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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In the present study a series of novel benzoxazepine (5a-h) derivatives were synthesized by the thermal cyclization reaction of various pyrazole-chalcones (3a-h) with 2-aminophenol, by conventional heating and microwave irradiation (180 W) in solvent-free conditions in short reaction times (9-12 min), giving high yields of products (80-88%). The homogeneity of all the newly synthesized compounds has been checked by TLC. Their IR, NMR, ESI-mass spectral data and elemental analysis are in accord with the assigned structure. The title compounds were evaluated for their antibacterial activity against Gram-positive bacteria Staphylococcus aureus, Bacillus subtilis, and Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli. Compounds 3c, 3h, 5b, 5c, 5g and 5h were found to show good antibacterial activity when compared with that of standard drug Ampicillin. Furthermore, the same library of compounds were evaluated for antifungal activity against Aspergillus nigerzeae, Penicillium italicum and Fusarium oxysporum using Grieseofulvin as standard drug. The results of the above studies show that the compounds 3b, 3c, 3e, 3h, 5a, 5c, 5g and 5h showed good antifungal activity against all the tested organisms.

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.