The CuI- or Ag₂CO₃-catalyzed [3+2] cycloaddition of propargyl-substituted dihydroisoindolin-1-one (3) with arylnitrile oxides 1a–d (Ar = Ph, p-MeC₆H₄, p-MeOC₆H₄, p-ClC₆H₄) produces in good yields novel 3,5-disubstituted isoxazoles 4 of the ethyl-2-benzyl-3-oxo-1-((3-arylisoxazol-5yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylate type. With aryl azides 2a–d (Ar = Ph, p-MeC₆H₄, p-OMeC₆H₄, p-ClC₆H₄), a series of 1,4-disubstituted 1,2,3-triazoles 6 (ethyl-2-benzyl-3-oxo-1-((1-aryl-1H-1,2,3-triazol-4-yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylates) was obtained. The reactions proceed in a regioselective manner affording exclusively racemic adducts 4 and 6. Compared to the uncatalyzed cycloaddition, the yields are significantly improved in the presence of CuI as catalyst, without alteration of the selectivity. The regio- and stereochemistry of the cycloadducts has been corroborated by an X-ray diffraction study of 4a, and in the case of 6a by XH-correlation and HMBC spectra.

Novel 1,2,3-triazolo-linked-1,5-benzodiazepinones were designed and synthesized via a Cu(I)-catalyzed 1,3-dipolar alkyne-azide coupling reaction (CuAAC). The chemical structures of these compounds were confirmed by ¹H NMR, ¹³C NMR, HMBC, HRMS, and elemental analysis. The compounds were screened for their in vitro antibacterial and antifungal activities. Several compounds exhibited good to moderate activities compared to those of established standard drugs. Furthermore, the binding interactions of these active analogs were confirmed through molecular docking.

1,5-Benzodiazepin-2-one is a significant class of heterocyclic compounds that have attracted considerable attention due to these versatile scaffolds and their multifunctional properties. Owing to the presence of a fused benzene–diazepine core, these compounds display rich chemical reactivity and various physicochemical characteristics, making them valuable structures in both fundamental and applied research. This review provides a comprehensive and critical overview of the advances reported to date on 1,5-benzodiazepin-2-ones, with particular emphasis on their diverse synthetic methodologies, reaction mechanisms, and structure–property relationships. Classical and modern synthetic approaches are discussed, including condensation reactions, multicomponent processes, catalytic and green chemistry approaches, as well as recent developments toward more sustainable and efficient protocols. The intrinsic reactivity of the 1,5-benzodiazepin-2-one framework enables access to structurally diverse derivatives. Furthermore, the review summarizes the broad range of applications of these heterocycles, especially in medicinal chemistry, where they have demonstrated significant biological activities, as well as in corrosion inhibition and photoluminescent materials. Finally, current challenges, limitations, and future perspectives are outlined to provide guidance for further research and development of 1,5-benzodiazepin-2-one-based systems.