[Br:1][C:2]1[CH:15]=[CH:14][C:5]([CH2:6][N:7]2[CH2:11][C:10](=[O:12])[NH:9][C:8]2=[O:13])=[CH:4][CH:3]=1.[C:16](=O)([O-])[O-].[K+].[K+].IC>CN(C=O)C>[Br:1][C:2]1[CH:15]=[CH:14][C:5]([CH2:6][N:7]2[CH2:11][C:10](=[O:12])[N:9]([CH3:16])[C:8]2=[O:13])=[CH:4][CH:3]=11-(4-Bromobenzyl)imidazolidine-2,4-dione (1B4) (1.86 mmol, 500 mg) was dissolved in DMF (7 ml) and potassium carbonate (5.57 mmol, 770 mg) and iodomethane (1B5) (1.86 mmol, 0.116 ml, 264 mg) were added and the reaction mixture was stirred at 50° C. under nitrogen. The reaction was monitored by TLC and after 48 h of heating some starting material remained. An additional 2 equivalents of iodomethane (3.72 mmol, 0.232 ml, 528 mg) was added and the mixture stirred at 75° C. under nitrogen overnight. The reaction mixture was cooled to room temperature, filtrated and concentrated, then purified on silica eluting with heptane/EtOAc/EtOH 5/4/1 to give 1-(4-bromobenzyl)-3-methylimidazolidine-2,4-dione (1B6) 438 mg, (83%); 1H NMR (400 MHz, CDCl3) 7.51 (d, 2H) 7.15 (d, 2H) 4.53 (s, 2H) 3.74 (s, 2H) 3.06 (s, 3H).
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