A novel approach to coumarin derivatives has been developed starting from readily available 2-(1-hydroxyprop-2-ynyl)phenols, based on an unprecedented palladium-catalyzeddicarbonylation process. Reactions were carried out in thepresence of catalytic amounts of PdI2 in conjunction withan excess of KI in MeOH as the solvent at room temperatureand under 90 atm of CO to give 3-[(methoxycarbonyl)methyl]coumarins in good to high isolated yields (62−87%).