The ring closure and rearrangement of N-2-aminobenzoyl -N-methylhydrazones of β-dicarbonyl compounds

Conformational Complexity in Seven-Membered Cyclic Triazepinone/Open Hydrazones. 1. 1D and 2D Variable Temperature NMR Study

“…Many of the early benzotriazepinone structures were reassigned later as quinazolinones, imidazolines, oxadiazoles, and other structures, i.e. the reactions of β-aminocarbohydrazides with oxo reagents can result in hydrazone, pyrimidinone, or triazepinone derivatives, depending on the substituents and the conditions employed …”

“…The first example of the formation of a seven-membered ring from an o -amino-substituted aromatic hydrazide was the reaction of anthranilic acid N , N ‘-dimethylhydrazide with carbonyl compounds 5a…”

“…Factors such as N -substitution, ring-closure, possibility of conjugation, and steric hindrance have been found to govern the equilibria 5c. Thus, it is evident that, like other seven-membered benzoheterocyclic compounds, the substituted benzotriazepines are extremely complex and rather flexible systems.…”