Efficient synthesis of methyl lycotetraoside, the tetrasaccharide constituent of the tomato defence glycoalkaloid α-tomatine
作者:Nigel A. Jones、Sergey A. Nepogodiev、Robert A. Field
DOI:10.1039/b508752j
日期:——
oligosaccharide lycotetraose, beta-D-glucopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucopyranosy l-(1-->4)-beta-D-galactopyranose, is a key constituent of many steroidal saponins, including glycoalkaloid alpha-tomatine, which is involved in protection of plants from invading pathogens. A new synthesis of the methyl beta-lycotetraoside () is described. Key steps of the synthesis include two
支链低聚糖四糖,β-D-吡喃葡萄糖基-(1-> 2)-[β-D-吡喃吡喃糖基-(1-> 3)]-β-D-吡喃葡萄糖基l-(1-> 4)-beta -D-吡喃半乳糖,是许多甾体皂苷的关键成分,包括糖碱生物碱α-番茄碱,它参与保护植物免受病原体侵袭。描述了甲基β-糖四糖苷()的新合成方法。合成的关键步骤包括二糖受体甲基(4,6-O-亚苄基-3-Op-甲氧基苄基-β-D-吡喃葡萄糖基)-(1-> 4)-2,3,6-的两个连续的糖基化反应三-O-苄基-β-D-吡喃半乳糖苷与α-D-吡喃葡萄糖和α,β-D-吡喃葡萄糖的苯甲酰化三氯乙亚氨酸酯。由于在第一糖基化步骤的酸性条件下方便地原位去除对-甲氧基苄基保护基,所以该方案允许在一个锅中进行顺序的糖基化。脱保护后,在八步中以19%的产率获得四糖。