An improved catalyst for the asymmetric arylation of ketone enolates.
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.
Hamada
Takayuki
T
Contribution from the Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
Chieffi
André
A
Ahman
Jens
J
Buchwald
Stephen L
SL
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
D003517:Cyclopentanes; D006841:Hydrocarbons, Aromatic; D007659:Ketones; D009942:Organometallic Compounds; C007201:cyclopentanone; D010165:Palladium