Rhizobial Saccharides Part 3. Unexpected α-Selective Glycosylation During Synthesis of Pyruvated Tetrasaccharide Fragments Related to Exopolysaccharides of <i>Rhizobium Leguminosarum</i>
作者:Thomas Ziegler、Elisabeth Eckhardt、Dirk Keller
DOI:10.1080/07328309708006537
日期:1997.8.1
1→6)-α-D-Galp-(1→O-allyl) related to the exopolysaccharide of Rhizobium leguminosarum biovar phaseoli 127 K 87 having an (R)- and (S)-configurated pyruvic acid acetal, respectively at positions 3 and 4 of the galactopyranosyl residue of the non-reducing end, were prepared from two disaccharide blocks. The fully benzoylated diastereomeric disaccharide donors having the structure 3,4-Py-β-D-Galp-(1→6)-α-D-Galp-(1→X)
两个非对映体四糖烯丙基糖苷3,4-PY-β-d-Gal的p - (1→6)-β-d-Gal的p - (1→6)-β-d-GLC p - (1→6) -α-d-Gal的p有关的胞外多糖(1→O-烯丙基) -根瘤菌生物变种菜豆127ķ87具有([R )-和(小号) -构型丙酮酸缩醛,分别在位置3和4非还原端的吡喃半乳糖基残基是由两个二糖嵌段制备的。具有结构3,4- PY-β-d-Gal的完全苯甲酰化非对映体的二糖供体p - (1→6)-α-d-Gal的p通过逐步方法从苯甲酰化的3,4-丙酮酸的半乳糖基供体(氯化物,溴化物,三氯乙酰-tim酸酯)以及苄基和苯基1-硫代2,3,分别为4-三-O-苯甲酰基-β-D-吡喃半乳糖苷。具有以下结构的β-d-GLC二糖受体p(1→6)-α-d-Gal的- p,通过偶合得到的(1→O-烯丙基)烯丙基2,3,4-三- Ö -benzoyl- α-D-吡喃半乳糖苷及其6-