Electronic and Steric Effects of Atropisomeric Ligands SYNPHOS® and DIFLUORPHOS®vs. BINAPs in Rh(I)-Catalyzed Asymmetric Pauson–Khand Reaction
作者:Dong Eun Kim、Choong Choi、In Su Kim、Séverine Jeulin、Virginie Ratovelomanana-Vidal、Jean-Pierre Genêt、Nakcheol Jeong
DOI:10.1002/adsc.200600623
日期:2007.8.6
electronic and steric effects of chiral biaryl diphosphine ligands on the Rh(I)-catalyzed asymmetric Pauson–Khand type reaction were examined. We demonstrated that enantioselectivity and reaction yield were influenced by the electronic density on phosphorus, the dihedral angle of ligands and the electronic density of the alkyne substrate. Ligands bearing a narrower dihedral angle than Binap, such as Synphos
检查了手性联芳基二膦配体对Rh(I)催化的不对称Pauson-Khand型反应的电子和空间效应。我们证明对映选择性和反应产率受磷的电子密度,配体的二面角和炔烃底物的电子密度的影响。与Binap型配体相比,发现具有比Binap窄的二面角的配体,例如Synphos(L4)和Difluorphos(L5),大大提高了反应的对映选择性。具有去屏蔽的膦的配体,例如p -CF 3 -Binap(L3)和Difluorphos(L5)提供了比Binap更好的对映选择性,并减少了副产物的形成,特别是对于电子贫乏的炔烃底物。