To a solution of compound 21D (106 mg, 0.498 mmol) in DMF (5 mL) was added sodium hydride (56.9 mg, 1.423 mmol). The resulting mixture was stirred at rt for 30 minutes and compound 2C (300 mg, 0.474 mmol) was added. The reaction mixture was stirred for 1 hour and 10% sodium hydroxide (1.897 mL, 4.74 mmol), THF (5 mL) and MeOH (3 mL) was added. The resulting mixture was stirred at 70° C. overnight, cooled, and filtered. The filtrate was acidified by HCl to pH 4. The precipitate was collected and dried to provide the desired product: 1H NMR (400 MHz, DMSO-D6) δ ppm 12.85 (1H, s), 9.45 (1H, s), 9.10 (1H, s), 8.61 (1H, s), 7.98-8.06 (3H, m), 7.78 (1H, d), 7.67 (1H, d), 7.42-7.50 (2H, m), 7.32-7.40 (2H, m), 7.09-7.16 (2H, m), 4.84 (2H, s), 4.06 (2H, t), 3.73 (2H, t), 3.14-3.24 (2H, m), 3.03 (2H, t), 1.98-2.12 (2H, m); LCMS (APCI): m/z 687 (M+H).
