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Fluorinated carbohydrate mimetics are valuable molecular fragments in contemporary Glycoscience. Available synthetic protocols are mainly restricted to the preparation of 'standard' monofluorinated derivatives, whereas their more complex C(sp(3))-CF3 congeners remain virtually underdeveloped. A protocol for accessing a series of previously uncharted 2-deoxy-2-trifluoromethyl-d-hexopyranosides from d-glycals is disclosed. The stereoselectivity of the glycosylation step, which is mainly governed by a combination of electronic and more dominant steric factors, revealed a pronounced substrate control rendering 1,2-trans glycosides as a result of the configuration of the CF3 moiety at C-2. The synthetic utility of this approach was demonstrated in the preparation of 2-CF3-glycoconjugates of natural origin, including disaccharides, cholesterol analogs, amino acids, and sphingosine/phytosphingosine derivatives.

Methods that site-selectively attach multivalent carbohydrate moieties to proteins can be used to generate homogeneous glycodendriproteins as synthetic functional mimics of glycoproteins. Here, we study aspects of the scope and limitations of some common bioconjugation techniques that can give access to well-defined glycodendriproteins. A diverse reactive platform was designed via use of thiol-Michael-type additions, thiol-ene reactions, and Cu(I)-mediated azide-alkyne cycloadditions from recombinant proteins containing the non-canonical amino acids dehydroalanine, homoallylglycine, homopropargylglycine, and azidohomoalanine.© 2022 Wiley-VCH GmbH.

The introduction of fluoroalkylthioether groups has attracted the attention of the drug-discovery community given the special physicochemical and pharmacokinetic features they confer to bioactive compounds, yet these are often limited to standard SCF3 and SCF2H moieties. Herein, two saccharin-based electrophilic reagents have been disclosed for the incorporation of uncommon SCF2CF2H and SCF2CF3 motifs. Their reactivity performance, multigram-scale preparation, and divergent derivatization have been thoroughly investigated with a variety of nucleophiles, including natural products and pharmaceuticals.

Regio- and stereoselective oxyamination of dienes through a tandem rhodium catalysed aziridination-nucleophilic opening affords racemic oxazolidinone derivatives, which undergo a kinetic resolution acylation process using ABCs (amidine-based catalysts) achieving s values up to 117. This protocol was applied to the enantioselective synthesis of sphingosine.

© 2018 American Chemical Society. We herein present a flexible approach for the incorporation of CF3 units into a predefined site of electron-rich alkenes that exploits the regiocontrolled introduction of an iodine handle and subsequent trifluoromethylation of the C(sp2)-I bond using fluoroform-derived ligandless CuCF3. The broad substrate scope and functional group tolerance together with the scalability and purity of the resulting products enabled the controlled, late-stage synthesis of single regioisomers of complex CF3-scaffolds, such as sugars, nucleosides (antivirals), and heterocycles (indoles and chromones), with potential for academic and industrial applications.

Sphingosine analogues with a rigid triazole moiety in the aliphatic chain and systematic modifications in the polar head and different degrees of fluorination at the terminus of the alkylic chain were synthesized from a common alkynyl aziridine key synthon. This key synthon was obtained by enantioselective organocatalyzed aziridination and it was subsequently ring opened in a regioselective manner in acidic medium. Up to 16 sphingosine analogues were prepared in a straightforward manner. The in vitro activity of the obtained products as SPHK1 and SPHK2 inhibitors was evaluated, displaying comparable activity to that of DMS.

DOI: 10.1021/acs.joc.7b00210 URL: http://www.sciencedirect.com/science/article/pii/S0926337317301832 Filiació URV: SI, Herein we present a chemical approach for the ready preparation of d-sarmentosyl donors enabling the first total synthesis and structure validation of cardenolide N-1, a challenging 2,6-dideoxy-3-O-methyl-¿-d-xylo-hexopyranoside extracted from Nerium oleander twigs that displays anti-inflammatory properties and cell growth inhibitory activity against tumor cells. The strategy highlights the synthetic value of the sequential methodology developed in our group for the synthesis of 2-deoxyglycosides. Key steps include Wittig-Horner olefination of a d-xylofuranose precursor, [I+]-induced 6-endo cyclization, and 1,2-trans stereoselective glycosylation.

