Synthesis of Ferrocene Oxazoline N,O ligands and Their Application in Asymmetric Ethyl- and Phenylzinc Additions to Aldehydes
作者:Chris Nottingham、Robert Benson、Helge Müller-Bunz、Patrick J. Guiry
DOI:10.1021/acs.joc.5b01766
日期:2015.10.16
The synthesis of a range of novel gem-disubstituted ferrocene–oxazoline ligands and their application in both the asymmetric ethyl- and phenylzinc additions to aldehydes is reported. These studies reveal that gem-disubstitution of i-Pr-containing ferrocene oxazolineligands results in increased enantioselectivity compared to their unsubstituted counterparts. Utilizing zinc catalysis, these ligands provided
The use of 5,5(dimethyl)-i-Pr-PHOX as a practical equivalent of t-Bu-PHOX in asymmetric catalysis is reported. This new member of the phosphinooxazoline (PHOX) ligand family behaves similarly in terms of stereoinduction to t-Bu-PHOX with the key advantage of being readily accessible as both enantiomers starting from either (S)- or (R)-valine.