Selective N1-Acylation of Indazoles with Acid Anhydrides Using an Electrochemical Approach.

An electrochemical synthesis method for the selective N1-acylation of indazoles has been developed. This "anion pool" approach electrochemically reduces indazole molecules generating indazole anions and H2. Acid anhydrides are then introduced to the solution resulting in selective acylation of the N1-position of the indazoles. This procedure can also be applied to the acylation of benzimidazoles and indoles. The reaction can also be performed using a 9 V battery without loss of reaction efficiency.