Formation of Quaternary Stereogenic Centers by Copper-Catalyzed Asymmetric Conjugate Addition Reactions of Alkenylaluminums to Trisubstituted Enones
作者:Daniel Müller、Alexandre Alexakis
DOI:10.1002/chem.201302856
日期:2013.11.4
undergo asymmetric copper‐catalyzedconjugateaddition (ACA) to β‐substituted enones allowing the formation of stereogenic all‐carbon quaternary centers. Phosphinamine–copper complexes proved to be particularly active and selective compared with phosphoramidite ligands. After extensive optimization, high enantioselectivities (up to 96 % ee) were obtained for the addition of alkenylalanes to β‐substituted
Readily Accessible Chiral Diene Ligands for Rh-Catalyzed Enantioselective Conjugate Additions of Boronic Acids
作者:Barry M. Trost、Aaron C. Burns、Thomas Tautz
DOI:10.1021/ol201754c
日期:2011.9.2
the broad scope of the Pd-catalyzed asymmetric alkylation of meso- and d,l-divinylethylene carbonate, several chiral diene ligands were prepared in two steps from commercial materials. Subsequently, these ligands were evaluated in the Rh-catalyzed asymmetric conjugateaddition of boronic acids to enones.
it both ways: A novel class of chiral sulfoxide‐olefin ligands was synthesized from a single chiral source. These ligands were evaluated in rhodium‐catalyzed 1,4‐additions of arylboronic acids to electron‐deficient olefins, and remarkable olefin‐directed reversal of stereoselectivity (up to >99 % ee, R isomer; 98 % ee, S isomer) was observed when the reversal ligand pair L1 (branched olefin) and L2
Chiral dihydrobenzofuran-based diphosphine (BICMAP): optical resolution and application to rhodium(I)-catalyzed asymmetric 1,4-addition of aryl- and alkenylboronic acids to cyclic enones
Chiral dihydrobenzofuran-based diphosphine ligand (BICMAP) 1 was used as a ligand for the rhodium(I)-catalyzed asymmetric1,4-addition of arylboronicacids to cyclic enones up to 99% ee. We also found that the BICMAP-rhodium system was an efficient catalyst for the 1,4-addition of alkenylboronic acids to 2-cyclohexenone in good enantioselectivities.
Simple Chiral Diene Ligands Provide High Enantioselectivities in Transition-Metal-Catalyzed Conjugate Addition Reactions
作者:Kazuhiro Okamoto、Tamio Hayashi、Viresh H. Rawal
DOI:10.1021/ol801931v
日期:2008.10.2
Chiral dienes possessing the bicyclo[2.2.2]octadiene framework were prepared readily through the [4 + 2] cycloaddition of ( R)-alpha-phellandrene with methyl propiolate as the key step. Diene 9, substituted with a tertiary alcohol on one of the two double bonds, is prepared in just one step from the cycloadduct and is highly effective as a chiralligand for rhodium-catalyzedasymmetricconjugate addition