Chiral bis(oxazolinylphenyl)amines proved to be efficient auxiliary ligands for iron and cobalt catalysts with high activity for asymmetrichydrosilylation of ketones and asymmetric conjugate hydrosilylation of enones.
Influence of the Double-Bond Geometry of the Michael Acceptor on Copper-Catalyzed Asymmetric Conjugate Addition
作者:Magali Vuagnoux-d'Augustin、Alexandre Alexakis
DOI:10.1002/ejoc.200700424
日期:2007.12
aspects, a study of the influence of the (E)/(Z) double-bond geometry of the Michael acceptor on the enantioselectivity of copper-catalyzedasymmetricconjugateaddition reactions has been realized. In spite of numerous articles concerning copper-catalyzedasymmetricconjugateaddition reactions, the major factors of such a reaction are quite difficult to elucidate. Although our experiments have not allowed
The effects of solvent on switchable stereoselectivity: copper-catalyzed asymmetric conjugate additions using D2-symmetric biphenyl phosphoramidite ligands
A highly enantioselective copper-catalyzed conjugateaddition of diethylzinc to acyclic aromatic enones was developed with phosphoramidite ligands bearing a D2-symmetric biphenyl backbone. This type of reaction demonstrated that toluene and THF solvents can completely reverse the absolute configuration of the products, thus simplifying the process of accessing either enantiomer (S: 92% ee, 94% yield;
Enantioselective Catalytic Conjugate Addition of Dialkylzinc Reagents using Copper–Phosphoramidite Complexes; Ligand Variation and Non-linear Effects
作者:Leggy A Arnold、Rosalinde Imbos、Alessandro Mandoli、André H.M de Vries、Robert Naasz、Ben L Feringa
DOI:10.1016/s0040-4020(00)00142-3
日期:2000.4
cyclohexenone and chalcone in order to assess the structural features that are important for stereocontrol. A sterically demanding amine moiety is essential to reach high e.e.’s. Enantioselectivities for chalcones up to 89% and for cyclic enones up to 98% were found. Studies on non-linear effects with the best ligands for both cyclohexenone and chalcone showed clear non-linear effects for both cyclic
Switchable Stereoselectivity: The Effects of Substituents on the D2-Symmetric Biphenyl Backbone of Phosphoramidites in Copper-Catalyzed Asymmetric Conjugate Addition Reactions with Triethylaluminium
A highly enantioselective copper‐catalyzed conjugateaddition with triethylaluminium was developed using phosphoramidite ligands bearing a D2‐symmetric biphenylbackbone. For these ligands we demonstrated that the 3,3′,5,5′‐substituents on the biphenylbackbone can completely reverse the absolute configuration of the products.