Preparation of Cyclic 1,3-Diketones and Their Exploitation in the Synthesis of Heterocycles

Owing to their high reactivity and availability 1,3-dicarbonyl compounds occupy an important place in organic synthesis. It is mainly their high reactivity that predetermines them for the synthesis of various types of compounds, particularly heterocycles. Cyclic 1,3-diketones I(n) (where n is the number of ring carbon atoms), which are suitable precursors for preparation of bicyclic or polycyclic condensed heterocycles, respectively, are an important group of 1,3-dicarbonyl compounds. However, at the same time it must be added that in spite of the relatively simple structure of 1,3- cycloalkanediones their syntheses have yet to be satisfactory solved, especially those for medium-sized and large rings. Therefore, currently the chemistry of common cyclic β-diketones, such as 1,3-cyclohexanedione, 5,5-dimethyl-1,3- cyclohexanedione (dimedone), but also that of 1,3-cyclopentanedione remains best known. In the literature one can already find a large scope of heterocycles synthesized on the basis of the above three diketones, and also data about their biological activity. Works dealing with exploitation of other, higher cyclic diketones are scarce. This article is a continuation of two reviews published by Strakov [1,2], and expands them by results published till the end of 2001.