Double diastereoselection explains limitations in synthesizing mannose-containing beta-(1,3)-glucans.
It is known that 3-O-glycosylation of glucosidic acceptors bearing acyl groups in the 4 and 6 positions instead of a 4,6-O-benzylidene ring mainly affords alpha-glycosides. Described here is an unexpected stereochemical outcome for elongation at glucose O-3 of a beta-d-Glcp-(1-->3)-alpha-d-Manp disaccharide using peracetylated ethyl thioglucoside as a donor. This unexpected reaction was correlated with match-mismatch effects, as shown by efficient coupling of the same acceptor by a donor of l-configuration.
Sylla
Balla
B
Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France.
Descroix
Karine
K
Pain
Christophe
C
Gervaise
Cédric
C
Jamois
Frank
F
Yvin
Jean-Claude
JC
Legentil
Laurent
L
Nugier-Chauvin
Caroline
C
Daniellou
Richard
R
Ferrières
Vincent
V
D002236:Carbohydrate Conformation; D005936:Glucans / Q000138:chemical synthesis* / Q000737:chemistry*; D006031:Glycosylation; D008358:Mannose / Q000737:chemistry*; D008958:Models, Molecular; D013237:Stereoisomerism; D013379:Substrate Specificity
D005936:Glucans; D008358:Mannose