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 **

Abstract

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.