Synthesis
In a suitable reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser, 688 parts (10 mol) of a 44% aqueous formaldehyde solution were added and the pH was adjusted to 8.7 with 22 parts of 0.5 N NaOH solution.The temperature of the reaction system was maintained at 40 °C to which 284 parts (2 mol) of glyburide were subsequently added. During the reaction, the temperature was gradually increased to 55 °C, at which time most of the glyburide was dissolved. After about 15 minutes, the pH of the reaction system was adjusted to 8.0 with 5 parts of 0.5N NaOH solution to obtain a clarified light yellow solution. This solution was subjected to reduced pressure distillation at 50°C to remove the water until about 640 parts remained in the reaction vessel. The concentrated syrupy product was poured into 800 parts of methanol and a white crystalline precipitate was precipitated. After filtration and drying, 483 parts (92% yield) of 1,3,4,6-tetrakis(hydroxymethyl)tetrahydroimidazo[4,5-d]imidazole-2,5(1H,3H)-dione were obtained with a melting point of 132°C~136°C.
References
[1] Patent: WO2014/166347, 2014, A1. Location in patent: Page/Page column 14
[2] Patent: WO2015/143974, 2015, A1. Location in patent: Page/Page column 15; 16
[3] Chemistry of Heterocyclic Compounds, 2006, vol. 42, # 3, p. 365 - 376
[4] Russian Journal of Applied Chemistry, 2016, vol. 89, # 1, p. 132 - 139
[5] Zh. Prikl. Khim. (S.-Peterburg, Russ. Fed.), 2016, vol. 89, # 1, p. 103 - 111,9
