870281-84-8

870281-85-9

3. Preparation of tert-butyl (S)-[1-(5-fluoro-4-oxo-3-phenyl-3,4-dihydroquinazolin-2-yl)propyl]carbamate In a 200 mL reaction flask, compound (V) (8.9 g, 0.02 mol) was dissolved in 100 mL acetic acid and stirred until completely dissolved. Zinc powder (9.1 g, 0.14 mol) was added to the reaction system in batches, the reaction temperature was controlled at 25°C and stirring was continued for 3 hours. Upon completion of the reaction, the reaction mixture was collected by vacuum filtration and the filter cake was washed with acetic acid (50 mL). The filtrate was concentrated and the filter cake was washed with dichloromethane (100 mL) and water (50 mL). Subsequently, the aqueous layer was extracted with dichloromethane (50 mL) and the organic phases were combined and washed sequentially with saturated sodium carbonate solution (50 mL) and saturated brine (50 mL). The organic layer was dried with anhydrous magnesium sulfate and concentrated to give the white solid compound (VI), i.e., tert-butyl (S)-[1-(5-fluoro-4-oxo-3-phenyl-3,4-dihydroquinazolin-2-yl)propyl]carbamate (6.2 g) in 78% yield and 95% purity.