Synthesis and Solution Structure of 1H‐Benzo‐1,5‐diazepine Derivatives with a Perfluoroalkyl Side Chain

Abstract

The reaction of perfluorinated 3,5‐dioxoesters with 1,2‐diaminobenzenes or 2,3‐diaminonaphthalenes afforded two types of 1H‐benzo‐1,5‐diazepine derivatives containing a perfluorinated side chain. 2,5‐Dihydro‐1H‐benzo‐1,5‐diazepin‐2‐ones were formed by cyclocondensation via the central keto and the ester group, whereas 1H‐benzo‐1,5‐diazepines resulted from cyclocondensation via the two keto groups. The tautomerism and isomerization of these compounds have been investigated by 1H‐, 13C‐, and 19F‐NMR spectroscopy. The 1,5‐diazepines appear in CDCl3 solution as mixtures of two tautomeric forms, the enaminoimine I and diaminodiene II. In DMSO solution, besides I and II, two further species, III and IV, are formed by (E/Z) isomerization on the exocyclic C=C bond.