A solution of 7-[(1S)-1-aminoethyl]-6-(3-fluorophenyl)-3-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidin-5-one (0.10 g, 0.33 mmol) and 2-amino-6-bromopurine (0.11 g, 0.49 mmol) in 1-butanol (0.66 mL) was treated with N,N-diisopropylethylamine (86 μL, 0.49 mmol), degassed with nitrogen for 5 min and heated at 100° C. for 18 hours. The reaction was not complete and was, therefore, heated at 115° C. for an additional 5 hours. The reaction mixture was diluted with methanol (10 mL), stirred, and filtered. The filtrate was purified by RP-HPLC (XBridge C18 column, eluting with a gradient of acetonitrile/water containing 0.1% ammonium hydroxide, at flow rate of 60 mL/min) to give the desired product (27 mg, 19%) as a white solid. LCMS for C20H18FN8OS (M+H)+: m/z=437.0.
