Alkoxy- and amidocarbonylation of functionalised aryl and heteroaryl halides catalysed by a Bedford palladacycle and dppf: a comparison with the primary Pd(II) precursors (PhCN)2PdCl2 and Pd(OAc)2

The versatility of a Bedford-type palladacycle , namely {Pd(micro-Cl){kappa2-P,C-P(OC6H(2)-2,4-tBu2)(OC6H(3)-2,4-tBu2)2}}2], as a primary Pd source, in combination with the ligand bis-1,1'-(diphenylphosphino)ferrocene (dppf) has been established in carbonylation reactions of aryl and heteroaryl bromides with methanol, piperidine and related nucleophiles. Palladacycle has been compared with other primary Pd sources, e.g. (PhCN)2PdCl2 and Pd(OAc)2. The efficacy of the carbonylation processes appear to be linked to the Pd] concentration, substrate : catalyst ratio, CO pressure and reaction temperature. In amidocarbonylation, double carbonylation is observed for certain organohalides. In the case of 2,5-dibromopyridine, regioselective amination (Hartwig-Buchwald type) also occurs as a side-reaction.