Catalytic activity of Pd(II) and Pd(II)/DAB-R systems for the Heck arylation of olefins
| Autor: | Gabriela A. Grasa, Rohit Singh, Edwin D. Stevens, Steven P. Nolan |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
chemistry.chemical_classification
Base (chemistry) Chemistry Ligand Aryl Organic Chemistry chemistry.chemical_element General Medicine Biochemistry Medicinal chemistry Coupling reaction Catalysis Inorganic Chemistry Reaction rate chemistry.chemical_compound Heck reaction Functional group Materials Chemistry Organic chemistry Physical and Theoretical Chemistry Palladium |
| Zdroj: | Journal of Organometallic Chemistry. 687:269-279 |
| ISSN: | 0022-328X |
| DOI: | 10.1016/s0022-328x(03)00375-9 |
| Popis: | Palladium-catalyzed reactions of aryl bromides with various olefins involving Pd(II)/diazabutadiene (DAB-R) systems have been investigated. The scope of a coupling process using Pd(II) sources and an α-diimine as ligand in the presence of Cs2CO3 as base was tested using various substrates. The Pd(OAc)2/DAB-Cy (1, DAB-Cy=1,4-dicyclohexyl-diazabutadiene) system presents the highest activity with respect to electron-neutral and electron-deficient aryl bromides in coupling with electron rich olefins. The synthesis and X-ray characterization of a Pd(II)-diazabutadiene ligand is reported. Extensive optimization experiments showed that another Pd(II) source, Pd(acac)2 (acac=acetylacetonate), proved to activate aryl bromides at high temperatures, low catalyst loadings when the appropriate concentration of nBu4NBr additive was employed. The effect of the DAB-Cy ligand is important at very low catalyst loadings and high temperatures. Pd(acac)2 and Pd(acac)2/DAB-Cy precatalysts were very effective for the arylation of various olefins with aryl bromides with respect to reaction rate, catalyst loadings, and functional group tolerance. |
| Databáze: | OpenAIRE |
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