Synthesis of the capsular polysaccharide of Streptococcus pneumoniae type 14. 2. Synthesis of methyl-6-O-acetyl-4-O-(2,3,46-tetra-O-benzoyl -beta-D-galactosylpyranosyl)-2-deoxy-2-phthalimido-beta-D-gluco- pyranoside--a lactosamine precursor in the monomer synthesis for polycondensation

Glycosylation of methyl 6-O-acetyl-3-O-benzoyl-2-deoxy-phthalimido-beta-D-glucopyranoside and its 4-trityl ether by benzobromogalactose, 1-O-acetyl-2,3,4,6-tetra-O-benzoyl-beta-D-galactopyranose, 1,2-(alpha-p-tolylthio)benzylidene]- and 1,2-O-(alpha-cyano)benzylidene]-3,4,6-tri-O-benzoyl-alpha-D- galactopyranoses proceeds non-stereospecifically. The best yield of beta-linked disaccharide was obtained upon glycosylation by benzobromogalactose in the presence of silver triflate and tetramethylurea in nitromethane.