Ruthenium-Catalyzed Regioselective Olefin Migration of Dihydropyran Acetals: A Strategy toward β-2,6-Dideoxypyranoglycosides.

Here, we report a synthetic strategy toward β-2,6-dideoxypyranoglycosides. The key event is the ruthenium-catalyzed regioselective olefin migration of dihydropyran allylic acetals to homoallylic acetals. In combination with other metal-catalyzed reactions, this new protocol led to the synthesis of β-2,6-dideoxypyranoglycosides in a highly efficient manner. Using this sequential metal catalysis, various mono-, di-, and trisaccharide forms of β-2,6-dideoxypyranoglycosides were prepared.