Access to 5,6-Spirocycles Bearing Three Contiguous Stereocenters via Pd-Catalyzed Stereoselective [4+2] Cycloaddition of Azadienes

We present herein a highly diastereo- and enantioselective Pd-catalyzed [4 + 2] cycloaddition of benzofuran-derived azadienes with vinyl benzoxazinanones, which represents a rare highly stereoselective cycloaddition of this class of fused azadienes as a two-atom synthon. The use of a phosphoramidite ligand bearing a chiral secondary amine with a simple biphenyl backbone proved to be the key to construct the novel spirocyclic tetrahydroquinoline scaffold containing three contiguous stereocenters as a single diastereomer in high enantioselectivity.