Palladium-catalyzed carbonylation of aryl and benzyl halides was pioneered by Heck and co-workers in 1970s and is an efficient way to prepare carboxylic acid derivatives. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 Based on the mechanistic studies reported so far, 14, 15 and 16 it is generally accepted that alkoxycarbonylation of aryl halides with CO proceeds through the following steps (Fig. 1): oxidative addition of an aryl halide (ArX) to Pd(0)Ln (I) to form ...