Application of a new dicationic ionic liquid catalyst in the efficient synthesis of 4H-pyran and pyrano[2,3‐d]pyrimidinone derivatives

4H-pyrans and pyrano[2,3‐d] pyrimidinones are two important classes of heterocyclic compounds which constitute the structural unit of many natural products. The simplest and the most straightforward protocol for the preparation of 4H-pyrans and pyrano[2,3‐d] pyrimidinones is based on the acceleration of three‐component reaction of aromatic aldehydes, malononitrile, dimedone or barbituric acid in the presence of different types of catalysts. Although the introduced catalysts and procedures are effective, they have some disadvantages. Herein we wish to report an efficient and green procedure for the preparation of 4H- pyrans [1] and pyrano[2,3- d]pyrimidinones [2] via a domino Knoevenagel-cyclocondensation reaction using a nowel dicationic ionic liquid catalyst as a highly efficient, general and homogeneous catalyst, in a mixture of EtOH/water as a solvent. The promising reasons for the presented protocol are efficiency, generality, high yields of the products, short reaction times, cleaner reaction profile, simplicity, low cost and recyclability of the catalyst.