Fe/S-Catalyzed synthesis of 2-benzoylbenzoxazoles and 2-quinolylbenzoxazoles via redox condensation of o-nitrophenols with acetophenones and methylquinolines

Abstract

An Fe/S catalyst generated in situ from FeCl₂·4H₂O and elemental sulfur S₈ in the presence of a tertiary amine as a base was found to catalyze efficiently a 6e⁻ redox condensation of o-nitrophenols with acetophenones and methylquinolines. The condensed products 2-benzoylbenzoxazoles and 2-quinolylbenzoxazoles were obtained in reasonable yields with water as the only byproduct at a temperature as low as 80 °C.