摘要/Abstract

以2，3，4-三-O-苯甲酰基-α-L-鼠李糖三氯乙酰亚胺酯、2，4-二-O-苯甲酰基-α-L-鼠李糖对甲氧基苯基苷、2，3，4，6-四-O-苯甲酰基-β-D-葡萄糖三氯乙酰亚胺酯和2，3-O-异丙叉基-α-L-鼠李糖对甲氧基苯基苷为原料，采用[2+2]偶联策略，对巴西固氮螺菌（Azospirillum brasilense type strain Sp246）表面脂多糖的四糖重复单元α-L-鼠李糖-（1→3）-α-L-鼠李糖-（1→3）-[β-D-葡萄糖-（1→4）]-α-L-鼠李糖结构进行全合成.在合成单元子的反应中，采用硅胶负载高氯酸（HClO₄-SiO₂）作为酸性催化剂，三乙基硅基作为选择性保护基，简单高效地构建全保护的四糖.该合成路线步骤短，试剂种类少，反应后处理简单，以L-鼠李糖为原料计算，目标化合物四糖总收率达到23%，化合物结构经¹H NMR和¹³C NMR、HRMS和IR确证.
关键词: 鼠李糖, 硅胶负载高氯酸(HClO₄-SiO₂), 固氮螺菌, 寡糖合成
A natural tetrasaccharide of α-L-Rhap-(1→3)-α-L-Rhap-(1→3)-[β-D-Glup-(1→4)-]α-L-Rhap was synthesized via [2+2] assembly from 2,3,4-tri-O-benzoyl-α-L-rhamnopyranosyl trichloroacetimidate, p-methoxyphenyl 2,4-di-O-benzoyl-α-L-rhamnopyranoside, 2,3,4,6-tetra-O-benzoyl-β-D-glucopyranosyl trichloroacetimidate and p-methoxyphenyl 2,3-O-isopro-pyl-α-L-rhamnopyranoside. This tetrasaccharide is a repeating unit of the lipopolisaccharides of the nitrogen fixing bacterium Azospirillum brasilense Sp246. In the reaction of the synthesis unit, silica gel loaded perchloric acid (HClO₄-SiO₂) was used as acid catalyst, and triethylsilyl group was used as selective protective group to construct a fully protected tetrasaccharide. The synthetic route is short, the reagents are few, and the post-processing is simple. The total yield of target tetrasaccharide is 23% based on L-rhamnose. The structures of the tetrasaccharide were confirmed by ¹H NMR, ¹³C NMR, HRMS and IR spectra.
Key words: rhamnose, silica gel supported perchloric acid (HClO₄-SiO₂), Azospirillum brasilense, oligosaccharide synthesis


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