Title:The Photochemical Isomerisation of Hexatomic Heterocyclic Compounds
Volume: 25
Issue: 14
Author(s): Maurizio D'Auria*
Affiliation:
- Dipartimento di Scienze, Universita della Basilicata, V.le dell’Ateneo Lucano 10, 85100 Potenza,Italy
Keywords:
Pyridine, quinoline, isoquinoline, pyrazine, pyridazine, pyrimidine.
Abstract: The photochemical isomerisation of hexatomic heterocyclic compounds has been
discussed. The attention was focused on the mono- and dinitrogen hexatomic heterocycles. To
justify the photochemical isomerisation of pyridines, Dewar isomers, azaprismane, and azaprefulvene
derivatives have been proposed. The photoisomerisation of pyridinium salts requires a
ring reduction with the formation of arizines. Pyridinium ylides gave photoisomerisation reaction
through the formation of the corresponding azirines, while pyridinium N-oxide was required
to react for the formation of the corresponding oxaziridines. The photochemical isomerisation
of pyrazine derivatives, Dewar isomers, diazaprismane, and benzvalene intermediates
has been proposed to justify the observed reactivity. Finally, in the case of pyridazine and
pyrimidine derivatives, Dewar isomers were used to explain the obtained reaction products. In
the discussion of the results, the presence of different mechanistic hypotheses has been evidenced.