Fmoc-Hyp-OBn 10 was obtained from commercially available Fmoc-Hyp(tBu)-OH 9 that was first benzylated on the carboxylic acid moiety, and subsequently subjected to tert-butyl removal using TFA, providing the secondary alcohol. With arabinose donor 8 and hydroxyproline acceptor 10 in hand, stereoselective 1,2-cis glycosylation was performed to monoarabinosylate hydroxyproline (Scheme 2). As the intramolecular aglycon delivery (IAD) reaction of the acetal formed between hydroxyproline 10 and either donor 8 or donor S4 led to the same 1,2-cis-linked product, the absolute stereochemistry at the anomeric center of precursor does not affect the outcome of this glycosylation method. To be more specific, this IAD glycosylation method involves an approach in which the p-methoxybenzyl group acts as the initial transient attachment point for the acceptor, in this case hydroxyproline 10. Upon activation of the thioglycoside using IDCP, which forms an sp 2 hybridized C1 atom, the glycosyl donor is relocated to C1 from the same face as C2-O and the 1,2-cis-glycosyl bond is formed stereoselectively (Figure ). Prior to their application in SPPS, the various arabinosylated hydroxyproline building blocks that were collected along the previously described synthesis path were converted into Fmocprotected peracetylated amino acid constructs. For this, the three AraHyp moieties 11-13 were debenzylated in order to liberate carboxylic acid for peptide coupling, and to exchange the glycosyl O-benzyl groups with O-acetyl groups. Consequently, Fmoc-Hyp[(3,5-OBn)Ara]1-OBn 11, Fmoc-Hyp[(3,5-OBn)Ara]2-OBn 12, and Fmoc-Hyp[(3,5-OBn)Ara]3-OBn 13 were subjected to hydrogenolysis using Pd(OH2)/C and H2 gas. Interestingly, striking differences in debenzylation rates were observed for the different monomers. Whereas debenzylation of Ara1Hyp 11 required multiple Pd(OH)2/C refreshing and extended reaction times (48 hours), the di-and tri-arabinosylated building blocks did not require refreshing of Pd(OH)2/C and were completed overnight. Similarly, whereas debenzylation of 11 and 13 was accompanied with Fmoc-removal, hydrogenation of 12 resulted in removal of only the benzyl groups.