Glycopeptide derivatives glycosylation

The preparation of glycopeptides by glycosylation of peptides with glycals using N-iodosuccinimide is covered in Chapter 3, and the preparation of chlorodeoxy-l,4 3,6-dianhydroalditols is mentioned in Chapter 18. The synthesis of 1-chloro-1-deoxy-ketoses by a 1 carbon homologation of lactone derivatives is outlined in Chapter 12. 

Although the reaction conditions did not yield optimal results, Ziegler did show that it was possible to achieve complex glycopeptide derivatives using anomeric glycosyl isocyanides or isocyanoglucoses. 

Paulsen and associates (58) synthesized mono- and di-D-galactopyranosyl derivatives of L-serine/L-threonine. Condensation of the 2-azido-2-deoxy-glycosyl halides 61 and 62 with the benzyl or tert-butyl esters of iV-benzyl-oxycarbonyl (Z)-protected L-serine, L-threonine, and L-leucyl-L-serine (63 -65) in the presence of silver carbonate, silver perchlorate, Drierite, and molecular sieves gave (59) the corresponding O-glycopeptides 67-69. The free glycopeptides were obtained after total deprotection. 

The solid-phase synthesis of glycopeptides was first realized by applying the polymeric benzyl ester principle of Merrifield. According to this methodology, Lavielle and associates (50) used 7V-(tm-butyloxycarbonyl)-<9-glycosyl serine derivative 153 for condensation with resin-linked alanine 154. 

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