Evaluation of thioglycosides of Kdo as glycosyl donors.
The use of Kdo thioglycosides as glycosyl donors using DMTST, IBr/AgOTf and NIS/AgOTf as promoters has been evaluated. Activation at low temperature allowed to escape the formation of 2,3-glycal byproducts to give glycosides in high yield and with good beta-anomeric selectivity. The use of diethyl ether as solvent and (especially) isopropylidene acetals as protecting groups improved the alpha-anomeric selectivity. NIS/AgOTf as promoter surprisingly yielded the 3-iodo-product via the glycal intermediate.
Mannerstedt
Karin
K
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden.
Ekelöf
Kerstin
K
Oscarson
Stefan
S
D004220:Disulfides / Q000737:chemistry; D006031:Glycosylation; D008698:Mesylates / Q000737:chemistry; D013400:Sugar Acids / Q000737:chemistry*; D013865:Thioglycosides / Q000737:chemistry*
D004220:Disulfides; D008698:Mesylates; D013400:Sugar Acids; D013865:Thioglycosides; C414104:dimethyl(methylthio)sulfonium; C012077:trifluoromethanesulfonic acid; C120356:3-deoxy-manno-oct-2-ulopyranosonic acid