Use of XtalFluor-E as an Alternative to POCl3 in the Vilsmeier-Haack Formylation of C-2-Glycals.

We report the use of XtalFluor-E ([Et2NSF2]BF4) as an alternative to POCl3 in the Vilsmeier-Haack formylation reaction of C-2-glycals. Employing a XtalFluor-E/DMF combination allowed the desired C-2-formyl glycals to be isolated in 11-90% yield. This method was extended to the synthesis of a C-2 -formylated disaccharide glycal.