GENERAL STEPS: To a solution of (E)-5-(2-carboxyvinyl)-1-(2-deoxy-β-D-erythro-pentofuranosyl)pyrimidine-2,4(1H,3H)-dione (5.777 g, 19.37 mmol) in dimethylformamide (29 mL) was added K2CO3 (5.890 g, 42.61 mmol), and the suspension was stirred at room temperature for for 15 min. A solution of N-bromosuccinimide (3.655 g, 20.53 mmol) was added dropwise over a period of 30 min at 20 °C. After completion of the reaction, the resulting suspension was filtered and the solid was washed with DMF. The combined filtrate and washings were evaporated to dryness under vacuum and the residue was dissolved in methanol. Silica gel was added to this solution, the suspension was evaporated to dryness, and the solid was loaded onto the top of the column. Column chromatography using chloroform/methanol (92:8, v/v) as eluent gave a white solid (5.787 g, 71.9% yield). A white powder was obtained by recrystallization from water. The structure of the product was confirmed by 1H-NMR and 13C-NMR: 1H-NMR (DMSO-d6; 300 MHz) δ 11.59 (1H, bs, NH-3), 8.08 (1H, s, H-6), 7.25 (1H, d, 3J = 13.6 Hz, H-5B), 6.85 (1H, d, J = 13.6 Hz, H-5A) , 6.13 (1H, t, 3J = 6.5 Hz, H-1'), 5.29 (1H, bs, OH-3'), 5.13 (1H, bs, OH-5'), 4.24 (1H, m, H-3'), 3.79 (1H, m, H-4'), 3.66 (2H, m, H-5'), 2.51 (1H, m, H-2'), 2.14 (1H, m, H-2'); 13C-NMR (DMSO-d6; 75 MHz) δ 40.2 (C-2'), 61.3 (C-5'), 70.3 (C-4'), 84.8 (C-3'), 87.8 (C-1'), 108.9 (C-5B), 110.0 (C-5), 130.3 (C-5A), 149.6 , 162.1 (c-2, c-4).
