AI Article Synopsis
- The text discusses the creation of new ruthenium-based metathesis catalysts featuring a specific ligand known for their effectiveness in ring-closing (RCM) and ring-opening cross-metathesis (ROCM) reactions.
- Catalyst 1 demonstrates moderate performance in enyne metathesis while catalyst 2 excels in cyclopolymerization, producing a polymer predominantly made of five-membered rings.
- Both catalysts, when immobilized on different supports, maintain high reactivity and produce minimal ruthenium contamination in the final products, showcasing their potential for sustainable applications.
Article Abstract
The synthesis of novel ruthenium-based metathesis catalysts containing the saturated 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene ligand, that is, [RuCl2(NHC)[=CH-2-(2-PrO)-5-NO(2)-C6H3]] (1) and [Ru(CF3COO)2(NHC)[=CH-2-(2-PrO)-5-NO2-C6H3]] (2) (NHC=1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) is described. Both catalysts are highly active in ring-closing metathesis (RCM) and ring-opening cross-metathesis (ROCM). Compound 1 shows moderate activity in enyne metathesis. Compound 2 is not applicable to enyne metathesis since it shows high activity in the cyclopolymerization of diethyl dipropargylmalonate (DEDPM). Poly(DEDPM) prepared by the action of 2 consists of 95% five-membered rings, that is, poly(cyclopent-1-enevinylene)s, and 5 % of six-membered rings, that is, poly(cyclohex-1-ene-3-methylidene)s. The polymerization proceeds in a nonliving manner and results in polyenes with broad polydispersities (1.9< or =PDI< or =2.3). Supported analogues of 2 were prepared by immobilization on hydroxymethyl-Merrifield resin and a monolithic support derived from ring-opening-metathesis polymerization (ROMP). Catalyst loadings of 1 and 2.5%, respectively, were obtained. Both supported versions of 2 showed excellent reactivity. With 0.24-2% of the supported catalysts, yields in RCM and ROCM were in the range of 76-100%. Leaching of ruthenium was low and resulted in Ru contaminations of the products of less than 0.000014% (0.14 ppm).
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/chem.200400278 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Unveiling the molecular mechanism of Mn and Zn-catalyzed Ullmann-type C-O cross-coupling reactions.
Phys Chem Chem Phys
December 2024
Department of Chemistry, CMS College Kottayam (Autonomous) Mahatma Gandhi University, Kottayam, Kerala, 686001, India.
A detailed theoretical study delving into the molecular mechanisms of the Ullmann-type -arylation reactions catalyzed by manganese and zinc metal ions has been investigated with the aid of the density functional theory (DFT) method. In contrast to the redox-active mechanisms proposed for classical Ullmann-type condensation reaction, a redox-neutral mechanism involving σ-bond metathesis emerged as the most appealing pathway for the investigated high-valent Mn(II) and Zn(II)-catalyzed -arylation reactions. The mechanism remains invariant with respect to the nature of the central metal, ligand, base, This unusuality in the mechanism has been dissected by considering three cases: ligand-free and ligand-assisted Mn(II)-catalyzed -arylation reaction and ligand-assisted Zn(II)-catalyzed -arylation reactions.
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 PDFReactivity Study of the Bis(phosphine)-Stabilized Antimony(I) Cation.
Inorg Chem
December 2024
Department of Chemistry, Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008 Maharashtra, India.
The 5,6-Bis(diisopropylphosphino)acenaphthene -stabilized Sb(I) cationic compound [LSb][OTf] (OTf = CFSO) possessing two lone pairs of electrons on the Sb(I) center showed nucleophilic behavior toward methyl trifluoromethanesulfonate forming the oxidized product [LSbMe][OTf] (OTf = CFSO). Reaction of compound with Lewis acids such as GaCl and AlBr led to changes in the counteranions only giving products [LSb][GaCl] and [LSb][SbBr] , respectively. A metathesis reaction was observed when compound was reacted with PI.
View Article and Find Full Text PDFIridium Complexes of a Bis(-pyrrolyl)boryl/Bis(phosphine) PBP Pincer Ligand.
Inorg Chem
December 2024
Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States.
This work reports the synthesis of a bis(pyrrolylphosphino)phenyl borane (PBP)Ph () and its incorporation of Ir by metal insertion into B-Ph to afford the dipyrrolylboryl/bis(phosphine) pincer complex (PBP)Ir(Ph)Cl (). Hydrogenolysis of afforded (PBP)Ir(H)Cl (). Compound was converted into (PBP)IrCl () via reaction with -chlorosuccinimide, and exposure of to CO produced (PBP)IrCl(CO) ().
View Article and Find Full Text PDFCarbosiloxane Bottlebrush Networks for Enhanced Performance and Recyclability.
Macromolecules
November 2024
Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
Silicone bottlebrush copolymers and networks derived from cyclic carbosiloxanes are reported and shown to have enhanced properties and recyclability compared with traditional dimethylsiloxane-based materials. The preparation of these materials is enabled by the synthesis of well-defined heterotelechelic macromonomers with Si-H and norbornene chain ends via anionic ring-opening polymerization of the hybrid carbosiloxane monomer 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane. These novel heterotelechelic α-Si-H/ω-norbornene macromonomers undergo efficient ring-opening metathesis copolymerization to yield functional bottlebrush polymers with accurate control over molecular weight and functional-group density.
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!