To a solution of (1-benzenesulfonyl-1H-pyrrol-3-yl)-acetic acid (1.3 g, 4.90 mmol) in THF was added LiN(TMS)2 (12 mL, 1.0M in THF, 12 mmol) at −78° C. The resulting solution was stirred at this temperature for 1 hour and 0° C. for 1 hour and then was cooled to −78° C. again. To this solution was added 2,3-difluoro-benzoic acid methyl ester (1.1 g, 6.40 mmol) and the reaction was stirred at room temperature for 14 hours. The solution was poured into 2N HCl and extracted with EtOAc. The combined organic layers were dried over MgSO4, filtered, and evaporated. The crude product was purified by flash column eluting with 20% of EtOAc in hexanes to afford the title compound as a yellow oil (1.1 g, 58%). 1H NMR (500 MHz, CDCl3) δ7.77 (d, 2H), 7.50 (m, 2H), 7.42 (t, 2H), 7.28 (m, 1H), 7.05 (m, 3H), 6.18 (m, 1H), 3.98 (s, 2H) ppm. MS (ES+): m/e=362.1 (M+H); LC/Method A/3.98 min.
