Microwave assisted Cobalt(III)-catalysed C-H aminocarbonylation reactions with isocyanates for the synthesis of thiophenecarboxamides

A mild and efficient cobalt(III)-catalysed C-H aminocarbonylation procedure for thiophenes and benzo[b]thiophenes, using pyridine and pyrimidine directing groups to control site selectivity has been developed under MW assisted conditions. The reaction is effective with aromatic isocyanates with wide substitution patterns, although aliphatic isocyanates showed less reactivity. The introduced amide group can act as directing group in further iterative C-H functionalization reactions, allowing the diversification of the heterocyclic structures. DFT calculations have shed light on the mechanistic course and reactivity patterns