Abstract The microwave irradiation of a series of 2‐diazo‐1,3‐diketones in the presence of an o ‐phenylenediamine derivative triggered a domino Wolff rearrangement/nucleophilic addition/intramolecular imination sequence to provide a new synthetic entry to 1,3‐dihydr‐2 H ‐1,5‐benzodiazepin‐2‐ones, a class of molecules with important biological properties.