56248-10-3

The general procedure for the synthesis of 4-phenyl-1(3)H-imidazole-2-carboxaldehyde from glyoxal dimethyl acetal and phenylpropanol hydrate was as follows: phenylglyoxal monohydrate (102 g, 0.67 mol) and glyoxal dimethyl acetal (60% aqueous solution, 232 mL, 1.54 mol) were dissolved in methanol (1.1 L), followed by the addition of ammonium acetate (820 g 2.61 mol) to the methanol solution (1.1 L). The reaction mixture was stirred at room temperature for 16 hours. Upon completion of the reaction, the volatile solvent was removed by distillation under reduced pressure. The residue was suspended in 2N HCl solution (1.1 L) and heated at 80 °C for 30 min. After cooling, the reaction mixture was extracted with EtOAc (200 mL). The aqueous layer was separated and adjusted to pH 9 with 9N NaOH solution. the precipitated solid was filtered, washed with water and dried under vacuum to afford 4-phenyl-1(3)H-imidazole-2-carboxaldehyde (97.2 g, 84% yield) as a light brown solid. the LC-MS analysis resulted in: m/z = 173.0 (MH+), and the retention time tR = 0.66 min (Method C). the reaction was carried out at a pressure of 1.5 mL. the reaction mixture was extracted with EtOAc (200 mL).

[1] Patent: US2010/16303, 2010, A1. Location in patent: Page/Page column 19
[2] Patent: WO2012/7006, 2012, A1. Location in patent: Page/Page column 60
[3] Patent: WO2009/152825, 2009, A1. Location in patent: Page/Page column 46