Carbohydrate-lectin interactions are involved in a multitude of recognition processes on cellular level. One of these interactions is the binding of bacterial toxins, such as Shiga toxin or Shiga-like toxins, to cells. Inhibition of these toxins is of high medicinal interest. An approach to target these lectins is the application of high-affinity carbohydrate-based molecules. Up to now, a variety of inhibitors (e.g. divalent, star-shaped, polymeric compounds, and glycan-coated nanoparticles) has been reported in literature [1].
Here, we present a synthetic pathway for disaccharide 7, bearing a handle for multivalent presentation. Compound 7 can be used as a building block for the preparation of different inhibitors. The design is based on a crystal structure of the Shiga toxin B₅ subunit in complex with its natural receptor Gb₃ [2]. Key steps of the synthesis are the α-selective glycosylation of thioglycoside 1 and the use of n-pentenyl orthoester 6 to stereoselectively introduce a linker at the anomeric center and providing an opportunity for further modification at the adjacent 2-position.
