Facile Synthesis of 1,6-Anhydrohalosugars via a Novel Rearrangement of Galactal

A novel intramolecular vinylogous substitution of D-galactal (1) is described. The resulting 1,6-anhydro-2,3-dideoxy-β-D-threo-hex-2-enopyranose (4) can, after protection with various groups, easily be transformed into mono- and dihalocompounds (6), (9), (10), (11), (15), (16) and (17) either directly or via the Cerny epoxides (12) and (14).