Sodium borohydride → 1-Cyclopropylpiperidin-4-ol

To a cold (0° C.) solution of 1-cyclopropyl-piperidin-4-one (1.5 g, 11 mmol, 1.0 eq.) in absolute ethanol was added sodium borohydride (306 mg, 8 mmol, 0.75 eq.). The reaction mixture was stirred at room temperature for 65 h. The mixture was concentrated in vacuo. Ice water (10 mL) was added, followed by an aqueous solution of sodium hydroxide (28% w/w, ca. 10 mL) and dichloromethane (20 mL). The mixture was stirred at room temperature for 2 h. After phase separation, the aqueous layer was extracted with dichloromethane. The combined organic layers were washed with brine, dried over sodium sulfate, filtered and evaporated in vacuo. The crude mixture was purified on silica eluting with DCM/2N NH3 in methanol 93/7, yielding to 1.44 g (95%) of the desired product as a colorless oil. MS (m/e): 423.1 (MH+, 100%)