Effect of Microwave Irradiation on the Condensation of 6-Substituted 3-Formylchromones with Some Five-membered Heterocyclic Compounds

• Main Authors: Nada Pronayova, Tibor Liptay, Dusan Loos, Renata Gasparova, Margita Lacova
• Format: Article
• Language: English
• Published: MDPI AG 2000-02-01
• Series: Molecules
• Subjects: Creatinine; thiohydantoin; rhodanine; carbamoic acids; guanidine derivatives; Diels - Alder reaction; IR; 1H NMR; 13C NMR
• Online Access: http://www.mdpi.com/1420-3049/5/2/167/
• ISSN: 1420-3049

Different types of 3-substituted 4H-4-oxobenzopyrans were prepared by microwave irradiation as well as by a classical method. The beneficial effect of microwave irradiation on the aldol condensation of 3-formylchromones with 2-imino-1-methylimidazolidine-4-one (creatinine), 2-thioxoimidazolidine-4-one (thiohydantoin) and 2-ethyl-2-thioxothiazolidin-4-one (3-ethylrhodanine) in different reaction media is described. Our results show that the effect of microwave irradiation on the reactions studied was a shortening of the reaction times and a smooth increase in the yields. The subsequent reactions of the product with some nucleophiles are discussed. The structure of the products was proven by elemental analysis, IR and NMR spectra.