Synthesis of benzimidazoles from <i>o</i> -phenylenediamines with α-keto acids <i>via</i> amino acid catalysis

A green and simple method for the synthesis of benzimidazoles by amino acid catalysis of <i>o</i>-phenylenediamines with α-keto acids has been developed. The reaction proceeded smoothly in water under air and metal catalyst-free conditions to obtain 2-substituted benzimidazoles. Furthermore, the method was performed in an open system at room temperature, making the experimental operation very simple and greatly enhancing the accessibility of the method.