Highly regioselective synthesis of a 3-O-sulfonated arabino Lewisa asparagine building block suitable for glycopeptide synthesis

Using the stannylene method, the trisaccharide 2-acetamido-3-O-[6-O-benzyl-β-d-galactopyranosyl]-4-O-[2,3,4-tri-O-benzyl-β-d-arabinopyranosyl]-6-O-benzyl-2-deoxy-β-d-glucopyranosyl azide was regioselectively sulfonated and, after reduction of the anomeric azide, coupled to Fmoc α-allyl aspartate. After Pd(0)-catalyzed deallylation, the sulfatyl Lewisa asparagine building block was obtained, suitable for solid-phase glycopeptide synthesis applying the fluoride labile PTMSEL linker system.

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