反应详情

To a stirred solution of diethyl (R)-[2-benzyloxy-1-(hydroxymethyl)ethoxy]methylphosphonate (1.0 g, 3 mmol), triphenylphosphine (1.18 g, 4.5 mmol) and 2-[bis-(t-butoxycarbonyl)amino]-9-hydroxy-6-methoxypurine (1.15 g, 3 mmol) in dry THF (20 ml), cooled in ice and under a mitrogen atmosphere, was added, dropwise, diethyl azodicarboxylate (0.71 ml, 4.5 mmol). The resulting solution was allowed to warm to ambient temperature and left stirring for 16 hours. The solvent was evaporated under reduced pressure and the residue obtained chromatographed on silica gel using hexane/ethyl acetate 2:1 as eluant. The eluant was changed as follows: hexane/ethyl acetate 1:1, hexane/ethyl acetate 1:2 and finally to ethyl acetate to give (S)-2-[bis-(t-butoxycarbonyl)amino]-9-[3-benzyloxy-2-(diethoxyphosphorylmethoxy)propoxy]-6-methoxypurine as a colourless oil (1.85 g, 88%).

1. additionwas added
2. waitleft
3. customThe solvent was evaporated under reduced pressure
4. customthe residue obtained
5. customchromatographed on silica gel