Glycosylation method involving trivalent iodine reagent

A glycosylation method involving a trivalent iodine reagent, wherein the glycosylation method is a scheme 1 as follows:

• a glycosyl donor (I) is activated in presence of the trivalent iodine reagent and a transition metal catalyst, and then reacts with a acceptor (II) under acid catalysis to obtain a glycosylation product (III);
• a reaction formula is as follows:
• wherein
• wherein in the glycosyl donor (I), Gly is a glycosyl group in which one or more hydroxyl groups on a sugar ring are protected by a protecting group;
• X is an oxygen, sulfur, or selenium atom;
• R is an alkyl group or an aryl group;
• the acceptor (II) is a nucleophile selected from sugars, alcohols, phenols, flavonoids, phosphates, pyrimidines, purines, amides, sulfonamides, guanidines, arylamines, indoles, enol silyl ethers, thiols, or thiophenols comprising one or more nucleophilic groups,
• alternatively, the glycosylation method is a scheme 2 as follows:
• the glycosyl donor (I) is activated in the presence of the trivalent iodine reagent and the transition metal catalyst, and then reacts with the acceptor (II) to obtain the glycosylation product (III);
• a reaction formula is as follows:
• wherein
• in the glycosyl donor (I), Gly is the glycosyl group in which one or more hydroxyl groups on the sugar ring are protected by the protecting group;
• X is the oxygen, sulfur, or selenium atom;
• R is the alkyl group or the aryl group;
• the acceptor (II) is selected from carboxylic acids comprising one or more nucleophilic groups.