Switchable Synthesis of Arylalkynes and Phthalides via Controllable Palladium-Catalyzed Alkynylation and Alkynylation-Annulation of Benzoic Acids with Bromoalkynes.

A ligand-promoted palladium(II)-catalyzed synthesis of arylalkynes and phthalides from benzoic acids and bromoalkynes via carboxylate-assisted ortho-C-H activation is reported. A series of phthalides with various functional groups are prepared via ortho-alkynylation and alkynylation-annulation. Moreover, the key ortho-alkynylated products are also obtained by controlling the reaction conditions. In addition, heteroaryl acids could react smoothly to form the corresponding alkynylation and cyclization products.