An Improved Synthesis of a Galactosylated Hydroxylysine Building Block and its use in Solid-Phase Glycopeptide Synthesis

Different protective groups for (5R)-5-hydroxy-l-lysine were investigated in silver silicate promoted glycosylations with acetobromogalactose as glycosyl donor. Best results were obtained with Fmoc-Hyl(Cbz)-OAll, which was glycosylated in 80% yield. Removal of the allyl group gave a β-d-galactosylated building block which was used in solid-phase synthesis of a glycopeptide from type II collagen. Such glycopeptides are required for studies of rheumatoid arthritis in a mouse that is transgenic for HLA-DR4, i.e. the class II MHC molecule associated with rheumatism in humans.