Total synthesis of 3-deoxy and 3,6-dideoxy-dl-hexoses

Synthesis of stereoisomeric 3-deoxy-hexoses 24–27 and 3,6-dideoxy-hexoses 28–31 is reported. Butyl (E)-2,6-dihydroxy-hex-4-enoate (2) was used as the starting material for the synthesis of 3-deoxy-hexoses. For the synthesis of 3,6-dideoxy-hexoses, butyl (E)-2-acetoxy-hex-4-enoate (7) was employed. The synthesis involved the following successive steps: cis or trans hydroxylation of the double bond in 2 or 7, lactonisation of the resulting aldonic acid esters followed by acetylation and chromatographical separation of γ-lactones, reduction of lactones 16–23 to lactols with disiamylborane, and acetylation of lactols to free sugars. All compounds were obtained as pure diastereomers in racemic form.