Access to Chiral β-Boryl δ-Lactones via NHC-Catalyzed [4 + 2] Annulation (original) (raw)
Zhipeng Li, Jingyang Zhang, Jian Wang*
*School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, P. R. China, Email: wangjian2012
tsinghua.edu.cn
Z. Li, J. Zhang, J. Wang, Org. Lett., 2024, 26, 1965-1969.
DOI: 10.1021/acs.orglett.4c00426
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Abstract
A carbene-catalyzed [4 + 2] annulation of activated esters and β-borate enones provides enantioenriched organoborones with two consecutive stereogenic centers. This organocatalytic protocol greatly enriches the structural diversity of chiral organoboron compounds.
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proposed transition state
Details
The document discusses a study on the carbene-catalyzed [4 + 2] annulation of activated esters and β-borate enones, which provides an efficient method to synthesize enantioenriched organoborones with two consecutive stereogenic centers. This new organocatalytic approach generates chiral β-C−B bonds and enhances the structural diversity of chiral organoboron compounds. The study highlights the broad application of organoboron molecules in medicinal chemistry and materials science, emphasizing their importance in precise organic synthesis. The research team optimized reaction conditions, achieving high yields and excellent diastereo- and enantioselectivities using various NHC precatalysts and bases. The optimal conditions involved using NHC precatalyst E and PhCO2Na in THF, resulting in an 88% yield with >20:1 dr and 98% ee. The substrate scope was explored, demonstrating the method's efficiency with different esters and enones. A proposed mechanism suggests the reaction proceeds via an endo-Diels−Alder cycloaddition manner. The study's findings contribute to the development of new synthetic strategies for constructing chiral β-boron compounds and furthering the application potential of organoboron molecules in various fields. The research was supported by the National Natural Science Foundation of China and other institutions.
Key Words
3,4-dihydropyran-2-ones, organocatalysis
ID: J54-Y2024