Synthesis of a lactosamine-type trisaccharide: 6-(bromoacetamido)-hexyl 2-O-(4-O-β-D-galactopyranosyl-2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-D-mannopyranoside, designed to affinity label the leukoagglutinin sugar binding site

Abstract

We describe the synthesis of a D-lactosamine-type trisaccharide, 6-(bromoacetamido)hexyl 2-O-(4-O-β-D-galactopyranosyl-2-acetamido-2-(deoxy-β-D-glucopyranosyl)-α-D-mannopyranoside (18), designed for affinity labeling the Phaseolus vulgaris leukoagglutinin sugar binding site. The trisaccharide derivative was obtained by condensation of 4-O-(2, 3, 4, 6-tetra-O-acetyl-β-D-galactopyranosyl)-3,6-di-O-acetyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl trichloroacetimidate (8) with 6-(N-benzyloxycarbonylamino)-hexyl 3,4,6-tri-O-benzyl-α-D-mannopyranoside (13). Removal of the protecting groups afforded 6-aminohexyl 2-O-(4-O-β-D-galactopyranosyl-2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-D-mannopyranoside (17), which was converted into the corresponding bromoacetamido derivative by reaction with N-hydroxysuccinimido bromoacetate.