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
An NHC–Cu complex catalyzed the asymmetricconjugateaddition (ACA) of various Grignard reagents to nonactivated α-substituted cyclic enones to give 2,3-dialkylated cyclopentanones and cyclohexanones. The Michael addition features the formation of a magnesium enolate intermediate. One-pot diastereoselective trapping of this enolate by alkyl, propargyl, allyl, and benzyl halides led to ketones with
Formation of Contiguous Quaternary and Tertiary Stereocenters by Sequential Asymmetric Conjugate Addition of Grignard Reagents to 2-Substituted Enones and Mg-Enolate Trapping
作者:Nicolas Germain、Alexandre Alexakis
DOI:10.1002/chem.201500292
日期:2015.6.1
tolerated for the ACA to 2‐methylcyclohexenone. The sequential ACA–enolate trapping, which leads to quaternarystereocenters, was then studied. Thus, many electrophiles have been tested, thereby giving rise to highly functionalized cyclic ketones with contiguous α‐quaternary and β‐tertiary centers. The present technique is believed to bring a new approach to versatile terpenoid‐like skeletons of bioactive
Copper-Catalysed Conjugate Addition of Grignard Reagents to 2-Methylcyclopentenone and Sequential Enolate Alkylation
作者:Beatriz C. Calvo、Ashoka V. R. Madduri、Syuzanna R. Harutyunyan、Adriaan J. Minnaard
DOI:10.1002/adsc.201400085
日期:2014.6.16
The copper/Rev‐JosiPhos‐catalysed asymmetric conjugateaddition of Grignard reagents to 2‐methylcyclopentenone (1) provides 2,3‐disubstituted cyclopentanones in high yields and enantioselectivities, and good diastereoselectivities. Reaction of the in situ formed enolate with various alkylating reagents in the presence of 1,3‐dimethyltetrahydropyrimidine‐2(1H)‐one (DMPU) affords the corresponding products