| Abstract
| - Benzylated and benzoylated ethyl thioglycosides ofd-fructofuranose have been synthesized andtested as glycosyl donors in couplings to various primary and secondarycarbohydrate acceptors.Treatment of2-O-acetyl-1,3,4,6-tetra-O-benzoyl-d-fructofuranosewith ethyl mercaptan in a BF3·etherate-promoted reaction gave the benzoylated ethyl2-thio-α,β-d-fructofuranosides, whichafterdeacylation and benzylation afforded the benzylated derivatives.These thiofructofuranosides, usingdimethyl(methylthio)sulfonium triflate (DMTST) orN-iodosuccinimide as promoter, were found tobe excellent donors, which gave disaccharide coupling products inquantitative or almost quantitativeyields with all tested acceptors, yields rarely found inoligosaccharide synthesis. The benzoylateddonors gave only α-linked fructofuranosides, due to participation ofthe 3-O-benzoyl group, whereasthe benzylated donors gave α/β-mixtures.
|
