Ligand-Free Pd-Catalyzed Synthesis of 3-Allylbenzofurans by Merging Decarboxylative Allylation and Nucleophilic Cyclization

A new single Pd-catalyzed decarboxylative allylation-nucleophilic cyclization relay is reported by using alpha-alkynyl arylols and vinylethylene carbonates (or vinyl carbamates), and a wide range of 3-allyl benzofurans with generally good yields were stereoselectively synthesized under mild conditions, among which the complete stereoselectivity of some cases was also observed. Notably, the present catalysts can tolerate air conditions without any ligand, additive, or base, opening new avenues to build up oxa-heterocycle frameworks through catalytic difunctionalization of internal alkynes.