9-BBN as a convenient protecting group in functionalisation of hydroxylysine

9-BBN was used for regioselective protection of the α-amino and α-carboxyl groups of (5R)-5-hydroxy-l-lysine. The resulting 9-BBN complex was then employed in transformations such as N-Cbz protection, azido transfer, O-glycosylation, and O-silylation. Further manipulations led to improved methods for preparation of hydroxylysine and galactosylated hydroxylysine building blocks, suitable for direct use in peptide synthesis under standard Fmoc conditions.