Synthesis of phthalides via Pd/CNTs-catalyzed reaction of terminal alkynes and o-iodobenzoic acid under copper- and ligand-free conditions

A phosphine- and copper-free protocol for the synthesis of phthalides via Pd/CNTs-catalyzed tandem coupling-cyclization process has been developed. The palladium immobilized on CNTs showed high catalytic activity, and the reactions with a variety of terminal alkynes and o-iodobenoic acid proceeded smoothly to give phthalides in moderate to good yields catalyzed by 0.1% mmol Pd/CNTs.