To a solution of 2-amino-4-(1,1-difluoro-ethyl)-5-(2methyl-2H-pyrazol-3-yl)-benzoic acid methyl ester (430 mg, 1.43 mmol) in DCM (33 mL) were added Et3N (0.820 mL, 5.82 mmol) and then (CCl3O)2CO (353 mg, 1.16 mmol). The resulting mixture was stirred at r.t. for 3 h. The solvent was removed in vacuo and the residue was solubilised in THF (33 mL). CH3SO2NHNH2 (213 mg, 1.90 mmol) was added and the mixture was stirred at r.t for 2 h. Aq NaOH (1N, 1.9 mL, 1.9 mmol) was then added and the mixture was stirred at r.t. for 1 h. The solvent was removed in vacuo and water was added. The pH was adjusted to 3-4 by addition of 2N aq HCl. The aqueous phase was extracted with EtOAc (2×). The organic phases were combined, washed with brine, dried (Na2SO4) and concentrated in vacuo to afford a crude solid. The crude product was purified by flash chromatography (silica gel, EtOAc/hexanes to EtOAc/MeOH (1:1 to 8:2)) to give N-[7-(1,1-difluoro-ethyl)-6-(2-methyl-2H-pyrazol-3-yl)-2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl]-methanesulfonamide as a yellow solid (470 mg, 1.18 mmol, 80%) ES-MS: m/z 400.4 [M+H]+, rt 5.52 min. 1H-NMR (CDCl3, 300 MHz) 9.23 (br s, 1H); 8.06 (s, 1H); 7.90 (br s, 1H); 7.55 (d, J=2.05 Hz, 1H); 7.48 (s, 2H); 7.45 (s, 1H); 6.26 (d, J=1.8 Hz, 1H); 3.64 (s, 3H); 3.36 (s, 1H); 1.70 (t, J=18.7 Hz, 3H).
