A facile synthesis of pyrano[2,3‐d:6,5‐d′]dipyrimidines via microwave‐assisted multicomponent reactions catalyzed by β‐cyclodextrin

A facile three‐component reaction of aromatic aldehyde, 2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione, and 6‐amino‐1,3‐dimethyluracil was developed for the first time using β‐cyclodextrin (β‐CD) as a macrocyclic host for aldehyde and an efficient catalyst that leads to a batch of novel pyrano[2,3‐ d :6,5‐ d ′]dipyrimidines ( 4a‐k ). The synthesis was accomplished with the aid of microwave irradiations in solvent‐free conditions. The product obtained was in contrast to the previous report in which a similar reaction resulted in a mixture of benzylidenepyrimidine and bisaminopyrimidine analogs in the presence of triethylbenzylammonium chloride in an aqueous medium. The formation of the pyrano[2,3‐ d :6,5‐ d ′]dipyrimidines may be in virtue of the property of β‐CD to construct new CC and CX (where X = heteroatom) bonds. Reusability of the catalyst up to three runs without any noteworthy change in catalytic activity is one of the main features of the reaction. Other noteworthy features are good to excellent yields, eco‐friendly procedure, non‐column chromatographic purification, and mild conditions.