5'-O-monomethoxytrityl-2,6,8-tris<2-(p-nitrophenyl)ethoxy>-9-(β-D-ribofuranosyl)-9H-purine 、 alkaline earth salt of/the/ methylsulfuric acid 以93%的产率得到Acetic acid (2R,3R,4R,5R)-4-acetoxy-5-{2,6-bis-[2-(4-nitro-phenyl)-ethoxy]-8-[2-(3-nitro-phenyl)-ethoxy]-purin-9-yl}-2-[(4-methoxy-phenyl)-diphenyl-methoxymethyl]-tetrahydro-furan-3-yl ester