An Expedient Method for the Synthesis of 1,2,4‐Triazolo‐fused 1,5‐Benzodiazepine, 1,5‐Benzoxazepine, and 1,5‐Benzothiazepine Scaffolds: A Novel Seven‐membered Ring System of Biological Interest

New heterocyclic compounds 1‐(3‐methyl‐9 H ‐dibenzo[ b , f ][1,2,4]triazolo[4,3‐ d ][1,4]diazepin‐6‐yl)ethanone 8a , 1‐(3‐methyldibenzo[ b , f ][1,2,4]triazolo[4,3‐ d ][1,4]oxazepin‐6‐yl)ethanone 8b , and 1‐(3‐methyldibenzo[ b , f ][1,2,4]triazolo[4,3‐ d ][1,4]thiazepin‐6‐yl)ethanone 8c are synthesized from benzodiazepinone, benzoxazepinone, and benzothiazepinone derivatives. These heterocyclic scaffolds have wide medicinal importance. Best results were obtained in antibacterial screening against Escherichia coli , Enterobacter cloacae , and Staphylococcus aureus and antifungal screening against Candida albicans and Fusarium oxysporum . 1,1‐Diphenyl‐2‐picrylhydrazyl radical scavenging activities of compounds 6c , 7c , and 8c were tested in doses 10, 20, 30, 40, and 50 μg/mL and were expressed as IC 50 values and percent of inhibition with means ± standard deviation of three different concentrations of synthesized compounds. The assignment of the structures of synthesized compounds was made by thin‐layer chromatography, elemental analysis, IR, 1 H‐NMR, 13 C‐NMR, and liquid chromatography–mass spectrometry.