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]­isoindol-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.