Iida M, Endo A, Fujita S, Numata M, Suzuki K, Nunomura S, Ogawa T
Tokyo Research Institute, NISSIN FOOD PRODUCTS CO., LTD., Tokorozawa-shi, Saitama, Japan.
Glycoconj J. 1996 Apr;13(2):203-11. doi: 10.1007/BF00731495.
The first total synthesis of glycononaosyl ceramide with a sialyl dimeric Le(x) sequence 1 is described. Regio- and stereo-selective glycosylations of sialyl donors 6,7,8 with the suitably protected Le(x) trisaccharide acceptors 9,10 beta were performed to give the expected tetrasaccharides 15 and 21, which were converted into the corresponding donors 20 and 22. Boron trifluoride etherate-promoted glycosylation of 20 with pentasaccharide acceptor 11 afforded regioselectively the expected nonasaccharide 23. After replacing benzyl groups of 23 by acetyl groups, the anomeric acetate was transformed into the alpha-trichloroacetimidate 27. The crucial coupling between 27 and (2S, 3R, 4E-3-O-benzoyl-2-N-tetracosanoylsphingenine 3 was executed to afford completely protected beta-glycoside 28. Finally, selective cleavage of the methyl ester and N,O-deprotection of 28 gave the target ganglioside 1.
本文描述了具有唾液酸化二聚体Le(x)序列1的糖九酰神经酰胺的首次全合成。将唾液酸供体6、7、8与适当保护的Le(x)三糖受体9、10β进行区域和立体选择性糖基化反应，得到预期的四糖15和21，然后将其转化为相应的供体20和22。用三氟化硼乙醚促进20与五糖受体11的糖基化反应，区域选择性地得到预期的九糖23。将23中的苄基用乙酰基取代后，将异头乙酸酯转化为α-三氯乙酰亚胺酯27。进行27与(2S, 3R, 4E)-3-O-苯甲酰基-2-N-二十四烷酰基鞘氨醇3之间的关键偶联反应，得到完全保护的β-糖苷28。最后，选择性裂解甲酯并对28进行N,O-脱保护，得到目标神经节苷脂1。
