| Heterogeneous versus homogeneous palladium catalysts for ligandless mizoroki-heck reactions: a comparison of batch/microwave and continuous-flow processing. | |
| | |
MedLine Citation:
|
PMID: 19086042 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
|
Mizoroki-Heck couplings of aryl iodides and bromides with butyl acrylate were investigated as model systems to perform transition-metal-catalyzed transformations in continuous-flow mode. As a suitable ligandless catalyst system for the Mizoroki-Heck couplings both heterogeneous and homogeneous Pd catalysts (Pd/C and Pd acetate) were considered. In batch mode, full conversion with excellent selectivity for coupling was achieved applying high-temperature microwave conditions with Pd levels as low as 10(-3) mol %. In continuous-flow mode with Pd/C as a catalyst, significant Pd leaching from the heterogeneous catalyst was observed as these Mizoroki-Heck couplings proceed by a homogeneous mechanism involving soluble Pd colloids/nanoparticles. By applying low levels of Pd acetate as homogeneous Pd precatalyst, successful continuous-flow Mizoroki-Heck transformations were performed in a high-temperature/pressure flow reactor. For both aryl iodides and bromides, high isolated product yields of the cinnamic esters were obtained. Mechanistic issues involving the Pd-catalyzed Mizoroki-Heck reactions are discussed. |
| | |
Authors:
|
Toma N Glasnov; Silvia Findenig; C Oliver Kappe |
Publication Detail:
|
Type: Journal Article |
Journal Detail:
|
Title: Chemistry (Weinheim an der Bergstrasse, Germany) Volume: 15 ISSN: 1521-3765 ISO Abbreviation: Chemistry Publication Date: 2009 |
Date Detail:
|
Created Date: 2009-01-14 Completed Date: 2009-02-24 Revised Date: 2009-08-04 |
Medline Journal Info:
|
Nlm Unique ID: 9513783 Medline TA: Chemistry Country: Germany |
Other Details:
|
Languages: eng Pagination: 1001-10 Citation Subset: - |
Affiliation:
|
Christian Doppler Laboratory for Microwave Chemistry (CDLMC) and Institute of Chemistry, Karl-Franzens-University Graz, Heinrichstrasse 28, 8010 Graz, Austria. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: 2-(2-aminoethylamino)-5-nitropyridine as a basic matrix for negative-mode matrix-assisted laser deso...
Next Document: Intermolecular olefin functionalisation involving aryl radicals generated from arenediazonium salts.