Synthesis
Boc₂O (7.75 mL, 33.4 mmol) was added to a solution of ethyl piperidine-3-carboxylate (15 g, 95 mmol) in THF (159 mL) at room temperature, and the mixture was stirred for 16 h at room temperature. The resulting reaction mass was diluted with water (50 mL) and then extracted with ethyl acetate (3 x 100 mL). The combined organic extract was washed with saturated NaHCO₃ solution (1 x 200 mL) and brine (20 mL), dried (Na₂SO₄), filtered, and concentrated. The resulting residue was purified by ELSD ISCO on a 120 g silica gel column, eluting the compound in hexane to approximately 25% ethyl acetate. The pure fraction was collected and concentrated to give the desired product, 1-tert-butyl-3-ethylpiperidine-1,3-dicarboxylate. The final product, ethyl Ethyl 1-Boc-3-piperidinecarboxylate, was obtained in a yield of 23.39 g, 91 mmol, 95%.
