Stereodivergent Access to [6.7]-Fused N‑Heterocycles Bearing 1,3-Nonadjacent Stereogenic Centers by Pd-Catalyzed [4 + 2] Annulations

We describe a highly efficient stereodivergent [4 + 2] annulation reaction of vinyl benzoxazinaones and seven-membered cyclic N-sulfonyl aldimines for the synthesis of a wide array of N-heterocycles with 1,3-nonadjacent stereogenic centers via palladium catalysis. The polarity of solvents was found to play a key role in the switch of diastereoselectivity. Furthermore, good enantioselectivities of these reactions were achieved by the employment of commercially available Wingphos as the chiral ligand.