A Facile Synthesis of Ethyl 2,6-Di-O-benzyl-3-O-(3,4,5-tri-O-acetyl-2-deoxy-2-N-phthalimido--D-glucopyranosyl)-1-thio--D-galactopyranoside and Studies on the Regioselectivity of 2,3,4-OH Groups of Galactosyl Acceptor

摘要

O-Antigenic part of Campylobacter jejuni gram negative bacteria was reported to consist of a repeated trisaccharide unit. The disaccharides, G]cNAc-Gal derivatives, as key intermediates for the synthesis of trisaccharide repeating units were synthesized. At the ￥a(1??3) glycoside bond formation step between 3,4,6-tri-O-acctyl-2-deoxy-2-N-phthalimido-￥a-D-glucopyranosyl bromide and galactosyl acceptors, high regioselectivities between 2, 3, and 4-OH groups of galactosyl acceptors were found. As a result, no further selective protection steps for OH groups of galactosyl acceptors was necessary, and more effective and compact synthetic scheme was achieved.