2,2-Difluoro-2-fluorosulfonyl-acetic acid (CAS no. 1717-59-5) (0.84 mL, 8.05 mmol) in acetonitrile (20 mL) was added with a syringe pump dropwise over 90 minutes to a degassed stirring mixture of methyl 3-[5-(dimethylcarbamoyl)pyrazin-2-yl]oxy-5-[(2S)-1-hydroxypropan-2-yl]oxy-benzoate (1.5 g, 22.0 mmol) and copper (I) iodide (154 mg, 4.55 mmol) in acetonitrile (300 mL) at 55° C. The volatiles were removed under reduced pressure and the residue taken up in DCM. The mixture was filtered to and the solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica, eluting with a gradient of 25%-100% ethyl acetate in isohexane to afford the product (16.5 g, 62%). 1H NMR δ (CDCl3): 1.38 (3H, d), 3.15 (3H, s), 3.18 (3H, s), 3.91 (3H, s), 3.93-4.05 (2H, m), 4.62-4.68 (1H, m), 6.27 (1H, t), 6.95 (1H, t), 7.44-7.45 (1H, m), 7.49-7.51 (1H, m), 8.36 (1H, s), 8.53 (1H, s); m/z 404 (M+H+)
