Provided is a method for producing a protected glycoside derivative, including reacting a sugar in which all hydroxyl groups of the sugar are protected by protective groups and protective groups of a hydroxyl group at a 1-position and a hydroxyl group at a 2-position are acyl groups, with a phenolic compound in the presence of at least one catalyst selected from the group consisting of trifluoromethanesulfonic acid and copper (II) trifluoromethanesulfonate, in which the phenolic compound is bonded to an anomeric position of the sugar and other hydroxyl groups of the sugar are protected.

Provided is method for producing a glycoside in which a phenolic compound is bonded to an anomeric position of a sugar, the method including: a step (1) of reacting a peracetylated sugar with the phenolic compound in the presence of an acid catalyst; and a step (2) of directly adding a deacetylating agent and a deacetylating solvent selected from the group consisting of water and an alcohol to a reaction mixture obtained in the step (1) to perform a deacetylation reaction.

A method for preparing cyano sulfonyl fluoride compounds is provided. Oxime ether compounds are used as free radical precursors, and under the condition of photocatalyst regulation, and in combination with the strategy of free radical sulfur dioxide insertion, the process involves photocatalytic oxidation, CC bond cleavage rings, free radical SO.sub.2 insertion and fluorination to achieve cyano/fluorosulfonyl reaction of oxime ether, yielding cyano sulfonyl fluoride products.