Method for synthesizing C-nucleoside compound

A method for preparing a C-nucleoside compound, comprising:

• 1) In a solvent, under the action of a secondary amine represented by Formula 4 and a metal lithium reagent, allowing the 4-position amino group in the compound represented by Formula 1 to undergo a bis-silicon protection by using 1,2-bis(chlorodimethylsilyl) ethane to generate a compound represented by the intermediate Formula 5;
• 2) Under the action of the secondary amine represented by Formula 4 and the metal lithium reagent, the compound represented by Formula 5 undergoing lithium-halogen exchange to generate a compound represented by the intermediate Formula 6, wherein M is Li;
• 3) the compound represented by Formula 6 undergoing an addition reaction with a compound represented by Formula II to generate a C-nucleoside compound represented by Formula III,
• wherein, in the compound represented by Formula 1, X is halogen;
• in the secondary amine represented by Formula 4, each R is independently isopropyl, isobutyl or cyclohexyl, or two Rs together with the nitrogen atom to which they are attached form a 2,2,6,6-tetramethylpiperidine;
• in the compound represented by Formula II or Formula III, Ra, Rb and Rc are each benzyl;
• in the compound represented by the Formula III, “” indicates that the bond is in the α configuration or the β configuration, or a mixture thereof in any ratio.