Chemical synthesis of polysaccharides

Here we summarize the chemical syntheses of glycans containing over 20 monosaccharide units, with the recent syntheses of ultra-long glycans, including a 92mer arabinogalactan, a 100mer and a 151mer mannan, and a 128mer rhamnomannan, being highlighted. The assembly strategies, glycosylation methods, and protecting group manipulations, which are crucial to the successful synthesis, are discussed to give guidance for the future synthesis of various polysaccharides.