Palladium-catalysed heteroannulation with terminal alkynes: synthesis of phthalides 1

The palladium–copper-catalysed heteroannulation of o-iodobenzoic acid 3 with terminal alkynes 4–18 leads to the synthesis of (Z)-3-alkylidenephthalides 19–33 as the major products. In certain cases, the formation of isocoumarins 34–37 is also observed.