Photosensitive Fluorous Tag-Assisted Convergent Synthesis of β-1,4-Mannuronates

Abstract

Rapid synthesis of saccharides by a chemical method is an efficient way to meet the demand for well-defined glycans to probe their biological functions. Herein, a feasible and convenient strategy for saccharide synthesis was established by introducing a photosensitive fluorous tag at the anomeric position of glycosides. The tag was used not only in polytetrafluoroethylene-assisted rapid purification but also as a temporary protecting group at the reducing end of carbohydrates. The tag-protected glycosides could be transformed into new glycosyl donors for convergent synthesis after orthogonal deprotection of the tag by photolysis. Via combination of the β-directing C-5 carboxylate glycosylation strategy, β-1,4-mannuronates were efficiently prepared.

Orthogonal Deprotection of Photolabile Protecting Groups and Its Application in Oligosaccharide Synthesis

“…Among the known PPGs, the ortho -nitrobenzyl (NB) group and its analogues , (Figure ) have been widely used as protecting groups for hydroxyl − or carboxyl groups on carbohydrate skeleton or linkers for tag-assisted oligosaccharide synthesis. − Compared with the NB group, the introduction of an electron-donating −OMe group on the aromatic ring (i.e., 6-nitroveratryl, NV, Figure b) permits cleavage with longer irradiation wavelengths and increases the rate of photolysis . Thus, NV has been frequently used in peptide synthesis and other fields. , Under ultraviolet irradiation (365 ± 20 nm), NV could be rapidly removed to provide the corresponding products in high yields .…”

S-o-(p-Methoxyphenylethynyl)benzyl (SMPEB) Glycosides for Catalytic Glycosylation and Their Application in the Synthesis of Polyporus Umbellatus Polysaccharides

“…Chemical synthesis is a reliable method to solve this bottleneck problem. To this end, a series of glycosylation methods, synthetic strategy, and purification means were explored to realize rapid preparation of saccharides. However, the key to the successful achievement of target saccharides relies on efficient installation of the desired glycosidic bonds.…”