Organocatalytic Arylation of α-Ketoesters Based on Umpolung Strategy: Phosphazene-Catalyzed S_NAr Reaction Utilizing [1,2]-Phospha-Brook Rearrangement

An organocatalytic arylation of α-ketoesters was developed on the basis of umpolung strategy. Phosphazene P2-tBu efficiently catalyzes the three-component coupling reaction of α-ketoesters, a silylated secondary phosphite, and electron-deficient fluoroarenes to provide α-hydroxyester derivatives possessing an electron-deficient aryl group at the α-position. The reaction involves the catalytic generation of α-oxygenated ester enolates from α-ketoesters through the [1,2]-phospha-Brook rearrangement followed by the S_NAr reaction.