Sulfinate glycosyl donor, method for preparing same, and use thereof

A glycosyl donor, or salts thereof, or stereoisomers thereof, or optical isomers thereof, characterized in that the structure of the glycosyl donor is as represented by formula W:

• wherein, n is selected from 0 or 1;
• a is selected from 3 or 4;
• R is each independently selected from L1Rx;
• or two adjacent R are linked to form a ring, while the other R is each independently selected from L1Rx. The ring is either unsubstituted or substituted with one or more L1Rx;
• L1 is selected from absence or C1-2 alkylene, and Rx is selected from the group consisting of H, OH, C1-6 alkyl, OAc, OBn, OR8, NR9R10,
• Ph, amino,
• and
• i is an integer selected from 0 to 6;
• R11, R12, R13, and R14 are each independently selected from L2Ry;
• L2 is selected from absence or C1-2 alkylene, and Ry is selected from the group consisting of H, OH, C1-6 alkyl, OAc, OBn, OR8, and NR9R10;
• R8 is selected from C1-6 alkyl;
• R9 is selected from the group consisting of H, C1-6 alkyl, Ac, and Bn;
• R10 is selected from the group consisting of H, C1-6 alkyl, Ac, and Bn;
• j is selected from 1, 2, or 3;
• Mj+ is a j-valent cation.