1142188-60-0

62458-96-2

24424-99-5

1142188-60-0

Preparation of Compound 12F: 7-Benzyl-5,6,7,8-tetrahydropyrido[3,4-D]pyrimidin-4(3H)-one (Compound 12E, 2.5 g, 10.4 mmol), 10% Pd/C (0.5 g) and di-tert-butyl dicarbonate (2.7 g, 12.4 mmol) were dissolved in methanol (40 mL). The reaction mixture was stirred overnight under hydrogen atmosphere (0.5 Mpa pressure). The reaction process was monitored by thin layer chromatography (TLC, unfolding agent ratio dichloromethane/methanol = 10:1). After completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated to afford purified tert-butyl 4-hydroxy-5,6-dihydropyrido[3,4-d]pyrimidine-7(8H)-carboxylate (Compound 12F, 2.6 g, 100% yield) as a yellow solid.