Glycosyl donors protected with bulky silyl protective groups (tert-butyldimethylsilyl, TBS), on the 2-, 3-, and 4-OH groups were found to have superior reactivity compared with benzylated thioglucosides. The enhanced reactivity is explained by the stereoelectronic effects associated with the conformational change induced by the silylation. A TBS silylated thioglucoside donor has axial OR groups, whereas a benzylated thioglucoside has equatorial OR groups, leading to much more favorable charge-dipole interactions in the transition state. This concept could be used to create "super armed" glucosyl, mannosyl, rhamnosyl, and galactosyl donors, which could cross-couple with the armed acceptors, phenyl 2,3,4-tri-O-benzyl-β-D-thioglucoside or phenyl 2,3,6-tri-O-benzyl-β-D-thioglucoside, to give the corresponding armed disaccharides in good to excellent yields.
|Original language||English (US)|
|Number of pages||14|
|Journal||Journal of the American Chemical Society|
|State||Published - Jul 25 2007|
ASJC Scopus subject areas
- Colloid and Surface Chemistry