8 - The Stereoselective Synthesis of β-Mannosides

Abstract

This chapter illustrates the importance of the β-mannosidic linkage within biological systems, and problems encountered with its synthesis. The most important class of compounds that contain a b-mannoside linkage are the N-linked glycoproteins. A β-mannoside linkage resides within an asparagine bound core pentasaccharide structure, which is common to all N-linked glycoproteins. These N-glycoproteins are classified into four main groups according to the nature of the carbohydrates that substitute the core pentasaccharide structure, namely, high mannose, complex, hybrid and poly-N-acetyllactosamine. A number of chemical preparative methods are compared, but it is obvious that there is no ideal method of universal utility. As with all carbohydrate chemistry, a careful assessment of the proposed preparative route must be performed before a specific technique for the incorporation of the β-mannosidic linkage is selected and pursued.