Synthesis of 3-azido-3-deoxy-beta-D-galactopyranosides.
Three efficient routes to 3-azido-3-deoxy-beta-D-galactopyranosides were developed relying on a double inversion protocol at C3. Two of the routes were demonstrated to work with both O- and S-glycosides. In all three routes, the 2-O-acetyl-3-azido-4,6-O-benzylidene-3-deoxy-beta-D-galactopyranosides were obtained by an azide inversion of the key intermediates 2-O-acetyl-4,6-O-benzylidene-3-O-trifluoromethanesulfonyl-beta-D-gulopyranosides. The intermediate gulopyranosides were in turn obtained from 2-O-acetyl-4,6-O-benzylidene-3-O-trifluoromethanesulfonyl-beta-D-galactopyranosides, installed in one pot from the 4,6-O-benzylidene-beta-D-galactopyranosides, by inversion with nitrite or acetate. For O-glycosides, the gulopyranoside configuration could alternatively be obtained from the 4,6-O-benzylidene-beta-D-galactopyranoside by elimination to give the 2,3-dianhydro derivative followed by a highly stereoselective cis-dihydroxylation.
Oberg
Christopher T
CT
Organic Chemistry, Lund University, PO Box 124, SE-22100 Lund, Sweden.
Noresson
Ann-Louise
AL
Delaine
Tamara
T
Larumbe
Amaia
A
Tejler
Johan
J
von Wachenfeldt
Henrik
H
Nilsson
Ulf J
UJ
D001386:Azides / Q000737:chemistry; D001597:Benzylidene Compounds / Q000737:chemistry; D005690:Galactose / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D010100:Oxygen / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry
D001386:Azides; D001597:Benzylidene Compounds; D013455:Sulfur; D010100:Oxygen; D005690:Galactose