Divergent Geminal Alkynylation-Allylation and Acylation-Allylation of Carbenes: Evolution and Roles of Two Transition-Metal Catalysts
Hongda Chen, Wenhan Yang, Jinyu Zhang, Bin Lu, Xiaoming Wang*
*Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling
Road, Shanghai 200032, China, Email: xiaoming
sioc.ac.cn
H. Chen, W. Yang, J. Zhang, B. Lu, X. Wang, J. Am. Chem. Soc., 2024, 146, 4727-4740.
DOI: 10.1021/jacs.3c12162
see article for more reactions
Abstract
A three-component reaction of a terminal alkyne, a diazo ester, and an allylic carbonate provides 1,5-enynes with an all-carbon quaternary center via cooperative Cu/Rh catalysis with Xantphos as the ligand. In reactions using propargylic alcohols, a Meyer-Schuster rearrangement results in an unprecedented acylation-allylation of carbenes.
see article for more examples
proposed mechanism
Details
The article discusses a novel three-component reaction involving terminal alkynes, diazo esters, and allylic carbonates, catalyzed by a cooperative Cu/Rh system with Xantphos as the ligand. This method efficiently produces 1,5-enynes with all-carbon quaternary centers, which are valuable for synthesizing complex cyclic molecules. The study highlights the importance of understanding the roles and evolution of the two transition-metal catalysts in dual catalysis. Mechanistic studies suggest that Cu(I) species aggregate into Cu clusters and nanoparticles (NPs), while Rh(II)2 dissociates into mono-Rh species. The Cu NPs are responsible for the alkynylation of carbenes, working in tandem with Rh-catalyzed allylic alkylation. The method shows excellent functional group tolerance and can be applied to various substrates, including propargylic alcohols, leading to acylation−allylation products via a Meyer−Schuster rearrangement. The research demonstrates the potential of this protocol for constructing complex structures from readily available starting materials, offering a powerful strategy for reaction development in transition-metal-catalyzed chemistry.
Key Words
alkynylation, allylation, multicomponent reactions
ID: J48-Y2024
