Reaction Steps
Compound 19b was prepared by the same procedure as described for the preparation of 19a using 3g43 (500 mg, 1.75 mmol) and a 2M solution of dimethylamine in methanol (20 mL): yield 238 mg (46%); MS m/z 295 (M+H)+; 1HNMR (DMSO-d6) δ 8.33 (s, 1H, H-8), 8.15 (s, 1H, H-2), 7.29 (bs, 2H, 6-NH2), 5.86 (d, 1H, H-1′, J1′,2′=5.4 Hz), 5.45 (d, 1H, OH-2′, J2′-2′OH=5.9 Hz), 5.22 (bd, 1H, OH-3′, J3′-3′OH=3.9 Hz), 4.65 (ddd, 1H, H-2′, J1′,2′=5.4 Hz, J2′,3′=5.5 Hz, H2′-2′OH=5.9 Hz), 4.10 (ddd, 1H, H-3′, J2′,3′=5.5 Hz, J3′,4′=4.5 Hz, J3′-3′OH=3.9 Hz), 3.94-4.0 (m, 1H, H-4′), 2.62 (dd, 1H, 5′-CH2), 2.48 (dd, 1H, 5′-CH2), 2.18 (bs, 6H, N—(CH3)2); UV λmax, nm, pH 1, 256.3 (∈ 15,100), pH 7, 259.2 (∈ 15,500), pH 13, 259.7 (∈ 15,600). Anal. (C12H18N6O3.0.35CH3OH) C, H, N.
