Gold nanocatalysed oxidation of free carbohydrates
Quehon, L.; Pourceau, G.; Wadouachi, A.
Carbohydrate Chemistry: Chemical and Biological Approaches Volume 46 2024, 46, 0.
Catalytic transformation of biomass-derived natural resources into valuable compounds is of great interest for sustainable development. Particularly, sugar acids obtained by selective oxidation of carbohydrates are very valuable molecules in many areas such as detergency, medicine (pharmaceuticals), and cosmetics. The choice of a robust and highly selective catalyst for oxidation of the aldehyde function vs. hydroxy groups is crucial for such transformations of polyhydroxy aldehyde compounds. In this respect, gold nanoparticles have been shown to be highly chemoselective, favouring high yields of the desired glyconic acid. Nevertheless, several key parameters from catalyst design to reaction conditions should be considered to perform highly efficient catalytic transformation. This chapter aims at highlighting the influence of catalyst material properties such as nature of the support, gold nanoparticle size or synthetic method, on the one hand, and of reaction parameters (pH, temperature, nature of the oxidant, ratio between carbohydrate and gold etc.) on the other hand. Particular emphasis is also placed on the versatility of the reaction (application to other mono- and oligosaccharides) and on the use of alternative methods for activating these heterogeneous catalysts.
https://dx.doi.org/10.1039/bk9781837672844-00101

Direct Synthesis of Sugar Amides by Aerobic One-Pot Oxidative Amidation of Unprotected Carbohydrates
Quéhon, L.; Bil, A.; Sauvage, F.; Wadouachi, A.; Pourceau, G.
ACS Sustainable Chemistry & Engineering 2024, 12, 14258-14264.
The development of eco-compatible and economically competitive methods enabling carbohydrate transformation into high-added value sugar-based derivatives is highly desirable to promote their valorization as petroleum-based chemical alternatives. We propose in this study a one-pot sequential procedure for the synthesis of sugar amides, used in various areas from detergency to medicine, starting from nonprotected abundant carbohydrates. The use of a small amount of a recyclable gold catalyst (0.36 mol % Au, Au/CeO2) is crucial for promoting the oxidative amidation reaction. In the presence of benzylamine, d-xylose (the main monomer of hemicellulose used as a model) was converted into corresponding benzyl xylonamide in 3 h at room temperature under an O2 atmosphere. The optimized conditions were then successfully applied to a series of abundant carbohydrates (glucose, galactose, and maltose) and a wide range of amines, thus demonstrating the procedure’s versatility. It is established as not sugar-dependent while being compatible with various functional groups such as alkene, alkyne, thiol, and hydroxyl. Finally, the greenness of the procedure was assessed by comparing the synthesis of N-decyl-d-xylonamide using four green metrics, underlining lower waste generation, higher atom economy, and more acceptable reaction conditions in terms of environmental impact.
https://dx.doi.org/10.1021/acssuschemeng.4c05016

Carboxymethyl β-Cyclodextrin Assistance for the 4-Nitrophenol Reduction Using Cobalt-Based Layered Double Hydroxides
Demeester, A.; Douma, F.; Cousin, R.; Siffert, S.; Pourceau, G.; Wadouachi, A.; Ponchel, A.; Monflier, E.; Noël, S.
International Journal of Molecular Sciences 2024, 25, 6390.
Cobalt-aluminum-layered double hydroxides containing carboxymethyl β-cyclodextrin (CMβCD) were synthesized by coprecipitation and evaluated as a cobalt source for the 4-nitrophenol reduction in an aqueous medium. Several physicochemical techniques (XRD, FTIR, TGA) indicated the intercalation of the anionic cyclodextrin without damages to the hydrotalcite-type structure. These lamellar cobalt-aluminum hybrid materials (CoAl_CMβCD) were evaluated in the 4-nitrophenol reduction and showed higher activities in comparison with the CMβCD-free standard material (CoAl_CO3). To rationalize these results, a set of experimental controls going from physical mixtures of CoAl_CO3 with different cyclodextrins to other cobalt-based materials were investigated, highlighting the beneficial effects of both the layered double hydroxide and CMβCD-based hybrid structures. CMβCD also showed a beneficial effect as an additive during the 4-nitrophenol reduction. CoAl_CO3, dispersed in a fresh CMβCD solution could be re-used for five successive cycles without the loss of activity.
https://dx.doi.org/10.3390/ijms25126390