Supercritical carbon dioxide (scCO2) is a suitable medium to perform transition metal-free glycosylations in the absence of volatile organic solvents (VOCs) using glycosyl halides as glycosyl donors. The methodology here described can be applied for obtaining O-glycosides in a totally green reaction, as well as orthoesters, depending on the reaction conditions. The process is much more sensitive to temperature changes than to pressure modification, glycosyl chlorides requiring higher temperatures to be activated than glycosyl bromides. Pivaloyl groups act as good CO2-philic units and showed to be the best choice to obtain good stereoselectivities. The relevance of the fluid nature and supercritical conditions was also evidenced.

In this work, a novel catalytic system for the sunlight-driven water splitting reaction, which exploits the photocatalytic ability of BiVO4 coupled to a new kind of noble-metal-free organic dye molecules, is proposed. Hence, mono- and di-substituted naphthalenediimides (NDIs) were designed to have different functional groups that provide to them both tunable optical properties and adjustable HOMO/LUMO levels, and were selectively prepared (starting from 1,4,5,8-naphthalenetetracarboxylic acid) achieving yields >69%. Smart anchoring groups (i.e. carboxylates or aromatic amines) were added to the dyes in order to allow them to covalently bond to acidic –OH groups present on the BiVO4 surface. An easy and low-cost room temperature dip-coating technique was used to dye-sensitize both BiVO4 powders and thin films. NMR, MS, FT-IR, TG, FESEM, XRD, XPS and optical analyses confirmed the successful organic synthetic routes and good dyes/BiVO4 linkages. Photochemical and photoelectrochemical water oxidation reaction tests, together with DFT calculations, demonstrated that a proper alignment of the semiconductor/NDI-based dye energy levels is fundamental for enhancing the photocatalyst performance through a Z-scheme mechanism. The ability of the NDI organic molecules to delocalize the electronic charges was also a key factor for minimizing recombination processes and achieving more than a ten-fold increase in the photocurrent density of a 6 cm2 BiVO4 photo-electrode. The here reported results open new perspectives for the utilization of this new series of core-substituted NDIs, which are able to improve the activity of photocatalysts for different sunlight-driven applications, e.g. waste water treatment and organic contaminants’ degradation, other than the production of sola

Central scaffold topology and carbohydrate density are important features in determining both the binding mechanism and potency of synthetic multivalent, polydisperse vs. monodisperse carbohydrate systems to a model plant toxin (RCA120). We found lower densities of protein receptors favour the use of heterogeneous, polydisperse glycoconjugate presentations as determined by surface plasmon resonance (SPR) and dynamic light scattering (DLS).

Acyclic nucleosides phosphonates have been prepared in a straightforward manner and in high yields by an enantioselective palladium-catalyzed allylic substitution involving nucleic bases as nucleophiles followed by cross-metathesis reaction with diethyl allylphosphonate.

Open Access, A series of small and well defined cobalt nanoparticles were synthesized by the chemical reduction of cobalt salts in water using NaBH4 as a reducing agent and using various polymeric stabilizers. The obtained nanocatalysts of similar mean diameters (ca. 2.6 nm) were fully characterized and tested in the aqueous phase Fischer-Tropsch Synthesis (AFTS). Interestingly, the nature and structure of the stabilizers used during the synthesis of the CoNPs affected the reduction degree of cobalt and the B-doping of these NPs and consequently, influenced the performance of these nanocatalysts in AFTS

New Rh-NPs stabilised by N-Heterocyclic Carbenes (NHC) were synthesized by decomposition of [Rh(g3-C3H5)3] under H2 atmosphere and fully characterized. Surface studies by FT-IR and NMR spectroscopy employing isotopically labelled ligands were also performed. The Rh0.2 NPs are active catalysts in the reduction of various aromatic substrates. In the reduction of phenol, high selectivities to cyclohexanone or cyclohexanol were obtained depending on the reaction conditions. However, this catalytic system exhibited much lower activity in the hydrogenation of substituted phenols. Pyridine was easily hydrogenated under mild conditions and interestingly, the hydrogenation of 4-methyl and 4- trifluoromethylpyridine resulted slower than that of 2-methylpyridine. The hydrogenation of 1- (pyridin-2-yl)propan-2-one provided the b-enaminone 13a in high yield as a consequence of the partial reduction of the pyridine ring followed by isomerization. Quinoline could be either partially hydrogenated to 1,2,3,4-tetrahydroquinoline or fully reduced to decahydroquinoline by adjusting the reaction conditions.

High molecular weight polypropylene carbonates were prepared by CO2/propylene oxide copolymerization catalyzed by salcy-naphthalene cobalt complexes. The introduction of methyl groups in the ortho position of naphthalene-based salcy ligands and the catalyst loading in the presence of hexane as a co-solvent were crucial to enhance the catalytic performance for the production of polycarbonates of high molecular weight.

