Cationic Gold(I)-Catalyzed Cascade Bicyclizations for Divergent Synthesis of (Spiro)polyheterocycles

We herein report an expeditious synthetic strategy to access diverse (spiro)polyheterocycles from easily available starting materials in two operational steps including an Ugi four-component reaction and a cationic gold(I)-catalyzed cascade bicyclization. Divergent synthesis of these structurally complex pyrido[2,1-a]isoindo1-4(6H)-ones and spiroisoquinoline-pyrrole-3,5'-diones via a cascade nucleophilic cyclization/intramolecular 1,3-migration/1,5-enyne cycloisomerization process and a tandem hydroamination/Michael addition sequence, respectively, was controlled by substituents, where the electronic effect on the migrating groups and steric effect of the secondary amide moieties play crucial roles.