Aims and Objective: In the current study, environmentally benign and cost-effective
procedures were suggested for the preparation of carboxy group functionalized imidazolium salts,
- or [Cmmim]Br- as a new, reusable Brønsted acidic ionic liquid (BAIL)
catalyst. Then, the catalytic performance of [Cmmim]BF4
- or [Cmmim]Br- were successfully
inspected towards the three-components onepot preparation of pyrano[2,3-d]pyrimidinone
derivatives 4a-4q. The mentioned procedures show short reaction times, easy work-up procedure,
green conditions, high yields of the products, high potent of recovering, and reusing capability. The
current study is useful and adequate for the application and development of imidazolium salts on
the basis of green chemistry principles.
Materials and Methods: An aromatic aldehyde (1 mmol), barbituric acid (1 mmol), and
malononitrile (1 mmol) were placed in a round-bottomed flask containing ethanol (5 mL). BAILs
A and B (0.1 mmol, 10 mol%) were added to the mixture. The suspension was magnetically stirred
at room temperature for an appropriate time (Table 2). After completion of the reaction, which was
monitored by TLC (n-hexane:ethyl acetate = 3:1), the pure product was filtered off to separate the
catalyst, washed with water, and recrystallized from ethanol to afford the pure compound. After
separation of the product, the catalyst was recovered by evaporation of water, washed with Et2O,
dried under vacuum for 2 h, and reused for the same reaction.
Results: The mentioned procedure shows short reaction times, easy work-up procedure, green
conditions, high yields of the products, and high potent of recovering and reusing capability.
Conclusion: In this study, we unveiled the synthesis of a new acetic acid functionalized ionic
- BAIL A or [Cmmim]Br- BAIL B and their application for the preparation of
pyrano[2,3-d]pyrimidinone derivatives via a three-component reaction among various aromatic
aldehydes, barbituric acid, and malononitrile under mild and metal-free conditions. A wide range
of pyrano[2,3-d]pyrimidinone derivatives bearing diverse functional groups was obtained in short
reaction and excellent yields. Operational simplicity, recoverability, and reusability of catalysts,
cheap and chemically stable reagents, high catalytic activity, easy work-up, and the eco-friendly
procedure, make this method environmentally benign and cost-effective.