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Synthesis of (1→4)-linked galacturonic acid trisaccharides, a proposed plant wound-hormone and a stereoisomer

✍ Scribed by Yoshiaki Nakahara; Tomoya Ogawa

Book ID
102994753
Publisher
Elsevier Science
Year
1990
Tongue
English
Weight
943 KB
Volume
200
Category
Article
ISSN
0008-6215

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✦ Synopsis

Syntheses of a-GalA-(1 +4)-a-GalA-(l-4)-GalA, a proposed plant wound-hormone, and its stereoisomer/?-GalA-(1+4)-a-GalA-(l-+4)-GalA are described. The key intermediates, tert-butyldiphenylsilyl O-(6-O-acetyl-2,3,4-tri-O-benzyl-a-o-galactop~anosyl)-( l~4)-O-(6-O-acetyl-2,3-di-O-benzyl-a-D-galactopyranosyl)-(1 ~4)-6-0-acetyl-2,3-di-O-benzyl-8-D-galactopyranoside and terf-butyldiphenylsilyl 0-(6-0acetyl-2,3,4-tri-0-benzyl-B-D-galactopyranosyl)-( 1~4)-0-(6-O-acetyl-2,3-di-O-benzyl-a-D-ga~actopyranosyl)-( 1 -t4)-6-0-acetyl-2,3-di-O-benzyl-P_Dgal~topyranoside, were prepared by stereoselective a-glycosylation of tert-butyldiphenylsilyl 6-O-acetyl-2,3-di-O-benzyl-B-D_galactopyranoside with O-(6-O-acetyl-2,3, 4-tri-0-benzyl-a-D-galactopyranosyl)-(1 ~4)-6-O-acetyl-2,3-di-O-benzyl-D-galactopyranosyJ fluoride and 0-(6-0-acetyl-2,3,4-tri-O-benzyl-~-o-galactopyranosyl)-( l-+4)-6-O-acetyl-2,3-di-O-benzyl-o-galactopyra-nosy1 fluoride, respectively. The correspondingp isomers were minor products. Characteristic features in the n.m.r. data of the key intermediates are discussed.

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