Norbornenone (5b), obtained from the reaction of 2,5-dimethyl-3,4-diphenylcyclopentadienone dimer (3) with bromomaleic anhydride (4b), provides an excellent base-triggered source of carbon monoxide for palladium-catalysed carbonylation reactions. Aminocarbonylation, ketoamide synthesis, and Suzuki–Miyaura reactions of aryl iodides carried out in a two-chamber reaction vessel gave good to excellent yields of carbonylated products.