Synthesis, conformation analysis and catalytic properties of chiral zirconium complexes containing etherfunctionalized Cp ligands
摘要:
A novel series of chiral ligands was synthesized having a cyclopentadienyl (Cp) ring attached to an ether moiety. Four chiral monoCp zirconium derivatives contain these ligands in a bidentate Cp/O coordination mode. Complexes 4d, 6d, and 7d bear an aryl group at the end of the ether chain. The racemic complexes 3d and 4d show moderate activity for the polymerisation of ethylene. Complexes 6d and 7d are enantiopure and were used as asymmetric Lewis acid catalysts for the hydrocyanation of benzaldehyde. The negligible enantiomeric excess thereby is due to decomplexation of the weakly coordinated aryl ether side-chains during catalysis. (C) 1999 Elsevier Science S.A. All rights reserved.
Planar Chiral [2.2]Paracyclophane-Based Bisoxazoline Ligands: Design, Synthesis, and Use in Cu-Catalyzed Inter- and Intramolecular Asymmetric O–H Insertion Reactions
作者:Shinji Kitagaki、Shunsuke Murata、Kisaki Asaoka、Kenta Sugisaka、Chisato Mukai、Naoko Takenaga、Keisuke Yoshida
DOI:10.1248/cpb.c18-00519
日期:2018.10.1
insertion reactions of α-diazo esters. The reactivities and enantioselectivities of Cu complexes of the synthesized bisoxazoline ligands were lower than those of ligands without central chirality. However, planar chiral [2.2]paracyclophane-based bisoxazoline ligands with an inserted benzene spacer that had a sterically demanding isopropyl substituent showed good enantioselectivities in inter- and intramolecular
Synthesis of 2-aryloxypropanoic acids analogues of clofibric acid and assignment of the absolute configuration by 1H NMR spectroscopy and DFT calculations
been synthesized through a simple strategy, in good yields and excellent enantiomeric excesses. Their absoluteconfiguration was assigned by means of a NMR-based approach consisting of the derivatization of the carboxylic acids with ethyl mandelate and the comparison of the chemical shifts of the obtained diastereomers. The effectiveness of such an approach has been tested against a larger set of chiral