ENANTIOMERICALLY PURE, HIGHLY FUNCTIONALIZED TETRAHYDROFURANS FROM SIMPLE CARBOHYDRATE PRECURSORS

6-Bromo-6-deoxy-1,4-aldonolactones and 6-bromo-6-deoxy-alditols with D-galacto-, D-altro-, D-manno- and D-ido-configuration were selectively converted into hydroxylated tetrahydrofuran derivatives by simple heating in water. The 6-bromo-6-deoxy-D-altritol (10) and 6-bromo-6-deoxy-D-iditol (25) reacted even at room temperature. Likewise, the 6-bromo-2,6-dideoxy-aldonolactones with D-arabino- (29) and D-lyxo-configuration (31) gave the corresponding 2-deoxy-3,6-anhydrides, when heated in water. The rate of formation of the furan ring by intramolecular nucleophilic substitution was determined by the conformation of the bromopolyols in water.