Sugar-Based Surfactants: Effects of Structural Features on the Physicochemical Properties of Sugar Esters and Their Comparison to Commercial Octyl Glycosides
Lu, H.; Pourceau, G.; Briou, B.; Wadouachi, A.; Gaudin, T.; Pezron, I.; Drelich, A.
Molecules 2024, 29, 2338.
Two series of sugar esters with alkyl chain lengths varying from 5 to 12 carbon atoms, and with a head group consisting of glucose or galactose moieties, were synthesized. Equilibrium surface tension isotherms were measured, yielding critical micellar concentration (CMC) surface tensions at CMC (γcmc) and minimum areas at the air–water interface (Amin). In addition, Krafft temperatures (Tks) were measured to characterize the ability of molecules to dissolve in water, which is essential in numerous applications. As a comparison to widely used commercial sugar-based surfactants, those measurements were also carried out for four octyl d-glycosides. Impacts of the linkages between polar and lipophilic moieties, alkyl chain lengths, and the nature of the sugar head group on the measured properties were highlighted. Higher Tk and, thus, lower dissolution ability, were found for methyl 6-O-acyl-d-glucopyranosides. CMC and γcmc decreased with the alkyl chain lengths in both cases, but Amin did not appear to be influenced. Both γcmc and Amin appeared independent of the ester group orientation. Notably, alkyl (methyl α-d-glucopyranosid)uronates were found to result in noticeably lower CMC, possibly due to a closer distance between the carbonyl function and the head group.
https://dx.doi.org/10.3390/molecules29102338

Mechanosynthesis and Polymerization of Biosourced Styrene Derivatives Based on Building Blocks of Lignin
Michalska-Walkowiak, J.; Sn Antonio, E.; Coumes, F.; Rieger, J.; Terrasson, V.; Pourceau, G.; Wadouachi, A.; Jeux, V.
ACS Sustainable Chemistry & Engineering 2024, 12, 2577-2587.
Finding and developing new biosourced materials that can compete with the current petro-sourced ones are a top priority in order to transition to a more sustainable society. Although the preparation of biosourced polyesters or polyamides is quite well described, finding biosourced and sustainable alternatives to petro-sourced polystyrene is still challenging. Herein, we report the synthesis of polystyrenes prepared in three steps from vanillin, 4-hydrobenzaldehyde, and syringaldehyde, compounds that can be obtained through lignin depolymerization under oxidative conditions. The synthesis involves the conversion of these biosourced platforms into polymerizable styrene derivatives through a methylation of the hydroxyl group followed by an olefination of the aldehyde function. The monomers were first synthesized under conventional conditions using solvents. Then, the synthesis was improved from the sustainability point of view by using a ball mill under solventless conditions, generating much less waste in the process. The three monomers were then converted into biosourced homopolymers through free radical polymerization in bulk, providing functional polystyrene derivatives with thermal properties comparable to those of common petro-sourced polystyrene.
https://dx.doi.org/10.1021/acssuschemeng.3c06050

Gold-Catalyzed Oxidative Transformation of Free Sugars into Biobased Platform Molecules
Quéhon, L.; Sauvage, F.; Ahouari, H.; Golonu, S.; Vezin, H.; Wadouachi, A.; Pourceau, G.
ACS Sustainable Chemistry & Engineering 2023, 11, 11041-11051.
Due to their easy conversion into high-added value products, sugar lactones and their derivatives are very attractive biobased platform molecules. Yet, conventional transformation of free sugars into such activated compounds is not so handy: a multistep procedure requiring protection/oxidation/lactonization-esterification/deprotection is often necessary. We report herein a procedure allowing one to rapidly and efficiently form lactones/esters directly from free sugars under mild conditions, catalyzed with a small amount (0.36 mol %) of recyclable gold nanocatalyst under oxygen atmosphere. The conditions were optimized using galactose as a model, quantitatively and selectively affording 1,4-galactonolactone in 2 h at room temperature. The procedure was then successfully applied to a variety of hexoses and pentoses leading to excellent conversion (>86%). Due to the equilibrium between lactone regioisomers and ester forms, a mixture of 1,4-lactone, 1,5-lactone and methyl ester can be generally obtained depending on the sugar series. A subsequent reaction of the crudes with benzylamine leads to a total conversion of lactones/esters into corresponding amides, confirming the efficiency of the procedure and paving the way to a one-pot transformation of free sugars into high added value sugar-based derivatives. Based on NMR and ESR analyses, a mechanism of the reaction involving CH3O• radical species seems to be taking shape.
https://dx.doi.org/10.1021/acssuschemeng.3c00975