© 2017 American Chemical Society. A method for the selective activation of thioglycosides that uses the N+-thiophilic reagent Omesitylenesulfonylhydroxylamine (MSH) as a promoter is presented. The reaction proceeds via anomeric mesitylensulfonate intermediates, which could be isolated and fully characterized by placing a fluorine atom at the C2 position. In the presence of a soft Lewis acid, glycosylation reaction proceeds at ambient temperature with good yields. It is further demonstrated that it is possible to orthogonally activate S-ethyl in the presence of S-phenyl donors, enabling the design of sequential glycosylation strategies.

In this work, a novel catalytic system for the sunlight-driven water splitting reaction, which exploits the photocatalytic ability of BiVO4 coupled to a new kind of noble-metal-free organic dye molecules, is proposed. Hence, mono- and di-substituted naphthalenediimides (NDIs) were designed to have different functional groups that provide to them both tunable optical properties and adjustable HOMO/LUMO levels, and were selectively prepared (starting from 1,4,5,8-naphthalenetetracarboxylic acid) achieving yields >69%. Smart anchoring groups (i.e. carboxylates or aromatic amines) were added to the dyes in order to allow them to covalently bond to acidic -OH groups present on the BiVO4 surface. An easy and low-cost room temperature dip-coating technique was used to dye-sensitize both BiVO4 powders and thin films. NMR, MS, FT-IR, TG, FESEM, XRD, XPS and optical analyses confirmed the successful organic synthetic routes and good dyes/BiVO4 linkages. Photochemical and photoelectrochemical water oxidation reaction tests, together with DFT calculations, demonstrated that a proper alignment of the semiconductor/NDI-based dye energy levels is fundamental for enhancing the photocatalyst performance through a Z-scheme mechanism. The ability of the NDI organic molecules to delocalize the electronic charges was also a key factor for minimizing recombination processes and achieving more than a ten-fold increase in the photocurrent density of a 6 cm2 BiVO4 photo-electrode. The here reported results open new perspectives for the utilization of this new series of core-substituted NDIs, which are able to improve the activity of photocatalysts for different sunlight-driven applications, e.g. waste water treatment and organic contaminants' degradation, other than the production of solar fuel

Supercritical carbon dioxide (scCO2) is a suitable medium to perform transition metal-free glycosylation reactions in the absence of volatile organic solvents (VOCs) using glycosyl halides as glycosyl donors. The methodology described here can be applied for obtaining O-glycosides in a totally green reaction, as well as orthoesters, depending on the reaction conditions. The process is much more sensitive to temperature changes than to pressure modification, with glycosyl chlorides requiring higher temperatures to be activated than glycosyl bromides. Pivaloyl groups act as good CO2-philic units and are shown to be the best choice to obtain good stereoselectivities. The relevance of the fluid nature and supercritical conditions was also evidenced.

Herein we present a chemical approach for the ready preparation of d-sarmentosyl donors enabling the first total synthesis and structure validation of cardenolide N-1, a challenging 2,6-dideoxy-3-O-methyl-¿-d-xylo-hexopyranoside extracted from Nerium oleander twigs that displays anti-inflammatory properties and cell growth inhibitory activity against tumor cells. The strategy highlights the synthetic value of the sequential methodology developed in our group for the synthesis of 2-deoxyglycosides. Key steps include Wittig-Horner olefination of a d-xylofuranose precursor, [I+]-induced 6-endo cyclization, and 1,2-trans stereoselective glycosylation.

A series of small and well defined cobalt nanoparticles were synthesized by the chemical reduction of cobalt salts in water using NaBH4 as a reducing agent and using various polymeric stabilizers. The obtained nanocatalysts of similar mean diameters (ca. 2.6 nm) were fully characterized and tested in the aqueous phase Fischer-Tropsch Synthesis (AFTS). Interestingly, the nature and structure of the stabilizers used during the synthesis of the CoNPs affected the reduction degree of cobalt and the B-doping of these NPs and consequently, influenced the performance of these nanocatalysts in AFTS

author can archive pre-print (ie pre-refereeing), A series of colloidal cobalt nanoparticles of ca. 2.6 nm stabilized by several polymeric stabilizers were synthesized in water using sodium borohydride as reducing agent and subsequently immobilized on TiO2. Both colloidal and TiO2 supported NPs were characterized by TEM, HRTEM, XRD, XPS, TGA and ICP techniques and the catalytic performance of the supported NPs evaluated in the Fischer-Tropsch synthesis. Important differences in terms of activity were observed depending on the polymeric stabilizers used for the synthesis of the CoNPs. These differences were correlated with the catalyst reducibility, the presence of polymer stabilizer and boron and the reduction degree at the metal surface.

