ABSTRACT
d-Galactono-1,4-lactone (3) is a useful chiral-starting material for the synthesis of various molecules. 1 For example, hex-2-enono-1,4-lactones (furan-2-ones) have been obtained by prolonged benzoylation of 3. 2 Diunsaturated 2,3 or monounsaturated 4,5 lactone derivatives can be formed, depending on the substitution pattern and reaction conditions. Hydrogenation of a diunsaturated product afforded a racemic 3,5-dideoxylactone derivative, 3 while hydrogenation of a per-O-acylated aldonolactone in the presence of Et3N gave a 3-deoxy derivative, 6 via a β-elimination/hydrogenation process. Bromination of 3 with HBr/AcOH and subsequent per-O-acetylation afforded the 6-bromo-6-deoxy per-O-acetylated lactone. 7 Similar to the enonolactones, hydrogenolysis of the bromides yielded also deoxylactones. 3,8 Therefore, combination of β-elimination and bromination reactions, followed by hydrogenolysis, have been applied for the synthesis of polydeoxygenated lactones, which are precursors of rare deoxy sugars such as 3,6-dideoxy-d-xylo-hexose (abequose). 9
