Divergent Asymmetric Synthesis of Chiral Spiroheterocycles through Pd-Catalyzed Enantio- and Diastereoselective [3+2] Spiroannulation

Abstract

The palladium-catalyzed divergent asymmetric synthesis of chiral spiro-furanindoline derivatives is described. The zwitterionic alkoxy pi-allyl Pd(II) intermediate, generated catalytically from vinyl ethylene carbonate (VEC), could undergo ligand-controlled enantio-and diastereoselective dipolar [3 + 2] spiroannulation with indole-based azadienes to afford the optically active spiro-furanindolines embedding an all-carbon quaternary stereocenter in high yields (up to 99%) with good to excellent stereoselectivities (up to 99% ee and up to >94:6 dr).