Stereoselective Synthesis of Glycosyl Cyanides by TMSOTf-Mediated Ring Opening of 1,6-Anhydro Sugars

We describe herein a convenient access to glycosyl cyanides by way of TMSCN ring opening of 1,6-anhydro sugars mediated by TMSOTf with modest to high stereocontrol in the D-gluco, D-galacto and D-manno series. The reaction is tolerant to various functional groups including free alcohols, alkenes and terminal alkynes. The straightforward synthesis of a constrained analogue of 1-cyano-D-glucal with a 3,6-anhydro sugar framework is presented to illustrate the interest of the TMSCN ring-opening reaction.