ISSN:
0170-2041
Keywords:
Glycosyl trichloroacetimidates
;
Glycosylation
;
D-Xylose
;
D-Quinovose
;
Steroids
;
Saponins
;
Starfish
;
Asterias amurensis
;
Carbohydrates
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Reaction of 2-O-acetyl-protected O-galactosyl trichloroacetimidate 3 as glycosyl donor and 2,4-di-O-unprotected xylopyranoside 2 as glycosyl acceptor furnished in the presence of Et2O · BF3 as catalyst regioselectively β-(1→4)-connected disaccharide 4 which gave upon subsequent reaction with O-quinovosyl trichloroacetimidate 5 as donor β-(1→2)-connection, thus affording trisaccharide 6. Removal of the 2-O-acetyl group from the galactosyl moiety yielded acceptor 7; its glycosylation with donor 5 furnished β-connected tetrasaccharide 8. This compound was transformed via 1-O-desilylation and then treatment with trichloroacetonitrile in the presence of a base into O-tetraosyl trichloroacetimidate 10 as glycosyl donor. Reaction of 10 with 3-O-unprotected 2,4-di-O-acetyl- and 2,4-di-O-benzyl-protected quinovosides 13 and 16 furnished the desired fully O-protected pentasaccharides 17 and 18, respectively. Hydrogenolytic O-debenzylation of 18 furnished the O-unprotected target molecule 19 which was characterized as its O-acetyl product 20.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.1992199201135
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