SYNTHESIS OF 2-ACETAMIDO-2-DEOXYGLUCOSYLASPARAGINE GLYCO-TRIPEPTIDES AND GLYCO-PENTAPEPTIDES BY SELECTIVE C-TERMINAL AND N-TERMINAL ELONGATION OF THE PEPTIDE-CHAIN

The synthesis of protected 2-acetamido-2-deoxyglucosylasparagine glycopeptides, using the allyl ester as the C-terminal protecting group, their deprotection, and some possible applications of these glycopeptides for the synthesis of modified silica gels and the construction of liposomes are described. The selective carboxyl deblocking is achieved under neutral conditions by rhodium(I)-catalyzed isomerization of the allyl group followed by hydrolysis of the resulting propenyl ester. The tert-butoxycarbonyl group can be cleaved selectively in the presence of the allyl ester with hydrogen chloride in ether. The allyl ester and the acetates can be removed simultaneously with ammonia in methanol. This method opens up a preparative route to glycopeptide model structures of biological interest. © 1990.