© 2014 Elsevier Masson SAS. Pyranoid-type glycomimetics having a cis-1,2-fused glucopyranose-2-alkylsulfanyl-1,3-oxazoline (Glc-PSO) structure exhibit an unprecedented specificity as inhibitors of mammalian β-glucosidase. Notably, their inhibitory potency against human β-glucocerebrosidase (GCase) was found to be strongly dependent on the nature of aglycone-type moieties attached at the sulfur atom. In the particular case of υ-substituted hexadecyl chains, an amazing influence of the terminal group was observed. A comparative study on a series of Glc-PSO derivatives suggests that hydrogen bond acceptor functionalities, e.g. fluoro or methyloxycarbonyl, significantly stabilize the Glc-PSO:GCase complex. The S-(16-fluorohexadecyl)-PSO glycomimetic turned out to be a more potent GCase competitive inhibitor than ambroxol, a non glycomimetic drug currently in pilot trials as a pharmacological chaperone for Gaucher disease. Moreover, the inhibition constant increased by one order of magnitude when shifting from neutral (pH 7) to acidic (pH 5) media, a favorable characteristic for a chaperone candidate. Indeed, the fluoro-PSO derivative also proved superior to ambroxol in mutant GCase activity enhancement assays in N370S/N370S Gaucher fibroblasts. The results presented here represent a proof of concept of the potential of exploiting long-range non-glycone interactions for the optimization of glycosidase inhibitors with chaperone activity.

12 meses de embarg author can archive pre-print (ie pre-refereeing) subject to Restrictions below, author can archive post-print (ie final draft post-refereeing), Cobalt nanoparticles of 2.6 nm were synthesized in water using NaBH4 as the reducing agent and PVP as stabilizer. The nanoparticles were fully characterized and their catalytic performances evaluated in the aqueous phase Fischer-Tropsch Synthesis (AFTS) at various pH values. The pH of the catalytic solution was shown to affect both the activity and selectivity of the AFTS reaction since side reactions such as WGS and formation of formate from CO2 were favored at basic pH.

author can archive pre-print (ie pre-refereeing) El título original que se cambio por sugerencia de los referees es el que consta en el pre print Remarkable Stability of Small Cobalt NanoparticlesPrepared by Sodium Borohydride Reduction in the Fischer-Tropsch Synthesis, tCobalt nanoparticles in the range of 1.7¿7 nm were synthesized in water using sodium borohydride asreducing agent and subsequently immobilized on TiO2. Both colloidal and TiO2supported NPs were char-acterized by TEM, XRD, HRTEM, XPS, TGA, ICP techniques and their catalytic performance of the supportedcatalysts evaluated in the Fischer¿Tropsch synthesis. As a general trend, an increase in activity and TOFwas observed when the particle size decreased. These results were rationalized by the higher reducibilityof the catalysts bearing the smaller nanoparticles. The unconventional stability of these relatively smallCoNPs in FTS was attributed to the promoting effect of boron on the stability of the cobalt nanocrystals

10.1016/j.ejmech.2014.11.002, Pyranoid-type glycomimetics having a cis-1,2-fused glucopyranose-2-alkylsulfanyl-1,3-oxazoline (Glc-PSO) structure exhibit an unprecedented specificity as inhibitors of mammalian ß-glucosidase. Notably, their inhibitory potency against human ß-glucocerebrosidase (GCase) was found to be strongly dependent on the nature of aglycone-type moieties attached at the sulfur atom. In the particular case of ?-substituted hexadecyl chains, an amazing influence of the terminal group was observed. A comparative study on a series of Glc-PSO derivatives suggests that hydrogen bond acceptor functionalities, e.g. fluoro or methyloxycarbonyl, significantly stabilize the Glc-PSO:GCase complex. The S-(16-fluorohexadecyl)-PSO glycomimetic turned out to be a more potent GCase competitive inhibitor than ambroxol, a non glycomimetic drug currently in pilot trials as a pharmacological chaperone for Gaucher disease. Moreover, the inhibition constant increased by one order of magnitude when shifting from neutral (pH 7) to acidic (pH 5) media, a favorable characteristic for a chaperone candidate. Indeed, the fluoro-PSO derivative also proved superior to ambroxol in mutant GCase activity enhancement assays in N370S/N370S Gaucher fibroblasts. The results presented here represent a proof of concept of the potential of exploiting long-range non-glycone interactions for the optimization of glycosidase inhibitors with chaperone activity.