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DOI: 10.1055/s-0028-1087319
Palladium-Catalyzed Asymmetric α-Arylation of Aldehydes
Contributor(s):Mark Lautens, Jane PanteleevMassachusetts Institute of Technology, Cambridge, USA
Asymmetric Palladium-Catalyzed Intramolecular α-Arylation of Aldehydes
Angew. Chem. Int. Ed. 2008, 47: 8108-8111
Publication History
Publication Date:
20 November 2008 (online)
Key words
palladium - asymmetric catalysis - quaternary stereogenic centers - cyclization
Significance
The authors report the first asymmetric version of the α-arylation of aldehydes under palladium catalysis. The examples illustrated are all intramolecular, generating five- and six-membered rings. The method forms all-carbon- substituted quaternary centers in high enantioselectivity and moderate yield.
Review
D. A. Culkin, J. F. Hartwig. Acc. Chem. Res. 2003, 36, 234-245.
Comment
Although α-arylation of carbonyl compounds has received considerable attention, the asymmetric process remains a challenge. The authors utilize phosphanyloxazoline-based (phox) ligands in tert-butanol as a solvent, producing moderate to excellent enantioselectivities. The scope is thorough and both alkyl and aryl substituents at the α position are tolerated. The authors also demonstrate the derivatization of the aldehyde moiety in the product through oxidations, reductions and rearrangements. Significant insight into structure-enantioselectivity relationship is provided, where the influence of the steric parameters of the ligand are investigated. X-ray structure analysis is used for unambiguous assignment of the stereocenters.