Reaction Steps
Compound 13b was prepared by the same procedure as described for the preparation of 13a using 4b (260 mg, 0.84 mmol), ethyl 3-chloropropionate (138 mg, 1.0 mmol), DIEA (53 mg, 0.07 mL, 0.41 mmol), and DMF (4 mL). After column chromatography (elution with 7:1:0.1 chloroform:methanol:NH4OH), a glassy sticky solid was obtained: yield 153 mg (44%), MS: m/z 409 (M+H)+; 1HNMR (DMSO-d6) δ 8.08 (s, 1H, H-2), 7.10 (bs, 2H, 6-NH2), 5.71 (d, 1H, H-1′, J1′,2′=5.5 Hz), 5.32 (bd, 1H, OH-2′, J2′-2′OH=5.0 Hz), 5.16 (bd, 1H, OH-3′, J3′-3′OH=5.1 Hz), 5.12 (ddd, 1H, H-2′, J1′,2′=5.5 Hz, J2′,3′=5.7 Hz, J2′-2′OH=5.0 Hz), 4.14 (ddd, 1H, H-3′, J2′,3′=5.7 Hz, J3′,4′=4.1 Hz, J3′-3′OH=5.1 Hz), 4.01 (q, 2H, OCH2CH3), 3.91-3.98 (m, 1H, H-4′), 2.87 (q, 2H, CH2 of 8-Et), 2.71-2.79 (m, 1H, 5′-CH2), 2.51-2.65 (m, 3H, 5′-CH2, CO—CH2), 2.38 (t, 2H, N(CH3)—CH2), 2.16 (bs, 3H, N—CH3), 1.30 (t, 3H, CH3 of 8-Et), 1.15 (t, 3H, OCH2CH3).
