(2R,3R,4R,5R)-5-(6-(tritylamino)-9H-purin-9-yl)-4-(trityloxy)-2-((trityloxy)methyl)tetrahydrofuran-3-ol

6-{(2R,3R,4R,5R)-5-[6-(Trityl-amino)-purin-9-yl]-4-trityloxy-2-trityloxymethyl-tetrahydro-furan-3-yloxy}-hexanoic acid ethyl ester

6-[(2R,3S,4R,5R)-5-(6-Amino-purin-9-yl)-4-hydroxy-2-hydroxymethyl-tetrahydro-furan-3-yloxy]-hexanoic acid 2-cyano-ethyl ester

6-{(2R,3R,4R,5R)-2-[(4-Methoxy-phenyl)-diphenyl-methoxymethyl]-5-{6-[2-(4-nitro-phenyl)-ethoxycarbonylamino]-purin-9-yl}-4-[2-(4-nitro-phenyl)-ethoxycarbonyloxy]-tetrahydro-furan-3-yloxy}-hexanoic acid 2-cyano-ethyl ester

6-((2R,3S,4R,5R)-4-Hydroxy-2-[(4-methoxy-phenyl)-diphenyl-methoxymethyl]-5-{6-[2-(4-nitro-phenyl)-ethoxycarbonylamino]-purin-9-yl}-tetrahydro-furan-3-yloxy)-hexanoic acid 2-cyano-ethyl ester