Cobalt-catalysed carbonylation of aryl halides

A novel method for carbonylation of aromatic and heteroatomatic halides is described. The catalytic system consists of a combination of alkylcobalt carbonyl complexes, either preformed or made "in situ", and bases such as alkoxides, NaOH and K2CO3 in aliphatic alcohols. Under these conditions new anionic cobalt complexes are formed which are characterized by a very high reactivity towards aromatic halides. The latter undergo the carbonylation reaction with high yield under very mild conditions.