Carbohydrate chemistry articles from across Nature Portfolio

The synthesis of unprotected C-heteroaryl glycosides is challenging because of the lack of methods to utilize native saccharides as substrates. Now these compounds, capped as redox-active glycosyl sulfide donors, undergo C–C coupling with N-heteroarenes through a photoinduced, thiyl radical-mediated reaction with control over the chemo-, site- and stereoselectivity.

Complex reaction networks can reach out-of-equilibrium steady states with multiple product-determining steps. Now it has been shown that a four-component photochemical network enables selective GlcNAc-to-GalNAc epimerization. Boronic ester co-catalysis tunes hydrogen-atom abstraction and donation to enhance site selectivity and diastereoselectivity, illustrating kinetic network control for selective catalysis.

Here, the authors report a radical cross-coupling approach in which the native hydroxyl group on saccharides is activated in situ by a phosphorus reagent, enabling C − C bond formation with aryl iodides to afford a broad range of aryl C-glycosides.

Human milk oligosaccharides (HMOs) have highly diverse and branched structures that present a significant challenge for chemical synthesis. Here, the author reports that masking the amino group in glucosamine with a p-nitrobenzyloxycarbonyl (pNZ) group enhances coupling and deprotection efficiency during the automated glycan assembly (AGA) of homogeneous HMOs.

Chemical synthesis of carbohydrates provides an efficient, scalable approach, facilitating therapeutic development and mechanistic studies. Herein, the authors report an O-glycosylation method utilizing bench-stable and readily accessible oxazolidinone-based glycosyl carbamates as donors.

Benjamin N. Bhawal examines the enigmatic history of ribose in chemistry, its multifaceted structure, and its role in the origin of life and the design of future therapeutics.

Design of anomeric leaving groups with pendant H-bond acceptors results in a stereospecific chemical O-glycosylation with broad scope and applicability to automated synthesis.

In nature, catalytic functions are typically restricted to proteins and ribozymes. Now, a synthetic glycan capable of catalysing a chemical reaction is demonstrated. The folded glycan scaffold positions an aromatic recognition site in proximity to a reactive functional group. This glycan catalyst accelerates the Pictet–Spengler functionalization of tryptophan and tryptophan-containing peptides in water.

A highly chemoselective method for the insertion of carbohydrates into existing oligosaccharides has been developed. The reaction sequence involves a selective Lewis-acid catalysed cleavage of one glycosidic bond followed by sequential construction of two new glycosidic bonds.

d-cyclodextrins are naturally occurring macrocyclic oligosaccharides that act as hosts for hydrophobic guests and are produced on a multi-tonne scale. Now, using chemical synthesis, mirror-image cyclodextrins are produced from l- instead of d-glucose units.

A preactivation-based one-pot glycosylation strategy was used to synthesize RN1 — a polysaccharide comprising 140 monosaccharide units isolated from Panax notoginseng, as well as a glycan fragment library. Evaluation of the biological activity of the glycans in vitro revealed that a decasaccharide fragment shows anti-pancreatic cancer activity.