This review focuses on the progress of the use of hypervalent iodine reagents in the search for a general and efficient methodology for the synthesis of a series of benzo- and heterocycle-fused 1,4-diazepine derivatives. The key cyclization step embraces the formation of a N-acylnitrenium intermediate, mediated by the hypervalent iodine reagent PIFA, and its succeeding intramolecular trapping by the (hetero)aromatic ring. Therefore, the presented general approach solves the need of starting from not very accessible amino (or a related functionality) aromatic starting materials, and its effectiveness is also demonstrated in the synthesis of the antitumor antibiotic DC-81.