Aldonolactones hydrogen bromide

The aim of this article is to focus on the diversity of aldonolactones as chiral synthons. The chemistry of aldonolactones was an almost unexplored area when, in 1979, we started our investigations on the reaction of aldonolactones with hydrogen bromide in acetic acid thereby obtaining bromodeoxyaldonolac-tones [1,2]. These compounds have over the years proven to be very versatile compounds for stereoselective synthesis, both in the carbohydrate field, giving access to otherwise less readily obtainable sugars, and as chiral, optically pure synthons in a broader sense within organic chemistry. 

Reaction of Aldonolactones with Hydrogen Bromide in Acetic Acid... 

The regioselective functionalisation of aldonolactones is possible at the position a to the lactone and at the primary (co) position. The most efficient method for this functionalisation is treatment of the aldonolactone/aldonic acid with hydrogen bromide in acetic acid (Scheme 1). In this strongly acidic medium the lactone is partly acetylated followed by formation of acetoxonium ions. These then undergo opening with bromide ions to give acetylated bromodeoxyaldonolactones (7). The formation of acetoxonium ions controls the... 

Oxirans. - The synthesis of l,2-anhydro-3,4-di-0-benzyl-6-deoxy-a-D-glucopyranose and its conformational analysis have been reported. A range of epoxides have been prepared by base treatment of bromohydrins, which were made by reaction of hydrogen bromide with aldonolactones. A one-pot conversion of vicinal diols into epoxides employs halohydrin ester intermediates generated from cyclic orthoacetates and either acetyl bromide or trimethylsilyl chloride. Levoglucosenone has been transformed into l,6 3,4-dianhydro-p-D-talopyranose by way of a trn/w-iodo-acetoxylation of the alkene moiety... 

---