Ethyl 2-Deoxy-2-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)-3,6-bis-O-(phenylmethyl)-1-thio-β-D-glucopyranoside is used to prepare β-human FSH-based glycopeptides containing an N-linked dodecasaccharide or chitobiose units. It is also used to synthesize a protected fucosylated biantennary N-glycan of erythropoietin.