Karmakar, Ananta and Maji, Tapan and Wittmann, Sebastian and Reiser, Oliver (2011) L-Proline/CoCl2-Catalyzed Highly Diastereo- and Enantioselective Direct Aldol Reactions. CHEMISTRY-A EUROPEAN JOURNAL, 17 (39). pp. 11024-11029. ISSN 0947-6539,
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The CoCl2/L-proline (1:2) system was found to be an excellent catalyst for direct aldol reactions. Excellent yields (up to 93%) and a significant improvement in diastereoselectivity (anti/syn up to 45:1) as well as enantioselectivity (up to more than 99% ee) compared with using proline as the sole catalyst were observed. This catalyst system was successfully applied to both cyclic and acyclic ketones in combination with aromatic and aliphatic aldehydes. In situ chelation of CoCl2 and proline (1:2) is proposed to promote the reaction through a six-membered Zimmermann-Traxler type transition state involving the positioning of proline-enamine and the aldehyde through chelation to Co-II.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CATALYTIC ASYMMETRIC ALDOL; L-PROLINE; AQUEOUS-MEDIA; ZINC-PROLINE; AMINO-ACID; MICHAEL ADDITION; INCREASED REACTIVITY; VERSATILE CATALYSTS; ORGANIC-MOLECULES; ENAMINE CATALYSIS; aldol reaction; aldehydes; cobalt; diastereoselectivity; ketones |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Oliver Reiser |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 02 Jun 2020 08:17 |
| Last Modified: | 02 Jun 2020 08:17 |
| URI: | https://pred.uni-regensburg.de/id/eprint/20222 |
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