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Glycosyl imidates. 49. Synthesis of the octasaccharide moiety of the dimeric Le x antigen
Author(s) -
Bommer René,
Kinzy Willy,
Schmidt Richard R.
Publication year - 1991
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.199119910178
Subject(s) - trisaccharide , chemistry , acceptor , moiety , fucosylation , stereochemistry , glycosyl , yield (engineering) , glycosylation , derivative (finance) , acetylation , glycosyl donor , organic chemistry , fucose , biochemistry , galactose , physics , materials science , economics , financial economics , metallurgy , gene , condensed matter physics
A versatile synthesis of the basic Galβ (1→4)[Fucα(1→3)]‐GlcNAc trisaccharide building block of the Le x antigen family based on two important findings could be developed. Firstly, selective 3‐O‐allylation of the readily available azidolactose derivative 3 led to an efficient synthesis of the 3‐O‐unprotected fucosyl acceptor 9 . Secondly, α‐fucosylation of 9 with O‐fucosyl trichloroacetimidate 11 as donor exhibited a dramatic increase in yield when carried out by an “inverted procedure”, i,e, the donor was added to an acceptor/catalyst solution. The obtained trisaccharide building block 12 could be readily transformed into acceptor 13 and donor 15 , respectively. Thus, the dimeric hexasaccharide 16 was obtained, which was then transformed into donor 19 . Its reaction with the 3′‐O‐unprotected lactose acceptor 20 provided the desired ocetasaccharide 21 , which gave upon azido group reduction, acetylation of the amino groups, and complete O‐deprotection the desired target molecule 2 characterized as its fully O‐acetylated product 24 .