Acylation of urea derivative (I) with cyanoacetic acid (II) in HOAc in the presence of Ac2O yields derivative (III), which is then cyclized by treatment with NaOH to provide (IV). Nitrosation of (IV) with NaNO2 and HCl affords nitroso derivative (V), which is then hydrogenated over Pd/C in EtOH to furnish substituted pyrimidinedione (VI). Finally, (VI) is coupled to Trolox (VII) with N-ethyl-N'-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC稨Cl) and 1-hydroxybenzotriazole (HOBt) in DMF or with 4-(dimethylamino)pyridine (DMAP) and N-dicyclohexylcarbodiimide (DCC) in CH2Cl2 to yield the target compound.