Catalytic Asymmetric and Divergent Synthesis of Tricyclic and Tetracyclic Spirooxindoles: Controllable Site-Selective Electrophilic Halocyclization of 1,6-Enynes.

Catalytic asymmetric and divergent assembly of tricyclic and tetracyclic 3,3'-pyrrolidonyl spirooxindoles was developed, involving a one-pot chiral Brønsted 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.