C-glycoside compounds, and method for preparing C-glycoside compounds

Method of preparing C-glycoside compounds of the tertiary alcohol type of formula (I) including a step of making a C-glycoside compound of formula (III′) react in an aqueous solvent and in the presence of a metal (M), with a halogenated compound of formula (IV) according to the following reaction diagram:

• where:
• S′ represents a monosaccharide radical, or a polysaccharide radical having up to 20 sugar units, in pyranose and/or furanose form and of series L and/or D;
• the bond S′—C H2C(O) represents a bond of C-anomeric nature;
• R represents a linear or branched alkyl radical that may have one or more insaturations and comprising 1 to 30 carbon atoms;
• Z represents an ethylenyl radical CH═CR1(R2) or acetylenyl radical C≡CR3 such that R1, R2 and R3 represent independently a hydrogen atom or a linear or branched alkyl radical, which may have one or more insaturations and comprising 1 to 30 carbon atoms;
• M represents a metal chosen from indium, zinc or magnesium;
• and X represents a halogen.

Method of preparing C-glycoside compounds of the tertiary alcohol type of formula (I) comprising making a monosaccharide or a polysaccharide S react with a phosphonate of formula (II′) in the presence of water, a metal (M) with a halogenated compound of formula (IV), in accordance with following reaction diagram:

• where:
• S represents a monosaccharide or a polysaccharide having up to 20 sugar units, in pyranose and/or furanose form and of series L and/or D, said mono- or polysaccharide having at least one free hydroxyl function;
• S′ represents a monosaccharide radical, or polysaccharide radical having up to 20 sugar units, in pyranose and/or furanose form and of series L and/or D derived from said monosaccharide or polysaccharide S;
• the bond S′—CH2C(OH) represents a bond of C-anomeric nature;
• R4 and R4′ represent independently a linear or branched alkyl radical comprising 1 to 6 carbon atoms;
• R represents a linear or branched alkyl radical, which may have one or more insaturations and comprising 1 to 30 carbon atoms;
• X represents a halogen,
• Z represents an ethylenyl function CH═CR1(R2) or acetylenyl function C≡CR3 such that R1, R2 and R3 represent independently a hydrogen or a linear or branched alkyl radical, which may have one or more insaturations and comprising 1 to 30 carbon atoms;
• and
• M represents a metal chosen from indium, zinc or magnesium;
• and
• B is an organic or mineral base.