3,4-Diacetylhexane-2,5-dione—an effective synthon for synthesis of substituted azulene heteroanalogs by cyclocondensation reactions

The one-pot method for the synthesis of 4,8-dialkoxy-6-aryl-1,3-dimethylcyclohepta [c]furanium perchlorates has been developed. The method is based on the cyclocondensation of 3,4-diacetylhexane-2,5-diones with aromatic aldehydes and trialkyl orthoformates under the action of a 16% perchloric acid solution in acetic anhydride. Under similar conditions, with hydrogen sulfide, cyclohepta[c]thiophenium perchlorates have been obtained, while cyclohepta[c]pyrrolium perchlorates have been prepared with arylamines, ammonium acetate, or aliphatic amine acetates. A heteroanalog of azulene, 4,8-diethoxy-1,3-dimethyl-2-azaazulene, has been obtained for the first time. Hydrolysis of aza- and thiaazulenium salts gives the corresponding cyclohepta[c]pyrrol-4-ones and cyclohepta [c]thiophen-4-ones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1596–1603, August, 1998.     

Acetals and Vinyl Ethers of Unsaturated Aldehydes and Ketones in the New Syntheses of Heterocyclic Compounds: XII. New Alternatives of Acid Condensation of Cyclohexane-1,4-diones with Hydroxyarylaldehydes under Dehydration Conditions. Fluorecence Spectra of the Products

1,3-Diethoxy-2-R-5,5-R',R'-1-cyclohexenylium perchlorates in condensation with 2-hydroxyarylaldehydes under dehydration conditions give rise to 3-ethoxy-1,2-dihydroxanthylium perchlorates that with the second molecule of 2-hydroxyarylaldehyde afford 13H-chromeno[3,2-b]xanth-5-ylium perchlorates, and with primary and secondary amines yield 3-(R²,R³-amino)-1,2-dihydroxanthylium perchlorates. The condensation of 2-bromodimedone with salicylaldehydes in triethyl orthoformate and perchloric acid medium furnished 6-bromo-13,13-dimethyl-13H-chromeno[3,2-b]xanth-5-ylium perchlorates. The latter compounds show strong fluorescence in 530-630 nm region with 0.48-0.98 quantum efficiency. Under similar conditions the dimedone and 2-acetyldimedone afford with 2-hydroxyarylaldehydes tris-condensation products: 2,10-dimethoxy-6-(3-methoxy-6-oxo-2,4-cyclohexadienylidenemethyl)-7,7-dimethyl-7H-chromeno[2,3-a]-xanth-13-ylium perchlorate and 2,10-dimethoxy-6-(6-methoxychromylium-2-yl)-13,13-dimethyl-13H-chromeno[3,2-b]xanth-5-ylium diperchlorate respectively.     

Condensed derivatives of benzazoles. 1. Synthesis of 6- and 5-substituted benzimidazo[2,1-b]quinazolin-12-ones

6(5)H-Benzimidazo[2,1-b]quinazolin-12-one was obtained in high yield by condensation of benzimidazole-2-sulfonic acid with anthranilic acid. Methods for the introduction of substituents selectively into the 5 and 6 positions of this heterocycle were developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1673–1677, December, 1987.     

Condensation of 2-aminobenzimidazoles with o-substituted benzoyl chlorides

Translated from Khimiya Geterotsiklicheksikh Soedinenii, No. 2, pp. 272–273, February, 1989.