4.1.11  Methyl (2S)-2-amino-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 (3)
Following method C with 22 (140 mg, 0.12 mmol, 1.00 eq) and a 0–30% linear gradient of acetonitrile in TEAAc buffer 50 mM, pH 7 for purification, 3 (28 mg, 35%) was obtained as a white powder with 98% purity determined by HPLC analysis at 260 nm. 1H NMR (600 MHz, D2O) δ 8.08 (s, 1H), 8.05 (s, 1H), 7.98 (s, 1H), 7.84 (s, 1H), 5.89 (d, J = 2.5 Hz, 1H), 5.75 (d, J = 3.3 Hz, 1H), 4.55–4.50 (m, 1H), 4.47 (dd, J = 5.1 Hz, J = 2.3 Hz, 1H), 4.38 (dd, J = 5.0 Hz, J = 3.2 Hz, 1H), 4.36–4.30 (m, 1H), 4.26 (dd, J = 10.5 Hz, J = 2.8 Hz, 1H), 4.13 (dd, J = 7.9 Hz, J = 5.1 Hz, 1H), 4.07 (dt, J = 6.2 Hz, J = 3.1 Hz, 1H), 4.05–3.86 (m, 2H), 3.84 (s, 3H), 3.82–3.64 (m, 2H), 3.22–3.01 (m, 3H), 2.88 (dt, J = 13.7, J = 3.9, 1H), 2.78 (d, J = 13.9 Hz, 1H), 2.66–2.58 (m, 1H), 2.19–2.02 (m, 2H). 13C NMR (150 MHz, D2O) δ 170.6, 154.9 (2C), 152.5, 152.2, 147.7, 147.4, 139.1, 138.3, 118.5, 118.1, 89.1, 86.8, 84.6, 81.8, 79.6, 73.9, 70.9, 69.1, 60.2, 54.8, 54.1, 53.5, 53.3, 52.3, 25.0. HRMS (ESI+): m/z calcd for C27H39N12O9 [M+H]+: 675.2957, found: 675.2944.