Cobalt‐Catalyzed Chemo‐ and Enantioselective Hydrogenation of Conjugated Enynes

• Published in: Angewandte Chemie International Edition Vol. 60; no. 31; pp. 16989 - 16993
• Main Authors: Hu, Yanhua, Zhang, Zhenfeng, Liu, Yangang, Zhang, Wanbin
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 26.07.2021; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: asymmetric hydrogenation; Chemistry; Chemistry, Multidisciplinary; chemoselectivity; Cobalt; Enantiomers; enynes; Hydrogenation; Physical Sciences; propargylamines; Science & Technology; Substrates; Zinc; propargylamines; chemoselectivity; ALKENES; cobalt; enynes; asymmetric hydrogenation
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202106566

Asymmetric hydrogenation is one of the most powerful methods for the preparation of single enantiomer compounds. However, the chemo‐ and enantioselective hydrogenation of the relatively inert unsaturated group in substrates possessing multiple unsaturated bonds remains a challenge. We herein report a protocol for the highly chemo‐ and enantioselective hydrogenation of conjugated enynes while keeping the alkynyl bond intact. Mechanism studies indicate that the accompanying Zn2+ generated from zinc reduction of the CoII complex plays a critical role to initiate a plausible CoI/CoIII catalytic cycle. This approach allows for the highly efficient generation of chiral propargylamines (up to 99.9 % ee and 2000 S/C) and further useful chemical transformations. The Co‐catalyzed chemo‐ and enantioselective hydrogenation of conjugated enynes has been realized for the synthesis of chiral propargylamines with high efficiency (up to 99.9 % ee and TON=2000). Mechanism studies indicate that the accompanying Zn2+ generated from zinc reduction of the CoII complex exhibits an activating effect for the initiation of the plausible CoI/CoIII catalytic cycle.