Enantioselective Henry reaction catalyzed by C2-symmetric chiral diamine–copper(II) complex
作者:Sermadurai Selvakumar、Dhanasekaran Sivasankaran、Vinod K. Singh
DOI:10.1039/b904254g
日期:——
A copper(II) complex of C2-symmetric diamine has been proved to be an efficient catalyst for the enantioselective Henry reaction between nitroalkanes and various aldehydes to provide β-hydroxy nitroalkanes in high yields (up to 97%), moderate diastereoselectivities (up to 71:29) and excellent enantiomeric excesses (up to 96%). The chiral nitroaldol adduct obtained has been further converted into chiral
Highly efficient and recyclable imidazolium-tagged bis(oxazolines), with an imidazolium tagged onto the 4,4′-position of the box, have been designed and prepared for the first time. They have been synthesized from dimethylmalonic acid and used as chiral ligands in the copper(II)-catalyzed classic asymmetric Henry reaction between aldehydes and nitromethane. A systematic analysis of the anions showed
Noncovalent Immobilization of Ionic-tagged Box-Cu(OAc)<sub>2</sub>
Complex and Its Application in Asymmetric Henry Reaction
作者:Zhi-Huai Li、Zhi-Ming Zhou、Xiao-Yan Hao、Jun Zhang、Xiao Dong、Ying-Qiang Liu
DOI:10.1002/chir.22104
日期:2012.12
Immobilized Cu(OAc)2‐bis(oxazolines) via hydrogen bonding by SBA‐15 was applied to asymmetricHenryreaction, and good enantioselectivities were obtained (up to 83% ee) between 2‐methoxybenzaldehyde and CH3NO2 in isopropyl alcohol (iPrOH). The catalyst could be reused seven times without any obvious loss in enantioselectivity. For the first time, this facile and clean immobilization method is applied
Catalytic effect and recyclability of imidazolium-tagged bis(oxazoline) based catalysts in asymmetric Henry reactions
作者:Zhi-Ming Zhou、Zhi-Huai Li、Xiao-Yan Hao、Jun Zhang、Xiao Dong、Ying-Qiang Liu、Wen-Wen Sun、Dan Cao、Jin-Liang Wang
DOI:10.1039/c2ob06434k
日期:——
imidazolium ionicliquids 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
Recyclable copper catalysts based on ionic-tagged C2-symmetric Indabox ligands and their application in asymmetric Henry reactions
作者:Zhi-Huai Li、Zhi-Ming Zhou、Xiao-Yan Hao、Jun Zhang、Xiao Dong、Ying-Qiang Liu、Wen-Wen Sun、Dan Cao
DOI:10.1016/j.apcata.2012.02.044
日期:2012.5
New imidazolium/pyrrolidinium-tagged Indabox ligands were designed and prepared. Catalysts based on these ligands with Cu(OAc)(2)center dot H2O were applied to the asymmetric Henry reaction using various aldehydes and CH3NO2, the products were obtained in high enantioselectivity. Specifically, (R)-1-(2-methoxylphenyl)-2-nitroethanol was obtained in 94% ee in MeOH. Furthermore, the catalyst based on 7 could be recycled at least 12 times by simple wash without an obvious loss of activity or enantioselectivity. This catalytic procedure demonstrated the potential for catalyst recyclability in the asymmetric Henry reaction. Additionally, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity. (C) 2012 Elsevier B.V. All rights reserved.