To a solution of crude N-((4S,6S)-4-(5-amino-2-fluorophenyl)-4-(fluoromethyl)-6-(trifluoromethyl)-5,6-dihydro-4H-1,3-oxazin-2-yl)benzamide (1k, 0.25 g, 0.605 mmol, step 9) in DMF (3 ml) was added 5-methoxypyrazine-2-carboxylic acid (0.117 g, 0.756 mmol, Ark Pharm), 1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxid hexafluorophosphate (0.345 g, 0.907 mmol, Oakwood Products) and di-isopropylethylamine (0.156 g, 1.210 mmol, Aldrich). The reaction was stirred at ambient temperature for 10 minutes. The reaction was diluted with water and EtOAc. The organic layer was separated and washed sequentially with aqueous saturated sodium bicarbonate solution, 1 M aqueous LiCl solution, and brine. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The crude material was purified via silica gel flash chromatography using a gradient of 0-45% EtOAc in hexanes to afford the title compound as a white solid (0.110 g, 0.2 mmol, 33% overall yield for this step and steps 9 in Example 1). MS m/z=550.0 [M+H]+. Calculated for C25H20F5N5O4: 549.449
