Using method C with 35 (140 mg, 0.14 mmol, 1.00 eq) and a 0–40% linear gradient of acetonitrile in TEAAc buffer 50 mM, pH 7 for purification, 15 (25 mg, 25%) was obtained as a white powder with 99% purity determined by HPLC analysis at 260 nm. 1H NMR (600 MHz, DMSO‑d 6) δ 8.35 (s, 1H), 8.23 (s, 1H), 8.11 (s, 1H), 8.07 (s, 1H), 7.89 (d, J = 1.9 Hz, 1H), 7.50 (d, J = 8.3 Hz, 1H), 7.45 (dd, J = 8.3 Hz, J = 2.0 Hz, 1H), 7.32 (br. s, 2H), 7.24 (br. s, 2H), 5.99 (d, J = 5.9 Hz, 1H), 5.83 (d, J = 5.1 Hz, 1H), 5.51–5.32 (m, 2H), 5.24 (br. s, 1H), 5.13 (br. s, 1H), 4.57 (t, J = 5.2 Hz, 1H), 4.45 (dd, J = 6.1 Hz, J = 4.8 Hz, 1H), 4.30 (t, J = 4.1 Hz, 1H), 4.05 (t, J = 5.0 Hz, 1H), 4.02–3.95 (m, 2H), 3.73–3.63 (m, 4H), 3.58–3.51 (m, 2H), 2.83 (dd, J = 14.0 Hz, J = 4.4 Hz, 1H), 2.73 (dd, J = 14.0 Hz, J = 7.2 Hz, 1H), 2.69–2.63 (m, 2H). 13C NMR (150 MHz, DMSO‑d 6) δ 156.1, 156.0, 152.5 (2C), 149.3, 148.9, 147.2, 140.1, 139.8, 139.6, 133.7, 131.0, 125.0, 122.9, 119.3, 119.2, 87.8, 86.2, 86.1, 82.2, 81.3, 72.4, 71.8, 68.9, 68.1, 61.3, 56.8, 56.0, 53.0. HRMS (ESI+): m/z calcd for C29H34N12O9Cl [M+H]+: 729.2255, Found 729.2256.