The general procedure for the synthesis of 6-amino-9-((2R,3R,4S,5R)-3,4-dihydroxy-3,4-diol of 6-amino-9-((2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-7H-purine-8(9H)-thione from (2R,3R,4S,5R)-2-(6-amino-8-bromo-9H-purin-9-yl)-5-(hydroxymethyl)tetrahydrofuran-2-yl) was as follows :
1. NaSH (0.8 g, 10 equiv) was added to a solution of 8-bromoadenine (0.5 g, 1.44 mmol) in DMF (7 mL).
2. heat the mixture to 100 °C and add a small amount of water to increase solubility.
3. Stir the reaction mixture at 100°C overnight.
4. the solvent is evaporated under high vacuum and the residue is co-evaporated with methanol several times until a solid is formed.
5. the residue is dissolved in water and neutralized with NaOH solution.
6. After freeze-drying, the product was purified by silica gel column chromatography (eluent: CHCl3:MeOH = 10:1).
7. The target compound was obtained as a light yellow powder (100% yield, melting point 169-170°C).
Product characterization data:
1H-NMR (CD3OD, 200 MHz): δ 8.09 (s, 1H, H-2), 6.65 (d, J = 7 Hz, 1H, H-1'), 5.01 (dd, J = 7, 5.5 Hz, 1H, H-2'), 4.39 (dd, J = 5.5, 2.5 Hz, 1H, H-3'), 4.13 (q, J = 2.5 Hz. 1H, H-4'), 3.87 (dd, J = 12.5, 2.5 Hz, 1H, H-5'), 3.71 (dd, J = 1.25, 3 Hz, 1H, H-5'').
13C-NMR (CD3OD, 300 MHz): δ 167.88 (C-6), 151.92 (C-2), 148.12 (C-4), 147.88 (C-8), 107.00 (C-5), 88.62 (C-1'), 85.59 (C-4'), 70.70 (C-2'), 70.62 (C-3') , 62.13 (C-5').
MS (CI/NH3): m/z 317 [M + NH4]+.
