2004-07-1

Colourless Crystalline Solid

6-Substituted purines; a novel class of inhibitors of endogenous protein degradation

GENERAL STEPS: (2R,3R,4R,5R)-2-(Acetoxymethyl)-5-(2-amino-6-chloro-9H-purin-9-yl)tetrahydrofuran-3,4-diyl diacetate (1.56 g, 3.64 mmol) was dissolved in acetone (10 mL), phosphate buffer (58 mL, pH 8) and Novozyme (1.6 g) were added. The reaction mixture was stirred at 60°C for 8 days. After completion of the reaction, the enzyme was removed by filtration and washed with ethanol (50 mL) and acetone (50 mL). The filtrate was concentrated under reduced pressure and the resulting crude product was purified by silica gel column chromatography (eluent: CH2Cl2:MeOH, 85:15) to afford (2R,3R,4S,5R)-2-(2-amino-6-chloro-9H-purin-9-yl)-5-(hydroxymethyl)tetrahydrofuran-3,4-diol (0.61 g, 55% yield) as a light blue powder.1H NMR ( 400 MHz, DMSO-d6) δ 8.38 (s, 1H, H-8), 6.99 (s, 1H, NH2), 5.81 (d, J = 5.80 Hz, 1H, H-1'), 5.49 (br s, 1H, OH-2'), 5.19 (br s, 1H, OH-3'), 5.05 (t, J = 5.24 Hz, 1H, OH -5'), 4.47 (t, J = 4.85 Hz, 1H, H-2'), 4.20-4.02 (m, 1H, H-3'), 3.90 (q, J = 3.98 Hz, 1H, H-4'), 3.69-3.60 (m, 1H, H2-5'), 3.59-3.52 (m, 1H, H2-5'); 13C NMR (100 MHz, DMSO-d6) δ 160.5, 154.7, 150.2, 141.9, 124.2, 87.4, 86.0, 74.2, 70.9, 61.9; high resolution ES-MS m/z 302.0649 ([M + H]+, C10H1335ClN5O4 calculated value 302.0651).

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