To a solution of the title compound from Example 2 Step B (ca. 0.073 mmol) in 1,4-dioxane (0.5 mL) was added lithium hydroxide (0.50 mL, 2.0 M in water, 1.00 mmol), and the resulting mixture was stirred at 50° C. After 2 h, the reaction mixture was rendered acidic by addition of aqueous hydrochloric acid, then was diluted with 1,4-dioxane and passed through a 0.45 micron syringe filter. Purification by reverse phase HPLC (50 to 100% acetonitrile in water, each with 0.1% v/v TFA) provided the title compound: LCMS m/z 584.1 [M+H]+; 1H NMR (500 MHz, d6-DMSO) δ 8.30 (s, 1H), 8.18 (d, J=8.0 Hz, 1H), 8.14 (t, J=8.0 Hz, 1H), 7.88 (d, J=8.0 Hz, 2H), 7.80 (d, J=8.0 Hz, 2H), 7.75-7.71 (m, 4H), 7.56 (d, J=8.0 Hz, 2H), 7.46-7.43 (m, 1H), 7.30 (d, J=7.5 Hz, 1H), 7.11 (t, J=7.5 Hz, 1H), 5.32 (s, 2H).
