| Carbohydrates have the potential as the ultimate raw materials for highly functionalized, optically pure chemicals which were extensively used in pharmaceutical, agrichemical and biotech industry. However, these high potentials of carbohydrates remain nearly untouched due to the complex structure and often redundant hydroxyl groups of carbohydrates. The aim of this work is to develop strategies to overcome these difficulties and transform complex carbohydrates to advanced derivatives.;A protocol for the transformation of glycosides to anhydroalditols was established using Me-D-glucoside as the model compound (Chapter 2). Transformation of the free hydroxyl groups to allyl ether followed by reductive cleavage of the glycosidic bond using triethylsilane gave the protected 1,5-anhydroglucitol. Cleavage of the allyl ether bond was achieved by employing PdCl2/CuCl 2 catalytic system. This Protection-Reduction-Deprotection protocol was successfully used in the transformation of complex carbohydrates, such as cellulose, starch and levan, to the corresponding anhydroalditols. The anhydroalditol, 1,5-anhydro-D-glucitol, was transformed to its 6-phosphate, and 2, 3-deoxy derivatives in Chapter 3.;The carbohydrate derivated (S)-2-hydroxyl-butyrolactone and (S)-2-hydroxyl-tetrahydrofuran were transformed to their iodo derivatives in Chapter 4. By controlling the neighboring group effect, the mono and diiodo derivatives were selectively formed. Chapter 5 presents an efficient route to prepare cyclic nitrone from D-ribose. Optically pure iminosugar and isoxazolidines were prepared from the nitrone through stereoselective addition reactions and cycloaddition reactions. |
