To a stirring solution of 3,4-difluoro-2-(2-fluoro-4-iodo-phenylamino)-benzoic acid (4.52 g, 11.5 mmol) in freshly distilled tetrahydrofuran (20 mL) at −15° C. was added diphenylphosphinic chloride (2.85 mL, 14.95 mmol). The resultant reaction mixture was stirred for 30 minutes at −15° C. N-Methylmorpholine (1.26 mL, 11.5 mmol) was added and stirring was continued for 90 minutes at −15° C. The reaction was then charged with O-(2,2-dimethyl-[1,3]dioxolan-4-ylmethyl)-hydroxylamine (2.03 g, 13.8 mmol) and allowed to stir at −15° C. for 30 minutes. N-methylmorpholine (1.9 mL, 17.25 mmol) was added and the reaction was allowed to warm to room temperature. After 17 hours, the mixture was diluted with ethyl acetate and partitioned twice with saturated NaHCO3 solution, then twice with water, and twice with saturated brine solution. Organic layers were collected, dried over sodium sulfate, filtered and concentrated in vacuo. The afforded residue was purified by silica column chromatography in 3:1 hexanes/ethyl acetate. The corresponding fractions were collected, dried in vacuo, and crystallized from ethyl acetate/hexanes affording N-(2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-3,4-difluoro-2-(2-fluoro-4-iodo-phenylamino)-benzamide (4.12 g, 68.6%) as light brown solid: m.p.=114-115° C.; 1NMR (400 MHz, DMSO-d6) δ 11.89 (s, 1H), 8.62 (s, 1H), 7.53-7.55 (m, 1H), 7.31-7.37 (m, 2H), 7.17 (dd, 1H, J=16.9, 9.3), 6.60-6.65 (m, 1H), 4.22 (t, 1H, J=6.1), 3.96 (t, 1H, J=8.3), 3.76-3.77 (m, 2H), 3.63 (t, 1H, J=4.9), 1.26 (s, 3H), 1.21 (s, 3H); MS(APCI+)=522.9; Anal.calcd/found for C19H18F3IN2O4: C, 43.70/43.88; H, 3.47/3.43; N, 5.36/5.20; F, 10.91/10.87.
