An improved method for the synthesis of protected glycosyl fluorides from thioglycosides using N,N-diethylaminosulfur trifluoride (DAST)
作者:Katsuhiko Suzuki、Yukishige Ito、Osamu Kanie
DOI:10.1016/j.carres.2012.07.003
日期:2012.10
examined using N,N-diethylaminosulfur trifluoride (DAST). Although the reaction proceeded without N-bromosuccinimide (NBS), in some cases it was found that the electrophilicity of the Vilsmeier-type electrophilic sulfinium cation species was not sufficient for the activation of certain less-reactive thioglycosides. Here, we report the results of fluorinationreactions of a series of monosaccharides using
A library composed of a complete set of fucopyranosyl-galactopyranosides was synthesized. A perbenzylated phenylthio fucopyranoside and a series of tri-O-benzyl-galactopyranosyl fluorides having single hydroxyl groups at the 2-, 3-, 4-, and 6-positions were used as the glycosyl donor and glycosyl acceptors, respectively. The chosen set of functionalities at the anomeric centers enabled rapid access to the oligosaccharides based on chemoselective activation. The first coupling reaction was achieved by the action of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST). The resulting disaccharide fluoride was readily activated by hafnocene bistrifluoromethanesulfonate [Cp2Hf(OTf)(2)] and glycosidated with n-octanol. (c) 2006 Elsevier Ltd. All rights reserved.