An effective synthesis of an arabinogalactan with a beta-(1-->6)-linked galactopyranose backbone and alpha-(1-->2) arabinofuranose side chains.
An octasaccharide, beta-D-Galp-(1-->6)-[alpha-L-Araf-(1-->2)]-beta-D-Galp-(1-->6)-beta-D-Galp-(1-->6)-[alpha-L-Araf-(1-->5)-alpha-L-Araf-(1-->2)]-beta-D-Galp-(1-->6)-beta-D-Galp-1-->OMP was synthesized. 4-methoxyphenyl 2,3,4-tri-O-benzoyl-beta-D-galactopyranoside (5), 2,6-di-O-acetyl-3,4-di-O-benzoyl-alpha-D-galactopyranosyl trichloroacetimidate (9), and 4-methoxyphenyl 2-O-acetyl-3,4-di-O-benzoyl-beta-D-galactopyranoside (11), 2,3,4,6-tetra-O-benzoyl-alpha-D-galactopyranosyl trichloroacetimidate (12), and 2,3,5-tri-O-benzoyl-alpha-L-arabinofuranosyl trichloroacetimidate (17) were used as the synthons. A concise route was used to gain the tetrasaccharide donor 19 by the use of 11, 12, 5, and 17. Meanwhile, treatment of 5 with 9 yielded beta-(1-->6)-linked disaccharide 20, and subsequent selective 6-O-deacetylation produced the disaccharide acceptor 21. Reaction of 21 with 19 gave 22, and subsequent selective 2-O-deacetylation afforded the hexasaccharide acceptor 23. Condensation of 23 with alpha-L-(1-->5)-linked arabinofuranose disaccharide 24, followed by deprotection, yielded the target octasaccharide.
Li
Aixiao
A
Research Center for Eco-Environmental Sciences, Academia Sinica, PO Box 2871, Beijing 100085, China.
Zeng
Ying
Y
Kong
Fanzuo
F
D001089:Arabinose / Q000031:analogs & derivatives* / Q000737:chemistry*; D002240:Carbohydrate Sequence; D005685:Galactans / Q000138:chemical synthesis* / Q000737:chemistry*; D005690:Galactose / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure
D005685:Galactans; C431714:arabinofuranose; D001089:Arabinose; C005653:arabinogalactan; D005690:Galactose