Synthesis
The general procedure for the synthesis of 4-(4-fluoro-3-(piperazine-1-carbonyl)benzyl)phthalazin-1(2H)-one from tert-butyl 4-(2-fluoro-5-((4-oxo-3,4-dihydrophthalazin-1-yl)methyl)benzoyl)piperazine-1-carboxylate was carried out as follows: the raw material (13.6 g, 29 mmol) was dissolved in 30 ml of ethanol at room temperature and slowly 6 ml of concentrated hydrochloric acid (60 ml) was added and the reaction was continuously stirred for 3 hours. After completion of the reaction, the reaction solution was concentrated to about 50 ml. The pH was adjusted to 10 with 4N NH4OH solution. subsequently, the reaction mixture was extracted with dichloromethane (3 x 50 ml), the organic phases were combined and washed with 50 ml of water. The organic phase was dried by adding anhydrous sodium sulfate for 30 min. After drying, the sodium sulfate was removed by filtration and the filtrate was allowed to stand overnight to precipitate the product. Finally, the white solid product 4-(4-fluoro-3-(piperazine-1-carbonyl)benzyl)phthalazin-1(2H)-one (9.9 g, 92% yield) was collected by filtration.
References
[1] Journal of Medicinal Chemistry, 2008, vol. 51, # 20, p. 6581 - 6591
[2] Patent: CN106946792, 2017, A. Location in patent: Paragraph 0074; 0081-0084
[3] Patent: CN106928149, 2017, A. Location in patent: Paragraph 0006; 0015; 0028; 0036; 0044-0046
[4] Journal of Medicinal Chemistry, 2015, vol. 58, # 21, p. 8683 - 8693
[5] Patent: WO2008/47082, 2008, A2. Location in patent: Page/Page column 22
