Lipopolysaccharides (LPSs) are major virulence determinants in Gram-negative bacteria and are responsible for many pathophysiological processes during bacterial infections. However, the accessibility of LPS-associated oligosaccharides for infectious mechanism study and vaccine development remains challenging. We report an efficient stereocontrolled approach for the synthesis of a common inner-core trisaccharide containing difficult-to-access, rare, higher-carbon sugars: a heptose (Hep) and 3-deoxy-α-d-manno-oct-2-ulosonic acid (Kdo). Key features include comprehensive elaboration of a practical synthesis of versatile Hep and Kdo building blocks, and stereoselective assembly of an inner-core trisaccharide from multiple pathogenic bacteria.

脂多糖（LPS）是革兰氏阴性细菌的主要毒力决定因素，并且与细菌感染期间的许多病理生理过程有关。然而，LPS 相关寡糖用于感染机制研究和疫苗开发的可及性仍然具有挑战性。我们报告了一种有效的立体控制方法，用于合成常见的内核三糖，其中含有难以获得的稀有高碳糖：庚糖（Hep）和3-脱氧-α-d-甘露糖-oct-2-糖酸（Kdo）。主要特点包括全面阐述多功能 Hep 和 Kdo 构建模块的实用合成，以及从多种病原菌中立体选择性组装内核三糖。