To the carboxylic acid from Step C (243 mg, 0.92 mmol) was added a solution of 4-(dimethylamino)pyridine (340 mg, 2.76 mmol) and 1-(3-dimethyl-aminopropyl)-3-ethylcarbodiimide hydrochloride (232 mg, 2.3 mmol) in t-butanol (5 mL) and dichloromethane (5 mL). The reaction mixture was stirred for 15 min, 2-chloro-5-methoxybenzenesulfonamide (190 mg, 0.86 mmol) was added, and the reaction mixture was stirred at room temperature overnight. Dichloromethane (200 mL) was then added, the mixture was extracted with 1 N hydrochloric acid (3×100 mL), and the separated organic phase was dried over magnesium sulfate and concentrated under reduced pressure to afford a solid. The solid was rinsed with diethyl ether to afford 240 mg of the title compound, a compound of the present invention, as a white solid, m.p. 211-212° C. 1H NMR (CDCl3) δ 10.10 (br s, 1H), 8.46 (s, 1H), 8.27 (s, 1H), 7.86 (d, 1H), 7.54 (s, 1H), 7.38 (d, 1H), 7.09 (dd, 1H) 3.91 (s, 3H).
