Differential reactivity of alpha- and beta-anomers of glycosyl acceptors in glycosylations. A remote consequence of the endo-anomeric effect?
When phenyl tri-O-benzyl-1-thio-beta-D-galactopyranosiduronic acid esters were coupled with a 1/1 mixture of alpha and beta 2,3 di-O-protected D-galactopyranosiduronic acid esters, the beta-anomer proved to be more reactive. Data from theoretical calculations suggested that the enhanced reactivity of this anomer compared with the alpha one would be due to a stronger hydrogen bond of the C-4 OH with the ring oxygen.
Laboratoire de Synthèse Organique, Département de Chimie, Université de Sherbrooke, Sherbrooke (QC), Canada JIH 5N4.
D
D
Magaud
R
R
Dolmazon
D
D
Anker
A
A
Doutheau
Y L
YL
Dory
P
P
Deslongchamps
D002236:Carbohydrate Conformation; D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D020723:Glucuronic Acid / Q000737:chemistry / Q000378:metabolism; D006031:Glycosylation; D006603:Hexuronic Acids / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D013237:Stereoisomerism
D004187:Disaccharides; D006603:Hexuronic Acids; C007819:galacturonic acid; D020723:Glucuronic Acid