We have developed a method to achieve ring-opening metathesis polymerization (ROMP) mediated by oxidation of organic initiators in the absence of any transition metals. Radical cations, generated via one-electron oxidation of vinyl ethers, were found to react with norbornene to give polymeric species with microstructures essentially identical to those traditionally obtained via metal-mediated ROMP. We found that vinyl ether oxidation could be accomplished under mild conditions using an organic photoredox mediator. This led to high yields of polymer and generally good correlation between M(n) values and initial monomer to catalyst loadings. Moreover, temporal control over reinitiation of polymer growth was achieved during on/off cycles of light exposure. This method demonstrates the first metal-free method for controlled ROMP.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/ja512073m | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Synergistic Combination of Living Ring-Opening Metathesis Polymerization and Atom Transfer Radical Polymerization to Synthesize Structurally Tailored and Engineered Macromolecular Networks.
Langmuir
December 2024
Department of Chemistry, Carnegie Mellon University, 4400 Avenue, Pittsburgh, Pennsylvania 15213, United States.
Structurally tailored and engineered macromolecular (STEM) networks are attractive materials for soft robotics, stretchable electronics, tissue engineering, and 3D printing due to their tunable properties. To date, STEM networks have been synthesized by atom transfer radical polymerization (ATRP) or the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and ATRP. RAFT polymerization could have limited selectivity with ATRP inimer sites that can participate in radical-transfer processes.
View Article and Find Full Text PDFAddition and Oxidation Reactivity of a Pentacoordinate Nickelacyclobutane.
Chemistry
December 2024
Universiteit Utrecht, Chemistry, Universiteitsweg 99, 3584CG, Utrecht, NETHERLANDS, KINGDOM OF THE.
Nickelacyclobutanes are reactive intermediates in catalytic cycles involving cyclopropanation and insertion reactions. The stoichiometric study of these intermediates has shown that their reactivity is highly influenced by the coordination environment of the nickel center. A pentacoordinated nickelacyclobutane embedded in a diphosphine pincer ligand has been shown to selectively undergo various reactions with exogenous ligands, including [2+2] cycloreversion and carbene transfer to an isocyanide.
View Article and Find Full Text PDFDoubly Metathetic NiCl-Catalyzed Coupling Between Bis(2-oxazolines) and Aldehydes: A Novel Access to Bis(ester-imine) Derivatives.
Molecules
December 2024
Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio 9, 22100 Como, Italy.
The coupling between bis(2-oxazolines) and two equivalents of aromatic aldehydes in the presence of catalytic amounts of NiCl affords an ester-imine product in synthetically useful yields. This virtually unknown, 100% atom-economic transformation involves the formal metathesis between the C=N double bond of the bis(2-oxazoline) moiety, which undergoes ring-opening, and the C=O double bond of the aldehyde. The scope of this transformation is studied, and a mechanism is proposed based on DFT calculations.
View Article and Find Full Text PDFRare-Earth Metal-Enabled Ring-Opening Metathesis of Benzene.
J Am Chem Soc
December 2024
Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare-Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Activation and transformation of inert C-C bonds within arenes are challenging and important topics in synthetic chemistry. While there have been some reports on the activation of C-C bonds in arene rings, the realm of metathesis reactions involving arene C-C bonds remains unexplored. Here, we report a rare-earth metal-enabled intramolecular metathesis reaction of one benzene C-C bond and another C-C single bond, assisted by the high reactivity and unique synergistic effect of rare-earth metallacycles.
View Article and Find Full Text PDFAromatic ring-opening metathesis.
Nature
December 2024
Department of Chemistry, University of Basel, Basel, Switzerland.
Aromatic compounds are used across chemistry and materials science as a result of their stability, characteristic interactions, defined molecular shape and the numerous synthetic approaches for their synthesis by a diversity of cyclization reactions. In contrast, the cleavage of inert aromatic carbon-carbon bonds remained largely unfeasible due to the unfavourable energetics of disrupting aromaticity on ring opening. For non-aromatic structures, alkene metathesis catalysed by transition metal alkylidenes is established as one of the most versatile carbon-carbon bond-forming and breaking reactions.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!