Methyl 1-[(2'-cyanobiphenyl-4-yl)methyl]-2-ethoxy-1H-benzimidazole-7-carboxylate

78-09-1

136304-78-4

139481-44-0

Using methyl 3-amino-2-(((2'-cyano-[1,1'-biphenyl]-4-yl)methyl)amino)benzoate (MBA) and tetraethyl orthocarbonate (TEC, 397 kg) as the raw material, the mixture was heated at reflux in the presence of acetic acid (62 kg) at 78 to 82 °C for 1 to 2 hours. After completion of the reaction, the reaction solution was cooled and methanol (1680 L), 24% aqueous sodium hydroxide (65 L) and water (2030 L) were added sequentially. The mixture was stirred at 60 to 30 °C for 2 h and the pH was adjusted with aqueous sodium hydroxide solution to 5 to 7. After cooling to below 5 °C, the precipitated crystals were separated and washed with cold water (2500 L) and cold ethyl acetate (500 L) to obtain the first batch of crystals. The mother liquor and washings were concentrated under reduced pressure, cooled to below 5 °C, and the precipitated crystals were separated and washed with cold ethyl acetate (20 L) to obtain the second batch of crystals. The first and second batches of crystals were combined, dissolved in ethyl acetate (4890 L) and heated to reflux. The crystal seeds were added at about 70 °C and then cooled to 5 °C. The crystals were separated, washed with cold ethyl acetate (200 L) and dried to give methyl 1-[(2'-cyanobiphenyl-4-yl)methyl]-2-ethoxy-1H-benzimidazole-7-carboxylate (BEC, 361 kg, 84.8% yield). The product melting point was 168.5-169.5 °C. 1H-NMR (200 MHz, CDCl3) δ: 1.42 (3H, t), 3.71 (3H, s), 4.63 (2H, q), 5.59 (2H, s), 7.09 (2H, d), 7.20 (1H, t), 7.45-7.59 (5H, m), 7.69- 7.80 (2H, m), 7.92 (1H, dd).IR (KBr) cm-1: 2225, 1725, 1550, 1480, 1430, 1280, 1250, 1040, 760, 750.