25063-68-7

To a preheated mixture of 3-aminopyridine (0.37 g, 4.0 mmol) and 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid, 0.69 g, 4.8 mmol) was added triethyl orthoformate (4.0 mL, 24.0 mmol). The reaction mixture was stirred at 100 °C for 2 h. The formation of a yellow precipitate was observed during the reaction and the color of the solution gradually changed from yellow to burgundy. Upon completion of the reaction, the mixture was cooled to room temperature and the excess triethyl orthoformate was subsequently removed by vacuum distillation. The resulting solid was purified by silica gel column chromatography with the eluent being a gradient of 70% to 100% ethyl acetate in hexane solution.

[1] Journal of the American Chemical Society, 2009, vol. 131, # 2, p. 763 - 777
[2] Journal of Medicinal Chemistry, 2017, vol. 60, # 4, p. 1343 - 1361
[3] Patent: WO2017/31255, 2017, A1. Location in patent: Paragraph 0086