Palladium(II)-Catalyzed Heteroannulation Route to Dihydrobenzofurans

Significance

Reported is the synthesis of di­hydrobenzofurans 2 from homobenzylic alcohols 1 via an intramolecular palladium-catalyzed C-H activation/C-O cyclization sequence. Both EDGs and EWGs are tolerated at various positions around the ring. Yields are excellent (>75%) in almost all cases, except for R^³ = CO₂Et (50%) and R^³ = H (42%). The stability of halogen substituents (R^¹ = Cl, Br) to the reaction conditions, providing a handle for further functionalization, is worthy of note. Two examples of spirocyclic dihydrobenzofurans (a model system for the core structure of the natural product stachybotrylactam) were also prepared in high yield.