Fast and Efficient Mechanosynthesis of Aldonamides by Aminolysis of Unprotected Sugar Lactones
Bil, A.; Abdellahi, B.; Pourceau, G.; Wadouachi, A.
Sustainable Chemistry 2022, 3, 300-311.
Sugar amides, such as aldonamides, are interesting, sugar-based molecules used in various fields, from detergency to medicine. Nevertheless, their valorization, especially as alternatives to petroleum-based substances, can be slowed down by their synthetic pathway, which is generally not in accordance with green chemistry principles, and is also not economically competitive. We propose herein a fast procedure for the synthesis of aldonamide-derived glycoconjugates with mechanochemistry. The conditions were first optimized with galactonolactone, used as a model lactone, and dodecylamine. After only 5 min of grinding of stoechiometric amounts of amine and lactone, in the presence of water used as a Liquid Assisted Grinding (LAG) agent, the corresponding galactonamide was isolated with a high yield (90%) after a simple aqueous work-up. The optimized conditions were then applied to a wide variety of amines and sugar lactones, showing the versatility of the methodology. Gluco- and ribono-lactone exhibited similarly excellent reactivity, showing that the procedure is not sugar-dependent. Furthermore, the procedure was shown to be compatible with various functional groups such as alkene, alkyne, thiol, ester and hydroxyl.
https://dx.doi.org/10.3390/suschem3030019

Synthesis and interfacial properties of new 6-sulfate sugar-based anionic surfactants
Abdellahi, B.; Bois, R.; Golonu, S.; Pourceau, G.; Lesur, D.; Chagnault, V.; Drelich, A.; Pezron, I.; Nesterenko, A.; Wadouachi, A.
Tetrahedron Lett. 2021, 153113.
Three families of anionic sugar-based surfactants bearing a sulfate functional group on the primary position of a monosaccharide were synthesized and their physicochemical properties were compared. The first family corresponds to 6-sulfate derivatives of commercially available octa- and dodecyl β-D-gluco- and galactopyranosides. The second and the third families contain an amide linker between the sulfated monosaccharide (galactose, glucose or xylose) and the hydrophobic alkyl chain. Twelve of the as-synthesized anionic glycolipids, including nine novel sulfated compounds, were investigated for their surface activity at the air/liquid interface and for their self-assembling properties. These sugar-based surfactants show surface properties similar to those of commercial anionic surfactants (SDS and SLES) with good ability to reduce surface tension. The obtained results confirm the interest in these new bio-based molecules for potential substitution of anionic surfactants in various formulations.
https://dx.doi.org/10.1016/j.tetlet.2021.153113

