Palladium-Catalyzed Site-Selective Benzocylization of Aromatic Acids with o-Fluoro-Substituted Diaryliodonium Salts toward 3,4-Benzocoumarins.

By using 2-fluoro-substituted diaryliodonium salts, a novel benzocylization has been accomplished for the synthesis of 3,4-benzocoumarin derivatives via a cascade of ortho-arylation and defluorination in the presence of palladium catalysts. The reaction exhibits a broad compatibility of readily available aromatic acids with an excellent level of site-selectivity. Mechanistic investigations revealed a unique reactivity of carboxylic acid directed arylation by followed nucleophilic substitution of aromatic fluoride in the present system.