The p-methoxybenzyl ether as an in situ-removable carbohydrate-protecting group: a simple one-pot synthesis of the globotetraose tetrasaccharide
作者:Sumita Bhattacharyya、Bengt G. Magnusson、Ulf Wellmar、Ulf J. Nilsson
DOI:10.1039/b009448j
日期:——
A one-pot synthesis of the globotetraose tetrasaccharide is reported. The synthetic method relies on the use of a p-methoxybenzyl ether as an in situ-removable protecting group. N-Iodosuccinimide/trifluoromethanesulfonic acid-promoted glycosylation of 2-bromoethyl-2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-β-D-galactopyranosyl)-β-D-glucopyranoside 5 at −45 °C with phenyl 2,4,6-tri-O-benzyl-3-O-(4-methoxybenzyl)-1-thio-β-D-galactopyranoside 6 gives an intermediate trisaccharide from which the p-methoxybenzyl ether is removed by allowing the reaction temperature to rise to 0 °C for 40 min. Again lowering the temperature to −45 °C, followed by addition of methyl 3,4,6-tri-O-acetyl-2-trichloroethoxycarbonylamino-2-deoxy-1-thio-β-D-galactopyranoside 8, affords the globotetraose tetrasaccharide 11 in one-pot in an excellent yield of 76%.
报告了一种一锅合成球四糖的四糖的方法。该合成方法依赖于使用对甲氧基苄醚作为原位可去除的保护基。N-碘代苏氨酸酯/三氟甲磺酸促进的糖苷化反应在-45 °C下,将2-溴乙基-2,3,6-三-O-苯甲酰基-4-O-(2,3,6-三-O-苯甲酰基-β-D-半乳糖吡喃糖) 5与苯基2,4,6-三-O-苯甲酰基-3-O-(4-甲氧基苄基)-1-硫代-β-D-半乳糖吡喃糖 6反应得到中间三糖体,随后通过将反应温度升高到0 °C反应40分钟去除对甲氧基苄醚。再次降低温度至-45 °C,然后添加甲基3,4,6-三-O-乙酰基-2-三氯乙氧基羰基氨基-2-脱氧-1-硫代-β-D-半乳糖吡喃糖 8,最终在一锅中以76%的优异产率获得球四糖四糖 11。