Catalyst-Free Assembly of δ-Lactam-Based Hydrazide–Hydrazone Compounds from 3-Arylglutaconic Anhydrides and Aldazines

A novel general approach to cyclic hydrazide–hydrazone compounds with a dihydropyridine-2-one core has been developed, involving annulation of symmetrical aldazines with 3-arylglutaconic anhydrides. This approach provides the benefits of straightforward and catalyst-free procedures, diastereoselectivity, and the ability to switch between two isomeric dihydropyridine-2-one cores based on the reaction temperature. Several post-modifications were performed on the side functional groups and the core to demonstrate the synthetic potential of the resulting products. This approach significantly expands the chemical diversity of medicinally relevant N-functionalized δ-lactams.