To a room temperature solution of methyl 2-[3-bromo-4-[(2,4-difluorobenzyl)oxy]-6-methyl-2-oxopyridin-1(2H)-yl]-4-[(methylamino)carbonyl]benzoate (1.05 g, 2.02 mmol) in THF (10.0 mL) was added dropwise an aqueous solution of sodium hydroxide (3.0 M, 3.5 mL, 10 mmol). The reaction was then heated to 60° C. for 8.0 hours. The resulting suspension was then diluted with 500 mL of ethyl acetate and neutralized with an aqueous solution of hydrochloric acid (2.0 N, 5.0 mL, 10 mmol). The resulting biphasic solution was separated and the resulting aqueous layer was further extracted with ethyl acetate (2×200 mL). The resulting combined organic extracts were Na2SO4 dried, filtered and concentrated in vacuo to a volume of 50 mL. At this time a white solid began to form and the resulting solid suspension was allowed to sit until precipitation appeared to stop (approximately 1.0 hour). The precipitate was collected and dried in vacuo (1.0 mm Hg) to furnish the solid acid as an intermediate (806 mg, 78%). 1H NMR (400 MHz, d7-DMF) δ 13.19 (s, 1H), 8.63 (app d, J=4.5 Hz, 1H), 8.09 (d, J=8.0 Hz, 1H), 8.00 (dd, J=8.0, 1.6 Hz, 1H), 7.71-7.67 (m, 2H), 7.34 (app dt, J=9.6, 1.6 Hz, 1H), 7.16 (app dt, J=8.7, 1.8 Hz, 1H), 6.66 (s, 1H), 5.33 (s, 2H), 3.29 (s, 3H), 1.92 (s, 3H); LC/MS C-18 column, tr=2.15 minutes (5 to 95% acetonitrile/water over 5 minutes at 1 ml/min with detection 254 nm, at 50° C.). ES-MS m/z 507 (M+H). ES-HRMS m/z 507.0344 (M+H calcd for C22H18BrF2N2O5 requires 507.0362).
