Enantioselective Hydrogenation of Endocyclic Enones: the Solution to a Historical Problem

• Published in: Chinese journal of chemistry Vol. 39; no. 4; pp. 933 - 936
• Main Authors: Lang, Qiwei, Yang, Huaxin, Gu, Guoxian, Feng, Qiang, Wen, Jialin, Zhang, Xumu
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag GmbH & Co. KGaA 01-04-2021; Wiley Subscription Services, Inc
• Subjects: Asymmetric catalysis; Catalysis; Citral; Citral reduction; Citronellal; Cyclic enone; Enantiomers; Hydrogenation; Rhodium
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.202000617

Main observation and conclusion
The enantioselective hydrogenation of endocyclic enones has been a historical problem for homogeneous catalysis. We herein report an efficient method to reduce endocyclic enones with molecular hydrogen. Catalyzed by a rhodium/Zhaophos complex, a variety of enones with five‐, six‐ or seven‐member ring were hydrogenated with high enantioselectivity (92%—99% ee). Excellent chemo‐ and enantioselectivity demonstrated this method was successfully applied in the enantioselective hydrogenation of citral to produce enantio‐enriched citronellal.
The enantioselective hydrogenation of cyclic enones has been a historical problem for homogeneous catalysis. We herein report an efficient method to reduce cyclic enones with molecular hydrogen. Catalyzed by a rhodium/Zhaophos complex, variety of enones with five‐, six‐ or seven‐member ring were hydrogenated with high enantioselectivity (92%—99% ee). Excellent chemo‐ and enantioselectivity demonstrated this method was successfully applied in the enantioselective hydrogenation of citral to produce enantio‐enriched citronellal.