Carbonylativecycloaddition of allyl tosylates and alkynes proceeded in the presence of palladium catalysts to afford a range of cyclopentenones. In the presence of methanol, five-component coupling reactions gave methyl cyclopentenyl acetates, whereas in the absence of methanol, (cyclopentenoylmethylidene)furanones were formed from six components. Allyl tosylate was found to be essential for these