Synthesis and biological activities of benzimidazole derivatives from peptides.

About 30 dipeptides and some tripeptides were led to new benzimidazole derivatives by incorporating their carboxyl groups into benzimidazole ring by the reaction with o-phenylene-diamine. The ring closure to benzimidazole was well achieved by heating mildly at a moderate temperature in acetic acid. Some benzimidazole derivatives of peptides had remarkable phytotoxicities.