EFFICIENT SYNTHESIS OF O-LINKED GLYCOCONJUGATES OF AMINO ACIDS FROM CARBOHYDRATE-DERIVED DONOR-ACCEPTOR CYCLOPROPANES

N-Iodosuccinimide (NIS) mediated ring opening of carbohydrate-derived donor-acceptor cyclopropanes with free ``CO2H'' group of N-protected L-amino acids at ambient conditions afforded iodo derivatives of glycosyl ester of L-amino acids. The iodides were subsequently converted easily into corresponding azides using NaN3 in DMF followed by reduction with Zn/AcOH to produce ester linked glycosyl amino acids. A similar strategy was adopted to synthesize C-linked glycoamino acid derivatives from different N-protected L-amino alcohols. By using an orthogonal strategy C- and O-linked glycopeptides were also synthesized