Glycopeptide bond synthesis

H. Kunz and C. Unverzagt, Protecting group-dependent stability of intersaccharide bonds— synthesis of a fucosyl-chitobiose glycopeptide, Angew. Chem. lnt. Ed. Engl. 27 1697 (1988). 

Kunz, H. and Unverzagt, C. (1988) Protecting-group-dependant stability of intersaccharide bonds-Synthesis of a fucosyl-chitobiose glycopeptide. Angew. Chem. Int. Ed. 27, 1697-1699. 

TABLE 17.7 Linkages and enzymes involved in the synthesis of glycopeptide bonds... 

However, better results have been reported when the polarity of the reaction is reversed. In this indirect path, an initial radical addition of a thio- or selenophenyl group affords a compound that can be the precursor of a difluoromethyl radical. This latter species can further add onto an activated double bond. These radical approaches have also allowed the synthesis of glycopeptides and difluorophosphonates (Figure... 

For glycopeptide synthesis, much attention has to be paid to the stereoselective formation of the natural-type glycosidic bond which must remain unchanged in the course of the synthesis. Therefore, in comparison to peptide synthesis, the compatibility and chemoselectivity of the applied reaction is fundamental in glycopeptide synthesis. 

Glycopeptides contain many functional groups of different reactivity as well as O- and /V-glycosidic bonds. Therefore, the compatibility and chemoselectivity of the applied reactions is a fundamental prerequisite in glycopeptide synthesis. In this chapter, efficient and generally applicable methods and their combinations will be illustrated by examples [5,8,91. 

Offer, J., Quibell, M., and Johnson, T. (1996) On-resin solid-phase synthesis of asparagine-AMinked glycopeptides use of /V-(2-accloxy-4-mc(hoxybenzyl) (AcHmb) aspartyl amide-bond protection to prevent unwanted aspartimide formation./. Am. Chem. Soc. Perkin TransI., 175-182. 

Finally, the synthesis of a key building block for the glycopeptide mimics with urea-glycosyl bonds has been achieved, as shown in Figure 13. 

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