Physicochemical, foaming and biological properties of lowly irritant anionic sugar-based surfactants
Bois, R.; Abdellahi, B.; Mika, B.; Golonu, S.; Vigneron, P.; Chagnault, V.; Drelich, A.; Pourceau, G.; Wadouachi, A.; Vayssade, M.; Pezron, I.; Nesterenko, A.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 607, 125525.
Surface-active compounds derived from biomass, especially sugar-based amphiphiles, have received wide attention regarding their biodegradability, low toxicity and ecological acceptability. Compared to nonionic sugar-based surfactants, the anionic ones show significantly better solubility, higher surface activity and foaming performance. Thus they are largely used in personal care formulations and many technological applications. However, anionic surfactants are well known to induce skin and eye irritation. In this study, three sugar-based anionic surfactants, bearing a lipidic chain grafted to the anomeric position of a monosaccharide (glucose or xylose) and a sulfate group on the primary hydroxyl, were synthesized: 6-O-sulfo-N-(β-d-glucopyranosyl) dodecanamide (GlcNC12S), N-dodecyl-6-O-sulfo-d-gluconamide (GlcCC12S) and N-dodecyl-6-O-sulfo-d-xylonamide (XylCC12S). These molecules were investigated in details for their self-assembling behavior, foaming properties and biological effects. All their properties were compared to those of two commercially available anionic surfactants, sodium laureth sulfate (SLES) and sodium dodecylsulfate (SDS). Results revealed that the three anionic glycolipids show surface properties and foaming behavior comparable to those of SDS. Furthermore, their cytotoxic and irritation potentials are significantly lower compared to commercial molecules, which make these renewable molecules potential candidates for replacement of petroleum-based compounds.
https://doi.org/10.1016/j.colsurfa.2020.125525

Insight on the Contribution of Plasmons to Gold-Catalyzed Solar-Driven Selective Oxidation of Glucose under Oxygen
Golonu, S.; Pourceau, G.; Quéhon, L.; Wadouachi, A.; Sauvage, F.
Solar RRL 2020, 4, 2000084.
With the increasing concerns about pollution and reduction of energy demands, the use of solar energy to drive chemical transformations is becoming increasingly attractive. Within the context of sustainability, sunlight-driven organic transformation of biomass feedstock, such as free carbohydrates, to obtain high added-value products is an important topic in which the recent progress should contribute to the development of solar biorefineries. Among the variety of photocatalysts, gold nanoparticles (NPs) loaded onto large bandgap semiconductors represent the state of the art. Such catalysts are known to accelerate the targeted reaction upon plasmonic excitation. In addition, as noble metal NPs, they also hold an additional role related to surface catalysis, which has been exploited for aerobic oxidation of free sugars. Nevertheless, the respective contribution of each role during transformation is not well established. Herein, the enhancement of the O2-mediated oxidation of free sugars using Au NPs on CeO2 under standard air mass 1.5G illumination conditions is reported. The results highlight that the plasmonic contribution of Au NPs is totally annihilated and this enhancement stems solely from a thermal activation process induced by NIR radiation from standard white-light conditions.
https://dx.doi.org/10.1002/solr.202000084

Nitroxide-Grafted Nanometric Metal Oxides for the Catalytic Oxidation of Sugar
Omri, M.; Becuwe, M.; Courty, M.; Pourceau, G.; Wadouachi, A.
ACS Applied Nano Materials 2019, 2, 5200-5205.
A new series of ([2,2,6,6-tetramethylpiperidin-1-yl]oxy) (TEMPO) catalysts supported on nanometric metal oxides (TiO2, AlO2, CeO2) and their efficiency for sugar oxidation are herein described. The preparation of such hybrid catalysts was carried out by modification of a metal oxide surface with a monolayer of phosphonic linker bearing a TEMPO radical. All prepared catalysts were carefully characterized by diffuse reflectance Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. The efficiency of these new hybrid TEMPO supported materials for sugar oxidation was evaluated on methyl α-d-glucoside, as a model carbohydrate. The three hybrid catalysts showed high selectivity, activity, and stability, suggesting a promising potential for rapidly obtaining acid sugar derivatives.
https://dx.doi.org/10.1021/acsanm.9b01069

