Development of bifunctional aza-bis(oxazoline) copper catalysts for enantioselective Henry reaction.
Base-functionalized aza-bis(oxazoline) ligands were prepared to explore the concept of dual activation through the Lewis acid and a tethered tertiary amine base. The catalytic activity of the Cu complex was evaluated for the asymmetric Henry reaction. Compared with a corresponding unfunctionalized copper complex with external 1-benzyl-4-ethylpiperazine base, the ethylpiperazine-functionalized aza-bis(oxazoline) copper catalyst resulted in rate acceleration (2.5 times) as well as improved enantioselectivity (72% ee vs 92% ee).
Lang
Kai
K
Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, USA.
Park
Jongwoo
J
Hong
Sukwon
S
D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry; D001372:Aza Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry*; D013237:Stereoisomerism
D000438:Alcohols; D000447:Aldehydes; D001372:Aza Compounds; D008024:Ligands; D009942:Organometallic Compounds; D010080:Oxazoles; D003300:Copper