Reaction Steps
Compound 9 (0.44 g, 0.56 mmol) was treated with an aqueous solution of acetic acid 80% (17 mL) at room temperature for 5 h. The mixture was concentrated to dryness, the residue was dissolved in water (20 mL) and washed with diethyl ether (2×15 mL). The aqueous layer was concentrated and co-evaporated with toluene and methanol. The desired 2′-deoxy-β-L-adenosine (β-L-dA) (0.12 g, 83%) was obtained after purification by silica gel column chromatography (0-12% MeOH in dichloromethane) and filtration through a Millex HVA unit (0.45μg, Millipore): mp 193-194° C. (crystallized from water)(Lit. 184-185° C. for L-enantiomer [Ref.: Robins, M. J.; Khwaja, T. A.; Robins, R. K. J. Org. Chem. 1970, 35, 636-639] and 187-189° C. for D-enantiomer [Ref.: Ness, R. K. in Synthetic Procedures in Nucleic Acid Chemistry; Zorbach, W. W., Tipson, R. S., Eds.; J. Wiley and sons: New York, 1968; Vol 1, pp 183-187]; 1H NMR (DMSO-d6): δ 2.2-2.3 and 2.6-2.7 (2m, 2H, H-2′ and H-2″), 3.4-3.6 (2m, 2H, H-5′ and H-5″) 3.86 (pq, 1H, H4′), 4.3-4.4 (m, 1H, H-3′), 5.24 (t, 1H, OH-5′, JH,OH=5.8 Hz), 5.30 (d,1H, OH-3′, JH,OH=4.0 Hz), 6.32 (dd, 1H, H-1′, J1′,2′=6.2 Hz, J1′, 2″=7.8 Hz), 7.3 (br s, 2H, NH2-6), 8.11 and 8.32 (2s, 2H, H-2 and H-8); ms: matrix G/T, (FAB+) m/z 252 [M+H]+, 136 [BH2]+, (FAB−) m/z 250 [M−H]−, 134 [B]−; UV (95% ethanol): λmax 258 nm (ε 14300), λmin 226 nm (ε 2100); [α]D20=+25 (c 1.03, H2O), (Lit. [α]D20=+23 (c 1.0, H2O) for L-e3nantiomer [Ref.: Robins, M. J.; Khwaja, T. A.; Robins, R. K. J. Org. Chem. 1970, 35, 636-639] and [α]D20=−25 (c 0.47, H20) for D-enantiomer [Ref.: Ness, R. K. in Synthetic Procedures in Nucleic Acid Chemistry; Zorbach, W. W., Tipson, R. S., Eds.; J. Wiley and sons: New York, 1968; Vol 1, pp 183-187]). Anal. Calcd for C10H13N5O3+1.5 H2O (M=278.28): C, 43.16; H, 5.80; N, 25.17. Found: C, 43.63; H, 5.45; N, 25.33.
