Glycosyl threonine building block

A comparison of direct O-mannosylation of serine or threonine on resin-bound peptides, with the incorporation of mannosylated serine or threonine building blocks, resulted in a higher overall yield for the building block approach (12.5 vs 5% for direct condensation). 134 Later it was demonstrated that resin-bound peptides are able to be glycosylated with different glycosyl trichloroacetimidates without protection of the hydroxy groups of the oligosaccharide moiety (Section 6.3.2.8). 135,136 ... 

SCHEME 15.7 a-Glycosylation of serine and threonine building blocks with mannosyl donors carrying 0-acetyl participating groups favors formation of an a-mannoside. 

SCHEME 15.11 Preparation of the Tn antigen building blocks by a-glycosylation of serine and threonine building blocks, or by direct a-glycosylation of a soUd-phase supported peptide. In both cases galactosyl donors, i.e. 100 and 105, which have the 2-acetamido functionality masked as an azide were used. 

SCHEME 15.13 The cassette approach synthesis of T antigen building blocks by a-glycosylation of serine and threonine building blocks with three different disaccharide glycosyl donors. 

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