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

• successfully obtained. Subsequently, the compound was used for the synthesis of zwitterionic polysaccharide A1 (PS A1) precursor, and a clear structural elucidation was applied by using nuclear magnetic resonance and X-ray. Keywords: carbohydrates; capsular polysaccharides; diastereochemistry; glycosylation

• modifications of bacterial polysaccharides, and the interaction of 4,6-O-pyruvylated pyranoses with lectins depends on the stereochemistry of the pyruvate ketal. Moreover, this chemical modification is crucial, as the distinct R or S diastereochemistry at the ketal center directly influences its biological

• ][23][24][25][26][27]. However, these chemical shifts can vary depending on the molecular structure, making it difficult to characterize the isomers across different systems. To address this, the current study aimed to develop a method for installing pyruvate ketals with precise diastereochemistry and

One-pot double annulations to confer diastereoselective spirooxindolepyrrolothiazoles

• Juan Lu,
• Bin Yao,
• Desheng Zhan,
• Zhuo Sun,
• Yun Ji and
• Xiaofeng Zhang

Beilstein J. Org. Chem. 2022, 18, 1607–1616, doi:10.3762/bjoc.18.171

• products. The diastereochemistry of non-stabilized azomethine ylides for decarboxylative [3 + 2] cycloaddition could be identified in reported literature [54][55][56][57][58][59][71]. Through the study of the mechanism, it elucidates that the double annulations using ʟ-cysteine undergoes three stages