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Glycosyl Imidates, 56. Synthesis of the Hexasaccharide Moiety of Pectinioside E
Author(s) -
Jiang ZiHua,
Schmidt Richard R.
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1992199201160
Subject(s) - chemistry , disaccharide , moiety , glycosylation , trisaccharide , acceptor , glycosyl donor , stereochemistry , glycosyl , yield (engineering) , fucosylation , organic chemistry , biochemistry , fucose , galactose , physics , materials science , metallurgy , condensed matter physics
The synthesis of the hexasaccharide moiety 2 of pectinioside E ( 1 ), isolated from the whole bodies of the starfish Asterina pectinifera Müller et Troschel, is described. Building block 4 was prepared by a six‐step procedure from D ‐glucose. A reasonable yield was obtained via selective glycosylation of 4 at 2‐OH with donor 5 to give the desired disaccharide 6 which served as an acceptor in the following fucosylation with 9 to afford the crucial trisaccharide 10 . This was easily transformed into trichloroacetimidate 12 . Disaccharide 17 , obtained in high yield by glycosylation of donor 13 with acceptor 14 followed by deacetylation, turned out to be more reactive at 4b‐OH than at 2b‐OH. Thus, the reaction of donor 12 with acceptor 17 gave the desired pentasaccharide 18 β in an acceptable yield; 18 β was readily transformed into the hexasaccharide 20 by glycosylation with donor 15 . Debenzylation of 20 followed by deacylation furnished the target hexasaccharide 2 which was characterized by its per‐ O ‐acetylated product 21 .