Synthesis of galactosides locked in a 1,4B boat conformation and functionalized at the anomeric position

A new methodology for the preparation of carbohydrates locked in a 1,4B boat conformation is presented. The constrained molecules thus obtained are functionalized at the anomeric position by iodo-, fluoro-, hydroxyl- or/and phosphono-methylene moieties. A remarkable diastereoselective opening of these quaternary acetals was also observed under non-acidic conditions.