• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.199-199
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• 2011

The addition of a carbanion to ${\yen}{\acute{a}}{\yen}{\hat{a}}$-unsaturated carbonyl compounds is of importance in the C-C bond formation reactions for modern pharmaceuticals and organic synthesis. Recently, heterogeneous asymmetric catalysis became more attractive area of research because of the easy recovery and separation of the catalyst from the reaction system. Most of synthetic methods for heterogeneous catalysts were grafting or immobilization of homogeneous catalyst onto the solid supports. Trans-1,2-Diaminocyclohexane(DACH) and L-proline ligands have been enormously used as chiral ligands in several catalytic transformation under homogenous conditions. Our group prepared l-proline functionalized mesoporous silica was synthesized under acidic condition using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template (EO20PO70EO20, Pluronic P-123, BASF). Furthermore, we successfully directly synthesized trans-1,2 diaminocyclohexane functionalized mesoporous silica by using microwave method. The direct functionalization of chiral ligand into the framework of mesoporous materials is expected to be useful for the heterogeneous asymmetric catalysis. So, we adopt the direct synthesis of chiral ligand functionalized mesoporous silica by using thermal and microwave irradiation. Then, chiral ligand functionalized mesoporous silicas were applied to enantioselective asymmetric catalytic reactions.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1590-1600
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• 2014

Cinchona-based bifunctional catalysts have been extensively employed in the field of organocatalysis due to the incorporation of both hydrogen-bonding acceptors (quinuclidine) and hydrogen-bonding donors (e.g., alcohol, amide, (thio)urea and squaramide) in the molecule, which can simultaneously activate nucleophiles and electrophiles, respectively. Among them, cinchona-derived (thio)urea and squaramide catalysts have shown remarkable application potential by using their bifurcated hydrogen bonding donors in activating electrophilic carbonyls and imines. However, due to their bifunctional nature, they tend to aggregate via inter- and intramolecular acid-base interactions under certain conditions, which can lead to a decrease in the enantioselectivity of the reaction. To overcome this self-aggregation problem of bifunctional organocatalysts, we have successfully developed a series of sulfonamide-based organocatalysts, which do not aggregate under conventional reaction conditions. Herein, we summarize the recent applications of our cinchona-derived sulfonamide organocatalysts in highly enantioselective methanolytic desymmetrization and decarboxylative aldol reactions. Immobilization of sulfonamide-based catalysts onto solid supports allowed for unprecedented practical applications in the synthesis of valuable bioactive synthons with excellent enantioselectivities.

• Korean Membrane Journal
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• 제1권1호
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• pp.38-42
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• 1999

Membrane technology can be applied in two ways to produce pure enantiomers. In one case a membrane separation process can be cmbined with an enantiospecific reaction to obtain so-called 'en-antiospecific membrane reacto' These systems are useful to carry out asymmetric synthesis or kinetic resolution and simulatneously separate the produced enantiomer. As for general membrane reactors the result is a more compact system with a higher conversion: in fact removal of a product drives equilibrium-limited reactions towards completion. The other way to apply membrane technology to chiral production is the use of intrinsically enantioselective membranes that are able to distinguish between two isomers favouring preferential transport of only one isomer in absence of reaction. In this paper the current development of chiral membrane processes will be discussed.

• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.31-34
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• 1999

Membrane technology can be applied in two ways to produce pure enantiomers. In one case, a membrane separation process can be combined with an enantiospecific reaction to obtain so-called 'enantiospecific membrane reactor'. These systems are useful to carry out asymmetric synthesis or kinetic resolution and simultaneously separate the produced enantiomer. As for general membrane reactors, the result is a were compact system with a higher conversion; in fact, removal of a product drives equilibrium-limited reactions towards completion. The other way to apply membrane technology to chiral production is the use of intrinsically enantioselective membranes that are able to distinguish between two isomers favouring preperential transport of only one isomer in absence of reaction. In This paper, the current development of chiral membrane processes will be discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.198-198
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• 2011

Organocatalysis is a relatively new and popular area within the field of chiral molecule synthesis. It is one of the main branches of enantioselective synthesis with enzymatic and organometallic catalysis. In recent years, immense high quality studies on catalysis by chiral secondary amines were reported. These progresses instantly led to different organocatalytic activation concepts, so thousands of researchers from academia and the chemical industry are currently involved in this field and new ideas, new approaches, and creative thinking have been rapidly emerged. Organocatalysts, some of which are natural products, appear to solve the problems of metal catalysts. Compared to metal-based catalysis, they have many advantages including savings in cost, time, and energy, easier experimental procedure, and reduction of chemical waste. These benefits originate from the following factors. First, organocatalysts are generally stable in oxygen and water in the atmosphere, there is no need for special equipments or experimental techniques to operate under anhydrous or anaerobic conditions. Second, organic reagents are naturally available from biological materials as single enantiomers that they are easy and cheap to prepare which makes them suitable for small-scale to industrial-scale reactions. Third, in terms of safety related catalysis, small organic molecules are non-toxic and environmentally friendly. Therefore, the purpose of this research is to develop novel synthetic methods and design for various organocatalyst. Furthermore, it is expected that these organocatalysts can be applied to a variety of asymmetric reactions and study the transition state of these reactions using a metal sulface. Here, we report the synthesis of unprecedented organocatalysts, proline and pyrrolidine derivatives with quaternary carbon center.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.769-776
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• 2008

