The introduction of two hydroxy groups with differential protection at the endo positions of C(5) and C(6) of the ''naked sugars of the first generation'' has been achieved by seleno-Pummerer rearrangement of 5-endo-hydroxy-6-exa-phenylseleno-7-oxabicyclo[2.2.1]heptan-2-one derivatives followed by deselenation with Bu(3)SnH.