In this paper, we describe the synthesis of mono-, di-, and triarabinosylated hydroxyproline building blocks in which the L- arabinose units are linked via linear β-1,2-linkages, their incorporation in the 18 amino acid long plant peptide hormone PSY1, and the optimal deprotection protocol that leads to the fully unprotected peptide (Figure ). As this peptide is a member of the PSY peptide family that is found in all higher plants and mosses, we expect that this synthesis will lead to PPHs and derivatives that increase our understanding of the intercellular communication of such organisms, and in particular the role of the PTMs in these processess. Here, we reveal a strategy to prepare more complex peptides than the ones reported so far, showing compatibility of the 1,2-cis-glycosidic connectivity between attached saccharides and amino acid unit with the synthetic incorporation of other PTMs in peptides. It was envisioned that synthesis of the polyamide backbone of PSY1 would be accessible with Fmoc/tBu-based solid-phase peptide synthesis (SPPS) using the appropriate building blocks, i.e., Fmoc-Hyp(OtBu)-OH, Fmoc-Tyr(SO3Np)-OH and Fmoc-Hyp[L-Ara3(OAc)7]-OH. Whereas the first two are obtained from commercial sources, the arabinosylated hydroxyproline derivative could be synthesized using a repetition of stereoselective glycosylation reactions using hydroxyproline and the proper protected arabinose donor. To achieve that, we apply a glycosylation strategy that involves the use of mild activator iodonium di-collidine perchlorate (IDCP) in order to stereoselectively couple the arabinose donor to Fmoc-Hyp-OBn.