키랄성 말단기의 에폭사이드는 키랄중간체나 여러 출발물질로서 다양하게 이용되기 때문에 그 선택적인 합성법은 매우 유용하다. 본 연구에서는 염화코발트(II), 염화철(III) 및 질산아연(II)을 각각 함유한 키랄 코발트 살렌 촉매를 새로이 합성하고 그 특성을 평가하였다. 질량분석과 EXAF분석을 통하여 형성된 촉매 착체의 구조를 평가하였다. 합성한 촉매는 방향족 에폭사이드인 스타이렌 옥사이드와 페닐글리시딜 에테르의 속도차에 의한 비대칭 가수분해적 고리열림반응과 글리시틸부틸레이트의 합성반응에 적용하여 그 활성과 선택성을 조사하였다. 합성이 용이한 전이금속염함유 살렌착체 촉매는 물을 친핵체로 하는 라세믹 에폭사이드의 고리 열림을 통하여 99%ee 이상을 나타낼 정도의 매우 높은 광학선택성을 보였으며, 적은 양의 첨가로도 높은 활성을 보였다. 본 연구에서 적용한 촉매씨스템은 키랄 에폭사이드 및 1,2-디올 중간체의 제조에 매우 효과적이었다.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.515-522
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• 2005

Enzyme-metal combo catalysis is described as a useful methodology for the synthesis of optically active compounds. The key point of the method is the use of enzyme and metal in combination as the catalysts for the complete transformation of racemic substrates to single enantiomeric products through dynamic kinetic resolution (DKR). In this approach, enzyme acts as an enantioselective resolving catalyst and metal does as a racemizing catalyst for the efficient DKR. Three kinds of enzyme-metal combinations - lipase-ruthenium, subtilisin-ruthenium, and lipase-palladium –have been developed as the catalysts for the DKRs of racemic alcohols, esters, and amines. The scope of the combination catalysts can be extended to the asymmetric transformations of ketones, enol acetates, and ketoximes via the DKRs. In most cases studied, enzyme-metal combo catalysis provided enantiomerically-enriched products in high yields.

• 대한화학회지
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• 제39권10호
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• pp.812-817
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• 1995

방향족 니트로 화합물을 선택적으로 환원시켜 치환체가 있는 아닐린을 생성하는 것은 산업적 측면에서 볼때 의미있는 반응이다. 본 연구에서는 Bakers' Yeast-NaOH의 환원작용에 의하여 m-Bromonitrobenzene 의 니트로기가 선택적으로 빠르게 환원되어 치환체가 있는 아닐린 화합물이 형성됨을 확인하였고 특히 Nitrosobenzene이 수산화 나트륨이 없는 조건에서 Bakers' Yeast만의 작용에 의해 환원되어 아닐린을 생성함을 확인하였다. 또한 Nitrosobenzene의 Bakers' Yeast 환원에 미치는 저해제들의 효과 및 온도, pH의 영향 등을 조사하였다.

• Applied Biological Chemistry
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• 제46권3호
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• pp.240-245
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• 2003

여러종류의 리파제를 이용하여 $({\pm})-2-(4-chlorophenyl)-2-cyano-2-phenyl-1-hexanol(2)$와 이의 acetate ester(3)을 광학분할하고 분할된 화합물들을 이용하여 (R) 및 (S)-systhane을 합성하였다. 현재 상품으로 팔리고 있는 $({\pm})-systhane$과 (R) 및 (S)-systhane의 항균활성을 조사하여 2 ppm의 농도에서 모든 systhane이 밑붉은녹병과 보리흰가루병에 대하여 92%의 항균활성을 보여주었으나 (R) 및 (S)-systhane이 $({\pm})-systhtne$보다 더 좋은 항균팔성을 보여주지는 않았다.

• 생명과학회지
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• 제27권11호
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• pp.1381-1392
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• 2017

본 총설에서는 유기용매 내성 리파아제와 그들의 산업, 생물공학 및 환경에서의 잠재적인 영향에 대하여 서술하고자 한다. 유기용매 내성 리파아제는 유기용매 내성 세균에서 처음 보고되었으나, 많은 유기용매 내성 리파아제들이 유기용매 내성 세균 뿐만 아니라 잘 알려진 Bacillus, Pseudomonas, Streptomyce 그리고 Aspergillus sp. 균주 같은 유기용매 비내성 세균 그리고 균류 균주들에서도 보고되고 있다. 이들 리파아제들은 유기용매에서 쉽게 불활성화되지 않기 때문에 유기용매에 의한 효소 불활성화를 방지하기 위하여 별도로 그들을 고정화할 필요가 없다. 그러므로 다수의 생물공정 및 생물변환 공정에서 이용될 수 있는 잠재적인 유용성을 가지고 있다. 이들 유기용매 내성 리파아제들을 사용하면, 유기용매계 또는 비수계에서 다수의 불용성 기질들의 용해도가 증가하며, 수계에서는 불가능한 다양한 화학반응들이 일어나고, 가수분해 대신에 합성반응이 일어나며, 물에 의한 부반응이 억제되며, 화학, 위치 그리고 엔안티오(대칭) 선택성(chemo, regio and enantioselective) 변환반응의 가능성이 증가한다. 나아가 고정화하지 않아도 효소의 회수와 재이용이 가능하며, 유기용매계와 비수계에서는 리파아제의 안정성이 더 좋아지는 경향도 있다. 그러므로 유기용매 내성 리파아제는 유기용매계와 비수계를 이용한 생물변환공정에 생물촉매로써 그들을 이용가능하다는 점에서 많은 주목을 받고 있다.