title: An improved catalyst for the asymmetric arylation of ketone enolates.
abstract: A new catalyst system for the enantioselective alpha-arylation of ketones is reported. This catalyst, prepared from Pd(2)(dba)(3) and a bulky dialkylphosphino-binaphthyl ligand, is able to effect the asymmetric arylation of ketone enolates with aryl bromides utilizing NaO(t)()Bu as base. These new catalysts enjoy much higher reactivity than previous systems; arylation reactions could be effected at room temperature with only 2 mol % of the Pd catalyst. The coupling of alpha-alkyl-alpha'-protected cyclopentanones proceeded in high yield, and the resulting quaternary stereogenic center was installed in up to 94% ee.
authors.affiliation: Contribution from the Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hamada
authors.forename: André
authors.initials: A
authors.lastname: Chieffi
authors.forename: Jens
authors.initials: J
authors.lastname: Ahman
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Buchwald
mesh_terms: D002384:Catalysis; D003517:Cyclopentanes / Q000138:chemical synthesis; D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis*; D007659:Ketones / Q000138:chemical synthesis*; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D003517:Cyclopentanes; D006841:Hydrocarbons, Aromatic; D007659:Ketones; D009942:Organometallic Compounds; C007201:cyclopentanone; D010165:Palladium