Carbamoylation of Aryl Halides by Molybdenum or Tungsten Carbonyl Amine Complexes

When aryl halide is treated with molybdenum carbonyl amine complex in the presence of base, carbamoylation proceeds to give amide in good yield. The proposed mechanism involves oxidative addition of aryl halide to molybdenum(0) complex, migratory insertion to carbon monoxide giving acyl(amino)molybdenum(II) or aryl(carbamoyl)molybdenum(II) intermediate, and reductive elimination of the amide. This method is simple and provides an alternative method to the conventional palladium-catalyzed amide formation using gaseous carbon monoxide.