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Byung Tae Cho;Cheol Kyu Han
- Bulletin of the Korean Chemical Society
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- v.12 no.5
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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.
https://doi.org/10.5012/bkcs.1991.12.5.565 인용 PDF

Lee, Kwang-Yeon;Kawthekar, Rahul B.;Kim, Geon-Joong
- Applied Chemistry for Engineering
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- v.17 no.6
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- pp.565-574
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- 2006
The trend towards the application of single enantiomers of chiral compounds is undoubtedly increasing. Among the various methods to obtain one single enantio-riched compound selectively, enantioselective catalysis is the most attractive method. Especially, it is important to increase the activity, selectivity and lifetime of usually expensive chiral catalysts with a minute quantity in the enantioselective synthesis. Immobilization of active homogeneous catalysts is a fashionable topic in asymmetric catalysis, providing the inherent advantage of easy separation and better handling properties. Many different ways have been investigated to improve the enantioselectivity of products and to recycle the catalysts. This review mainly focused on the present scope and limitations of different types of enantioselective heterogeneous catalysts.
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윤성준;이은열
- KSBB Journal
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- v.15 no.6
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- pp.630-634
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- 2000
Chiral epoxides are useful chiral synthons in organic synthesis, and various biological methods have been investigated for their production. In this work, the enantioselective resolution of racemic styrene oxide was investigated using Aspergillus niger sp. for the production of optically pure (S)-styrene oxide. The enantioselectivity and initial hydrolysis rates of the racemic substrate were highly dependent of the pH, temperature, and the volume ratio of cosolvent. Experimental sets of pH, temperature, and the volume ratio of cosolvent were investigated using a central composite experimental design, and reaction conditions were optimized by response surface analysis. The optimal conditions of pH, temperature, and the volume ratio of cosolvent were determined to be 7.78, $28.32^{\circ}C$, and 2.4%(v/v), respectively, and optically pure (S)-styrene oxide (>99% ee) was obtained at 35% yield using this microbial enantioselective hydrolysis reaction.
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Kim, Aejin;Sharma, Satyasheel;Kwak, Jong Hwan;Kim, In Su
- Bulletin of the Korean Chemical Society
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- v.34 no.1
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- pp.75-78
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- 2013
Asymmetric synthesis of (+)-trans-aerangis lactone was achieved from commercially available 1-hexanol or 1-hexanal in four steps via iridium-catalyzed diastereoselective and enantioselective carbonyl crotylation from the alcohol or aldehyde oxidation level, and ruthenium-catalyzed olefin metathesis.
https://doi.org/10.5012/bkcs.2013.34.1.75 인용 PDF KSCI