N-连接的糖蛋白核心甘露五糖及其异构体的合成研究

A Facile Large Scale Synthesis of the Core Mannose Pentasaccharide of N-Linked Glycoprotein and Its Isomer

以1,2-O-亚乙基-4,6-O-亚苄基-β-D-甘露糖（2）和2,3,4,6-四-O-苯甲酰基-α-D-甘露吡喃糖基三氯乙酰亚胺酯（3）为基本原料,经一些简单的化学转换和选择性的糖基化反应,得到了甘露核心五糖及其异构体.

Condensation with 1,2-O-ethylidene-4,6-O-benzylidene-β-D-mannopyranose (2) as the acceptor and 2,3,4,6-tetra-O-benzoyl-α-D-mannopyranosyl trichloroacetimidate (3) as the donor gave 3-O-linked dis-accharide (4), subsequent debenzylidenation afforded the disaccharide acceptor 5. Coupling of 5 with 3 selec-tively furnished 6-O-linked trisaccharide 6, then deethylidenation, acetylation, selective 1-O-deacetylation, and trichloroacetimidation yielded the trisaccharide donor 10. Condensation of 10 with 5 afforded 6-O -linked pentasaccharide 11, its deethylidenation followed by acetylation gave the required pentasaccharide 13. Coupling of 10 with 2 gave the tetrasaccharide 14, its debenzylidenation afforded the tetrasaccharide acceptor 15. Con-densation of 15 with 3 gave the pentasaccharide isomer.