1.利用鈀金屬催化反應製備唾液酸衍生物 2.利用(TCT/DMF)試劑製備氯醣供體 3.二甲基甲醯胺促進(alpha)選擇性醣質化反應

(1) Synthesis of Analogues of N-acetyl Neuraminic Acid Using Pd(0)-catalyzed Approach (2) Preparation of alpha-Glycosyl Chloride via TCT/DMF (3) DMF-mediated alpha-Stereoselective Glycosylation

張智為(Chih-Wei Chang)

指導教授 ： 蒙國光

國立交通大學/理學院/應用化學系所/博士(2010年)

https://doi.org/10.6842/NCTU.2010.00021

摘要

1.利用鈀金屬催化反應製備唾液酸衍生物 2.利用(TCT/DMF)試劑製備氯醣供體 3.二甲基甲醯胺促進(alpha)選擇性醣質化反應

關鍵字

唾液酸 ； 鈀金屬催化反應 ； 氯醣供體 ； 選擇性醣質化反應

並列摘要

ABSTRACTS
This dissertation is divided into four parts:
Part I. A highly effective regio- and stereoselective palladium-catalyzed allylic substitution of
2,3-unsaturated derivatives of N-acetyl neuraminic acid (Neu5Ac2en) has been developed. We
show that the efficiency of the allylation reaction depends on suitable protecting groups on the
starting material and that, with sodium malonate anion as a nucleophile, regioselectivity can
be fine tuned by the nature of the ligands associated with the palladium complex. The reaction
was also applied to other nucleophiles for constructing C-C, C-N and C-O bonds and led to
the major formation of the C-4 regioisomers. The selective transformation of some of the
substitution products provided easy entry to a variety of modified sialic acid derivatives.
Part II. Preparation of α-glycosyl chloride derived from glycosyl hemiacetals (1-hydroxy
sugars) can be performed by treatment of Vilsmeier-Haack complex generated from
stoichimetric 2,4,6-trichloro-1,3,5-triazine (TCT) and N,N-dimethylformamide (DMF) to
afford the corresponding chloride in excellent yields. This mild condition has been approved
being compatible with acid-labile functionalities. In addition, this protocol can be applied to
the synthesis of N-acetylneuraminic acid glycal in one-pot manner.
Part III. DMF-mediated α−selective glycosylation has been systematically investigated in
aspects of mechanistic understanding, the applicable scope and experimental manipulation.
We found the several distinguished features:1. Only stoichiometric DMF is required; 2. Better
α−selectivity is usually obtained at the low temperature; 3. Pre-activation of glycosyl
chlorides with DMF is for the first time proved feasible. 4. Plausible IAD mechanism may be
contributed to stereoselectivity. This Applications by using DMF as an additive could be
practical in glycol-assembly.
.
Part IV. A tetrasaccharide containing the core structure of a glycoglycerolipid isolated from
Meiothermus taiwanensis ATCC BAA-400 has been efficiently synthesized by using the
convergent [2+2] glycoyslation strategy. DMF-mediated α−selective and low-concentration
1,2-trans β−selective glycosylation strategy are for the first time applied to construct the
specific α− or β−linkage in oligosaccharide synthesis.

並列關鍵字

sialid acid ； palladium ； glycosyl chloride ； selective glycosylation

參考文獻

Chapter 1

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