4-Benzyl-piperidine-4-carboxylic acid ethyl ester (2.5 g, 10 mmol), (2-bromo-ethyl)-carbamic acid benzyl ester (2.58 g, 10 mmol) and DIPEA (1.7 mL, 10 mmol) are dissolved in THF (50 mL) and heated at 80° C. for 15 h. The mixture is poured into Et2O (200 mL) and washed with sat. Na2CO3 (50 mL). The ether phase is extracted with 1M aqueous HCl (3×50 mL), the aqueous extracts washed with ether (50 mL) and adjusted to pH 14 with cooled 33% aqueous NaOH. The aqueous phase is extracted with CH2Cl2 (4×50 mL). The organic extracts are dried (Na2SO4), filtered and evaporated to provide the title compound.
