Reaction Steps
6b (1.33 mmol) was dissolved in saturated methanolic ammonia (62 mL) and stirred at room temperature for 20 h. The reaction mixture was then evaporated to dryness under reduced pressure. The residue was dissolved in water and washed twice with ethyl acetate. The aqueous layer was evaporated and purified on reverse phase column chromatography (C 18) eluting with a gradient 2-15% of acetonitrile in water. The residue obtained was then dissolved in hot ethyl acetate, filtered and dried to give the title compound (134 mg, 33%). Yellow solid. Molecular Formula C12H12FN5O4 1H NMR (DMSO-d6, 400 MHz) δ(ppm) 10.70 (ls, 1H, NH), 7.98 (s, 1H, H-8), 6.60 (ls, 2H, NH2), 6.21 (d, 1H, OH-3′, JOH-3′=7.6 Hz), 5.83 (d, 1H, H-1′, J1′-F=16.9 Hz), 5.29 (t, 1H, OH-5′, JOH-5′=5.2 Hz), 4.50 (td, 1H, H-3′, J3′-F=22.8 Hz, J3′-4′=9.2 Hz), 3.93-3.81 (m, 3H, H-4′, H-5′ and ethynyl), 3.70 (m, 1H, H-5″). 13C NMR (DMSO-d6, 100 MHz) δ(ppm) 157.2 (C-6), 154.3 (C-2), 151.05 (C-4), 135.1 (C-8), 116.7 (C-5), 96.4 (d, C-2′, 1JC-F=182.1 Hz), 87.4 (d, C-1′, 2JC-F=39.2 Hz), 83.1 (d, CCH, JC-F=9.1 Hz), 82.4 (C-4′), 76.2 (d, CCH, 2JC-F=31.2 Hz), 73.2 (d, C-3′, 2JC-F=20.1 Hz), 59.5 (C-5′). 19F NMR (DMSO-d6, 235 MHz) δ(ppm) −158.5 (m). LC/MS (A): (M+H+) 310.1 (5.55 min). LRFAB-MS (GT): 619 (2M-41)+, 310 (M+H)+, 152 (B+H)+, 617 (2M−H)−, 308 (M−H)−. UV λmax 253 nm
