Palladium-Catalyzed Asymmetric Cascade Intramolecular Cyclization/Intermolecular Michael Addition Reaction of Allenyl Benzoxazinones with 1-Azadienes

Nitrogen-containing heterocycles are pivotal scaffolds in various biologically active natural products and pharmaceuticals and exhibit broad biological and medicinal activity.1 The strategies to access N-heterocyclic compounds have drawn great attention; among them, palladium-catalyzed decarboxylative cycloaddition reactions are powerful synthetic tool.2 Recently, vinyl benzoxazinones have emerged as versatile blocks for constructing nitrogenous skeletons.3,4 As shown in Scheme 1, in the presence of a palladium catalyst, vinyl benzoxazinone leads to a pi-allyl Pd-intermediate bearing a Nnucleophile, and the zwitterion could undergo four paths (a- d) to form N-heterocycles. Path a is well developed, and