A concise and practical synthesis of antigenic globotriose, alpha-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-beta-D-Glc.
A concise and practical synthesis of the antigenic globotriose, alpha-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-beta-D-Glc (13), was achieved by coupling of a monosaccharide donor, 3-O-allyl-2-O-benzoyl-4,6-O-benzylidene-alpha-D-galactopyranosyl trichloroacetimidate (4) with a disaccharide acceptor, p-methoxyphenyl 2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl-(1-->4)-2,3,6-tri-O-benzoyl-beta-D-glucopyranoside (8), followed by deprotection. In spite of the existence of a C-2-ester substituent capable of neighboring-group participation in the donor, the coupling gave exclusively the alpha-linkage in satisfactory yield. The acceptor 8 was readily obtained from selective 3-O-benzoylation of the galactosyl ring of p-methoxyphenyl 2,6-di-O-benzoyl-beta-D-galactopyranosyl-(1-->4)-2,3,6-tri-O-benzoyl-beta-D-glucopyranoside (7), which was prepared from p-methoxyphenyl beta-D-lactoside (5) via isopropylidenation, benzoylation, and deisopropylidenation. Donor 4 was obtained from p-methoxylphenyl 3-O-allyl-2,4,6-tri-O-benzoyl-beta-D-galactopyranoside (1) via selective 4,6-di-O-debenzoylation, oxidative removal of 1-O-MP, benzylidenation, and trichloroacetimidate formation.
Chen
Langqiu
L
Institute of Chemistry, Xiangtan University, Hunan Province 411105, PR China. chengood2003@263.net
Zhao
Xing-E
XE
Lai
Duan
D
Song
Zhiwei
Z
Kong
Fanzuo
F
D000818:Animals; D000941:Antigens / Q000737:chemistry*; D002240:Carbohydrate Sequence; D006801:Humans; D008969:Molecular Sequence Data; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000276:immunology
D000941:Antigens; D014312:Trisaccharides; C113460:globotriose