Department of Chemistry, Lucknow University, Lucknow 226 007, India.
Carbohydr Res. 2008 Nov 3;343(16):2822-5. doi: 10.1016/j.carres.2008.08.006. Epub 2008 Aug 12.
Synthesis of the trisaccharide, allyl α-l-rhamnopyranosyl-(1→3)-2-acetamido-2-deoxy-β-d-glucopyranosyl-(1→4)-α-l-rhamnopyranoside related to O-chain glycans isolated from the deaminated LPSs of Klebsiella pneumoniae serotype 012, was achieved through condensation of suitably synthesized disaccharide, allyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-β-d-glucopyranosyl-(1→4)-2,3-di-O-benzoyl-α-l-rhamnopyranoside and donor, ethyl 2,3,4-tri-O-acetyl-1-thio α-l-rhamnopyranoside starting from l-rhamnose and d-glucosamine hydrochloride. The trisaccharide can be utilized for the synthesis of neoglycoconjugates for use as a synthetic vaccine by coupling it with a suitable protein after deprotection. Various regio- and stereoselective protecting group strategies have been carefully considered, as protecting groups can influence the reactivity of the electrophile and nucleophile in glycosylation reactions on the basis of steric and electronic requirements.
从脱氨 LPS 中分离出的肺炎克雷伯氏菌 012 型 O 链聚糖的三糖，即烯丙基 α-L-鼠李吡喃糖基-(1→3)-2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖基-(1→4)-α-L-鼠李吡喃糖苷的合成，是通过将适当合成的二糖，即烯丙基 4,6-O-苄叉-2-脱氧-2-邻苯二甲酰亚氨基-β-D-吡喃葡萄糖基-(1→4)-2,3-二-O-苯甲酰基-α-L-鼠李吡喃糖苷与供体，即乙基 2,3,4-三-O-乙酰基-1-硫代-α-L-鼠李吡喃糖苷缩合而实现的，起始原料为 L-鼠李糖和 D-葡萄糖胺盐酸盐。三糖可在脱保护后与合适的蛋白质偶联，用于合成糖缀合物作为合成疫苗。已经仔细考虑了各种区域和立体选择性保护基策略，因为保护基可以根据立体和电子要求影响糖苷化反应中亲电试剂和亲核试剂的反应性。
