Automated oligosaccharide synthesis approaches

Although of limited scope, one approach for solid phase carbohydrate synthesis has actually incorporated coupling chemistry into an automated solid phase oligosaccharidesynthe-sizer (123). In addition, there is the use of gly-cosyltransferase-regenerating beads that are potentially applicable to automated oligosaccharide synthesis (124). 

In conclusion, compared with solution-phase synthesis, solid-phase enzymatic synthesis, generally, needs higher concentrations of enzyme, longer reaction times, and a large excess of donors. Although there is still room for improvement in terms of yields and scale-up of syntheses, in solid-phase synthesis purification procedures are straightforward so it is expected that this approach will open the route to automated oligosaccharide synthesis in the near future. 

Our approach to oligosaccharide synthesis relied on the acceptor-bound solid-phase method. This method formally reduces the synthesis of carbohydrates to a repetitive cycle of glycosylation and deprotection events. It was reasoned that the repetitive nature of an acceptor-bound glycosylation method rendered it ideal for automation. Therefore, we set out to investigate the potential variables in such a scheme. 

We have developed an automated solid-phase approach for the chemical synthesis of oligosaccharides. Using an acceptor-bound solid-phase... 

In the last years, chemoenzymatic and automated approaches have been shown to be useful for the synthesis of oligosaccharides corresponding to regular regions of GAG. The advancement in the knowledge of structure... 

These syntheses established the automated synthesis as an efficient and rapid way of assembling oligosaccharides. Both trichloroacetimidates and phosphates were competent donors and acetate and levulinoate could be used as temporary protecting groups for the synthesis. These two approaches were combined for an automated synthesis of a trisaccharide on a 100 (xmol scale (Scheme 8). 

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