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Regio- and stereoselective β-mannosylations using 1,2-anhydromannose and diol sugar acceptors in the presence of a boronic acid catalyst proceeded smoothly to give the corresponding β-mannosides with high regio- and β-stereoselectivities in high yields without further additives under mild conditions. In addition, this glycosylation method was applied successfully to the synthesis of a tetrasaccharide repeating unit of lipopolysaccharide (LPS) derived from E. coli O75.

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Fully unprotected D‐glucose, D‐mannose, and D‐fructose were regioselectively glycosylated with several phenylthioglycosides to afford glycosyl‐β(1→6)‐α/β‐D‐glucopyranose, glycosyl‐β(1→1)‐α‐D‐mannofuranoside, and glycosyl‐β(1→1)‐β‐D‐fructopyranose in good yields. The regioselectivity might have arisen from a thermodynamically controlled bis(phenylboronate) intermediate, which leaves only one free hydroxy group to be glycosylated in complete regioselectivity.