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
[2+2] Cycloaddition of 1,3-Dienes by Visible Light Photocatalysis
作者:Anna E. Hurtley、Zhan Lu、Tehshik P. Yoon
DOI:10.1002/anie.201405359
日期:2014.8.18
[2+2] Photocycloadditions of 1,3‐dienes represent a powerful yet synthetically underutilized class of reactions. We report that visiblelight absorbing transition metal complexes enable the [2+2] cycloaddition of a diverse range of 1,3‐dienes. The ability to use long‐wavelength visiblelight is attractive because these reaction conditions tolerate the presence of sensitive functional groups that might
Copper-Catalyzed Asymmetric Conjugate Addition of Trialkylaluminium Reagents to Trisubstituted Enones: Construction of Chiral Quaternary Centers
作者:Magali Vuagnoux-d'Augustin、Alexandre Alexakis
DOI:10.1002/chem.200701001
日期:2007.11.26
vinylalane species undergo enantioselective conjugateaddition to a wide range of 2- or 3-substituted enones (cyclopent-2-enones, cyclohex-2-enones, 3-methyl cyclohept-2-enone) in the presence of catalytic amount of copper salt (copper thiophene carboxylate, [Cu(CH3CN)4]BF4 or [CuOTf]2C6H6) and tropos-phosphoramidite-based ligand. Thus, chiral quaternarycenters can be built, with up to 98% ee after rigorous
that attractive dispersion forces may be responsible for a change of the binding mode. The catalytic [2+2] photocycloaddition was shown to proceed on the triplet hypersurface with a quantum yield of 0.05. The positive effect of Lewis acids on the outcome of a given intramolecular [2+2] photocycloaddition was illustrated by optimizing the key step in a concise total synthesis of the sesquiterpene (±)‐italicene
Opening of cyclopropyl ketones with SmI2. Synthesis of spirocyclic and bicyclic ketones by intramolecular trapping of an electrophile
作者:Gary A. Molander、Cristina Alonso-Alija
DOI:10.1016/s0040-4020(97)00499-7
日期:1997.6
A method for the opening of cyclopropyl ketones with samarium(II) iodide followed by the intramolecular trapping of an electrophile is described. This process leads to the obtainment of functionalized spirocyclic, bicyclic, and tricyclic ketones in moderate to good yields.