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Highly efficient and reusable pre-formed mono- and dinuclear heteroleptic copper(I) dithiocarbamate and dithiocarbimate complex based catalysts, [Cu(PPh3)2(L)] and [Cu2(PPh3)4(L)] (L = N-(4-methylpyridyl)-N-(3-methylpyridyl)dithiocarbamate− L1 1, N-methylfuryl-N-methylthiophenedithiocarbamate- L2 2; 4-chlorobenzenesulfonyl dithiocarbimate2- L3 3, 4-bromobenzenesulfonyldithiocarbimate2- L4 4) have been utilized in the cycloaddition reactions of azide and alkyne to form a variety of glycoconjugate triazoles in Click chemistry. These new pre-catalysts have been characterized by elemental (C, H, N) analysis, IR, UV–vis., 1H, 13C{1H}, and 31P{1H} NMR spectroscopy and their structures have been revealed by X-ray crystallography. In the structures of (1,2)/(3,4) the copper atoms are situated within a four coordinate (P2S2)/(P2NS) distorted tetrahedral geometry. Notably in the dinuclear complexes 3 and 4, the dithiocarbimate ligands are bonded in a S, S- chelating mode to one copper atom and simultaneously bridge the other copper centre via N, S- donor atoms. 1-4 are strongly luminescent in CH2Cl2 solution at room temperature.

A practical method for the selective and controlled oxidation of thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably, oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide.

Metal-free different catalytic systems have been investigated for [3+2] cycloaddition reaction of glycosyl azides with nitro-olefins for the synthesis of 1,5-disubstituted-1H-1,2,3-triazolyl glycoconjugates. A competitive study between p-TsOH and diverse ammonium salts including phase transfer catalysts and room temperature ionic liquids as environmentally benign medium have been described to search the best one for glycoconjugation. Tetra butyl ammonium bromide was found to be the most appropriate catalyst and a series of 1,5-disubstituted glyco-triazoles has been achieved in good yield. All the developed glycoconjugates were characterized using spectroscopic analysis (IR, MS, 1H NMR, 13C NMR).

Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC), popularly known as the "click reaction", serves as the most potent and highly dependable tool for facile construction of simple to complex architectures at the molecular level. Click-knitted threads of two exclusively different molecular entities have created some really interesting structures for more than 15 years with a broad spectrum of applicability, including in the fascinating fields of synthetic chemistry, medicinal science, biochemistry, pharmacology, material science, and catalysis. The unique properties of the carbohydrate moiety and the advantages of highly chemo- and regioselective click chemistry, such as mild reaction conditions, efficient performance with a wide range of solvents, and compatibility with different functionalities, together produce miraculous neoglycoconjugates and neoglycopolymers with various synthetic, biological, and pharmaceutical applications. In this review we highlight the successful advancement of Cu(I)-catalyzed click chemistry in glycoscience and its applications as well as future scope in different streams of applied sciences.

A controlled and facile synthesis of various glycosyl 1,3-oxazolidine-2-thiones and 1,3- thiozolidine-2-thiones has been accomplished from corresponding sugar azido alcohols utilizing Staudinger reaction (PPh3 and CS2) via isothiocynate route. A series of reactions were performed to investigate the effects of CS2 and PPh3 on the selectivity of product formed. The excessive addition of CS2 with PPh3(1.2 equiv) afforded oxazolidine-2-thione alone, while the solitary addition of PPh3 for 30 min followed by addition of CS2 to the reaction mixture resulted both the products in different ratios, which were successfully isolated using column chromatography (SiO2). Furthermore, synthesis of 1,3-oxathiolan-2-imine from glycosyl epoxide has also been attempted. Structures of all the developed compounds have been elucidated using extensive spectroscopic techniques including IR, NMR and MS analysis.

The 1,3-dipolar cycloaddition of deoxy-azido sugars 1 with alkyne derivatives of p-vanillin, 3-methoxy-4-(prop-2-ynyloxy)benzaldehyde (2) and 2-methoxy-1-(prop-2-ynyloxy)-4-((prop-2-ynyloxy)methyl)benzene) (4) to afford regioselective triazole-linked vanillinglycoconjugates 5 and 6 was investigated in the presence of CuI/DIPEA in dichloromethane. All the developed glycoconjugates were characterized on the basis of IR, NMR, and MS. Graphical abstract Triazolyl vanillin glycoconjugates via click chemistry.

Carbohydrates, one of the most abundant classes of biomolecules, are the structural building blocks of genetic materials and vital source of energy. They are integral part of the living cells as they play key roles in many cellular and intracellular interactions in the form of cell surface receptors, signaling molecules, and bacterial adhesives. These roles of carbohydrates underlie their potential as pharmaceutical and diagnostic agents and therefore stimulate the synthetic chemists to develop various facile ways to synthesize diverse eccentric glycoconjugates. Many carbohydrates and their derivatives of natural and synthetic origin are clinically used for treatment of various diseases. The immense structural diversity in terms of functional groups, linkages, and number of rings offers these molecules as a valuable tool for design and development of biologically active glycoconjugates. The promising biological activity of carbohydrate-based entities makes them valuable molecular scaffold after their thorough chemical and biological investigations. The carbohydrate moieties in glycoconjugates impart properties like hydrophilicity and decreased toxicity, which enhance the bioavailability to give the optimum pharmacokinetics. This chapter will abridge the cardinal developments in the synthesis and analysis of biologically significant carbohydrate-based molecules from the leading laboratories, highlighting the certainty of carbohydrates in creating an ideal therapeutic platform for drug discovery and development.