Stabilization of Glucosyl Dioxolenium Ions by “Dual Participation” of the 2,2-Dimethyl-2-(<i>ortho</i>-nitrophenyl)acetyl (DMNPA) Protection Group for 1,2-<i>cis</i>-Glucosylation
Wouter A. Remmerswaal, Kas J. Houthuijs, Roel van de Ven, Hidde Elferink, Thomas Hansen, Giel Berden, Herman S. Overkleeft, Gijsbert A. van der Marel, Floris P. J. T. Rutjes, Dmitri V. Filippov, Thomas J. Boltje, Jonathan Martens, Jos Oomens, Jeroen D. C. Codée
Abstract
-nitrophenyl)acetyl (DMNPA) protection group was shown to offer enhanced stereoselective steering compared to other acyl groups. Here, we investigate the origin of the stereoselectivity induced by the DMNPA group through systematic glycosylation reactions and infrared ion spectroscopy (IRIS) combined with techniques such as isotopic labeling of the anomeric center and isomer population analysis. Our study indicates that the origin of the DMNPA stereoselectivity does not lie in the direct participation of the nitro moiety but in the formation of a dioxolenium ion that is strongly stabilized by the nitro group.