Synthesis of 2-methyl-1H-benzo[d]imidazole and 2-ethyl-1H-benzo[d]imidazole from L-serine, L-threonine and L-cysteine

2-Methyl-1H-benzo[d]imidazole (5) and 2-ethyl-1H-benzo[d]imidazole (6) were obtained by the reaction of o-phenylenediamine with L-serine, L-cysteine or L-threonine respectively. The induction of the reaction was carried out by using two alternative methodologies: Fusion or Microwave (MW) radiation. The use of these synthetic processes proved to be simple and efficient. However, it is essential to use adequate safety measures to carry out these chemical reactions. The molecular structure of 5 and 6 was determined by 1H NMR, 13C NMR and X-ray diffraction. The probable reaction mechanism proposed in the present work involves the loss of water, hydrogen cyanide and migration of hydrogen atoms (or the methyl group).