According to Scheme 3 Step 5: A suspension of compound 6(D) (60 mg, 0.22 mmol), 4-isopropylbenzyl bromide (41 μL, 0.24 mmol) and potassium carbonate (90 mg, 0.65 mmol) was stirred at 60° C. for 15 h in acetonitrile (2 mL). The mixture was diluted with AcOEt and water. The organic layer was washed twice with water and once with brine. The resulting organic layer was dried over MgSO4 and concentrated under reduced pressure. The crude product was purified by flash chromatography over silica gel (Merck Flashmart prepacked column 10 g SiO2) using CH2Cl2/MeOH 98/2 as eluent to afford N-(3-(4-(4-isopropylbenzyl)-6-methoxy-3,5-dioxo-4,5-dihydro-1,2,4-triazin-2(3H)-yl)phenyl)acetamide 6(E) (10 mg, 11%) as a yellow solid.
