Tayebeh S. Mokhtari, Mohammad A. Amrollahi*, Enayatollah Sheikhhosseini, Hassan Sheibani and Shahla S. Nezhad Pages 54 - 59 ( 6 )
Background: A variety of methods have been reported for the synthesis of pyrano[2,3- d]pyrimidines in the literature. Many of these methods are associated with some limitations and generally need expensive or non-available reagents, prolonged reaction times and high temperatures. Thus, the introduction of new methods and /or further work on technical improvements to overcome these limitations is still needed. Pyrano[2,3-d]pyrimidines were prepared by condensation reaction of aldehyde, malononitrile and barbituric acid or 2-thiobarbituric acid by a new efficient procedure and antibacterial activity of selected products was evaluated.
Methods: A mixture of barbituric acid or thiobarbituric acid (2 mmol) aldehyde (2 mmol), and malononitrile (2 mmol)) in the presence of poly (4-vinylpyridine) (0.10 g) was refluxed in H2O:EtOH H2O:EtOH under normal and ultrasonic irradiation conditions for appropriate time. After cooling, the resulting precipitate was filtered, and the crude product was purified by recrystalization from EtOH:H2O to obtain a pure product. Antibacterial activity of products was evaluated using Staphylococcus aureus, Bacillus cereus, Pseudomonasn aeruginosa, and Escherichia coli bacteria strains.
Results: 2,4-Dioxo-1H-pyrano[2,3-d]pyrimidine and 4-oxo-2-thioxo-1H-pyrano[2,3-d]pyrimidine derivatives were synthesized under the optimized conditions. In all cases, the reactions proceeded efficiently at reflux temperature in H2O:EtOH to afford the corresponding products. All the products were characterized by mp. IR, 1H- and 13C-NMR spectra. Antibacterial activity of selected synthesized pyrano[2,3- d]pyrimidines was tested against gram-positive and gram-negative bacteria strains. The verification of antibacterial screening data revealed that the selected compounds have bactericidal properties against Staphylococcus aureus, Bacillus cereus, Pseudomonasn aeruginosa, and Escherichia coli bacteria strains.
Conclusion: We have developed an efficient procedure for the synthesis of pyrano[2,3-d]pyrimidine derivatives via three-component condensation of aromatic aldehydes, malononitrile and barbituric acid or thiobarbituric acid in two different reaction conditions in the presence of catalytic amount of a cheap and readily available catalyst poly (4-vinylpiridine). The bacterial activity study revealed that two compounds showed moderate to good antibacterial activities.
Antibacterial active, biologically active, poly(4-vinylpyridine), pyrano[2, 3-d]pyrimidine, three-component reaction, ultrasonic irradiation.
Department of Chemistry, Yazd University, Yazd, Department of Chemistry, Yazd University, Yazd, Department of Chemistry, Kerman Branch, Islamic Azad University, Kerman, Department of Chemistry, Kerman Shahid Bahonar University, Kerman, Department of Biology, Islamic Azad University, Jiroft Branch, Jiroft