6-N-(4-Monomethoxytrityl)-9-(3-O-benzoyl-2-deoxy-5-O-(4-mono-methoxytrityl)-beta-L-erythro-pentofuranosyl)adenine → 6-N-(4-Monomethoxytrityl)-9-(2-deoxy-5-O-(4-monomethoxytrityl)-beta-L-erythropentofuranosyl)adenine

Participants

Reaction Steps

Compound 8 was treated by a solution (saturated at −10° C.) of methanolic ammonia (20 mL), at room temperature for 24 h, then the reaction mixture was concentrated to dryness. The residue was dissolved in dichloromethane (30 mL) and washed with water (20 mL). The aqueous layer was extracted by dichloromethane (2×20 mL) and the combined organic phase was dried, filtered and concentrated. Pure compound 9 (0.50 g, 76% from 7) was obtained as a foam after purification by silica gel column chromatography (0-2% MeOH in dichloromethane): 1H NMR (DMSO-d6): δ 2.2-2.3 (m, 1H, H-2′), 2.8-2.9 (m, 1H, H-2″), 3.1-3.2 (m, 2H, H-5′ and H-5″), 3.64 and 3.65 (2s, 6H, 2×OCH3), 3.97 (pq, 1H, H-4′), 4.4-4.5 (m, 1H, H-3′), 5.36 (d, 1H, OH-3′, JH,OH=4.5 Hz), 6.34 (t, 1H, H-1′, J1′,2′=J1′,2″=6.4 Hz), 6.8-6.9 and 7.1-7.4 (2m, 29H, 2 MMTr and NH-6), 7.81 and 8.32 (2s, 2H, H-2 and H-8); ms: matrix G/T, (FAB+) m/z 796 [M+H]+, 408 [BH2]+, (FAB−) m/z 794 [M−H]−, 406 [B]−; UV (95% ethanol): λmax 276 nm (ε 42600), λmin 248 nm (ε 23300); [α]D20=+29 (c 1.05, DMSO).

Provenance & Evidence