Direct Assembly of Phthalides via Calcium(II)-Catalyzed Cascade ortho -C-Alkenylation/Hydroacyloxylation of 3-Aminobenzoic Acids with Alkynes in Hexafluoroisopropanol.

By virtue of a calcium(II)/hexafluoroisopropanol cocatalytic system, the efficient and practical coupling of 3-aminobenzoic acids with alkynes has been realized, giving direct and regioselective access to the phthalide framework with good substrate/functional group compatibility. Mechanistic studies identified 3-amino-2-vinylbenzoic acid species as the active intermediate, thereby revealing an ortho -C-alkenylation/hydroacyloxylation cascade for this transformation.