Preparation of tert-butyl 4-(3-(1H-tetrazol-5-yl) phenylcarbamoyl)-4-methylpiperidine-1-carboxylate. To a solution of 1-(tert-butoxycarbonyl)-4-methylpiperidine-4-carboxylic acid (100 mg, 0.41 mmol) in dichloroethane (2.0 mL) were added DMF (2 drops) and pyridine (0.13 g, 1.6 mmol), followed by oxalyl chloride (57 mg, 0.45 mmol). The mixture was stirred for 40 minutes, and 3-(1H-tetrazol-5-yl)-phenylamine was added. The mixture was stirred for 2 hours, and a pink precipitate formed. The mixture was filtered, and the filtrate was washed with 1.0 N aq. HCl and brine, dried over MgSO4, and concentrated to give the title compound in 70% yield. MS (ES+) [M+H]+=387.
