Réactivité du nucléophile azoture vis-à-vis de cations hétérocycliques aromatiques. VIII. Réarrangement de β-tétrazolo-trans-benzalacétophénones

Abstract

β-Tetrazolyl-trans-benzalacetophenones (T) isomerize upon heating into the corresponding azido-azomethines (A). These non-isolable products undergo various transformations depending on the reaction conditions. With organic bases such as triphenylphosphine or pyridine, their interception can occur. In aromatic solvents, a rearrangement involving loss of nitrogen leads to five-membered diazoted heterocycles:-N-benzoyl imidazoles and pyrazoles, via intermediate diazirines and oxazepines. Protic solvents have been found to facilitate the isomerisation of tetrazoles into azidoazomethines. Solvolysis of the azidooxazine and in some cases of the oxazinium species resulting from the equilibrium and reaction:[Formula: see text]are then observed.