Enantioselective palladium-catalyzed addition of 1,3-dicarbonyl compounds to an allene derivative

Publikation: Beitrag in FachzeitschriftForschungsartikelBeigetragenBegutachtung

Beitragende

  • Barry M. Trost - , Stanford University (Autor:in)
  • Alessandro B.C. Simas - , Stanford University (Autor:in)
  • Bernd Plietker - , Stanford University (Autor:in)
  • Christoph Jäkel - , Stanford University (Autor:in)
  • Jia Xie - , Stanford University (Autor:in)

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

OriginalspracheEnglisch
Seiten (von - bis)7075-7082
Seitenumfang8
FachzeitschriftChemistry - A European Journal
Jahrgang11
Ausgabenummer23
PublikationsstatusVeröffentlicht - 15 Nov. 2005
Peer-Review-StatusJa
Extern publiziertJa

Externe IDs

PubMed 16196061
ORCID /0000-0001-8423-6173/work/161891590

Schlagworte

ASJC Scopus Sachgebiete

Schlagwörter

  • Alkylation, Allylic compounds, Asymmetric catalysis, Palladium, Proelectrophiles, Pronucleophiles