No abstract

Carbohydrates have been demonstrated to perform imperative act in biological processes. This review highlights recent uses of photoinduced glycosylation in carbohydrate chemistry for the synthesis of oligosaccharides, thiosugars, glycoconjugates and glycoprotein.

Its even more than a centennial that the systematic researches of chemical alteration of sugars have been advancing. Out of all the interest in the field of N‐glycoside has assembled pace over the past few years. Therefore, N‐functionalization of sugar is one of the most fundamental modifications along with other group like azide, amide etc also play a remarkable role in the field of glycoscience. Different approaches to access structurally modified N‐glycosides in carbohydrate derivatives are reviewed. The goal of this review is to provide an overview of different way of N‐functionalization of amino sugar and induction of nitrogen scaffolds for the synthesis of various orthogonal protective groups of the N‐glycoside. The N‐functionalization of sugars designate as follows: (a) glycosylamine, (b) glycosyl azide, and (c) introduction of N‐functionality to the sugar for formation of N‐glycosides. This is the first review focus on N‐functionalization of sugars which will be a future scope that influence the readers to work in this area further.

A general strategy was developed for the synthesis of Sulfonyl-1,2,3-triazolyl glycoconjugates (5a-n) and fully decorated 1,2,3triazolyl glycoconjugates (6a-w & 6 aa-6 ah) in the presence of catalytic amounts of organocatalyst. Ramachary-Bressy-Wang organocatalytic azide-ketone [3 + 2]-cycloaddition (OrgAKC) reaction of b-keto sulfones act as internal alkynes with glycosyl azides are reported for the synthesis of Sulfonyl-1,2,3-triazolyl glycoconjugates at 50 8C in good to excellent yields of products in the presence of catalytic amounts of pyrrolidine (10 mol %). In the similar way, Ramachary OrgAKC reaction of a variety of substituted phenyl ketones as internal alkynes with different glycosyl azides are reported for the synthesis of 1,2,3-triazolyl glycoconjugates at room temperature in good to excellent yields with high regioselectivity in the presence of catalytic amounts of DBU (10 mol %) using DMSO as solvent. The work mainly focuses on the application of this methodology to making glycoconjugates and establishes an alternative tool for the synthesis of fully decorated glyco-triazoles from the already known copper catalysed azide-alkyne [3 + 2] cycloaddition (CuAAC), RuAAC and IrAAC click reactions.

No abstract

The base-promoted intramolecular cyclization of Ugi-azide adduct has been demonstrated for the synthesis of highly substituted aziridinyl glycoconjugates in one pot. The reactions are scalable and efficient and have an operationally simple broad substrate scope. To gain insight into the mechanism of aziridine formation, DFT and control experiments show that the cyclization of the aziridine glycoconjugate pathway was preferred, as it proceeds with a low activation energy barrier (0.57 kcal mol–1), which supports our experimental observation.

The liquid−liquid interface offers a fascinating avenue for generating hierarchical compartments. Herein, the dynamic imine chemistry is employed at the oil−water interface to investigate the effect of dynamic covalent bonds for modulating the droplet shape. The imine bond formation between oil-soluble aromatic aldehydes and water-soluble polyethyleneimine greatly stabilized the oil−water interface by substantially lowering the interfacial tension. The successful jamming of imine-mediated assemblies was observed when a compressive force was applied to the droplet. Thus, the anisotropic compartmentalization of the liquid−liquid interface was created, and it was later altered by changing the pH of the surrounding environment. Finally, a proof-ofconcept demonstration of a pH-triggered cargo release across the interfacial membrane confirmed the feasibility of stimuli-responsive behavior of dynamic imine assemblies.

A practical route to access synthetically challenging and chemoselective α,α′-diarylmethyl N-glycosides via Sc(OTf)3-catalyzed 1,6-conjugate addition of unprotected amino sugars with p-QMs.