Abstract
A versatile green chemical procedure for the highly selective construction of 2-aryl substituted benz-/naphthimidazoles starting from the reaction of aromatic 1,2-diamines with a series of substituted arylthioprolines with three to five drops of water under simple grinding at ambient temperature in good yields is described. The short reaction time, simplified experimental procedure, the absence of extraction and chromatographic purification steps in addition to the environment affability makes this green strategy highly attractive in view of green chemistry. The expected reaction to furnish the thiazole grafted benz-/naphthimidazole did not occur. Perhaps the arylthioprolines could be in zwitterionic form, which could react with 1,2-diamine giving dihyrobenzimidazole, which undergoes air oxidation to furnish the 2-aryl benzimidazole rather than the expected thiazole grafted imidazoles. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.