Microwave-Assisted One-Pot Synthesis of 2-Substituted Benzoxazoles from Nitrophenol and Carboxylic Acids

Abstract

We have developed a convenient microwave-assisted synthesis of benzoxazoles starting from nitrophenol and carboxylic acids. The reaction sequence can be performed as a one-pot synthesis comprising an initial reductive transfer hydrogenation of the nitro-group with 1,4-cyclohexadiene and Pd/C followed by subsequent formation of the heteroaromatic moiety with propylphosphonic anhydride (T3P). The method gives facile access to various 2-substituted benzoxazoles in 56–83 % yield.