Investigation of ligand loading and asymmetric amplification in CHAOx-catalyzed asymmetric diethylzinc additions
作者:Peter Wipf、Joshua G. Pierce、Xiaodong Wang
DOI:10.1016/j.tetasy.2003.07.022
日期:2003.11
The recently developed (cyclohexylsulfonylamino)oxazoline (CHAOx) ligand was found to provide high ee's and consistent reaction rates in the asymmetric diethylzinc addition to benzaldehyde over a remarkably large loading range of 0.05-10 mol%. Turnover numbers of 1000-2000 can be explained by the absence of a nonlinear effect and the formation of a catalytically active monomer complex. Substituents at the nitrogen donor atoms of the bidentate ligand prevent zinc-complex dimerization. (C) 2003 Elsevier Ltd. All rights reserved.