L. I. Markova

Chemistry of 1,5-diketones: II. Specificity of transformations of polycyclic 1,5-diketones in acid media

Abstract2-(1,3-Diaryl-3-oxopropyl)cyclohexan-1-ones underwent carbo-and heterocyclization in a mixture of acetic acid with acetic anhydride in the presence of perchloric acid. The transformation of 2-(1,3-diaryl-3-oxopropyl)cyclohexan-1-ones into 2,4-diaryl-5,6,7,8-tetrahydrochromenylium salts was shown to involve intermediate 2,4-diarylbicyclo[3.3.1]non-2-en-9-ones. The structure of 2,4-diaryl-substituted bicyclo[3.3.1]non-2-en-9-ones and products of their reactions with halogens and hydroxylamine hydrochloride was confirmed by 1H and 13C NMR spectroscopy.

Tetrahydrochromenylium and -Thiochromenylium Salts from Triketones of the 2-(3-Oxopropyl)cyclohexane-1,3-dione Series

We have worked out the optimal conditions for synthesis of 2,4-diaryl-5-oxo-5,6,7,8-tetrahydrochromenylium and -thiochromenylium salts based on triketones of the 2-(1,3-diaryl-3-oxopropyl)cyclohexane-1,3-dione series. For the first time, along with 5-oxo-substituted salts, we have obtained 5-thioxo-5,6,7,8-tetrahydrothiochromenylium salts. A necessary condition for the formation of the latter on treatment with acids and S-nucleophiles is the presence of electron-donor groups on the aryl substituents of the indicated triketones.

Halogenation of 1,5-Diketones

Published and experimental data of authors on halogenation of 1,5-diketones from acyclic (among them chalcogen-containing), semicyclic and bicyclic series resulting in formation of mono-, di-, tri-, and tertahalosubstituted 1,5-dioxo compounds, pyrylium halides, and their fused analogs or aroylfurans are reviewed.

SELECTIVE HYDROGENATION OF POLYCARBONYL COMPOUNDS

Die Triketone (II) werden katalytisch, entweder mit Raney-Ni in EtOH, NaOH/HzO oder mit Rh/C in Hexan zu den Hexahydfochmmefwnen (I),den Perhydrochromanen (III), bzw. zum Alkohol (IV) hydriert.