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Updated: May 29, 2026

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
L-Proline/CoCl2-catalyzed highly diastereo- and enantioselective direct aldol reactions
Ananta Karmakar1, Tapan Maji, Sebastian Wittmann
1Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
Abstract:
The CoCl(2)/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 CoCl(2) 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).
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