Glycosylation is one of the most important post- or cotranslational modifications of proteins, which affects the biological activities of the parent proteins by influencing the higherorder structure. This modification has been classified into two subtypes: namely
N-linked type and
O-linked type. Recently, a highly novel variant of glycoproteins that incorporate a
C-glycosylated amino acid was identified in various proteins. The total synthesis of one such
C-glycosyl amino acid, namely,
C2-α-D-
C-mannosylpyranosyl-L-tryptophan and related peptides was successfully achieved. The mannose and tryptophan moieties were connected via a ring opening of benzyl-protected 1, 2-anhydro-mannose by a lithiated indole derivative. After the functional group conversion and deprotection steps, the glyco-amino acid was synthesized in a concise and stereoselective manner, in high overall yields. Furthermore, intermediate azide acid can serve as a useful building block for peptide elongation. The stereoisomer,
C2-α-D-
C-glucosylpyranosyl-L-tryptophan was synthesized in a similar way.
We describe here the synthesis of
C-Man-Trp including by other groups and the possibility of application to clinical methods.
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