以N-乙酰基-5-N,4-O-噁唑烷酮保护的唾液酸对甲基苯硫苷给体合成神经节苷脂GM_3三糖甲苷衍生物

Synthesis of the Methyl Glycoside of Ganglioside GM_3 Trisaccharide Derivative with N-Acetyl-5-N,4-O-Oxazolidinone Protected p-Toluenethiosialoside

详细研究了N-乙酰基-5-N,4-O-噁唑烷酮保护的唾液酸对甲基苯硫苷给体1与四种苄基或苯甲酰基保护的半乳糖甲苷二醇的唾液酸化反应,以较高的产率(72%～89%)得到了相应的唾液酸化产物,α/β=(1.6～2.0)∶1.在此基础上,以乳糖为原料通过7步反应以19%的总产率制得了2,3,6,2',6'-五-O-苯甲酰基-β-乳糖甲苷17,使用唾液酸给体1将化合物17唾液酸化,成功地得到神经节苷脂GM3三糖甲苷衍生物18,产率68%,α/β=1.6∶1.

The coupling reaction of N-acetyl-5-N,4-O-oxazolidinone protected p-toluenethiosialoside 1, with four kinds of benzyl or benzoyl protected methyl galactoside diols was deeply studied, which showed α-selectivity with α/β= 1.6-2.0 and afforded the corresponding sialylation products in high yields （72%- 89%）. Based on these results, a methyl 2,3,6,2′,6′-penta-O-benzyl-β-lactoside 17 was prepared from lactose with 7 steps in a 19% total yield. Sialylation of compound 17 with donor 1 successfully produced the methyl glycoside ganglioside GM3 trisaccharide derivative in a 68% yield and α/β= 1.6 ： 1.