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- Title
Cobalt catalyzed practical hydroboration of terminal alkynes with time-dependent stereoselectivity.
- Authors
Wen, Jinglan; Huang, Yahao; Zhang, Yu; Grützmacher, Hansjörg; Hu, Peng
- Abstract
Stereodefined vinylboron compounds are important organic synthons. The synthesis of E−1-vinylboron compounds typically involves the addition of a B-H bond to terminal alkynes. The selective generation of the thermodynamically unfavorable Z-isomers remains challenging, necessitating improved methods. Here, such a proficient and cost-effective catalytic system is introduced, comprising a cobalt salt and a readily accessible air-stable CNC pincer ligand. This system enables the transformation of terminal alkynes, even in the presence of bulky substituents, with excellent Z-selectivity. High turnover numbers (>1,600) and turnover frequencies (>132,000 h−1) are achieved at room temperature, and the reaction can be scaled up to 30 mmol smoothly. Kinetic studies reveal a formal second-order dependence on cobalt concentration. Mechanistic investigations indicate that the alkynes exhibit a higher affinity for the catalyst than the alkene products, resulting in exceptional Z-selective performance. Furthermore, a rare time-dependent stereoselectivity is observed, allowing for quantitative conversion of Z-vinylboronate esters to the E-isomers. Stereodefined vinylboron compounds are important organic synthons, but the selective generation of the thermodynamically unfavorable Z-isomers remains challenging. Here, the authors develop a cobalt catalytic system, enabling the transformation of terminal alkynes with excellent Z-selectivity, even in the presence of bulky substituents.
- Subjects
ALKYNES; COBALT; HYDROBORATION; STEREOSELECTIVE reactions; TURNOVER frequency (Catalysis)
- Publication
Nature Communications, 2024, Vol 15, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-024-46550-y