Impact of the chemical structure on amphiphilic properties of sugar-based surfactants: A literature overview
Gaudin, T.; Lu, H.; Fayet, G.; Berthauld-Drelich, A.; Rotureau, P.; Pourceau, G.; Wadouachi, A.; Van Hecke, E.; Nesterenko, A.; Pezron, I.
Adv. Colloid Interface Sci. 2019, 270, 87-100.
In this review, structure-property trends are systematically analyzed for four amphiphilic properties of sugar-based surfactants: critical micelle concentration (CMC), its associated surface tension (γCMC), efficiency (pC20) and Krafft temperature (TK). First, the impact on amphiphilic properties of the alkyl chain size and the presence of branching and/or unsaturation is investigated. Then, various polar head parameters are explored, such as the degree of polymerization of the sugar unit (mono- or oligosaccharides), the chemical nature of the linker and the sugar configuration. Some systematic comparisons between ethoxylated surfactants and sugar-based surfactants are also carried out. While some structural trends with the impact of alkyl chain length or the polar head size are now well understood, this analysis points out that systematic studies of more specific effects of alkyl chain (e.g. branching, unsaturation, presence of rings, position on the polar head) and polar head (e.g. linker, anomeric configuration, internal stereochemistry, cyclic vs. acyclic sugar residues) were scarcer or not available to date. This work encourages the use of these structural trends in the perspective of developing new bio-based surfactants and their consideration in predictive models. It also highlights the need of further experimental tests to fill remaining gaps notably to explore some specific structural features (such as the introduction of rings in the alkyl chain or the position of the alkyl chain on the polar head) and towards applicative properties (like foaming capacity or wettability).
https://doi.org/10.1016/j.cis.2019.06.003

First Sustainable Aziridination of Olefins Using Recyclable Copper-Immobilized Magnetic Nanoparticles
Toumieux, S.; Khodadadi, M.; Pourceau, G.; Becuwe, M.; Wadouachi, A.
Synlett 2019, 30, 563-566.
The first copper-catalyzed aziridination of olefins using recyclable magnetic nanoparticles is described. Magnetic nanoparticles were modified with dopamine and used as a support to coordinate copper. The methodology was optimized with styrene as olefin and using [N-(p-toluenesulfonyl)imino]phenyliodinane (PhI=NTs) as nitrene source. A microwave irradiation decreased the reaction time by 4-fold compared to conventional heating method. The catalyst was recovered by simple magnetic extraction and could be reused successfully up to five times without significant loss of activity. The methodology was applied to a range of different olefins leading to moderate to excellent yields in the formation of the expected aziridine.
http://dx.doi.org/10.1055/s-0037-1611717

Lactose derivatives as potential inhibitors of pectin methylesterases
L'Enfant, M.; Kutudila, P.; Rayon, C.; Domon, J.-M.; Shin, W.-H.; Kihara, D.; Wadouachi, A.; Pelloux, J.; Pourceau, G.; Pau-Roblot, C.
Int. J. Biol. Macromol. 2019, 132, 1140-1146.
The discovery of molecules that can inhibit the action of phytopathogens is essential to find alternative to current pesticides. Pectin methylesterases (PME), enzymes that fine-tune the degree of methylesterification of plant cell wall pectins, play a key role in the pathogenicity of fungi or bacteria. Here we report the synthesis of new lactoside derivatives and their analysis as potential PME inhibitors using three plants and one fungal PME. Because of its structure, abundance and reduced cost, lactose was chosen as a case study. Lactoside derivatives were obtained by TEMPO-mediated oxidation of methyl lactoside, followed by an esterification procedure. Three derivatives were synthesized: sodium (methyl-lactosid)uronate, methyl (methyl-lactosid)uronate and butyl (methyl-lactosid)uronate. The inhibition of the plant and pathogen enzyme activities by lactoside derivatives was measured in vitro, showing the importance of the substitution on lactose: methyl (methyl-lactosid)uronate was more efficient than butyl (methyl-lactosid)uronate. These results were confirmed by docking analysis showing the difference in the interaction between lactoside derivatives and PME proteins. In conclusion, this study identified novel inhibitors of pectin remodeling enzymes.
http://dx.doi.org/10.1016/j.ijbiomac.2019.04.049

Photocatalyzed Transformation of Free Carbohydrates
Omri, M.; Sauvage, F.; Golonu, S.; Wadouachi, A.; Pourceau, G.
Catalysts 2018, 8, 672.
In the growing context of sustainable chemistry, one of the challenges of organic chemists is to develop efficient and environmentally friendly methods for the synthesis of high-added-value products. Heterogeneous photocatalytic transformations have brought revolution in this regard, as they take advantage of an unlimited source of energy (solar light) or artificial UV light to onset organic chemical modifications. The abundance of free carbohydrates as chemical platform feedstock offers a great opportunity to obtain a variety of industrial interest compounds from biomass. Due to their chirality and polyfunctionality, the conversion of sugars generally requires multi-step protocols with protection/deprotection steps and hazardous chemical needs. In this context, several selective and eco-friendly methodologies are currently under development. This review presents a state of art of the recent accomplishments concerning the use of photocatalysts for the transformation and valorization of free carbohydrates. It discusses the approaches leading to the selective oxidation of free sugars, their degradation into organic chemicals, or their use for hydrogen production.
http://dx.doi.org/10.3390/catal8120672

