• 공업화학
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• 제25권5호
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• pp.437-446
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• 2014

비고리 알릴아민 화합물의 이중알코올화 반응은 아미노 다이올 구조를 도입할 수 있는 효율적인 합성법으로 아미노 다이올 구조를 포함하는 다양한 생리활성 천연물의 효율적인 합성에 적용될 수 있다. 본 리뷰에서는 기질 그 자체, 혹은 카이랄 리간드를 이용한 다양한 입체선택적 이중알코올화 반응들을 소개하고 이를 실제 천연물의 합성에 적용한 최근의 반응 결과들을 살펴보고자 한다.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.273-277
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• 2005

Dynamic resolution of $\alpha$-bromo tertiary acetamides in asymmetric nucleophilic substitution reaction is described. Intermolecular substitution of $\alpha$-bromo tertiary acetamides with dibenzylamine in the presence of TBAI and $Et_3N$ gave the dipeptide analogues 7-10 with high stereoselectivities up to 90 : 10 dr. Also, cyclic dipeptide analogues 20-29 were produced by the intramolecular nucleophilic cyclization of $\alpha$-bromo tertiary acetamides with low stereoselectivities in 84-42% yields.

• Bulletin of the Korean Chemical Society
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• 제12권5호
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• pp.565-569
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• 1991

Enantioselective synthesis of 1-substituted tetrahydroisoquinoline alkaloids (1) via asymmetric reduction of 1-substituted 3,4-dihydroisoquinolines (2) and the corresponding iminium salts (3) with the selected chiral hydride reagents, such as K glucoride (5), Itsuno's reagent (6), and Mosher's reagent (7) were examined. In these reactions, dihydroisoquinolines were not reduced by the hydride reagents, whereas the iminium salts were easily reduced under the same reaction conditions found in successful reduction of ketones. Thus, the reduction of 6,7-dimethoxy-3,4-dihydroisoquinolium iodide(3a) with 5, 6 and 7 provided the product 1a with 52.3 % ee, 18 % ee, and 66.4 % ee, respectively. For 1-benzyl derivatives (3b-3d), syntheses of 1b-1d with 0.7-6.2 % ee, 5.9-21 % ee, and 1.4-2.7 % ee were achieved with chiral reducing agents 5, 6 and 7, respectively. For 1-aryl derivatives, use of 5, 6 and 7 resulted in optical inductions in the range of 25.2-43 % ee, 13-21.1 % ee, and 6.3-16 % ee, respectively.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1049-1052
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• 2011

In this study, we demonstrated the asymmetric synthesis of L-tert-leucine from trimethylpyruvate using branched-chain aminotransferase (BCAT) from Escherichia coli in the presence of L-glutamate as an amino donor. Since BCAT was severely inhibited by 2-ketoglutarate, in order to overcome this here, we developed a BCAT/aspartate aminotransferase (AspAT) and BCAT/AspAT/pyruvate decarboxylase (PDC) coupling reaction. In the BCAT/AspAT/PDC coupling reaction, 89.2 mM L-tert-leucine (ee>99%) was asymmetrically synthesized from 100 mM trimethylpyruvate.

• 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.

• 공업화학
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• 제18권6호
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• pp.562-567
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• 2007

키랄성 에폭사이드는 키랄중간체나 여러 출발물질로서 다양하게 이용되기 때문에 입체선택적인 합성방법은 학술적으로나 산업적인 관점에서 대단히 흥미롭다. 본 연구에서는 염화탈륨(III) 및 염화철(III)을 함유한 고분자형의 키랄성 코발트 살렌 촉매를 새로이 합성하고 그 특성을 평가하였다. 합성한 촉매는 여러 종류의 라세믹 에폭사이드 유도체의 가수분해의 속도차에 의한 비대칭 고리열림반응과 페놀 친핵체에 한 에폭사이드 산소 고리 열림반응에 적용하여 그 활성과 선택성을 조사하였다. 합성이 용이한 고분자구조의 살렌착체 촉매는 물과 페놀류를 친핵체로 하는 라세믹 에폭사이드의 고리 열림을 통하여 98% ee 이상을 나타낼 정도의 매우 높은 광학선택성을 보였다. 본 연구에서 적용한 촉매시스템은 키랄 에폭사이드, 1,2-디올 중간체 및 아릴옥시알코올 유도체의 제조에 매우 효과적이었다

• 대한화학회지
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• 제59권3호
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• pp.205-208
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• 2015

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.699-700
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• 2014

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.475-481
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• 1998

Details of various equilibria involved in the reactions of oxaza- and thiazazincolidine catalysts, generated from either β-amino alcohol or β-amino thiol, with aldehyde were studied by colligative measurements. The results indicated that the coordination of diethylzinc prior to the coordination of aldehyde is essential for high enantioselectivity of the thiol catalyzed reaction. The probable origin of asymmetric nonlinearity is also presented.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.362.2-362.2
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• 2002

Antofine belongs to the Phenathroindolizidine group of alkaloids. This natural products exhibit interesting biological properties such as antitumour activity. and anti-inflammentory. Wittig reaction of phenathrenealdehyde with the phosponium salt provided the phenathreneazidealkene in good yield. Intramolecular 1.3-dipolar cycloaddition of the resulting azidealkent in refluxing benzene proceeded the imine. It was reduced with cyanoborohydride of Noyori's Asymmetric Hydrogenation. (omitted)