Collect. Czech. Chem. Commun. 1991, 56, 2879-2883

3-Acetoxy-2-cycloalken-1-ones by acetylation of cyclic 1,3-diketones with ketene

Andrej Boháč and Pavel Hrnčiar

Department of Organic Chemistry, Comenius University, 842 15 Bratislava


Acetylation of lower 1,3-cycloalkenediones with ketene takes place exclusively at oxygen in contrast to acyclic β-diketones. Thus, 1,3-cyclopentanedione (I), 1,3-cyclohexanedione (II) and 5,5-dimethyl-1,3-cyclohexanedione (III) afforded the corresponding 3-acetoxy-2-cycloalken-1-ones VI - VIII in quantitative yields. 1,3-Cycloheptanedione (IV) and 1,3-cyclooctanedione (V) differed considerably from the preceding diketones by low reactivities.