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Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Copper and Silver Catalysis in the (3 + 2) Cycloaddition of Neutral Three-Atom Components with Terminal Alkynes
Dominic Campeau1, Alice Pommainville1, Mila Gorodnichy1
1Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa K1N 6N5, Canada.
Copper and silver catalysts significantly enhance intramolecular cycloadditions of alkynes with alkynyl sulfides. This discovery expands the synthetic utility of these reactions, previously limited by thermal conditions.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Chemistry
Background:
- The copper-catalyzed azide-alkyne coupling (CuAAC) revolutionized 1,3-dipolar cycloadditions in synthetic chemistry.
- Coinage metal acetylides accelerate cycloaddition reactions, broadening their scope with terminal alkynes.
Purpose of the Study:
- To investigate copper and silver catalysts for intramolecular (3 + 2) cycloaddition of terminal alkynes with neutral three-atom components (TACs).
- To explore catalytic conditions that overcome limitations of thermally promoted cycloadditions.
Main Methods:
- Reaction optimization studies.
- Experimental investigations.
- Density Functional Theory (DFT) mechanistic studies.
- Utilized alkynyl sulfides as neutral TACs.
Main Results:
- Copper and silver catalysts induce significant rate enhancements in the intramolecular cycloaddition.
- A reaction pathway involving a proton-coupled cyclometallation key step was proposed.
- Developed catalytic conditions overcome previous scope limitations.
Conclusions:
- Catalytic intramolecular (3 + 2) cycloaddition of neutral TACs is feasible with copper and silver.
- The developed methods expand the synthetic and applicative potential of these cycloadditions.
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