Ru-Catalyzed Hydroboration of Ynones Leads to a Nontraditional Mode of Reactivity
Qiang Feng, Shijia Li, Zhiyang Li, Qiaolin Yan, Xiangfeng Lin, Lijuan Song*, Xinhao Zhang*, Yun-Dong Wu* and Jianwei Sun*
*HIT, Shenzhen 518055; PKU Grad School, Shenzhen 518055; Shenzhen Res. Institute, Shenzhen 518057, China,
Email: songlijuanhit.edu.cn, zhangxh
pkusz.edu.cn,
wuyd
pkusz.edu.cn, sunjw
ust.hk
Q. Feng, S. Li, Z. Li, Q. Yan, X. Lin, L. Song, X. Zhang, Y.-D. Wu, J. Sun, J. Am. Chem. Soc., 2022, 144, 14846-14855.
DOI: 10.1021/jacs.2c06024
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Abstract
A ruthenium-catalyzed hydroboration of ynones provides vinyl α-hydroxylboronates under mild conditions. This reaction features high efficiency, a broad scope, and complete chemo-, regio-, and stereoselectivity, in spite of many possible competitive pathways.
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proposed reaction pathway
Details
The article discusses a novel Ru-catalyzed hydroboration reaction of ynones, leading to the formation of vinyl α-hydroxyboronates, which are structurally unique and synthetically valuable products. This reaction is characterized by high efficiency, broad scope, and complete chemo-, regio-, and stereoselectivity. The process involves a two-step mechanism: an initial rate-determining conjugate addition of hydroborane to form a boryl allenolate intermediate, followed by a fast second hydroboration of the enolate motif. The study includes detailed experimental and theoretical investigations, including DFT calculations, to understand the reaction pathway and selectivity. The optimized conditions for the reaction involve using [Cp*Ru(MeCN)3]PF6 as the catalyst in DCE solvent. The reaction tolerates a wide range of functional groups and steric hindrance, producing single product isomers with high selectivity. The vinyl α-hydroxyboronate products can be further transformed into other useful synthetic building blocks. The study provides insights into the unusual reactivity and intrinsic origin of selectivity in this hydroboration process, highlighting the potential of this method in organic synthesis.
Key Words
allylboronates, α-hydroxyboronates, pinacolborane
ID: J48-Y2022