A flexible approach to Pd-catalyzed carbonylations via aroyl dimethylaminopyridinium salts

4-Dimethylaminopyridine (DMAP) is shown to undergo Pd/P(t)Bu(3) catalyzed coupling with aryl halides and carbon monoxide to form electrophilic aroyl–DMAP salts. The reaction is easily scalable to prepare multigram quantities with low catalyst loadings, while the precipitation of these salts as they form leads to products with low impurities. These reagents rapidly react with a variety of nucleophiles, including those that contain potentially incompatible functional groups under standard carbonylative conditions.