Structural analysis of stereoselective galactose pyruvylation toward the synthesis of bacterial capsular polysaccharides

• Tsun-Yi Chiang,
• Mei-Huei Lin,
• Chun-Wei Chang,
• Jinq-Chyi Lee and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2025, 21, 1671–1677, doi:10.3762/bjoc.21.131

• ; pyruvate ketals; Introduction Pyruvate ketals are essential non-carbohydrate modifications in polysaccharides from bacteria and serve as a key immunodominant group with many biological functions [1]. For example, the pyruvylated galactose moiety is a key component of Bacteroides fragilis capsular

• facilitating cell–cell interactions [1]. Additionally, various glycans containing pyruvate ketals have been identified, including those found in Pseudomonas strain 1.15 (1.15 EPS) (2) and Rhizobium leguminosarum (R. leguminosarum bv. viciae VF39 EPS) (3) (Figure 1). These exopolysaccharides have been well

• -studied and are considered good candidates for drug development [1][6]. The synthesis of bacterial capsular polysaccharides, particularly in the installation of the pyruvate ketal on galactose, presents significant challenges. Owing to pyruvate ketals are considered immunogenic, non carbohydrate