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Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
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Acrylate metathesis via the second-generation Grubbs catalyst: unexpected pathways enabled by a PCy3-generated
Gwendolyn A Bailey1, Deryn E Fogg1
1Center for Catalysis Research and Innovation and Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N6N5 Canada.
Journal of the American Chemical Society
|June 2, 2015
Summary
Grubbs catalyst GII can cause unexpected side reactions in acrylate metathesis. The phosphine ligand attacks the acrylate, leading to carbanion formation and catalyst deactivation, impacting synthesis and polymer depolymerization.
Area of Science:
- Organic Chemistry
- Polymer Chemistry
- Catalysis
Background:
- Acrylate metathesis offers diverse applications, including synthesizing valuable α,β-unsaturated esters and depolymerizing unsaturated polymers.
- Grubbs catalyst GII is a key catalyst in these transformations.
Purpose of the Study:
- To investigate unexpected side reactions involving Grubbs catalyst GII in acrylate metathesis.
- To elucidate the mechanism of these side reactions and their impact on catalytic processes.
Main Methods:
- Detailed mechanistic studies using Grubbs catalyst GII.
- Analysis of reaction pathways including carbanion formation and subsequent reactions.
Main Results:
- Evidence for the attack of the phosphine ligand (PCy3) on the acrylate olefin was observed.
- This attack generates a reactive carbanion intermediate.
- The carbanion participates in Michael addition, proton abstraction, and catalyst deactivation pathways.
Conclusions:
- Unexpected side reactions can occur with Grubbs catalyst GII in acrylate metathesis.
- Labile metal-phosphine complexes catalyzing reactions with electron-deficient olefins may exhibit similar reactivity.
- Understanding these pathways is crucial for optimizing acrylate metathesis and related catalytic processes.
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