Synthesis Of Higher Carbon Sugars And Higher Carbon Amino Sugars As Well As Nucleosides Containing Higher Carbon Sugar

In this thesis, a new synthetic method for the novel higher carbon sugars from D-xylose was developed. A series of higher carbon sugars, higher carbon amino sugars as well as nucleosides cotaining higher carbon sugar were stereoselectively synthesized. In the course of synthetic studies, two novel approachs 'One-pot multi-step route for the synthesis of higher carbon sugar from D-xylose' caused by oxidation with PDC in CH3CN and 'autoxidation-condensation reaction of higher carbon sugar' were discovered, the mechanisms for the reactions were offered and definitely rationalized.1. C10 higher carbon sugars were selectively synthesized via a novel reaction of D-xylose with PDC in one-pot. The main influence factors on this reaction such as temperature, solvents and reaction time were discussed.The formation pathway of 3 was proposed and definitely rationalized. The 3-ketofuranose 2 formed from the PDC oxidation lost a molecule of PhCOOH to form an a,P-unsaturated ketone intermediate. Two molecules of the intermediate underwent the hetero Diels-Alder reaction to afford the novel higher carbon sugar 3 in situ. The stereochemistry of compound 3 was confirmed by the X-ray crystallographic analyses of its reduced products 4 and 6.Several higher carbon sugar derivatives have been synthesized from compound 3 and characterized by elemental analysis, *H NMR, 13C NMR, MS and IR spectra.3. The compound 3, which contains the unit of cyclic enol ether similar to that in vitamin C, was oxidized by air to generate a novel higher carbon sugar 21 with a cryptand cage.To uncover the mechanism, an important intermediate 22 was trapped and isolated, and its absolute configuration was conformed by X-ray crystallographic analyses. The reaction underwent autoxidation followed by ketalization. In order toinvestigate the influence factor, a seriers of reactions were carried out in various conditions. We found that copper ion could restrain the reaction, whereas, potassium, sodium, zinc ions could accelerate the reaction.4. A series of higher carbon amino sugars were stereoselectively synthesized by using higher carbon sugar 3 and 8 to react with various substituted aniline compounds and following stereoselective reduction with NaBH4. Nitromethane and nitroethane were used as nucleophiles to react with compound 3 or 8 in the presence of Et3N. The adducts were then stereoselectively reduced with NaBH4 to give the corresponding higher carbon sugar-derived amino alcohols with reasonable yields.5. Several higher carbon sugar nucleosides were synthesized from higher carbon sugar 7 and were characterized by elemental analysis, 1H NMR, 13C NMR, MS and IR spectra.In conclusion, several new higher carbon sugars, higher carbon nucleosides and higher carbon amino sugars, as well as branched-chain higher carbon sugars were synthesized from D-xylose. Two novel approachs were discovered in the synthetic studies and their reaction mechanisms were definitely confirmed. 66 new compounds were synthesized and characterized by 1H NMR, 13C NMR, HRMS, IR spectra. The stereochemistry of 10 compounds among them were confirmed by X-ray crystallographic analyses.