Synthesis and characterization of propyl O-beta-D-galactopyranosyl-(1----4)-O-beta-D-galactopyranosyl-(1----4)- alpha-D-galactopyranoside.
Allyl 4-O-(4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl-beta-D-galactopyranosyl)- 2-O-benzoyl-3,6-di-O-benzyl-alpha-D-galactopyranoside was O-deallylated to give the 1-hydroxy derivative, and this was converted into the corresponding 1-O-(N-phenylcarbamoyl) derivative, treatment of which with dry HCl produced the alpha-D-galactopyranosyl chloride. This was converted into the corresponding 2,2,2-trifluoroethanesulfonate, which was coupled to allyl 2-O-benzoyl-3,6-di-O-benzyl-alpha-D-galactopyranoside, to give crystalline allyl 4-O-[4-O-(4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl- beta-D-galactopyranosyl)-2-O-benzoyl-3,6-di-O-benzyl-beta-D-galactopyran osyl]- 2-O-benzoyl-3,6-di-O-benzyl-alpha-D-galactopyranoside (15) in 85% yield, no trace of the alpha anomer being found. The trisaccharide derivative 15 was de-esterified with 2% KCN in 95% ethanol, and the product O-debenzylated with H2-Pd, to give the unprotected trisaccharide. Alternative sequences are discussed.
D009682:Magnetic Resonance Spectroscopy; D009844:Oligosaccharides / Q000138:chemical synthesis*; D014312:Trisaccharides / Q000138:chemical synthesis*
D009844:Oligosaccharides; D014312:Trisaccharides; C043175:propyl O-beta galactopyranosyl-(1-4)-O-beta galactopyranosyl-(1-4)-alpha galactopyranoside