Copper-Catalyzed Synthesis of Benzoxazoles via a Regioselective C−H Functionalization/C−O Bond Formation under an Air Atmosphere

An efficient method for the synthesis of functionalized benzoxazoles is described that involves a copper(II)-catalyzed regioselective C-H functionalization/C-O bond formation protocol. The use of dichlorobenzene as a solvent at 160 degrees C allows the use of air as the terminal oxidant in the catalytic synthesis of benzoxazoles in a process that has high functional group tolerance. The presence of a directing group at the meta position markedly improves the reaction efficacy and a variety of 7-substituted benzoxazoles are selectively produced under mild reaction conditions. The mechanism of the reaction is also discussed in this report.