Borane → 4-Pyrazol-1-YL-benzylamine

To 4-(pyrazol-1-yl)benzonitrile (see WO 2005/095343A) (1.46 g, 8.63 mmol) was added a solution of 1M borane.tetrahydrofuran complex in tetrahydrofuran (93 ml, 93 mmol), followed by heating to reflux for 16 hours. After completion of the reaction, methanol (14 ml) was added to the reaction solution, followed by concentration under reduced pressure. 6N Hydrochloric acid (265 ml) was added to the residue, followed by further heating to reflux for 3 hours. After this solution was concentrated under reduced pressure, a small amount of water was added. The resulting solution was adjusted to pH 11 with a 30% aqueous sodium hydroxide solution under ice cooling, followed by extraction with methylene chloride. The separated organic layer was dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The resulting residue was subjected to silica gel column chromatography (eluent; chloroform:methanol:28% aqueous ammonia=90:10:1 (V/V/V)), and fractions containing the desired compound were concentrated under reduced pressure to afford the title compound (1.24 g) as a pale yellow solid. (Yield: 83%)