COAP-Pd Catalyzed Asymmetric Allylic Alkylation of Azlactones with MBH Carbonates: Access to Unnatural α-Quaternary Stereogenic Glutamic Acid Derivatives

Abstract

A palladium-catalyzed regioselective and asymmetric allylic alkylation of azlactones with MBH carbonates has been developed with chiral oxalamide-phosphine ligands. The corresponding reaction afforded a range of optically active γ-arylidenyl glutamic acid derivatives bearing an α-chiral quaternary stereocenter in good yields with excellent linear regio-and high enantioselectivity. This protocol furnishes an alternative approach for the construction of enantio-enriched unnatural α-amino acid derivatives.

Chiral Phosphine Ligands of COAP and SKP Switched Regiodivergent Asymmetric Allylic Alkylation of MBH Adducts

“…Based on privileged axially chiral 1,2-diamine scaffolds, our group designed one type of chiral oxalamide phosphine (COAP) ligand bearing an aryl phosphine unit and an oxamide moiety, which were successfully applied in Pd-catalyzed asymmetric allylic alkylation reactions and asymmetric [4 + 1]-cycloaddition reactions . In view of the high regio- and enantioselectivity of the COAP/Pd catalytic asymmetric transformations, we envisaged that the reaction between racemic 3′-indolyl-3-oxindoles with multifunctional MBH carbonates is very attractive for the construction of chiral 3,3′-bisindole skeletons with all-carbon quaternary stereogenic centers (Scheme c).…”