • Korean Chemical Engineering Research
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    • v.43 no.6
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    • pp.647-661
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    • 2005
  • The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this review, we investigate the research and development trend in the asymmetric ring opening reactions using cobalt salen catalysts. Hydrolytic kinetic resolution (HKR) technology is the very prominent way to prepare optically pure terminal epoxides among available methods. We have synthesized homogeneous and heterogeneous chiral dinuclear salen complexes and demonstrated their catalytic activity and selectivity for the asymmetric ring opening of terminal epoxides with variety of nucleophiles and for asymmetric cyclization to prepare optically pure terminal epoxides in one step. The resolved ring opened product combined with ring closing in the presence of base and catalyst afforded the enantioriched terminal epoxides in quantitaive yield. Potentially, these catalysts are using on an industrial scale to produce chiral intermediates. The experimental results of HKR technology applied to the synthesis of various chiral compounds are presented in this paper.

Biocatalytic production of chiral epoxide: Epoxide hydrolase-catalyzed enantioselective resolution

  • Lee, Eun-Yeol
    • Proceedings of the Korean Society of Life Science Conference
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    • 2001.11a
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    • pp.21-28
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    • 2001
  • A newly isolated Aspergillus niger possessing the novel epoxide hydrolase(EHase) activity was investigated for the enantioselective hydrolysis of racemic aromatic epoxides. The gene encoding EHase was cloned by RT-PCR, and molecular characteristics of the EHase gene were compared with other microbial EHases. The cloned gene encodes 398 amino acids with a deduced molecular mass of 44.5 kDa and pI of 4.83, and sequence homology with other microbial EHase was low. Functional recombinant EHase could be obtained by heterologous expressions in E. coli. Enantioselectivity of recombinant EHase was tested for valuable aromatic epoxide intermediates. Reaction conditions of EHase-catalyzed asymmetric resolution were optimized for the production of chiral styrene oxide.

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Fabrication of Meso/Macroporous Carbon Monolith and its Application as a Support for Adsorptive Separation of D-Amino Acid from Racemates

  • Park, Da-Min;Jeon, Sang Kwon;Yang, Jin Yong;Choi, Sung Dae;Kim, Geon Joong
    • Bulletin of the Korean Chemical Society
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    • v.35 no.6
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    • pp.1720-1726
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    • 2014
  • (S)-Alanine Racemase Chiral Analogue ((S)-ARCA) was used as an efficient adsorbent for the selective separation of D-amino acids (D-AAs), which are industrially important as chiral building blocks for the synthesis of pharmaceutical intermediates. The organic phase, containing (S)-ARCA adsorbent and phase transfer reagents, such as ionic liquid type molecules (Tetraphenylphosphonium chloride (TPPC), Octyltriphenylphosponium bromide (OTPPBr)), were coated on the surfaces of mesoporous carbon supports. For the immobilization of chiral adsorbents, meso/macroporous monolithic carbon (MMC), having bimodal pore structures with high surface areas and pore volumes, were fabricated. The separation of chiral AAs by adsorption onto the heterogeneous (S)-ARCA was performed using a continuous flow type packed bed reactor system. The effects of loading amount of ARCA on the support, the molar ratio of AA to ARCA, flow rates, and the type of phase transfer reagent (PTR) on the isolation yields and the optical purity of product D-AAs were investigated. D-AAs were selectively combined to (S)-ARCA through imine formation reaction in an aqueous basic solution of racemic D/L-AA. The (S)-ARCA coated MMC support showed a high selectivity, up to 95 ee%, for the separation of D-type phenylalanine, serine and tryptophan from racemic mixtures. The ionic liquids TPPC and OTPPBr exhibited superior properties to those of the ionic surfactant Cetyltrimethyl ammonium bromide (CTAB), as a PTR, showing constant optical purities of 95 ee%, with high isolation yields for five repeated reuses. The unique separation properties in this heterogeneous adsorption system should provide for an expansion of the applications of porous materials for commercial processes.

Synthesis of Optically pure Epichlorohydrine using Dimeric Chiral Salen Catalyst Containing BF3 (BF3 함유 이분자형 키랄 살렌 촉매에 의한 고광학순도의 에피클로로히드린 합성)

  • Lee, Kwang-Yeon;Rahul, B. Kawthekar;Kim, Geon-Joong
    • Applied Chemistry for Engineering
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    • v.18 no.4
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    • pp.330-336
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    • 2007
  • In this study, new dinuclear chiral Co (salen) complexes bearing $BF_3$ have been synthesized and their properties as the asymmetric catalyst have been examined. The NMR, UV and ESCA analyses were performed to determine the structure of synthesized catalysts. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99 %ee). The dimeric structured chiral salen showed remakablely enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues, and in addition no racemization happened during the separation of product epoxides. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

Efficient Synthesis of 2-Substituted 2,3-Dihydro-4-quinolones as Potential Intermediates for 2-Substituted 1,2,3,4-Tetrahydro-4-quinolone Antitumor Agents

  • Choi Sun;Jung Keumn-Yeo;Ryu Jae-Sang
    • Archives of Pharmacal Research
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    • v.29 no.5
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    • pp.369-374
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    • 2006
  • An efficient method for the synthesis of optically active 2-substituted 2,3-dihydro-4-quinolones has been developed. The key features include the introduction of a chiral side chain and the construction of quinolone skeleton by Mitsunobu alkylation and hydroarylation, respectively.

Production of (R)-Ethyl-4-Chloro-3-Hydroxybutanoate Using Saccharomyces cerevisiae YOL151W Reductase Immobilized onto Magnetic Microparticles

  • Choo, Jin Woo;Kim, Hyung Kwoun
    • Journal of Microbiology and Biotechnology
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    • v.25 no.11
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    • pp.1810-1818
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    • 2015
  • For the synthesis of various pharmaceuticals, chiral alcohols are useful intermediates. Among them, (R)-ethyl-4-chloro-3-hydroxybutanoate ((R)-ECHB) is an important building block for the synthesis of L-carnitine. (R)-ECHB is produced from ethyl-4-chloro-3-oxobutanoate (ECOB) by a reductase-mediated, enantioselective reduction reaction. The Saccharomyces cerevisiae YOL151W reductase that is expressed in Escherichia coli cells exhibited an enantioselective reduction reaction toward ECOB. By virtue of the C-terminal His-tag, the YOL151W reductase was purified from the cell-free extract using Ni2+-NTA column chromatography and immobilized onto Ni2+-magnetic microparticles. The physical properties of the immobilized reductase (Imm-Red) were measured using electron microscopy, a magnetic property measurement system, and a zeta potential system; the average size of the particles was approximately 1 μm and the saturated magnetic value was 31.76 emu/g. A neodymium magnet was used to recover the immobilized enzyme within 2 min. The Imm-Red showed an optimum temperature at 45℃ and an optimum pH at 6.0. In addition, Bacillus megaterium glucose dehydrogenase (GDH) was produced in the E. coli cells and was used in the coupling reaction to regenerate the NADPH cofactor. The reduction/oxidation coupling reaction composed of the Imm-Red and GDH converted 20 mM ECOB exclusively into (R)-ECHB with an e.e.p value of 98%.