Access to L- and D-Iminosugar C-Glycosides from a D-gluco-Derived 6-Azidolactol Exploiting a Ring Isomerization/Alkylation Strategy

A flexible synthetic access to six-membered and D-iminosugar C-glycosides is reported starting from the easily available 6-azido-6-deoxy-2,3,4-tri-O-benzyl-D-glucopyranose precursor. This methodology involves a highly diastereoselective tandem ring enlargement/alkylation and a stereocontrolled ring contraction. It allows an efficient synthesis of iminosugar C-glycosides displaying structural diversity at both C-1 and C-6.