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To a stirred solution of nucleoside 58 (4.18 9, 6.28 mmol) in methanol (50 cm3) was added sodium methoxide (0.75 g, 13.8 mmol) at 0° C. The reaction mixture was stirred for 2 h, and ice was added. The mixture was neutralised using a 20% aqueous solution of HCl. Extraction was performed using dichloromethane (3×75 cm3), the organic phase was separated, dried (Na2SO4) and evaporated under reduced pressure. The residue was purified by silica gel column chromatography using dichloromethane/methanol (98.5:1.5, v/v) as eluent to give nucleoside 59 as a white solid material (2.68 g, 73%). δH (CDCl3) 9.42 (1H, br s, NH), 8.58 (1H, s, H-8), 8.16 (1H, s, 2-H), 7.96 (2H, d, J 7.2, Bz), 7.52-7.08 (13H, m, Bn, Bz), 6.18 (1H, d, J 2.5, 1′-H), 4.85-4.38 (4H, m, Bn, 2′-H, 3′-H), 4.33 (2H, s, Bn) 3.90 (1H, d, J 11.9, 1″-Ha), 3.71 (1H, d, J 11.8, 1″-Hb), 3.50-3.39 (2H, m, 5-H). δC (CDCl3) 164.98 (NHCO), 152.19 (C-6), 151.00 (C-2), 149.34 (C-4), 142.28 (C-8), 137.32, 137.25, 133.46, 132.70, 128.69, 128.49, 128.40, 128.11, 128.03, 127.94, 127.83, 127.62, (Bz, Bn), 122.92 (C-5), 90.94, 88.75 (C-1′, C-4′), 77.65, 74.08, 73.44, 73.20, 71.12, 62.39 (C-1″, C-5′, C-2′, C-3′, 2×Bn). FAB-MS m/z 582 [M+H]+. Found: C, 65.6; H, 5.5; N, 11.7; C32H31N5O6 requires C, 66.1H, 5.4; N, 12.0%.

1. additionice was added
2. extractionExtraction
3. customthe organic phase was separated
4. dry with materialdried (Na2SO4)
5. customevaporated under reduced pressure
6. customThe residue was purified by silica gel column chromatography