Hydrolytic enantioselective protonation of dienyl esters and a β-diketone catalyzed by phase-transfer catalysts are described. The latter reaction is the first example of an enantio-convergent retro-Claisen condensation. Corresponding various optically active α,β-unsaturated ketones having tertiary chiral centers adjacent to carbonyl groups were obtained in good to excellent yields and enantiomeric ratios (83-99%, up to 97.5:2.5 er).
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/ol3027363 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Synthesis of Novel Pseudo-Enantiomeric Phase-Transfer Catalysts from Cinchona Alkaloids and Application to the Hydrolytic Dynamic Kinetic Resolution of Racemic 3-Phenyl-2-oxetanone.
Chem Pharm Bull (Tokyo)
October 2024
Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts.
Naturally occurring Cinchona alkaloids such as quinidine (QD)/cinchonine (CN) and their diastereomers, quinine (QN)/cinchonidine (CD), have been recognized as pseudo-enantiomeric pairs. Utilizing these pseudo-enantiomeric alkaloids as chiral resources provides complementary enantioselectivity in many asymmetric reactions. During the screening of Cinchona alkaloid phase-transfer catalysts (PTCs) in the hydrolytic dynamic kinetic resolution of racemic 3-phenyl-2-oxetanone (1) to tropic acid (2), we found that the introduction of a 4-trifluoromethylphenyl group at the vinyl terminus of BnQN significantly reduced the enantioselectivity to 41% enantiomeric excess (ee).
View Article and Find Full Text PDFImproving Hydrolytic Activity and Enantioselectivity of Epoxide Hydrolase from by Directed Evolution.
Molecules
October 2024
College of Life Sciences, Sichuan Normal University, Chenglong Avenue, Chengdu 610101, China.
Article Synopsis
- * This study created a mutation library using error-prone PCR and DNA shuffling, screening over 15,000 mutants, and eventually identifying 38 mutants with enhanced enzyme activity or enantioselectivity.
- * After extensive testing, one mutant, F3, showed over 95% increased activity compared to the wild type, suggesting its potential as an industrial biocatalyst, supported by molecular docking results.
Hydrolytic dynamic kinetic resolution of racemic 3-phenyl-2-oxetanone to chiral tropic acid.
RSC Adv
February 2024
Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts 97-1 Minamihokotate, Kodo, Kyotanabe Kyoto 610-0395 Japan
Tropic acid was synthesized in a good yield and with high enantioselectivity (81% ee) under non-biphasic conditions the novel hydrolytic dynamic kinetic resolution of racemic 3-phenyl-2-oxetanone (tropic acid β-lactone) in the presence of a chiral quaternary ammonium phase-transfer catalyst and strongly basic anion exchange resin as the hydroxide ion donor.
View Article and Find Full Text PDFRhodium-Catalyzed Hydrolytic Cleavage of the Silicon-Carbon Bond of Silacyclobutanes to Access Silanols.
Org Lett
October 2023
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education and Key Laboratory of Organosilicon Material Technology of Zhejiang Province, College of Material Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, P. R. China.
Herein, we report the first rhodium-catalyzed hydrolytic cleavage of the silicon-carbon bond in silacyclobutanes using water as the reactant. A series of silacyclobutanes could be employed in this reaction in the presence of the Rh/BINAP complex, resulting in the corresponding silanols in good yields. Additionally, a chiral 1,1,4,4-tetraaryl-2,3--isopropylidene-l-threitol-derived phosphoramidite ligand could be used in this reaction to yield Si-stereogenic silanol with promising enantioselectivity.
View Article and Find Full Text PDFEasy and Versatile Technique for the Preparation of Stable and Active Lipase-Based CLEA-like Copolymers by Using Two Homofunctional Cross-Linking Agents: Application to the Preparation of Enantiopure Ibuprofen.
Int J Mol Sci
September 2023
Department of Chemistry in Pharmaceutical Sciences, Pharmacy Faculty, Complutense University of Madrid (UCM), Ciudad Universitaria, Plaza de Ramon y Cajal, s/n., 28040 Madrid, Spain.
An easy and versatile method was designed and applied successfully to obtain access to lipase-based cross-linked-enzyme aggregate-like copolymers (CLEA-LCs) using one-pot, consecutive cross-linking steps using two types of homobifunctional cross-linkers (glutaraldehyde and putrescine), mediated with amine activation through pH alteration (pH jump) as a key step in the process. Six lipases were utilised in order to assess the effectiveness of the technique, in terms of immobilization yields, hydrolytic activities, thermal stability and application in kinetic resolution. A good retention of catalytic properties was found for all cases, together with an important thermal and storage stability improvement.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!