Alberta Ingenuity Centre for Carbohydrate Science and Department of Chemistry, The University of Alberta, Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada T6G 2G2.
Carbohydr Res. 2013 Aug 30;378:26-34. doi: 10.1016/j.carres.2013.05.005. Epub 2013 May 21.
2-Azido-4-benzylamino-4N,3-O-carbonyl-2,4,6-trideoxy-d-galactopyranosyl trichloroacetimidate 2 conveniently prepared in six steps from 6-deoxy-d-glucal glycosylated a selectively protected α1,3 linked methyl galabioside to afford the trisaccharide skeleton of a repeating unit of the Sp1 zwitterionic capsular polysaccharide. Lithium hydroxide hydrolysis of the 3,4-cyclic carbamate permitted the creation of a 2-acetamido-4-amino-2,4,6-trideoxygalactose residue. Selective cleavage of p-methoxybenzyl ethers by trifluoroacetic acid gave a selectively deprotected trisaccharide with two hydroxymethyl groups that were oxidized by the TEMPO reagent to afford access to trisaccharide glycoside 1 containing 2-acetamido-4-amino-2,4,6-trideoxygalactose and two galacturonic acid residues.
2-叠氮基-4-苄氨基-4N,3-O-羰基-2,4,6-三脱氧-D-半乳糖基三氯乙酰胺 2 可方便地通过六步从 6-脱氧-D-葡萄糖基糖基化选择性保护的α1,3 连接的甲基半乳糖苷制备，得到 Sp1 两性离子荚膜多糖重复单元的三糖骨架。3,4-环碳酸酯的氢氧化锂水解允许创建 2-乙酰氨基-4-氨基-2,4,6-三脱氧半乳糖残基。三氟乙酸选择性裂解对甲氧基苄基醚得到具有两个羟甲基的选择性去保护的三糖，该三糖可被 TEMPO 试剂氧化，从而获得含有 2-乙酰氨基-4-氨基-2,4,6-三脱氧半乳糖和两个半乳糖醛酸残基的三糖糖苷 1。
