2,6-Dichloropurine → 2,6-dichloro-9-(2,3-di-O-acetyl-5-O-methyl-beta-D-ribofuranosyl)-purine

Participants

Reaction Conditions

Reaction Steps

5-O-Methyl-1,2,3-tri-O-acetyl-D-ribofuranose (5.0 g, 17 mmol) and 2,6-dichloropurine (3.3 g, 17 mmol) were thoroughly mixed. A catalytic amount of p-toluene sulfuric acid (50 mg) was added and the reaction mixture was heated to 140° C. at which point a homogeneous melt was obtained. The fusion was continued at 140° C. under oil pump vacuum for 0.5 h. The reaction mixture was dissolved in chloroform (200 ml) and washed with aqueous sodium bicarbonate (3×50 ml) and water (2×50 ml). The organic phase was dried (MgSO4), evaporated in vacuo and purified by flash chromatography eluting with a mixture of n-heptane and ethyl acetate (1:1) to provide 9-(2',3'-di-O-acetyl-5'-O-methyl-β-D-ribofuranosyl)-2,6-dichloro-9H-purine (1.0 g, 14%) as an oil which crystallized from diethyl ether. A mixture of α/β-anomers (1.2 g, 17%) was also isolated, with mp 59°-61° C. 1H-NMR (400 MHz,CDCL3) δ2.06 (3H, s, --OCOCH3), 3.49 (3H, s, OCH3), 3.67, 3.72 (2H, ABX, H-5'a and H-5'b), 4.39 (1H, d, H-4'), 5.58 (1H, d, H-3'), 5.75 (1H, t, H-2'), 6.38 (1H, d, H-1'), 8.56 (1H, s, H-8). C15H16Cl2N4O6 requires C, 43.0; H, 3.9; N, 13.4. Found C, 43.1, H, 3.9, N, 13.2%.

Provenance & Evidence