Cu(I)/Fe(III) promoted dicarbonylation of aminopyrazole via oxidative CH coupling with methyl ketones

Cu(I)/Fe(III) promoted C4-dicarbonylation of 5-aminopyrazole is developed. The strategy involved radical triggered direct oxidative coupling of 5-aminopyrazoles with methyl ketones using aerial oxygen as a source of oxygen in newly generated carbonyl group. CuI is used as catalyst and FeCl₃·6H₂O is used as additive and the reaction proceeded at 120?°C in DMSO for 9–12?h. It is found that use of Cu(II) catalyst gives the thiomethylated product by reacting with DMSO instead of oxidative coupling. A plausible mechanism is also given.