Highly reactive 2-deoxy-2-iodo-D-allo and D-gulopyranosyl sulfoxide donors ensure ß-stereoselective glycosylations with steroidal aglycones

Identifier:  imarina:5133166

Handle: https://hdl.handle.net/20.500.11797/imarina5133166

Authors:  Mestre, J; Collado, D; Benito-Alifonso, D; Rodríguez, MA; Matheu, MI; Díaz, Y; Castillón, S; Boutureira, O

Abstract:
The preparation of well-defined D-xylo and D-ribo glycosides represents a synthetic challenge due to the limited configurational availability of starting materials and the laborious synthesis of homogeneous 2-deoxy-β-glycosidic linkages, in particular that of the sugar-steroid motif, which represents the "stereoselective determining step" of the overall synthesis. Herein we describe the use of 2-deoxy-2-iodo-glycopyranosyl sulfoxides accessible from widely available D-xylose and D-ribose monosaccharides as privileged glycosyl donors that permit activation at very low temperature. This ensures a precise kinetic control for a complete 1,2-trans stereoselective glycosylation of particularly challenging steroidal aglycones.