Gilles Demailly

From biomass to a renewable LixC6O6 organic electrode for sustainable Li-ion batteries.

Li-ion batteries presently operate on inorganic insertion compounds. The abundance and materials life-cycle costs of such batteries may present issues in the long term with foreseeable large-scale applications. To address the issue of sustainability of electrode materials, a radically different approach from the conventional route has been adopted to develop new organic electrode materials. The oxocarbon salt Li2C6O6 is synthesized through potentially low-cost processes free of toxic solvents and by enlisting the use of natural organic sources (CO2-harvesting entities). It contains carbonyl groups as redox centres and can electrochemically react with four Li ions per formula unit. Such battery processing comes close to both sustainable and green chemistry concepts, which are not currently present in Li-ion cell technology. The consideration of renewable resources in designing electrode materials could potentially enable the realization of green and sustainable batteries within the next decade.

Novel Glycolipids Based on Cyclodextrins

Novel amphiphilic cyclodextrins have been prepared by grafting a phospholipid on a modified cyclodextrin through a spacing arm to combine the selectivity in size of cyclodextrins and the transport properties of phospholipids. Synthesis and full characterization by NMR and mass spectrometry have been performed. The aggregation process in water has been characterized by light scattering, DSC and 31P NMR. This compound appears to assemble into large objects and displays a very low CMC. The detergent properties of the phospholipidyl-cyclodextrins have been evaluated.

One-pot stereoselective synthesis of glycosyl azides via 1,2-cyclic sulfite

Abstract In a one-pot procedure, treatment of partially protected or unprotected aldoses with N,N ′-thionyldiimidazole and then, lithium azide leads stereoselectively to glycosyl azides.

Efficient synthesis of α,ω-dibromodideoxyalditols as precursors for α,ω-dithioalkylalditols

Abstract The regioselective bromination of unprotected alditols ( d -arabinitol, xylitol, ribitol, d -glucitol, and d -mannitol) was achieved with acetyl bromide as the brominating reagent. The α,ω-dibromodideoxyalditols were isolated after acetylation in good overall yields (51–80%). 1,5-Dithioalkylpentitols, 1,6-dithioalkyl- d -mannitol, and d -glucitol were obtained from the dibromo derivatives and sodium alkanethiolates (with R = n -butyl, n -octyl, n -dodecyl, and n -hexadecyl).

Short and efficient synthesis of polyhydroxylated tetrahydrothiophene, tetrahydrothiopyrane and thiepane from bielectrophilic erythro, threo, xylo, ribo, arabino, manno and gluco α,ω-dibromoalditol derivatives

Polyhydroxylated tetrahydrothiophene, tetrahydrothiopyrane and thiepane rings have been readily obtained in excellent yields (78–95%) from thioheterocyclisation of the bielectrophilic peracetylated α,ω-dibrominated derivatives of tetritols (erythritol (1) and d,l-threitol (4)), pentitols (xylitol (7), ribitol (10) and d-arabinitol (14)) and hexitols (d-mannitol (17) and d-glucitol (20)), respectively. With 2,3,4,5-tetra-O-acetyl-1,6-dibromo-1,6-dideoxy-d-glucitol (21) as substrate, the unexpected 2,6-anhydro derivative 25 was obtained. This could be attributed to previous S= regioselective nucleophilic attack at C-1 position followed by 1,2-transesterification and 2,6-O-heterocyclisation. The preferential attack at C-1 of the d-glucitol derivative 21 subsequently allowed a facile direct synthesis in good yields of 2,3,4,5,6-penta-O-acetyl-1-bromo-1-deoxy-d-glucitol (26), 2,3,4,5-tetra-O-acetyl-6-bromo-6-deoxy-1-thiobutyl-1-deoxy-d-glucitol (28) and 2,3,4,5-tetra-O-acetyl-6-bromo-6-deoxy-1-thiooctyl-1-deoxy-d-glucitol (28).

Réaction du diméthyl(diazométhyl)phosphonate sur des glucides réducteurs: synthèse de glyco-1-ynitols

Resume Reaction of aldose derivatives with dimethyl(diazomethyl)phosphonate, generated in situ by methanolysis of dimethyl(1-diazo-2-oxopropyl)phosphonate, leads to glyco-1-ynitols derivatives. This synthesis presents two main advantages: it is a one-step synthesis, and tolerates free hydroxyl groups.

Direct Regioselective Chlorination of Unprotected Hexitols and Pentitols by Viehe's Salt

Abstract Viehes salt allows the transformation of unprotected hexitols and pentitols into linear 1,6 and 1,5 dichloro derivatives in high yields. Usual competitive heterocyclization is minimized.

Direct regioselective chlorination of unprotected hexitols and pentitols by Vilsmeier and Haack's salt

Abstract Unprotected hexitols and pentitols are converted into 1,6 and 1,5 dichloro derivatives respectively, by Vilsmeier and Haacks salt in DMF.

Heterocyclisation of free or partially protected alditols via their bis-cyclic sulfate derivatives. Versatile synthesis of aza and thiodeoxyanhydroalditol with erythro, threo, arabino, gulo, talo or manno configuration

The bis-cyclic sulfate derivatives of erythritol (1), d,l-threitol (5), 3,4-di-O-benzyl-d-mannitol (9), 1,2-O-isopropylidene-d-mannitol (14) and 1-O-benzyl-d,l-xylitol (18) were submitted to nucleophilic attack by allylamine or sodium sulfide. In both cases, heterocyclisation occurred and aza or thioanhydrodeoxyalditols were obtained in moderate to good yields (40 to 89%). With compound 9, 1,5-anhydro-5-thio-l-gulitol (12) was obtained as the main product, a result that is in contrast with previous results reported in the literature using bis-epoxide as bielectrophile intermediate.1

A new route to C-glycosyl compounds. Wittig-type reaction promoted by zinc

In recent years, methods for the preparation of C-glycosyl compounds have become increasingly important in synthetic organic chemistry. These compounds are useful as subunits for the synthesis of biological active products’ and as potential enzyme inhibitors’. Significant attention has been focused on the development of new routes to prepare functionalized C-glycosyl compounds that are synthetic precursors of more complex C-glycosyl compounds. The starting materials can be furanose or pyranose carbohydrates, the main problem being the stereoselective introduction of a functionalized carbon atom at C-l. A widely used procedure to obtain carbon-carbon bonding at the anomeric position of carbohydrates was first reported by Zhdanov ef al. 3 This two-step procedure involves the formation of an unsaturated, open-chain intermediate, followed by a cyclization leading to the expected C-glycosyl compound. The first step is a Wittig reaction with protected furanose and pyranose hemiacetals. When stabilized ylides are used4, subsequent cyclization of the unsaturated intermediate may occur by treatment with bases or, sometimes, spontaneously. But when the Wittig reaction takes place with unstabilized ylides, the cyclization can be obtained by the iodoor mercuro-cyclization process’. It should be noted that C-glycosyl compounds can be synthesized in the same way when phosphonates are used instead of phosphorane