一鍋化縮醛(酮)-乙醯反應及Gb3三醣衍生物

Abstract

本篇文章主要可分為三個部份。第一，延續先前一鍋化全乙醯化-硫化反應，應用TsOH 於一鍋化縮醛(酮)-乙醯化反應。並進一步推廣至三步一鍋化應，醣基化-縮醛-乙醯化反應及酯化-縮酮-乙醯化反應。最後利用上述合成技巧合成具有生物活性的Gb3 三醣衍生物。第二，原先致力於利用”遠端遙控”(remote control) 原理，希望得到具有a醣苷鍵選擇性，卻意外得到1,2-trans 醣苷鍵選擇性的結果，且不需要二號位醯基官能基輔助效應的狀況下。藉由溶劑效應改良反應條件，最佳化結果得到從NMR 上觀察幾乎只有1,2-trans 醣苷鍵產物並廣泛應用於寡醣合成。第三， M. taiwanesis ATCC BAA-400 為一個四醣其分離至台灣溫泉的喜溫性細菌的主要醣酯部份，有鑑於其生化潛力,我利用第二章的最佳化條件順利的合成四醣的核心部份。

The thesis divides into three parts. The first part describes the application of TsOH in one-pot peracetylation–thioglycosidation. Elaboration of such method to the one-pot Fischer glycosylation–acetalationacetylation of N-acetylglucosamine and one-pot esterification–acetalation–acetylation of N-acetyl neuraminic acid are demonstrated. Further utility of the one-pot method was illustrated in the synthesis of the biological relevant Gb3 trisaccharide derivative. The second part of this thesis describes an unexpected selective 1,2-trans glycosylation without the acyl participating functions on C-2 position. In the project, optimal reaction conditions were exploresulting in a highly selectivity 1,2-trans glycosylation. This novel 1,2-trans glycosylation method was then employed in the synthesis of a tetrasaccharide, that constitutes the carbohydrate moiety of a glycilipid extracted from Meiothermus taiwanensis. M. taiwanes is being a thermophilic bacteria was isolated from a hot spring in Taiwan.