Nitroxide supported on nanometric metal oxides as new hybrid catalysts for selective sugar oxidation
Omri, M.; Becuwe, M.; Davoisne, C.; Pourceau, G.; Wadouachi, A.
J. Colloid Interface Sci. 2019, 536, 526-535.
A new series of supported organocatalysts, prepared by a simple method, were used for selective sugar oxidation. This approach is based on the immobilization of a nitroxide derivative through a carboxylic function on nanometric metal oxides (TiO2, Al2O3 and CeO2), allowing the recovery of the catalyst. These hybrid materials were carefully characterized by Diffuse Reflectance FT-IR spectroscopy (DRIFT), ThermoGravimetric Analysis (TGA), X-Ray Diffraction (XRD), Brunauer-Emmet-Teller surface area measurements (B.E.T.), elemental and electrochemical analyses, showing different characteristics and behaviors depending on the nature of the metal oxide used. The activity of the supported nitroxide catalyst was evaluated on methyl α-d-glucoside oxidation, used as model reaction. In all cases, high catalytic activity was highlighted, with up to 25 times less nitroxyl radical required for complete conversion than under homogeneous conditions. The influence of several experimental conditions such as the use of phosphate buffer and recyclability of the catalyst were also investigated.
http://dx.doi.org/10.1016/j.jcis.2018.10.065

Gold Catalysis and Photoactivation: A Fast and Selective Procedure for the Oxidation of Free Sugars
Omri, M.; Sauvage, F.; Busby, Y.; Becuwe, M.; Pourceau, G.; Wadouachi, A.
ACS Catalysis 2018, 1635-1639.
A fast and efficient methodology for the selective oxidation of sugars into corresponding sodium aldonates is herein reported. Hydrogen peroxide was used as a cheap oxidant and electron scavenger, in the presence of only 0.003-0.006 mol % of gold in basic conditions. Three photocatalysts were studied, namely Au/Al2O3, Au/TiO2 and Au/CeO2, the latter being the most efficient (TOF > 750 000 h-1) and perfectly selective. Only 10 minutes exposition under standard incident sunlight irradiation (A.M.1.5G conditions - 100 mW/cm2) affords total conversion of glucose into the corresponding sodium gluconate. Demonstrating its versatility, this methodology was successfully applied to a variety of oligosaccharides leading to the corresponding aldonates in quantitative yield and high purity (>95%) without any purification step. The photocatalyst was recovered by simple filtration and re-used 5 times leading to the same conversion and selectivity after 10 min of illumination.
http://dx.doi.org/10.1021/acscatal.7b03394

Imidazolium-based titanium substrates against bacterial colonization
Cavoue, T.; Bounou Abassi, H.; Vayssade, M.; Nguyen Van Nhien, A.; Kang, I. K.; Kwon, G. W.; Pourceau, G.; Dubot, P.; Abbad Andaloussi, S.; Versace, D. L.
Biomater Sci 2017, 5, 561-569.
Nosocomial infections are often induced by the presence of pathogenic organisms on the surface of medical devices or hospital equipment. Chemical modifications of the surface are recognized as efficient strategies to prevent bacterial adhesion but they may have a negative impact on the material's interaction with living tissues. Here we have developed a photoactivated method for the modification of titanium substrates. A photoinduced technique employing a grafting-onto process has been successfully performed to covalently anchor an imidazolium-derivative siloxane onto titanium surfaces. Imidazolium surfaces showed higher bacteria-repellency performances than native titanium substrates, achieving more than 98% anti-adhesion efficiency against Escherichia coli after 24 h of incubation. In addition, these surfaces allowed for the adhesion and viability of osteoblasts cells without evidence of cytotoxicity.
http://dx.doi.org/10.1039/c6bm00715e

