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.