title: Catalytic effect and recyclability of imidazolium-tagged bis(oxazoline) based catalysts in asymmetric Henry reactions.
abstract: Functional imidazolium ionic liquids have been developed as a new class of versatile catalysts. C(2)-symmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered. The catalysts based on the new ligands and Cu(OAc)(2)·H(2)O were applied in asymmetric Henry reactions between various aldehydes 3 and CH(3)NO(2)4. The catalysts achieved a high level of enantioselectivity; product (R)-5n was attained at 94% ee in MeOH. Moreover, the catalyst could be recycled 6 times without an obvious loss of activity or enantioselectivity. In addition, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity.
authors.affiliation: R&D Centre for Pharmaceuticals, School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing, PR China. zzm@bit.edu.cn
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Zhou
authors.forename: Zhi-Huai
authors.initials: ZH
authors.lastname: Li
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Hao
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiao
authors.initials: X
authors.lastname: Dong
authors.forename: Ying-Qiang
authors.initials: YQ
authors.lastname: Liu
authors.forename: Wen-Wen
authors.initials: WW
authors.lastname: Sun
authors.forename: Dan
authors.initials: D
authors.lastname: Cao
authors.forename: Jin-Liang
authors.initials: JL
authors.lastname: Wang
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D007093:Imidazoles; D052578:Ionic Liquids; D010080:Oxazoles