Improvement of Gold-Catalyzed Oxidation of Free Carbohydrates to Corresponding Aldonates Using Microwaves
Omri, M.; Pourceau, G.; Becuwe, M.; Wadouachi, A.
ACS Sustainable Chemistry & Engineering 2016, 4, 2432-2438.
An efficient microwave-assisted methodology for the oxidation of free carbohydrates to corresponding aldonates is described. Supported gold catalyst, hydrogen peroxide and a mineral base were used to perform the oxidation reaction in water under microwave irradiation. These conditions combined with Au/Al2O3 catalyst allowed to reach in 10 minutes a quantitative conversion of glucose.The catalyst was highly selective and reusable and only 0.004 mol % of gold compared to sugar was used. The reaction was performed using a variety of substrates (mono or oligosaccharides, neutral or acidic sugars) and good to excellent conversion yields and selectivity to corresponding aldonates were obtained. After filtration and freeze-drying, sodium or potassium aldonates were obtained without any purification. Thanks to very high turn-over frequencies (up to 438 000 h-1), this methodology improves significantly the previously described methods for the gold-catalyzed oxidation of carbohydrates.
http://dx.doi.org/10.1021/acssuschemeng.6b00263

Catalytic Synthesis of a New Series of Alkyl Uronates and Evaluation of Their Physicochemical Properties
Lu, H.; Drelich, A.; Omri, M.; Pezron, I.; Wadouachi, A.; Pourceau, G.
Molecules 2016, 21, 1301-1315.
Large quantities (>3 g) of a new series of alkyl uronates were synthesized in two steps from commercial methyl hexopyranosides. Firstly, several tens of grams of free methyl α-d-glucopyranoside were selectively and quantitatively oxidized into corresponding sodium uronate using 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO)-catalyzed oxidation. Hydrophobic chains of different length were then introduced by acid-mediated esterification with fatty alcohols (ethyl to lauryl alcohol) leading to the desired alkyl glucuronates with moderate to good yields (49%–72%). The methodology was successfully applied to methyl α-d-mannopyranoside and methyl β-d-galactopyranoside. Physicochemical properties, such as critical micelle concentration (CMC), equilibrium surface tension at CMC (γcmc), solubility, and Krafft temperature were measured, and the effect of structural modifications on surface active properties and micelle formation was discussed.
http://dx.doi.org/10.3390/molecules21101301

On the chiroptical properties of Au(i)–thiolate glycoconjugate precursors and their influence on sugar-protected gold nanoparticles (glyconanoparticles)
Pourceau, G.; Valle-Carrandi, L. d.; Di Gianvincenzo, P.; Michelena, O.; Penadés, S.
RSC Adv. 2014, 4, 59284-59288.
Chiral gold nanoparticles passivated with glycoconjugates were prepared. By extensive washing, they lost their chiroptical activity, whereas highly luminescent compounds isolated from the washing reproduced the original ellipticity. A systematic characterization of these compounds, Au(i) precursors and glyconanoparticles allowed us to unravel the origin of the observed chiroptical activity.
http://dx.doi.org/10.1039/C4RA11741G

Efficient synthesis of glycosylamines in solventless conditions promoted by mechanical milling
Lingome, C. E.; Pourceau, G.; Gobert-Deveaux, V.; Wadouachi, A.
RSC Advances 2014, 4, 36350.
A mecanosynthesis of glycosylamines under solventless conditions was established. This environmentally friendly approach optimized with L-rhamnose, was investigated using a variety of amines and other carbohydrates. High reaction yields and simple work-up allow the clean and fast synthesis of a variety of glycosylamines and glycosyl-(di)-amines.
http://dx.doi.org/10.1039/C4RA04321A

Chapter 11 Anionic oligosaccharides: synthesis and applications
Grand, E.; Kovensky, J.; Pourceau, G.; Toumieux, S.; Wadouachi, A.
Carbohydrate Chemistry: Volume 40 2014, 40, 195-235.
http://dx.doi.org/10.1039/9781849739986-00195