Palladium-Catalyzed [5 + 1] Annulation of Salicylic Acid Derivatives and Propargylic Carbonates

A palladium-catalyzed annulation reaction between salicylic acid derivatives and propargylic carbonates via the cleavage of a propargylic carbon–oxygen bond is described. This rare annulation reaction uses propargylic compounds as the C1 component for heterocyclic products and can be applied to the preparation of unique five- or six-membered cyclic compounds. The corresponding products contain a fully substituted allylic carbon and the reaction is characterized by high functional-group tolerance. A palladium-catalyzed [5 + 1] annulation that uses propargylic carbonates as one-carbon (C1) components to afford five- or six-membered heterocycles is reported. Various salicylic acid and propargylic carbonate derivatives engage in this reaction to furnish complex heterocyclic products. Moreover, nucleophilic substrates other than salicylic acids can be used in this reaction.