181867-19-6

64-18-6

64910-49-2

181867-19-6

(d) Synthesis of 1-methyl-1H-benzimidazole-6-carbaldehyde: 4-amino-3-(methylamino)benzonitrile (0.40 g, 2.72 mmol) was dissolved in formic acid (9 mL) and the mixture was heated to 100 °C and maintained for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, nickel ruanne (0.4 g) and water (2 mL) were added, and the mixture was again heated to 100 °C and maintained for 1 hour. Subsequently, the reaction mixture was filtered through diatomaceous earth while hot, the filter cake was washed with methanol, the filtrates were combined and concentrated under reduced pressure. Water (1 mL) was added to the concentrated residue and saturated sodium bicarbonate solution was added slowly and dropwise to neutral. The precipitated solid was collected by filtration, washed with water and dried to afford 1-methyl-1H-benzimidazole-6-carbaldehyde (0.412 g, 95% yield) as a tan solid, which was used directly in the subsequent reaction.1H NMR (CDCl3) data: δ 10.12 (s, 1H), 8.05 (s, 1H), 8.00 (d, J = 0.8 Hz, 1H), and 7.92 (d, J = 8.0 Hz, 1H), 7.84 (dd, J = 1.2, 8.0 Hz, 1H), 3.94 (s, 3H).