To a solution of N-(4-iodo-2,5-dimethylphenyl)acrylamide (32.2 g, 107 mmol) in a 6:1 v/v mixture of N,N-dimethylformamide and isopropanol (700 mL) was added biphenyl-2-ylcarbamic acid piperidin-4-yl ester (36.3 g, 123 mmol). The resulting mixture was heated at 50° C. for 24 hours and then at 80° C. for 24 hours. The reaction mixture was then cooled to room temperature and concentrated under vacuum. The residue was dissolved in dichloromethane (1 L) and this solution was washed with 1N aqueous hydrochloric acid (500 mL), water (500 mL), brine (500 mL) and saturated aqueous sodium bicarbonate solution (500 mL). The organic layer was then dried over anhydrous magnesium sulfate and filtered. Ethanol (400 mL) was added and the resulting mixture was concentrated under vacuum to a volume of about 400 mL, at which time a precipitate had formed. The precipitate was filtered and dried to afford biphenyl-2-ylcarbamic acid 1-[2-(4-iodo-2,5-dimethylphenylcarbamoyl)ethyl]piperidin-4-yl ester (59.6 g, 84% purity, 79% yield). m/z: [M+H+] calcd for C29H32IN3O3 598.49; found 598.5.
