Synthesis
General procedure for the synthesis of 7-benzyloxy-4-chloro-6-methoxyquinazoline from 6-methoxy-7-(benzyloxy)quinazolin-4(3H)-one: 2.1 g of 6-methoxy-7-(benzyloxy)quinazolin-4(3H)-one (Compound IV), 9.1 g of phosphorus trichloride, and 60 mL of ethylene dichloride were mixed, and the reaction was carried out by refluxing the reaction for 1 hour at 85 °C. Upon completion of the reaction, the excess phosphorous trichloride was removed by rotary evaporation. Ice water was added to the residue and the mixture was extracted with dichloromethane. The organic phases were combined, washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The desiccant was removed by filtration and the filtrate was concentrated under reduced pressure and purified by silica gel column chromatography, using a gradient elution of n-hexane to ethyl acetate in 5:1, 3:1 and 1:1 volume ratios, respectively. The eluted fractions at a volume ratio of hexane to ethyl acetate of 1:1 were collected to give 2.1 g of off-white solid (7-benzyloxy-4-chloro-6-methoxyquinazoline, compound 5) in 93.9% yield.
References
[1] Patent: CN105541736, 2016, A. Location in patent: Paragraph 0044; 0049
[2] European Journal of Medicinal Chemistry, 2017, vol. 125, p. 245 - 254
[3] Patent: CN105884699, 2016, A. Location in patent: Paragraph 0062; 0063
[4] Bioorganic and Medicinal Chemistry Letters, 2011, vol. 21, # 18, p. 5342 - 5346
