Trapping σ-Alkyl-Palladium(II) Intermediates with Arynes Encompassing Intramolecular C-H Activation: Spirobiaryls through Pd-Catalyzed Cascade Reactions.

A palladium-catalyzed cascade reaction based on the trapping of transient alkyl-Pd intermediates with arynes encompassing a C-H activation step has been developed. This synthetic pathway gives rise to hetero-spirocyclic scaffolds containing a biaryl motif, and opens up new synthetic strategies in the design of cascade reactions since it gathers several aspects of Pd chemistry, i.e., intra- and intermolecular carbopalladation of unsaturated species, C-H activation and C-C coupling processes.