4-Chloro-6-methoxy-8-methylpteridin-7(8H)-one (4.00 g, 17.7 mmol, 1 equiv) and 1-piperidin-4-yl-1,3-dihydro-2H-benzimidazol-2-one (3.83 g, 17.7 mmol, 1 equiv) were suspended in anhydrous n-butanol (40 mL) in a 250 mL one-necked round-bottomed flask. Triethylamine (35.30 mmol, 3.57 g, 4.92 mL, 2 equiv) was added to the flask, and the stirred reaction mixture was heated to 80° C. The reaction was monitored by LC/MS and was complete after 6 hours. The resulting tan colored suspension was cooled to room temperature and filtered. The collected solid was washed with n-butanol (10 mL) and anhydrous ether (25 mL). The solid was air-dried to give the desired material, 6-methoxy-8-methyl-4-[4-(2-oxo-2,3-dihydro-1H-benzimidazol-1-yl)piperidin-1-yl]pteridin-7(8H)-one as a pale yellow colored solid (5.69 g, 79% yield.). 1H NMR (400 MHz, DMSO-d6): δ 10.83 (broad s, 1H), 8.33 (s, 1H), 7.13 (m, 1H), 6.93 (m, 3H), 5.30 (d, 1H), 4.54 (1H), 3.88 (s, 3H), 3.55 (s, 3H), 3.20 (t, 2H), 2.42 (dq, 2H), 1.82 (d, 2H). MS (EI) for C20H21N7O3: 408 (MH+).
