Glycopeptide dimers, synthesis

In fact, other studies have shown that TMSOTf catalyzes the glycosylation of a silylated acceptor with a silylated hemiacetal donor [49]. Nudel man s procedure was applied to the synthesis [1-glucuronide 30, isolated in 57% yield. Kiyoi and Kondo have applied the TMSOTf activation protocol to protected L-fucose hemiacetal donors for glycopeptide synthesis and obtained glycopeptide fragment 31 in 74% yield (a p, 20 1) [50], Posner and Bull have developed a procedure that uses excess TMSOTf in the presence of molecular sieves (SYLOSIV A4) to synthesize various l.l -linked disaccharides such as the galactopyranose dimer 32 [51,52]. 

Considerable effort has gone into the synthesis of aminoacid glycosides mainly because of their significance in glycopeptide chemistry. Reaction of the dimer of tri-Q-acetyl-2-deoxy-2-nitroso-a-D-glucopyranosyl chloride with methyl M substituted-L-serinate (and L-threoninate and L-tyrosinate) gave mixed anomers of the oximes (9), and their deacylated products on deoximation, reduction and reacetylation afforded the corresponding q-d-... 

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