To a solution of 2 g of 1-(tert-butoxycarbonyl)-3-piperidinecarboxylic acid (commercially available) (8.72 mmol) in 15 mL of DMF: DCM (3:1) was added 1.39 g 2-phenylpiperidine (commercially available) (8.72 mmol) and 3.04 mL DIPEA (17.4 mmol). The mixture was stirred at room temperature for 10 minutes. 2.5 g EDCI (13.1 mmol) and 2.04 g HOBT (13.1 mmol) was added. The mixture was stirred for 6 h at room temperature, diluted with brine (50 mL) and extracted with ethyl acetate (2×40 mL). The combined organic layers were dried over sodium sulfate, filtered and evaporated at reduced pressure to obtain the crude product, which was further purified by column chromatography on silica eluting with 30-35% ethyl acetate in hexane to yield 1 g (31%) of the title compound. (MH+) 372.18.
