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