Reaction Steps
To a solution of 18b (470 mg, 1.4 mmol) in 20 mL of anhydrous MeOH and 4 mL of anhydrous DMF under nitrogen was added hydroxylamine hydrochloride (258 mg, 3.7 mmol) and potassium hydroxide (206 mg, 3.7 mmol) and the resulting suspension was stirred at room temperature for 2 days. The reaction mixture was concentrated to dryness and the crude product was extracted with EtOAc (2×40 mL) and washed with brine solution (20 mL). The organic layer was dried over Na2SO4, filtered, washed with EtOAc and concentrated to dryness. The product was purified by column chromatography. The column was eluted with 4:1:0.5 chloroform:methanol:NH4OH and the desired fractions were combined, concentrated, and dried in vacuo to give a solid: yield 165 mg (32%), MS: m/z 367 (M+H)+; 1HNMR (DMSO-d6) δ 8.70 (bs, 1H, NOH), 8.33 (s, 1H, H-8), 8.15 (s, 1H, H-2), 7.27 (bs, 2H, 6-NH2), 5.86 (d, 1H, H-1′, J1′,2′=5.3 Hz), 5.43 (d, 1H, 2′-OH, J2′-2′=6.0 Hz), 5.35 (bs, 2H, C—NH2), 5.20 (d, 1H, 3′-OH, J3′-3′OH=5.2 Hz), 4.63 (ddd, 1H, H-2′, J1′,2′=5.3 Hz, J2′,3′=4.9 Hz, J2′-2′OH=6.0 Hz), 4.10 (ddd, 1H, H-3′, J2′,3′=4.9 Hz, J3′,4′=3.5 Hz, J3′-3′OH=5.2 Hz), 3.96-4.0 (m, 1H, H-4′), 2.64-2.75 (bm, 2H, 5′-CH2), 2.56 (t, 2H, N(CH3)—CH2), 2.20 (s, 3H, N—CH3), 2.09 (t, 2H, C—CH2). Anal. (C14H22N8O4.1.2C2H5OH.0.2CH3OH) C, H, N.
