Merging π-Acid and Pd Catalysis: Dearomatizing Spirocyclization/Cross-Coupling Cascade Reactions of Alkyne-Tethered Aromatics

A one-pot protocol for the dearomatising spirocyclisation/cross coupling of alkyne-tethered indoles/pyrroles is described. Mechanistic studies support a process by which palladium complexes generated in situ act as both π-acid and cross coupling catalysts. Overall, this facilitates an efficient cascade process that enables the simultaneous preparation of synthetically challenging quaternary spirocyclic carbons and tetrasubstituted alkenes in a single operation. KEYWORDS spirocycles, dearomatisation, cross coupling, palladium, catalysis