Enantioselective palladium-catalyzed addition of 1,3-dicarbonyl compounds to an allene derivative
Publikation: Beitrag in Fachzeitschrift › Forschungsartikel › Beigetragen › Begutachtung
Beitragende
Abstract
Enhancing atom economy of the metal-catalyzed asymmetric allylic alkylation (AAA) shifts from the usual nucleophilic displacement of a leaving group to an addition of a pronucleophile to a double bond. Using 1-alkoxyallenes as proelectrophiles, the palladium-catalyzed AAA proceeds with 1,3-dicarbonyl compounds as pronucleophiles with excellent regioselectivity and enantiomeric excess under optimized conditions. The pH of the medium proved crucial for reactivity/selectivity. By using the more acidic Meldrum's acids, the reactions required a co-catalytic amount of Brønsted acid, such as trifluoroacetic acid. Single regioisomeric products of 82-99% ee were obtained. On the other hand, the less acidic 1,3-diketones failed to react under such conditions. The fact that a less acidic acid like benzoic acid sufficed, suggested the need for general base catalysis as well. Thus, a mixture of triethylamine and benzoic acid proved optimal (ee's 93-99). Employment of the (R,R)-phenyl Trost ligand gave a product with S configuration. A model to rationalize the results has been developed.
Details
Originalsprache | Englisch |
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Seiten (von - bis) | 7075-7082 |
Seitenumfang | 8 |
Fachzeitschrift | Chemistry - A European Journal |
Jahrgang | 11 |
Ausgabenummer | 23 |
Publikationsstatus | Veröffentlicht - 15 Nov. 2005 |
Peer-Review-Status | Ja |
Extern publiziert | Ja |
Externe IDs
PubMed | 16196061 |
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ORCID | /0000-0001-8423-6173/work/161891590 |
Schlagworte
ASJC Scopus Sachgebiete
Schlagwörter
- Alkylation, Allylic compounds, Asymmetric catalysis, Palladium, Proelectrophiles, Pronucleophiles