Transition-metal-free regioselective C-H halogenation of imidazo[1,2- a ]pyridines: sodium chlorite/bromite as the halogen source.

A facile transition-metal-free regioselective halogenation of imidazo[1,2- a ]pyridines using sodium chlorite/bromite as the halogen source is presented. The reaction has provided an efficient method for the formation of C-Cl or C-Br bonds to synthesize 3-chloro or 3-bromo-imidazo[1,2- a ]pyridines which were then efficiently transformed into imidazo[1,2- a ]pyridine core π-systems by Suzuki-Miyaura reactions.