Design and synthesis of new carbohydrate-lithocholic acid conjugates linked via 1,2,3-triazole rings

Cu(I)-Catalyzed Click Chemistry in Glycoscience and Their Diverse Applications

Copper(I)-catalyzed 1,3-dipolar cycloaddition between organic azides and terminal alkynes, commonly known as CuAAC or click chemistry, has been identified as one of the most successful, versatile, reliable, and modular strategies for the rapid and regioselective construction of 1,4-disubstituted 1,2,3-triazoles as diversely functionalized molecules. Carbohydrates, an integral part of living cells, have several fascinating features, including their structural diversity, biocompatibility, bioavailability, hydrophilicity, and superior ADME properties with minimal toxicity, which support increased demand to explore them as versatile scaffolds for easy access to diverse glycohybrids and well-defined glycoconjugates for complete chemical, biochemical, and pharmacological investigations. This review highlights the successful development of CuAAC or click chemistry in emerging areas of glycoscience, including the synthesis of triazole appended carbohydrate-containing molecular architectures (mainly glycohybrids, glycoconjugates, glycopolymers, glycopeptides, glycoproteins, glycolipids, glycoclusters, and glycodendrimers through regioselective triazole forming modular and bio-orthogonal coupling protocols). It discusses the widespread applications of these glycoproducts as enzyme inhibitors in drug discovery and development, sensing, gelation, chelation, glycosylation, and catalysis. This review also covers the impact of click chemistry and provides future perspectives on its role in various emerging disciplines of science and technology.

Cu-Al mixed oxide-catalysed multi-component synthesis of gluco- and allofuranose-linked 1,2,3-triazole derivatives

A series of carbohydrate-linked 1,2,3-triazole derivatives were synthesized in good yields from glucofuranose and allofuranose diacetonides using as key step a three-component 1,3-dipolar azide-alkyne cycloaddition catalysed by a Cu-Al mixed oxide. In this multi-component reaction, Cu-Al mixed oxide/sodium ascorbate system serves as a highly reactive, recyclable and efficient heterogeneous catalyst for the regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles. The reported protocol has significant advantages over classical CuI/N,N-diisopropylethylamine (DIPEA) or CuSO4/sodium ascorbate conditions in terms of efficiency and reduced synthetic complexity. In addition, the selective deprotection of synthesized di-O-isopropylidene derivatives was also carried out leading to the corresponding mono-O-isopropylidene products in moderate yields. Some of the synthesized triazole glycoconjugates were tested for their in vitro antimicrobial activity using the disc diffusion method against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), as well as fungus (Aspergillus niger) and yeast (Candida utilis). The results revealed that these compounds exhibit moderate to good antimicrobial activity mainly against Gram-negative bacteria.