Synthesis
General procedure for the synthesis of 4-(1H-pyrazolyl)benzenemethanamine from 4-(1H-pyrazolyl)benzonitrile: To 4-(1H-pyrazolyl)benzonitrile (1.46 g, 8.63 mmol) was added a tetrahydrofuran solution (93 ml, 93 mmol) of 1 M borane-tetrahydrofuran complex and heated to reflux. After 16 hours of reaction, methanol (14 ml) was added to the reaction solution, which was subsequently concentrated under reduced pressure. To the residue 6N hydrochloric acid (265 ml) was added and heating to reflux was continued for 3 hours. After completion of the reaction, the solution was concentrated under reduced pressure and a small amount of water was added. The pH was adjusted to 11 with 30% aqueous sodium hydroxide under cooling in an ice bath and subsequently extracted with dichloromethane. The organic layer was separated, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluent: chloroform:methanol:28% ammonia = 90:10:1, V/V/V), the fraction containing the target compound was collected and concentrated under reduced pressure to afford the title compound 4-(1H-pyrazolyl)benzylamine (1.24 g, 83% yield) as a light yellow solid. Mass spectrum (CI, m/z): 174 (M++1). 1H-NMR spectrum (CDCl3, ppm): 7.91 (dd, J=2.5,0.5Hz, 1H), 7.72 (d, J=1.6Hz, 1H), 7.69-7.63 (m, 2H), 7.44-7.37 (m, 2H), 6.46 (dd, J=2.5, 1.6Hz, 1H). 1.6 Hz, 1H), 3.91 (s, 2H).
References
[1] Patent: EP2264009, 2010, A1. Location in patent: Page/Page column 103
[2] Patent: EP2415763, 2012, A1. Location in patent: Page/Page column 105
[3] Patent: WO2017/87837, 2017, A1. Location in patent: Paragraph 00270
[4] Patent: US2013/123281, 2013, A1. Location in patent: Paragraph 0127
[5] Patent: US9301951, 2016, B2. Location in patent: Page/Page column 231
