A mixture of 1-(2,2-difluoroethyl)-3-methyl-2-oxo-4-imidazolidinecarboxylic acid (125 mg, 0.6 mmol), 1-hydroxybenzotriazole hydrate (110 mg, 0.720 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (138 mg, 0.720 mmol) and N-ethylmorpholine (0.305 ml, 2.400 mmol) in dichloromethane (5 ml) was stirred for 10 minutes. [(2,4-Dichlorophenyl)methyl]amine (106 mg, 0.600 mmol) was added and the solution was stirred at room temperature for 3 days. The reaction mixture was diluted with dichloromethane (10 ml), washed with saturated sodium hydrogen carbonate solution (10 ml), water (10 ml) and brine (10 ml). The organic phase was dried (magnesium sulphate) and evaporated. The residue was purified by the mass-directed automated HPLC. The fraction containing the desired product was evaporated and the residue was triturated with diethyl ether and dried to give N-[(2,4-dichlorophenyl)methyl]-1-(2,2-difluoroethyl)-3-methyl-2-oxo-4-imidazolidinecarboxamide (25 mg). LC/MS [M+H]+=366, retention time=2.09 minutes.
