Summary Soil is a crucial component of the biosphere and is a major sink for organic carbon. Plant roots are known to release a wide range of carbon‐based compounds into soils, including polysaccharides, but the functions of these are not known in detail.Using a monoclonal antibody to plant cell wall xyloglucan, we show that this polysaccharide is secreted by a wide range of angiosperm roots, and relatively abundantly by grasses. It is also released from the rhizoids of liverworts, the earliest diverging lineage of land plants. Using analysis of water‐stable aggregate size, dry dispersion particle analysis and scanning electron microscopy, we show that xyloglucan is effective in increasing soil particle aggregation, a key factor in the formation and function of healthy soils.To study the possible roles of xyloglucan in the formation of soils, we analysed the xyloglucan contents of mineral soils of known age exposed upon the retreat of glaciers. These glacial forefield soils had significantly higher xyloglucan contents than detected in a UK grassland soil.We propose that xyloglucan released from plant rhizoids/roots is an effective soil particle aggregator and may, in this role, have been important in the initial colonization of land.

The monosaccharide N-acetyl-d-glucosamine (GlcNAc) is an abundant building block in naturally occurring oligosaccharides, but its incorporation by chemical glycosylation is challenging since direct reactions are low yielding. This issue, generally agreed upon to be caused by an intermediate 1,2-oxazoline, is often bypassed by introducing extra synthetic steps to avoid the presence of the NHAc functional group during glycosylation. The present paper describes new fundamental mechanistic insights into the inherent challenges of performing direct glycosylation with GlcNAc. These results show that controlling the balance of oxazoline formation and glycosylation is key to achieving acceptable chemical yields. By applying this line of reasoning to direct glycosylation with a traditional thioglycoside donor of GlcNAc, which otherwise affords poor glycosylation yields, one may obtain useful glycosylation results.

Functional pairing between cellular glycoconjugates and tissue lectins like galectins has wide (patho)physiological significance.T heir study is facilitated by nonhydrolysable derivatives of the natural O-glycans, such as Sand Se-glycosides.T he latter enable extensive analyses by specific 77 Se NMR spectroscopy,b ut stillr emain underexplored. By using the example of selenodigalactoside (SeDG) and the human galectin-1 and-3, we have evaluated diverse 77 Se NMR detection methods and propose selective 1 H, 77 Se heteronuclear Hartmann-Hahn transfer for efficient use in competitive NMR screening against as elenoglycoside spy ligand.B yf luorescence anisotropy,c ircular dichroism, and isothermal titration calorimetry (ITC), we show that the affinity and thermodynamics of SeDGb inding by galectins are similart ot hiodigalactoside (TDG) and N-acetyllactosamine (LacNAc), confirming that Se substitution has no major impact.I TC data in D 2 Ov ersus H 2 Oa re similar for TDG and LacNAcb inding by both galectins, but as olvent effect, indicating solvent rearrangement at the binding site, is hinted at for SeDG and clearly observed for LacNAcd imers with extendedc hain length.

By using iridium catalysed dehydrogenative decarbonylation, we converted a partly protected cellobioside into a fully protected xylobioside. We demonstrate good yields with two different aromatic ester protecting groups. The resulting xylobioside was directly used as glycosyl donor in further synthesis of a xylooctaose.

A method for introducing dimethylphenylsilyl at the 4‐position in carbohydrates has been developed. Two C‐silylated glycosyl donors were prepared via levoglucosenone, starting from cellulose. The glycosylation properties were studied using three glucoside acceptors, a 3‐OH, 4‐OH, and 6‐OH. Compared with the 4‐deoxy variant, it was found that the anomeric selectivity was influenced more by the C‐2 substituents orientation than the silyl in the 4‐position. In general, the reactivity of these donors was higher than the corresponding 4‐deoxy‐analogue, albeit a competition experiment showed that the introduction of a C−Si increases the relative reactivity by a modest factor of around two.