C-glycoside compounds for stimulating the synthesis of glycosaminoglycans

A process for preparing a C-glycoside derivative of the formula (II):

• in which S is a monosaccharide or a polysaccharide containing up to 20 sugar units, in pyranose and/or furanose form and of L and/or D series, said monosaccharide or polysaccharide containing at least one hydroxyl function that is necessarily free and/or optionally one or more optionally protected amine functions;
• the bond S—CH2X is a bond of anomeric-C nature;
• X is —CO—;
• R is a linear or branched, saturated or unsaturated alkyl, Derfluoroalkyl or hydrofluoroalkyl radical, a cycloalkyl, cycloperfluoroalkyl or cyclohydrofluoroalkyl radical containing from 1 to 18 carbon atoms, a phenyl or benzyl radical, said chain, said ring or said radical optionally being interrupted with one or more hetero atoms selected from among oxygen, sulfur, nitrogen and silicon, and optionally substituted with at least one radical selected from among —OR′—,—Sr″1, —NR″ ′1R′2, —COOR″2, —CONHR″ ′2, —CN, halogen, perfluoroalkyl and hydrofluoroalkyl and/or at least one optionally substituted cycloalkyl, aryl or heterocyclic radical, the radicals R′, R1 and R2, which may be identical or different, are each a radical R or a hydrogen atom or a hydroxyl radical;
• and the radicals R′1, R′2, R″1, R″2, R″ ′1 and R″ ′2, which may be identical or different, are each a hydrogen atom or a radical selected from among a linear or branched, saturated or unsaturated alIkyl radical, hydroxyl, perfluoroalkyl and/or hydrofluoroalkyl radical having from 1 to 30 carbon atoms;
• with the proviso that S is other than D-glucose, D-cellobiose and D-mannose when R is methyl, and with the exception of 1-(C-β-D-ribopyranosyl)-n-propanone;
• comprising dissolving, in water or in a mixture of water and a water-miscible solvent, 1 equivalent of a monosaccharide or a polysaccharide of formula S, adding between 1 and 2 equivalents of a β-diketone compound of general formula R″—CO—CH2—CO—R, in which R″ corresponds to R′, with the proviso that R″ is other than hydrogen, and between 1 and 2 equivalents of an organic or mineral base, and heating the reaction mixture to a temperature of between 40° and 100° C., for a period of between 3 and 30 hours;
• then, after cooling, washing the reaction medium with an organic selected from among ethyl acetate, dichloromethane, diethyl ether, diisopropyl ether, tert-butyl methyl ether, and methyl ethyl ketone;
• neutralizing the aqueous phase with a mineral or organic acid or by passing same through an acidic resin;
• concentrating and then co-evaporating with an organic solvent selected from among ethanol, methanol, toluene and/or isopropanol;
• drying the product obtained under vacuum, and then optionally purifying it by chromatography and/or crystallization.