To a stirred suspension of 3-bromo-1-(ethoxycarbonylmethyl)-6-methylpyrazinone (750 mg, 2.75 mmol), as prepared in step 5 of Example 2, in toluene (30 mL) was added 2,2-difluoro-2-phenylethylamine (900 mg, 5.75 mmol), as prepared in the preceding step. The mixture was refluxed for two days under nitrogen. The solution was allowed to cool to room temperature, and ethyl acetate (50 mL) was added. The diluted reaction mixture was washed with 10% HCl (2×20 mL) and the aqueous layer was extracted with ethyl acetate (3×20 mL). The combined organic layers were washed with 10% citric acid (50 mL), brine, and dried over Na2SO4. After evaporating the solvent, the solid was collected and washed with 15% ethyl acetate in hexane to give the title compound as an off-white solid (730 mg, 76%). 1H NMR (400 MHz, CDCl3) δ 7.54 (m, 2H), 7.43 (m, 3H), 6.67 (s, 1H ), 6.14 (s(br), 1H), 4.70 (s, 2H), 4.24 (q, 2H, J=7.1 Hz), 4.09 (td, 2 H, J=14.3, 6.5 Hz), 2.11 (s, 3H), 1.29 (t, 3H, J=7.1 Hz).
