A new series of novel highly substituted imidazole and imidazole bi‐heterocycles have been synthesized via atom economic, one‐pot condensation reaction using benzil, substituted benzaldehydes, various amine scaffolds, and ammonium acetate using ZnO nanoparticles as effective catalyst. Simple operation, cheap catalyst, good to excellent yield, etc, are some of the advantages of this protocol. The characterization of the synthesized imidazole analogues was performed by Fourier transform infrared, nuclear magnetic resonance (1H and 13C), mass analysis, and elemental analysis. The structures were unequivocally confirmed by single‐crystal X‐ray diffraction analysis. Synthesized compounds were tested for antibacterial activities by resazurin reduction assay. All compounds tested showed significant activity against bacteria. Among the 24 compounds tested, compounds 1c, 1i, 2c, 2g, and 3a proved to be more active against the bacterial strain tested.

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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.

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