摘要/Abstract

以廉价易得的β-D-四乙酰核糖为起始原料，经过9步反应，以15.7%的总产率完成了海洋天然核苷Kipukasin D的全合成.邻碘苯甲酸酯在Vorbrüggen糖基化反应中作为邻基导向基团，立体选择性地得到β型核苷.合成的关键步骤为Ph₃PAuOTFA选择性催化脱除核苷2'和5'位邻炔基苯甲酸酯基团，该方法为温和的中性反应条件，完全避免了核苷2'位和3'位的酯交换副反应.
关键词: 核苷, 邻基效应, 酯交换, 催化, 全合成
The first total synthesis of marine natural nucleoside kipukasin D was disclosed in 9 steps and 15.7% overall yield using commercially available tetra-O-acetyl-β-D-ribose as starting material. In Vorbrüggen glycosylation, ortho-iodinebenzoate acted as neighboring participating group leading to β-nucleoside. The key step was selectively deprotection of 2'-O and 5'-O ortho-alkynylbenzoates by freshing prepared Ph₃PAuOTFA in the presence of ethanol (6 equiv.) and H₂O (1 equiv.) in dichloromethane (DCM). The reaction condition of our newly developed approach is very mild and neutral, which effectively avoids the transesterification between 2'-OH and 3'-OH. The result further demonstrat that ortho-alkynylbenzoate is an orthogonal protecting group compatible with other ester groups, which could find wide applications in nucleoside and carbohydrate chemistry.
Key words: nucleoside, neighboring-group, transesterification, catalysis, total synthesis


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