[C:1]([O:4][C@@H:5]1[C@H:9]([O:10][C:11](=[O:13])[CH3:12])[C@@H:8]([CH2:14][O:15][C:16](=[O:18])[CH3:17])[O:7][C@H:6]1[N:19]1[CH:27]=[N:26][C:25]2[C:20]1=[N:21][C:22](N)=[N:23][C:24]=2[Cl:28])(=[O:3])[CH3:2].[I:30]CI.N(OCCCCC)=O>C(#N)C>[C:1]([O:4][C@@H:5]1[C@H:9]([O:10][C:11](=[O:13])[CH3:12])[C@@H:8]([CH2:14][O:15][C:16](=[O:18])[CH3:17])[O:7][C@H:6]1[N:19]1[CH:27]=[N:26][C:25]2[C:20]1=[N:21][C:22]([I:30])=[N:23][C:24]=2[Cl:28])(=[O:3])[CH3:2]To a solution of (2R,3R,4R,5R)-4-acetyloxy-5-(acetyloxymethyl)-2-(2-amino-6-chloropurin-9-yl)oxolan-3-yl acetate in acetonitrile was added diiodomethane and n-pentyl nitrite. The mixture was heated under nitrogen for 20 hours, then solvent removed under reduced pressure. The residue was purified by chromatography on silica gel, eluting with hexanes to hexanes/ethyl acetate 2:1, to provide (2R,3R,4R,5R)-4-acetyloxy-5-(acetyloxymethyl)-2-(6-chloro-2-iodopurin-9-yl)oxolan-3-yl acetate, which may be recrystallized from ethanol.
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