Direct C3 Carbamoylation of 2H-Indazoles

We developed a novel method for direct C3 carbamoylation of 2H-indazoles using oxamic acids as carbamoyl radical sources. In the presence of ammonium persulfate, carbamoyl radicals were generated from oxamic acids, then used for further reactions with 2H-indazoles to afford the desired products. The reaction proceeds under metal- and catalyst-free conditions. This simple process allows for the efficient synthesis of C3 carbamoylated 2H-indazoles, which are important scaffolds in organic synthesis.