General procedure for the synthesis of (2-ketoimidazolyl)-acetic acid from 1-(2-hydroxyethyl)-2-imidazolidinone: 15% aqueous sodium bicarbonate (21 ml) was added to a solution of 1-(2-hydroxyethyl)-2-imidazolidinone (1.00 g, 7.68 mmol) in acetone (70 ml) to form a white slurry, which was subsequently cooled to 0°C (Refs. JOC 2003, 68, 4999-5001). Sodium bromide (0.16 g, 1.54 mmol) and TEMPO (0.024 g, 0.15 mmol) were added sequentially and the mixture was stirred for 10 min. Subsequently, trichloroisocyanuric acid (3.57 g, 15.4 mmol) was added in five equal portions, each five minutes apart. The light yellow slurry was warmed to 25°C and stirring was continued for 12 hours to obtain a yellow solution. Isopropanol (9 ml) was added and stirred for 45 minutes to form a white slurry which was filtered through diatomaceous earth. The filter cake was washed with an appropriate amount of solvent. The filtrate was concentrated under reduced pressure, neutralized with saturated aqueous sodium bicarbonate and extracted with ethyl acetate (50 ml). The aqueous phase was adjusted to pH ≈ 2 with 4N HCl and then extracted continuously with a 5% methanol/dichloromethane solvent mixture (~120 ml) for 16 hours. The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give (2-oxoimidazolidin-1-yl)acetic acid (0.530 g, 48% yield) as a white solid.
