4.1.19  Methyl 4-({[(2R,5R)-5-(6-amino-9H-purin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl}(2-{[(2R,5R)-2-(6-amino-9H-purin-9-yl)-4-hydroxy-5-(hydroxymethyl)oxolan-3-yl]oxy}ethyl)amino)butanoate (7)
Following method C with 25 (116 mg, 0.13 mmol, 1.00 eq) and a 0–50% linear gradient of acetonitrile in TEAAc buffer 50 mM, pH 7 for purification, 7 (51 mg, 60%) was obtained as a white powder with 97% purity determined by HPLC analysis at 260 nm. 1H NMR (500 MHz, DMSO‑d 6) δ 8.37 (s, 1H), 8.33 (s, 1H), 8.14 (s, 1H), 8.13 (s, 1H), 7.38 (br. s, 2H), 7.29 (br. s, 2H), 5.97 (d, J = 6.3 Hz, 1H), 5.84 (d, J = 5.3 Hz, 1H), 5.52–5.32 (m, 3H), 5.19 (d, J = 5.3 Hz, 1H), 4.62 (q, J = 5.4 Hz, 1H), 4.49 (dd, J = 6.3, 4.7 Hz, 1H), 4.30 (dd, J = 4.8, 2.8 Hz, 1H), 4.04 (q, J = 4.9 Hz, 1H), 3.99–3.96 (m, 1H), 3.95–3.87 (m, 1H), 3.66 (dt, J = 12.1, 4.1 Hz, 1H), 3.62–3.45 (m, 6H), 2.79 (dd, J = 14.1, 4.6 Hz, 1H), 2.71–2.52 (m, 3H), 2.45–2.28 (m, 2H), 2.14 (td, J = 7.4, 5.9 Hz, 2H), 1.58–1.46 (m, 2H). 13C NMR (125 MHz, DMSO‑d 6) δ 173.3, 156.2, 156.1, 152.6, 152.5, 149.4, 148.9, 139.9, 139.8, 119.4, 119.2, 87.6, 86.4, 86.3, 82.4, 81.3, 72.6, 71.9, 69.2, 68.0, 61.6, 56.3, 53.5, 53.4, 51.2, 30.9, 21.8. HRMS (ESI+): m/z calcd for C27H38N11O9 [M+H]+: 660.2854, Found 660.2855.