(3-Adamantan-2-yl-1-benzyl-ureido)-acetic acid ethyl ester (450 mg) was dissolved in dry DCM (5 mL) and toluene (5 mL) under argon and cooled to −78° C. Diisobutylaluminium hydride (1 M solution in DCM, 1.46 mL) was added drop by drop over 5 minutes and the mixture was allowed to stir at −78° C. for 30 minutes. The cooling bath was removed and after 10 minutes, the reaction mixture was quenched by addition of aqueous potassium sodium tartrate solution (1M, 15 mL). The mixture was extracted with chloroform twice and the combined organic extracts were washed with brine. The combined organic layers were shaken with 25% HCl (30 mL) for 5 minutes and the layers were separated. The organic solution was dried with sodium sulfate, filtered and evaporated to give a crude product that was purified by flash chromatography using a gradient of 20% to 80% ethyl acetate in heptane as an eluent. The fractions containing the product were combined and evaporated to give 1-adamantan-2-yl-3-benzyl-1,3-dihydro-imidazol-2-one as a white solid (276 mg). MS (EI): 308.2 (M+).
