To a solution of the 4-methyl-piperidine-1,4-dicarboxylic acid mono-tert-butyl ester (5 g, 20.6 mmol) in toluene (40 mL) at 23° C. was added triethylamine (4.3 mL, 31 mmol) and diphenylphosphoryl azide (6.1 mL, 28.0 mmol). The resulting mixture was stirred at 23° C. for 45 minutes after which benzyl alcohol (11.1 mL, 103 mmol) was added. The reaction mixture was then heated to 80° C. for 16 hours. The reaction mixture was allowed to cool to room temperature and the excess solvents were removed under reduced pressure. The crude residue was purified by chromatography (silica gel, eluting with 10% ethyl acetate/90% hexane to 30% ethyl acetate/70% hexane) to provide the titled compound (5.6 grams). MS (CI) m/z 249 (M−99)+; 1H NMR (300 MHz, CDCl3) δ ppm 7.38-7.31 (m, 5H), 5.05 (s, 2H), 4.57 (s, 1H), 3.67-3.60 (m, 2H), 3.18 (m, 2H), 1.98-1.90 (m, 2H), 1.44 (s, 9H), 1.37 (s, 3H).
