| Summary: | 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.
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