M. Lacova et al., Effect of microwave irradiation on the condensation of 6-substituted 3-formylchromones with some five-membered heterocyclic compounds, MOLECULES, 5(2), 2000, pp. 167-178
Different types of 3-substituted 4H-4-oxobenzopyrans were prepared by micro
wave 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-o
ne (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 reaction
s of the product with some nucleophiles are discussed. The structure of the
products was proven by elemental analysis, IR and NMR spectra.