Construction Of Acyclic All-Carbon Quaternary Stereocenter Based On Asymmetric Michael Addition Of Chiral Amine

Acyclic asymmetric quaternary stereocenters, which are composed of four carbon-carbon bonds, were finely constructed by utilizing a face-selective alkylation of enolate intermediates derived from an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-alpha,beta-unsaturated esters. The present face-selective alkylation was able to employ diverse alkyl halides as an electrophile to afford various Michael adducts having an all-carbon quaternary stereocenter. With regard to the deprotection of the chiral auxiliary, N-iodosuccinimide used in our previous study did not work in the present cases; however, we found that py ridine iodine monochloride in the presence of H2O was effective to remove the bornyl group and the benzyl group on the amino group to provide the beta-amino ester derivative.