To a mixture of ethyl 3-(5-amino-3-tert-butyl-1H-pyrazol-1-yl)benzoate (60 g, 208.8 mmol) and K2CO3 (86.6 g, 626.4 mmol) in THF (1400 mL) was added phenyl chloroformate (98.1 g, 626.4 mmol). The reaction was stirred at room temperature overnight. The solid was removed by filtration and most of the solvent was evaporated under reduced pressure. The residual mixture was dissolved in EtOAc and washed with brine, then water. The organic layer was then dried and concentrated. The crude product was purified by recrystallization from CH2Cl2/hexanes to give the desired product as a white powder (78.5 g, 92%). MS m/z 408.1 (M+H)+; calcd. mass 407. Retention time (LC-MS): 3.92 min. 1H-NMR (DMSO-d6): δ 10.19 (s, broad, 1H); 8.11 (m 1H); 7.97 (d, J=7.6 Hz, 1H); 7.86 (m, 1H); 7.71 (t, 1H); 7.38 (m, 2H); 7.24 (m, 1H); 7.08 (m, 1H); 6.40 (s, 1H); 4.38 (q, 2H); 1.32 (t, 3H); 1.29 (s, 9H).
