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Outcompeting hydrofunctionalization: Asymmetric remote substitution of alkynes
Yi-Xiao Shen1,2, Chao Ma2, Guo-Qiang Lin1
1State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China.
This study introduces a novel asymmetric remote substitution for alkynes using palladium/amine catalysis. The method achieves high selectivity, enabling new synthetic pathways for complex molecules.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Methodology
Background:
- Propargylic substitution is a fundamental reaction but typically requires a leaving group adjacent to the alkyne.
- Existing methods face limitations in scope and selectivity for remote functionalization.
Purpose of the Study:
- To develop the first asymmetric remote substitution of alkynes with a linear alkyl-linked remote leaving group.
- To achieve high regio-, geometry-, and enantioselectivity in the coupling of alkynes and aldehydes.
Main Methods:
- Synergistic palladium (Pd) and amine catalysis.
- Utilized modified diamine organocatalysts.
- Investigated reaction mechanisms including intermediate formation and Pd redox pathways.
Main Results:
- Successfully demonstrated asymmetric remote substitution of alkynes.
- Achieved high levels of regio-, geometry-, and enantioselectivity.
- Completely inhibited competing hydrofunctionalization reactions.
- Validated the protocol through scale-up tests and derivatizations.
Conclusions:
- The developed protocol offers a reliable and valuable new method for remote alkyne functionalization.
- The reaction proceeds via a 1,3-diene intermediate and a complex Pd redox cycle.
- This work expands the synthetic utility of alkynes in asymmetric synthesis.
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