Pd-Catalyzed Chelation-Assisted Regioselective and Site Selective Cyclative C-H Annulation of Alkynyl Oximes with Activated Alkynes.

Electrophilic cyclization and concomitant C-H annulation constitute an expedient cascade strategy for the construction of multicyclic scaffolds with precise substitutional patterns. We report here a novel Pd-catalyzed cyclative annulation of ynone oxime with activated alkynes. The cascade features a dual regioselectivity including site selective C-H activation and chelation-assisted selective insertion of alkynes. Control experiments together with kinetic experiments give insights into the mechanism.