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Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
Published on: November 29, 2018
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Regioselective Termination Reagents for Ring-Opening Alkyne Metathesis Polymerization.
Hyangsoo Jeong1, Stephen von Kugelgen1, Donatela Bellone1
1Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.
Journal of the American Chemical Society
|October 7, 2017
Summary
Molybdenum carbyne complexes undergo regioselective alkyne cross-metathesis with ynamides. This reaction enables controlled polymer synthesis, yielding telechelic polymers and amphiphilic block copolymers.
Area of Science:
- Organometallic Chemistry
- Polymer Chemistry
- Catalysis
Background:
- Alkyne metathesis is a powerful tool for carbon-carbon bond formation.
- Ring-Opening Alkyne Metathesis Polymerization (ROAMP) allows for the synthesis of polymers with unique architectures.
- Controlled polymer chain termination is crucial for creating functional polymers.
Purpose of the Study:
- To investigate the alkyne cross-metathesis of molybdenum carbyne complexes with functional ynamines and ynamides.
- To explore the use of ynamides for controlled chain termination in ROAMP.
- To synthesize telechelic polymers and amphiphilic block copolymers.
Main Methods:
- Molybdenum carbyne complex synthesis and characterization.
- Alkyne cross-metathesis reactions with ynamines and ynamides.
- Ring-Opening Alkyne Metathesis Polymerization (ROAMP) of a strained annulene.
- Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray crystallography for structural analysis.
Main Results:
- High regioselectivity (>98%) in alkyne cross-metathesis reactions.
- Selective cleavage and irreversible deactivation of propagating molybdenum species by ynamides.
- Successful synthesis of telechelic polymers via controlled chain termination.
- Access to amphiphilic block copolymers through sequential polymerization strategies.
Conclusions:
- Ynamides serve as effective reagents for regioselective carbyne transfer and controlled polymer synthesis.
- The developed strategy provides a versatile route to functional polymers, including telechelic and block copolymers.
- This method offers precise control over polymer end-group functionality and architecture.
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