Preparation of tert-butyl 4-methyl-4-(3-(oxazol-5-yl)phenylcarbamoyl)piperidine-1-carboxylate. To a solution of 1-(tert-butoxycarbonyl)-4-methylpiperidine-4-carboxylic acid (61.3 mg, 0.252 mmol) and pyridine (79.7 mg, 0.08 mL, 1.01 mmol) in 1,2-dichloroethane (2 mL) at 0° C. was added DMF (1-2 drops) followed by oxalyl chloride (31.9 mg, 0.022 mL, 0.252 mmol). The reaction was stirred for 0.5 hour, and 3-(oxazol-5-yl)aniline (40.4 mg, 0.252 mmol) was added. The reaction was allowed to stir for another 1.5 hours. The mixture was diluted with ethyl acetate (10 mL), and the organics were washed with 0.1 N HCl (2×10 mL), brine (4 mL), dried over MgSO4, filtered, and concentrated to give the title compound, which was used in the next step without further purification. MS (ES+) [M+H]+386.2.
