(S)-tert-Butyl 1-(6-bromo-3-methyl-5-oxo-5H-thiazolo[3,2-a]pyrimidin-7-yl)ethylcarbamate (5.46 g, 14.1 mmol) and (3-fluorophenyl)boronic acid (2.95 g, 21.1 mmol) were suspected in 1,4-dioxane (110 mL). A solution of sodium carbonate (4.47 g, 42.2 mmol) in water (27 mL) was added to the mixture followed by tetrakis(triphenylphosphine)palladium(0) catalyst (0.81 g, 0.70 mmol). The reaction mixture was degassed and heated under nitrogen at 100° C. for 16 h. HPLC indicated the starting material was consumed. The reaction mixture was cooled to room temperature and water (100 mL) was added. The resultant mixture was extracted with ethyl acetate (2×100 mL). The ethyl acetate solution was washed with saturated aqueous sodium bicarbonate (100 mL), dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to give a residue. The residue was purified by flash column chromatography on silica gel using 1-50% ethyl acetate in hexane as eluent to give (S)-tert-butyl 1-(6-(3-fluorophenyl)-3-methyl-5-oxo-5H-thiazolo[3,2-a]pyrimidin-7-yl)ethylcarbamate (4.34 g, 10.8 mmol, 76%) as an off-white solid. LCMS calculated for C20H23FN3O3S (M+H)+: m/z 404.1. Found 404.1. 1H NMR (500 MHz, DMSO-d6) δ 7.48 (ddd, J=8.1, 7.8, 6.2 Hz, 1H), 7.18 (m, 3H), 7.05 (q, J=1.3 Hz, 1H), 6.96 (d, J=7.5 Hz, 1H), 4.41 (m, 1H), 2.66 (d, J=1.3 Hz, 3H), 1.33 (s, 9H), 1.13 (d, J=6.8 Hz, 3H).
