Application of Tridentate Bis(oxazoline) Ligands in Catalytic Asymmetric Nozaki–Hiyama Allylation and Crotylation: An Example of High Enantioselection with a Non-Symmetric Bis(oxazoline) Ligand
作者:Helen A. McManus、Pier Giorgio Cozzi、Patrick J. Guiry
DOI:10.1002/adsc.200505332
日期:2006.3
symmetric and non-symmetric bis(oxazoline) ligands was applied in the Nozaki–Hiyama allylation and crotylation of benzaldehyde. It was found that both the magnitude and sense of the asymmetric induction depended strongly on the nature and combination of the oxazoline substituents. For both reactions, the non-symmetric tert-butyl/benzyl-substituted ligand proved to be the optimal ligand and was applied successfully
Enantioselective catalytic addition of allyl organometallic reagents to aldehydes promoted by [Cr(Salen)]: the hidden role played by weak Lewis acids in metallo-Salen promoted reactions
作者:Marco Bandini、Pier Giorgio Cozzi、Achille Umani-Ronchi
DOI:10.1016/s0040-4020(00)01047-4
日期:2001.1
from NLE study in the [Cr(Salen)] catalysed addition of allyl halides to aldehydes. The results show the key role played by weak Lewis acids in the catalytic system. Weak Lewis acids such as manganese salts and the [Cr(Salen)X] complex drive the stereochemistry of the reaction toward a high level of diastero- and enantioselectivity. Therefore, the Lewis acids and their properties must be taken into