title: Studies on the synthesis of propyl 4-O-beta-D-galactopyranosyl-alpha-D-galactopyranoside.
abstract: 2-O-Benzoyl-3,6-di-O-benzyl-4-O-(chloroacetyl)-, 4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl-, and 2-O-benzoyl-3,4,6-tri-O-benzyl-alpha-D-galactopyranosyl chloride were converted into the corresponding 2,2,2-trifluoroethanesulfonates, and these were treated with allyl 2-O-benzoyl-3,6-di-O-benzyl-alpha-D-galactopyranoside, to give allyl 2-O-benzoyl-4-O-[2-O-benzoyl-3,6-di-O-benzyl-4-O-(chloroacetyl)- beta-D-galactopyranosyl]-3,6-di-O-benzyl-alpha-D-galactopyranoside (26; 41% yield), 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 (27; 62% yield), and allyl 2-O-benzoyl-4-O-(2-O-benzoyl-3,4,6-tri-O-benzyl-beta-D- galactopyranosyl)-3,6-di-O-benzyl-alpha-D-galactopyranoside (28; 65% yield). All disaccharides were free from their alpha anomers. Disaccharides 26 and 27 were found to be base-sensitive, and were de-esterified by KCN in aqueous ethanol, and debenzylated with H2-Pd. Attempts to produce (1----4)-beta-D-galactopyranosides from the coupling of a number of fully esterified D-galactopyranosyl sulfonates to allyl 2,3,6-tri-O-benzoyl-alpha-D-galactopyranoside were unsuccessful.
mesh_terms: D004187:Disaccharides / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism
chemical_list: D004187:Disaccharides; C043174:1-propyl-4-O-beta galactopyranosyl-alpha galactopyranoside