Reaction Steps
As described for the synthesis of 6-(morpholin-1-yl)-9-[2-deoxy-3,5-bis-O-(tert-butyldimethylsilyl)-β-D-erythro-pentofuranosyl]-purine, this morpholino derivative was prepared by a reaction between O6-(benzotriazol-1-yl)-2′,3′,5′-tris-O-(tert-butyldimethylsilyl)-inosine (27) (71.8 mg, 0.099 mmol), and morpholine (17.5 μL, 0.200 mmol) in the presence of Cs2CO3 (65.2 mg, 0.200 mmol) in dry DME (1.0 mL) at room temperature over 1 h. No additional purification was needed and 57.5 mg (85% yield) of the title compound was obtained. Rf (3% MeOH in CH2Cl2)=0.68. 1H NMR (500 MHz, CDCl3): δ 8.33 (s, 1H, Ar—H), 8.03 (s, 1H, Ar—H), 6.03 (d, 1H, H-1′, J=5.4), 4.72 (t, 1H, H-2′, J=4.9), 4.32-4.29 (br m, 5H, H-3′ and 2CH2), 4.11 (q, 1H, H-4′, J=3.6), 4.02 (dd, 1H, H-5′, J=11.2, 4.4), 3.83 (t, 4H, 2CH2, J=4.6), 3.77 (dd, 1H, H-5′, J=11.2, 3.2), 0.95, 0.93, 0.80 (3 s, 27H, tert-Bu), 0.124, 0.12, 0.104, 0.10, −0.05, −0.22 (6 s, 18H, SiCH3). 13C NMR (126 MHz, CDCl3): δ 153.9, 152.2, 150.9, 137.7, 120.5, 88.1, 85.4, 75.4, 72.1, 67.0, 62.6, 45.6, 26.1, 25.8, 25.7, 18.5, 18.1, 17.9, −4.4, −4.7, −5.0, −5.4, −5.41.
