Synthesis of the Disaccharide Core of Ezomycin Nucleosides.

The ezomycins make up a class of complex nucleoside antibiotics that share a common disaccharide core. Herein we present an efficient synthesis of this core from diacetone-d-allose, using a ruthenium-catalyzed asymmetric allylic etherification and a de novo carbohydrate synthesis based on the diastereoselective Henry reaction. Our strategy overcomes several challenges, such as introducing a dense array of functional groups and creating consecutive stereocenters with high selectivity. This approach enables the rapid preparation of disaccharides and paves the way for the total synthesis of ezomycins.