Showing papers by "J. Cristobal Lopez published in 2008"
TL;DR: In this article, a sulfoxide/metal exchange reaction is used to generate a glycosyllithium derivative that undergoes β-elimination of its C-2 substituent.
22 citations
TL;DR: In this article, the transformation of partially unprotected phenyl 1-thioglycosides into glycosyl fluorides can be conveniently carried out by treatment with NIS in the presence of HF-pyridine.
12 citations
03 Mar 2008
6 citations
1 citations
TL;DR: This article showed that the "normal" primary versus secondary hydroxyl preference holds only for disarmed donors, whereas armed donors are frequently secondary-OH selective, and that a three-component, in situ competition leads to a single double glycosidation product in which each donor goes to its preferred-OH.
Abstract: Three selectivities, stereo, chemo and regio, that confront organic synthesis in general, are encountered in glycosidation reactions. In these reactions, protecting groups are a necessary evil; but they do more than protect, for they profoundly affect all three selectivities. Case studies show that the "normal" primary versus secondary hydroxyl preference holds only for disarmed donors, whereas armed donors are frequently secondary-OH selective. These selectivities are so reliable, that a three-component, in situ competition leads to a single double glycosidation product in which each donor goes to its preferred-OH.
1 citations
TL;DR: In this article, a sulfoxide/metal exchange reaction is used to generate a glycosyllithium derivative that undergoes β-elimination of its C-2 substituent.
Abstract: Glycosyl sulfoxides can be conveniently transformed into pyranoid or furanoid glycals by treatment with organolithium reagents. The more likely reaction pathway involves a sulfoxide/metal exchange reaction to generate a glycosyllithium derivative that undergoes β-elimination of its C-2 substituent. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)