反应详情

A solution of 5 g (7.6 mmol) 5′-O-(4,4′-dimethoxytrityl)-3′-O-(tert-butyldimethylsilyl)thymidine 17 in 100 ml 80% aq. acetic acid was stirred until the removal of dimethoxytrityl group was completed. Saturated Na2CO3 was then added to adjust the pH of the solution to 6-7. The solution was then extracted with ethyl acetate. The extract was dried and the mixture was chromatographed on a silica gel column (CH2Cl2:MeOH=20:1) to give 2.5 g of 3′-O-(tert-butyldimethylsilyl)thymidine 18 (92.6%).: m.p.93-95° C. (lit. 83-84° C.); H NMR (200 MHz, CDCl3) δ9.18 (s, 1H, NH), 7.36 (b, 1H, H-6), 6.12 (t, J=6.8 Hz, 1H, H-1′), 4.44-4.48 (m, 1H, H-3′), 3.69-3.91 (m, 3H, H-4′, H-5′), 2.87 (m, 1H, OH), 2.15-2.35 (m, 2H, H-2′), 1.87 (S, 3H, C═CMe), 0.86 (s, 9H, CMe3), 0.05 (s, 6H, SiMe2); 13C NMR (125 MHz, CDCl3) δ163.9 (C-4), 150.4 (C-2), 137.1 (C-6), 110.9 (C-5), 87.6 (C-4′), 86.8 (C-1′), 71.5 (C-3′), 61.9 (C-5′), 40.4 (C-2′), 25.7 (SiCMe3), 17.9 (SiCMe), 12.5 (C═CMe), −4.7 (SiMe2), −4.9 (SiMe2).

1. extractionThe solution was then extracted with ethyl acetate
2. customThe extract was dried
3. customthe mixture was chromatographed on a silica gel column (CH2Cl2:MeOH=20:1)