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A formal synthesis of FR252921, a potent macrocyclic immunosuppressive agent, and a six-step synthesis of vitamin A have been demonstrated. The application of a ruthenium-catalyzed step-economic and environmentally benign strategy for the highly stereo- and chemoselective construction of valuable polyene motifs of FR252921 and vitamin A highlights the syntheses. The key features for the synthesis FR252921 include preparation of the triene moiety followed by two consecutive peptide couplings of the three fragments.

A Ru-catalyzed direct oxidative coupling reaction of vinyl ketones was developed.

A Ru-catalyzed direct oxidative coupling reaction of vinyl ketones was developed. It offers a straightforward and atom-economical protocol for the synthesis of functionalized (

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.

The 1,3-dipolar cycloaddition of deoxy-azido sugars 1 with O-benzylquercetin alkynes (5-7) to afford regioselective triazole-linked O-benzylquercetin glycoconjugates (8-10) was investigated in the presence of CuI/DIPEA in dichloromethane. All the developed glycoconjugates (8-10) were evaluated for anti-leishmanial activity against the promastigotes and amastigotes of Leishmania donovani. Graphical Abstract Click Inspired Synthesis of Antileishmanial Triazolyl O-Benzylquercetin Glycoconjugates.

A number of novel 7-O-noscapine glycoconjugates have been synthesized starting from noscapine, an alkaloid found in the opium plant, via two successive steps. The first step is a selective 7-O-demethylation of noscapine and the next is a subsequent propargylation which affords 7-O-propargyl noscapine (3) in good yield. The structure was confirmed by extensive spectroscopic data including single crystal X-ray data. The 1,3-dipolar cycloaddition of the developed noscapine derivative 3 with glycosyl azides 6a–m was investigated to give the triazole-linked second-generation noscapine analogs in their glycoconjugate forms (8a–m) to augment the therapeutic efficacy of noscapine.

A series of diverse glycosyl 1,2-azido alcohols, obtained from readily available carbohydrates, were converted to structurally varied rare and novel sugar derived morpholine fused [5,1-c]-triazoles via a one-pot strategy. After incorporating a propargyl functionality at the hydroxyl group of the sugar derived 1,2-azido alcohols, the resulting in situ generated azido–alkyne affords numerous C- and O-glycosyl bicyclic ring systems with medicinal value via a metal free cycloaddition reaction. The structures of all the developed molecules have been elucidated using 1H NMR, 13C NMR, IR and MS spectroscopy.

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.

Herein, we have probed a wide band gap material, CaGa2O4 co-doped with Eu3+/Na+, which is fairly transparent (≥95%) in the visible region and efficiently absorbs solar blind UV radiation. Importantly, the absorbed UV energy can be realized both in terms of fluorescence and photoconductivity as well. X-ray diffraction studies confirmed that CaGa2O4 exhibits two orthorhombic polymorphs: CaO·Ga2O3 I (major) and CaO·Ga2O3II (minor). Vibrational spectroscopy provided the first quantitative insight into the phonon frequency of the material. Upon UV illumination the host itself gives UV-blue and red emissions due to band to band and trap level transitions, respectively. (no additional dopant or activator ion were present). A substantial overlap between the emission spectrum of the host and the excitation spectrum of Eu3+; decrease in emission intensity and decay time (8.82 μs from 9.2 μs) of the host emission, after Eu3+ doping; and evolution of a short rise-time (∼10 μs) in decay curve of Eu3+ revealed that the host efficiently transfers its energy to the Eu3+ ions. Co-doping of Na+ further enhances the emission intensity (∼7 times), decay time and rise-time of the Eu3+ emission. Likewise the intrinsic behavior of Ga2O3 this material also shows significant transient photoconductivity under UV illumination, photocurrent is of the order of μA, but with slow time constant ∼40 min. Thus, the excellent optical properties prove to be superior for photoconductivity for UV-to-visible converter applications. Such WBG optical materials can be coupled to silicon-based commercial detectors for their wide use in areas ranging from invisible flame sensing to UV astronomy.

Thiobenzoate complexes of Cu(I), [Cu(SCOPh)]n(1), [Cu(bpy)(µ-SCOPh)]2 (2), [Cu(dppf)(SCOPh)] (3), [where bpy = 2,2′-bipyridyl; dppf = [1,1′-bis(diphenylphosphino)ferrocene] were synthesized and structurally characterized by X-ray crystallography. NBO calculations were performed to understand the nature of the Cu–Cu (2.706 A) interaction in 2. All of the complexes were found to catalyze azide–alkyne cycloaddition for the regioselective synthesis of glycoconjugate triazoles under click reaction.

