Synthesis of tri- and tetra-saccharide derivatives related to Klebsiella type 57

摘要

2,4,6-Tri-O-benzyl-#beta#-D-galactopyranosyl-(1->3)-1,6-anhydro-2-O-benzyl-#beta#-D-Galactopyranose 12 has been prepared from D-galactose. The disacharide 12 reacts with ethyl 2,3,4,6-tetra-O-benzoyl-1-thio-#alpha#-D-mannopyranoside in the presence of NIS/TfOH as promoter to give the tri- and tetra-saccharide derivatives 2,3,4,6-tetra-O-benzoyl-#alpha#-Dmannopyranosyl-(1->3)-2,4,6-tri-O-benzyl-#beta#-D-mannopyranosyl-(1->3)-1,6-anhydro-2-O-benzyl-#beta#-D-galactopyranose 15 and 2,3,4,6-tetra-O-benzoyl-#alpha#-D-mannopyranosyl)-(1->4)]-1,6-anhydro-2-O-benzyl-#beta#-D-galactopyranose 16 respectively in moderate yield.