Catalytic Asymmetric and Divergent Synthesis of Tricyclicand Tetracyclic Spirooxindoles: Controllable Site-Selective ElectrophilicHalocyclization of 1,6-Enynes

Catalytic asymmetric and divergent assembly of tricyclic and tetracyclic 3,3′-pyrrolidonyl spirooxindoles was developed, involving a one-pot chiral Bronsted base catalyzed asymmetric propargylation for the synthesis of oxindole 1,6-enynes and a subsequent switchable site-selective and highly diastereoselective electrophilic iodocyclization of 1,6-enynes. In addition, antitumor properties of the newly synthesized compounds were evaluated.