Reagent-controlled stereoselective glycosylation

A method of forming a glycosidic bond, comprising:

• combining a first solvent, a reducing sugar, and a first strong Bronsted base, thereby forming a first reaction mixture;
• combining a sulfonylating agent and the first reaction mixture, thereby forming a glycosyl sulfonate;
• combining a second solvent, a glycosyl acceptor, and a second strong Bronsted base, thereby forming a second reaction mixture;
• and
• combining the glycosyl sulfonate and the second reaction mixture, thereby forming a glycosidic bond;
• wherein the reducing sugar is a pyranose;
• the sulfonylating agent is a sulfonyl halide;
• and
• the glycosidic bond is formed with greater than or equal to 90% stereoselectivity for a β linkage.