Er3+ doped Y2O3 nanophosphor has been synthesized using solution combustion technique and further characterized for structure and optical properties. Optical properties of Er3+ ion have been studied both through frequency upconversion (UC) as well as through fluorescence (excitation, emission, and CIE co-ordinate analysis) processes. Further to enhance the UC emission of Er3+ ions, a two step process has been used. In the first step, Yb3+ ion has been co-doped, which acts as the sensitizer for Er3+ through energy transfer process. In the second step, different concentrations of Li+ ions have been co-doped in the Er3+/Yb3+:Y2O3 system. Fourier transform infrared analysis, and X-ray diffraction (XRD) followed by Le-Bail refinement of the XRD data reveal that the co-doping of Li+ ion decreases unit cell parameter, increases the particle size, and removes the quenching centers (like OH, NOx, etc.), which all together causes a significant enhancement in UC emission. Optimum UC luminescence is attained for 5 mol% Li+ doping concentration beyond which a quenching in UC emission is observed. This combined approach, i.e. Yb3+ sensitization and Li+ ion tailoring simultaneously enhances the UC emission intensity of Er3+ several times in yttria matrix effectively. The strategy can be generalized in other hosts also which could help in the development of efficient photonic materials for lighting and display devices.

In the present paper, Ho 3+ doped and Ho 3+ /Yb 3+ co-doped Y 2 O 3 phosphors have been synthesized using solution combustion technique and characterized for its structure and upconversion (UC) fluorescence as a function of Yb 3+ concentration. Effect of a variation in laser input power and external temperature on the UC emission intensity has been studied to explore the UC mechanism and temperature dependent behavior of the phosphor, respectively. On excitation with near infrared (NIR) light (976 nm), the phosphor emits strong green emission along with relatively weak emission bands in red and blue regions at 553, 670 and 497 nm due to 5 S 2 → 5 I 8 , 5 F 5 → 5 I 8 and 5 F 3 → 5 I 8 , respectively. The emission shows a decrease in intensity with an increase in external temperature, however contrary to the normal behavior of Ho 3+ , no significant change in the FIR (fluorescence intensity ratio) of 5 F 4 → 5 I 8 and 5 S 2 → 5 I 8 transitions is noted in the present host. This peculiar behavior of the sample with external temperature has been explained by temperature dependent lifetime study of the thermally coupled levels.

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.

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)...

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.

Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221 005, Uttar Pradesh, India E-mail : Tiwari_chem@yahoo.co.in Central Institute for Research on Cotton Technology, Matunga, Mumbai-400 019, India Manuscript received online 12 February 2015, accepted 04 March 2015 In addition to the wide range of pharmacological activities associated with β-lactams, their importance as synthetic intermediates in organic synthesis has been widely recognized. A series of glycosyl β-lactam of promising chemotherapeutic values has been developed from corresponding β-amino esters in good yield under mild reaction condition.

Synthesis of sugar based triazolyl azido-alcohols was accomplished via one pot click reaction of glycosyl alkynes with epichlorohydrin in aqueous medium. All the developed triazolyl azido-alcohols were further utilized for the synthesis of bis-triazolyl ethisterone glycoconjugates using CuAAC reaction. The developed triazole-linked ethisterone glycoconjugates would be crucial in androgen receptor pharmacology and chemical biology.

The synthesis of triazolyl azido alcohols from terminal alkyne via oxirane ring-opening of epichlorohydrin, followed by click reaction with alkynes, and subsequent azidation of chlorohydroxy triazoles was achieved under a one-pot methodology. The developed triazolyl azido alcohols were further utilized for the synthesis of a diverse range of morpholine-fused triazoles of chemotherapeutic value. The structure of all developed compounds has been elucidated using IR, NMR, MS, and elemental analysis, where four of them have been characterized by single-crystal X-ray analysis.

Numerous deoxy-azido sugars 3 were prepared by the reaction of tosyl/bromo sugars with NaN3 in dry DMF under heating condition. The 1,3-dipolar cycloaddition of deoxy-azido sugars 3 with ethisterone 4 to afford regioselective triazole-linked ethisterone glycoconjugates 5 was investigated in the presence of CuI and DIPEA in dichloromethane or CuSO4·5H2O and sodium ascorbate in aqueous medium. All the developed compounds were characterized by spectroscopic analysis (IR, 1H & 13C NMR, and MS spectra). Structure of triazolyl ethisterone glycoconjugate 5a has been further confirmed by its Single Crystal X-ray analysis.