Atom-economic and stereoselective catalytic synthesis of fully substituted enol esters/carbonates of amides in acyclic systems enabled by boron Lewis acid catalysis

Carboacyloxylation of internal alkynes is emerging as a powerful and straightforward strategy for enol ester synthesis. However, the reported examples come with limitations, including the utilization of noble metal catalysts, the control of regio- and Z / E selectivity, and an application in the syn...

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Published in:Chemical science (Cambridge) 2023-05, Vol.14 (21), p.568-5618
Main Authors: Xiao, Yuanjiu, Tang, Lei, Xu, Tong-Tong, Sheng, Jiang-Yi-Hui, Zhou, Zhongyan, Yue, Lei, Wang, Guoqiang, Oestreich, Martin, Feng, Jian-Jun
Format: Article
Language:English
Subjects:
Alkynes
Amides
Boron
Carbonates
Catalysis
Chemical synthesis
Chemistry
Esters
Lewis acid
Noble metals
Reaction mechanisms
Stereochemistry
Stereoselectivity
Substitutes
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Summary:Carboacyloxylation of internal alkynes is emerging as a powerful and straightforward strategy for enol ester synthesis. However, the reported examples come with limitations, including the utilization of noble metal catalysts, the control of regio- and Z / E selectivity, and an application in the synthesis of enol carbonates. Herein, a boron Lewis acid-catalyzed intermolecular carboacyloxylation of ynamides with esters to access fully substituted acyclic enol esters in high yield with generally high Z / E selectivity (up to >96 : 4) is reported. Most importantly, readily available allylic carbonates are also compatible with this difunctionalization reaction, representing an atom-economic, catalytic and stereoselective protocol for the construction of acyclic β,β-disubstituted enol carbonates of amides for the first time. The application of the carboacyloxylation products to decarboxylative allylations provided a ready access to enantioenriched α-quaternary amides. Moreover, experimental studies and theoretical calculations were performed to illustrate the reaction mechanism and rationalize the stereochemistry. A boron Lewis acid catalyzes trans-carboacyloxylations of ynamides with esters to afford fully substituted acyclic enol esters/carbonates in high yields and with excellent stereocontrol.
ISSN:2041-6520
2041-6539
DOI:10.1039/d3sc01394d