A solution of potassium tert-butoxide in tetrahydrofuran (1 M, 1.97 mL, 1.97 mmol) was added to a slurry of 2-[(2S)-1-hydroxypropan-2-yl]-7-(4-methyl-1H-imidazol-1-yl)-3,4-dihydro-2H-pyrido[1,2-a]pyrazine-1,6-dione (C54) (541 mg, 1.79 mmol) in tetrahydrofuran (6 mL), and the mixture was allowed to stir for 10 minutes. A solution of 1-fluoro-4-nitro-2-(pentafluoro-λ6-sulfanyl)benzene (P15) (478 mg, 1.79 mmol) in tetrahydrofuran (4 mL) was added, and the reaction mixture was stirred at room temperature for 18 hours. At that point, it was diluted with water and extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with saturated aqueous sodium chloride solution, dried over magnesium sulfate, filtered, and concentrated in vacuo. Purification via silica gel chromatography (Eluents: ethyl acetate, then 10% methanol in ethyl acetate) afforded the product as a yellow foam. Yield: 695 mg, 1.26 mmol, 70%. LCMS m/z 550.2 (M+1). 1H NMR (400 MHz, CDCl3) δ 1.53 (d, J=7.1 Hz, 3H), 2.34 (d, J=1.0 Hz, 3H), 3.73-3.85 (m, 2H), 4.30-4.47 (m, 4H), 4.99-5.08 (m, 1H), 7.16-7.21 (m, 2H), 7.28 (d, J=7.7 Hz, 1H), 7.52 (d, J=7.7 Hz, 1H), 8.40 (dd, J=9.2, 2.7 Hz, 1H), 8.44 (br s, 1H), 8.71 (d, J=2.6 Hz, 1H).
