Recyclable benzyl-type fluorous tags: Preparation and application in oligosaccharide synthesis

Abstract

We herein described the design, synthesis and application of two recyclable benzyl-type fluorous tags with double fluorous chains. The benzyl-type fluorous tags were prepared in 3 steps from a commercially available fluorous alcohol. The glycosylation of the benzyl-type tags with imidate donors proceeded smoothly to provide the corresponding fluorous-tagged carbohydrates in good to excellent yields, which were readily purified by fluorous solid-phase extraction (FSPE). Efficient removal of the tags from tag-tethered carbohydrates were conducted under the common catalytic hydrogenation condition and the initial benzyl-type fluorous tags could be regenerated via a 2-step simple procedure in 69%–93% yields. The utility of the new benzyl-fluorous tag was demonstrated via the FSPE-assisted synthesis of oligosaccharides Gb3.