Synthesis of two trisaccharides related to the triterpenoid saponin eryloside isolated from the sponge Erylus nobilis

The chemical synthesis of two trisaccharides related to the triterpenoid saponin eryloside from commercially available d-galactose, l-arabinose and d-glucosamine hydrochloride via rational protecting group manipulations is reported. The required glycosylations were carried out by the extensive use of thioglycoside chemistry where the activations were achieved by using NIS in the presence of La(OTf)3.