To the solution of 3-(4-methoxybenzyl)-9-pentyl-6,9-dihydro-5H-[1,2,4]triazolo[4,3-a]purin-5-one (0.40 g, 1.1 mmol) in THF was added N-Bromosuccinimide (0.29 g, 1.6 mmol). The mixture was stirred at 70° C. for 1 hour. The mixture was concentrated and purified by preparative LCMS to yield the desired product (290 mg, 60%). 1HNMR (300 MHz, d6-DMSO): δ 7.16 (d, J=8.3 Hz, 2H), 6.81 (d, J=8.3 Hz, 2H), 4.46 (s, 3H), 4.20 (t, J=7.2 Hz, 2H), 3.67 (s, 2H), 1.79 (m, 2H), 1.28 (m, 4H), 0.83 (m, 3H). LCMS calculated for C19H21BrN6O2 (M+H): 445.1. found: 445.0, 447.0.
