Catalytic enantioselective synthesis of 2-aryl-chromenes.

An enantioselective Pd-catalyzed 6-endo-trig reaction for the synthesis of 2-aryl-chromenes has been developed. A systematic optimization of a TADDOL-derived ligand set resulted in the identification of a novel monodentate phosphoramidite-palladium catalyst that accesses 2-aryl-2H-chromenes with high yield and enantioselectivity under mild conditions. The products obtained from this method can be transformed into biologically active compounds through functionalization of the chromene alkene.