Diastereoselective synthesis of 2,3,4-trisubstituted γ-lactols and γ-lactones via regio- and stereocontrolled opening of a 1,2-epoxy-4-hydroxyalkyl carbamate with hetero-nucleophiles

The acid-catalyzed ring opening of the title epoxide 1 takes place at the C-1 atom with retention of configuration at C-2 to form 2,3- cis -2-hydroxy-substituted γ-lactol derivatives 3. In basic media, nucleophiles attack the C-2 atom with inversion of configuration yielding 2,3- trans -lactols 5. Oxidation furnishes corresponding γ-lactones 6, 11 or 13.