Dehydrative glycosylation with activated diphenyl sulfonium reagents.: Scope, mode of C(1)-hemiacetal activation, and detection of reactive glycosyl intermediates
Dehydrative glycosylation with activated diphenyl sulfonium reagents.: Scope, mode of C(1)-hemiacetal activation, and detection of reactive glycosyl intermediates
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DOI：
10.1021/ja993595a
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发表时间：
2000-05-10
影响因子：
15
通讯作者：
Gin, DY
中科院分区：
文献类型：
--
作者：
Garcia, BA;Gin, DY
描述了一种使用三氟甲磺酸酐和二苯亚砜试剂组合，利用1 - 羟基糖基供体进行直接脱水糖基化的方法的开发。一锅法偶联是一种简便的过程，适用于多种碳水化合物偶联伙伴。氧 - 18标记研究与碳水化合物活化的第一步是形成端基氧硫鎓中间体相一致。当2,3,4,6 - 四 - O - 甲基 - D - 甘露吡喃糖作为糖基供体被活化时，这种活性糖基物质（35）在低温核磁共振实验中可被观察到。当在三氟甲磺酸清除剂2 - 氯吡啶存在下进行脱水糖基化反应时，核磁共振分析表明糖基氧硫鎓中间体35转化为相应的端基2 - 氯吡啶鎓物质36。
The development of a method for direct dehydrative glycosylations with 1-hydroxyglycosyl donors employing the reagent combination of triflic anhydride and diphenyl sulfoxide is described, The one-pot coupling method is a facile process which is applicable to a variety of carbohydrate coupling partners. Oxygen-18-labeling studies are consistent with the first step in carbohydrate activation being the formation of an anomeric oxosulfonium intermediate. This reactive glycosyl species (35) is observable in low-temperature NMR experiments when 2,3,4,6-tetra-O-methyl-D-mannopyranose is activated as the glycosyl donor. When the dehydrative glycosylation reaction is performed in the presence of the triflic acid scavenger 2-chloropyridine, NMR analysis reveals that the glycosyl oxosulfonium intermediate 35 is converted to the corresponding anomeric 2-chloropyridinium species 36.