Synthesis of the Mycobacterium tuberculosis Canetti Lipooligosaccharide II Nonasaccharide

Total Synthesis of 6-Deoxy-l-talose Containing a Pentasaccharide Repeating Unit of Acinetobacter baumannii K11 Capsular Polysaccharides

Herein, we report a concise synthetic approach for the first total synthesis of a pentasaccharide repeating unit of Acinetobacter baumannii K11 capsular polysaccharides containing a rare sugar 6-deoxy-l-talose. The pentasaccharide was synthesized in a convergent manner using a [3 + 2] block glycosylation strategy. During this synthetic strive, we used a 2,2,2-trichloroethoxycarbonyl (Troc)-protected monosaccharide unit to achieve a high yield during the glycosylation to synthesize a trisaccharide, and chemoselective deprotection of the Troc group from the trisaccharide was carried out under a mild, pH-neutral condition, keeping the O-glycosidic bond, azido, and acid/base sensitive group intact. A thiotolylglycoside disaccharide donor containing 6-deoxy-l-talose was synthesized for the first time by the armed-disarmed glycosylation method between two thiotolylglycosides.

Total Synthesis of a Trehalose-Containing Lipooligosaccharide Analogue from Mycobacterium linda

A short and efficient methodology has been developed to synthesize an analogue of a lipooligosaccharide from Mycobacterium linda isolated from Crohn's disease. The total synthesis of the tetrasaccharide was achieved via a convergent [2 + 2] glycosylation approach. The key features of the synthesis involve the selective functionalization of a trehalose core via highly regioselective acylations and regioselective glycosylations. The synthesis was completed via a longest linear sequence of 14 steps in a 14.2% overall yield.