Palladium‐Catalyzed Site‐Selective C7 Oxidative Arylation of 4‐EWG‐1H‐Indazoles

Abstract

An efficient palladium‐catalyzed oxidative arylation of substituted 1H‐indazole with various arenes and heteroarenes as coupling partners is reported. A site selective C7 oxidative arylation was perfectly achieved with a directing electron‐withdrawing groups (EWG) located at the C4 position of the 1H‐indazole. The desired products are obtained in moderate to good yields from 4‐NO2 or 4‐CO2Me 1H‐indazoles and various (hetero)aryls as coupling partners in the presence of Pd(OAc)2 as catalyst, phenanthroline as ligand, Ag2CO3 as oxidant and NaOH as the base. Density functional theory was also conducted for reaction mechanism comprehension. This approach provides a highly effective, direct, and atom economical way to build C7‐ (het)arylated 1H‐indazole compounds.