1-Aminopiperidine → 4-Chloro-N-1-piperidinylbutanamide

Add 4-chloro-butyryl chloride (5 mL, 43 mmol) to piperidin-1-ylamine (4.3 g, 43 mmol) in dichloromethane (100 mL) at room temp. Stir the reaction mixture at room temp for two hours. Add the reaction mixture into ice and saturated sodium bicarbonate solution. Extract the mixture with dichloromethane (100 mL). Wash the organic layer with saturated sodium bicarbonate solution (50 mL), dry with magnesium sulfate, filter and evaporate solvent under reduced pressure to obtain 5 g (57%) of the title compound as a white solid: Mass spectrum (ion spray): m/z=205.1 (M+H).