Mono- Vs. Di-flourous tagged Glucosamines for Iterative Oligosaccharide Synthesis.

Fluorous-tagged protecting groups are attractive tools for elongating carbohydrate chains in oligosaccharide synthesis. To eliminate the accumulation of failed sequences during automated oligosaccharide synthesis conditions, an additional C8F17 ester derived protecting group was attached to the glycosyl donor to better retain the desired doubly-tagged glycosylation product on fluorous solid phase extraction (FSPE) cartridges. Initial studies show that the double-fluorous-tagging strategy offers a robust enough separation using a commercial FSPE cartridge using simple gravity filtration to separate the desired product from the singly-fluorous-tagged starting materials and their decomposition products. In addition, removal of the fluorous acetate and its byproducts after sodium methoxide treatment and neutralization required only dissolution of the desired sugar in toluene and subsequent removal of the toluene layer from the denser fluorous byproducts.

氟标记保护基是寡糖合成中用于延长碳水化合物链的有吸引力的工具。为了在自动化寡糖合成条件下消除失败序列的积累，将一个额外的由C8F17酯衍生的保护基连接到糖基供体上，以便在氟固相萃取（FSPE）柱上更好地保留所需的双标记糖基化产物。初步研究表明，双氟标记策略使用市售的FSPE柱，通过简单的重力过滤，就能够提供足够有效的分离，将所需产物与单氟标记的起始原料及其分解产物分离开来。此外，在甲醇钠处理和中和之后，去除氟乙酸酯及其副产物仅需将所需的糖溶解在甲苯中，然后从密度较大的氟副产物中除去甲苯层。