Goeran Magnusson

Galabiosyl donors; efficient synthesis from 1,2,3,4,6-penta-O-acetyl-β-d-galactopyranose

1,2,3,4,6-Penta-O-acetyl-beta-D-galactopyranose was transformed into phenyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-galactopyranoside (5) and 4-methoxyphenyl 2,3,6-tri-O-benzoyl-beta-D-galactopyranoside (8) in 73% (two steps) and 58% (three steps) yield, respectively. Glycosylation of the acceptor 8 with donor 5 using N-iodosuccinimide-trimethylsilyl trifluoromethanesulfonate as promoter furnished the galabioside 9 (8.8 g) in 95% yield. Further transformations provided in high yields anomerically-activated galabiosides (thioglycoside (1), trichloroacetimidate (2), and bromosugar (3)) suitable for use as glycosyl donors in syntheses of galabiose-containing oligosaccharides. Several of the compounds reported here are crystalline, which greatly simplified purifications.

A short and practical route to 3-O-benzoyl azidosphingosine

A short and practical route to 3-O-benzoyl azidosphingosine from D-xylose is described. The synthesis avoids the use of expensive and hazardous chemicals (i.e. mercury salts), and it is reproducible up to at least a 20 g scale. Furthermore, the synthesis proceeds to 3-O-benzoyl azidosphingosine with a minimum of protection group manipulation, by exploiting a regioselective protection of the primary HO-1 with thexyldimethylsilyl chloride.

SYNTHESIS OF THE LINEAR B TYPE 2 TRISACCHARIDE Galα3Galβ4GlcNAcβOTMSEt, AND COUPLING OF THE CORRESPONDING 2-CARBOXYETHYL β-THIOGLYCOSIDE TO SEPHAROSE

The synthesis of the Linear B type 2 trisaccharide (Galα3Galβ4GlcNAcβOTMSEt) and the corresponding 2-carboxyethyl β-thioglycoside is described, as well as coupling of the latter to Sepharose. *Deceased June 2000.