Triple cross-electrophile coupling enabled by palladium/norbornene cooperative catalysis
Jinxiang Ye1, Lifang Qi1, Shuang Deng1
1Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Engineering Research Center of Organosilicon Compounds and Materials (Ministry of Education), Hubei Key Lab on Organic and Polymeric OptoElectronic Materials, College of Chemistry and Molecular Sciences, The Institute for Advanced Studies, and TaiKang Center for Life and Medical Sciences, Wuhan University, 430072 Wuhan, China.
This study introduces a novel triple cross-electrophile coupling (XEC) reaction using palladium catalysis. This method efficiently synthesizes diverse tetrasubstituted allenes, including challenging asymmetric variants.
Area of Science:
- Synthetic Organic Chemistry
- Catalysis
- Organometallic Chemistry
Background:
- Cross-electrophile coupling (XEC) is crucial for C-C bond formation.
- Reactions involving three distinct electrophiles are underdeveloped.
- Palladium catalysis offers versatile synthetic routes.
Purpose of the Study:
- To develop a novel formal triple XEC reaction.
- To synthesize diverse tetrasubstituted allenes.
- To achieve asymmetric synthesis of allenes with axial chirality.
Main Methods:
- Palladium/norbornene cooperative catalysis.
- Utilizing aryl iodides, alkyl/aryl bromides, and propargyl esters as electrophiles.
- Employing chiral norbornene for asymmetric catalysis.
Main Results:
- Successful synthesis of diverse tetrasubstituted allenes via triple XEC.
- Realization of asymmetric formal triple XEC using sterically hindered aryl bromides.
- Demonstration of a key role for propargyl esters in reaction termination.
Conclusions:
- The developed triple XEC is a powerful method for constructing tetrasubstituted allenes.
- Asymmetric catalysis provides access to valuable axially chiral biaryl-containing allenes.
- Propargyl esters are critical for a thermodynamically favored reaction pathway.
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