(1)Total Synthesis Study toward Glycolipid Derivatives of Meiothermus taiwanensis ATCC BAA-400 (2)Stereoselective Synthesis of Galactosamine Serine Conjugates

• Main Authors: Lai, Yen-Hsun, 賴彥勳
• Other Authors: 蒙國光
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/93690724198692420362

碩士 === 國立交通大學 === 應用化學系碩博士班 === 99 === This thesis is divided into two parts. Part I describes a total synthesis of a tetrasaccharide derivatives, which simulates the core structure of thermophilic bacteria Meiothermus taiwanensis ATCC BAA-400. In our approach, we employed DMF-modulating glycosylation via pre-activation and low concentration ??selective glycosylation (LCG) methods to construct 1,2-cis ?? and 1,2-trans ??glycosidic linkage respectively. Such glycosidic bonds were constructed with high efficiency and satisfactory stereoselectivity. Both the convergent [2 + 2] and sequential [1 + 1 + 2] glycosylation approaches were adopted. Further, the global deprotection of this molecular was demonstrated in this thesis. Moreover, we also synthesized the ??Glc(1→1)-glycerol structure with excellent selective via conditional optimized DMF modulating glycosylation. Part II concerns the development of a new methodology towards ??GalNAc-O-Ser (Tn antigen) structure. First, the ??glycosidic bond between a galactosamine building block and a serine moiety employed the DMF modulating glycosylation. The highly selective glycosidic bond formationswas afforded via this coupling strategy. Second, we developed a more accessible route to selective open the 6-position for further modifications. Based on this result, a trisaccharide Tn derivative (F1? antigen) was successfully synthesized in our laboratory.