Comprehensive SummaryTreponema is a Gram‐negative anaerobic bacterium, among which the pathogenic Treponema can cause various diseases, such as venereal syphilis (Treponema pallidum), yaws (Treponema carateum), and oral diseases (Treponema denticola and Treponema medium). Although different from conventional lipopolysaccharides, the extracellular glycoconjugate of Treponema may still be a potential antigen and provide a candidate for vaccine development. Hence, we completed the first chemical synthesis of Treponema medium ATCC 700293 tetrasaccharide precursor containing L‐ornithine (L‐Orn) and D‐aspartic acid (D‐Asp) derivatives. The efficiency of non‐reducing end disaccharide formation has been improved by optimizing the assembly of the protecting groups in the donors and acceptors. Our [3+1] glycosylation strategy attempted to reduce the length of the acceptor to increase the nucleophilicity of the hydroxyl group, thereby improving the efficiency of synthesizing the target tetrasaccharide. The L‐Orn derivative was introduced at the final stage due to its influence on the glycosylation stereospecificity and efficiency. Therefore, the successful introduction of two amino acid derivatives and the synthesis of a tetrasaccharide precursor with complex functional‐group modifications have provided valuable insights for synthesizing other complex bacterial glycans.

中文翻译：

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与密螺旋体培养基 ATCC 700293 中四糖重复单元相关的关键前体的化学合成

综合总结密螺旋体是一种革兰氏阴性厌氧菌，其中致病性密螺旋体可引起多种疾病，如性梅毒（梅毒螺旋体), 雅司病 (T红雷波内马）和口腔疾病（齿螺旋体和密螺旋体培养基）。尽管与传统的脂多糖不同，密螺旋体的胞外糖复合物仍然可能是一种潜在的抗原，并为疫苗开发提供候选者。至此，我们完成了第一个化学合成密螺旋体培养基ATCC 700293 四糖前体，含有 L-鸟氨酸 (L-Orn) 和 D-天冬氨酸 (D-Asp) 衍生物。通过优化供体和受体中保护基团的组装，提高了非还原端二糖形成的效率。我们的[3+1]糖基化策略试图减少受体的长度以增加羟基的亲核性，从而提高合成目标四糖的效率。由于 L-Orn 衍生物对糖基化立体特异性和效率的影响，因此在最后阶段引入。因此，成功引入两种氨基酸衍生物以及合成具有复杂官能团修饰的四糖前体，为合成其他复杂细菌聚糖提供了宝贵的见解。