Heterocyclic photorearrangements. Some investigations of the photochemical behaviour of 3-acylamino-1,2,4-oxadiazoles. Synthesis of the quinazolin-4-one system
- 1 January 1991
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 2,p. 187-189
- https://doi.org/10.1039/p29910000187
Abstract
Some mechanistic investigations on the photochemical behaviour of 1,2,4-oxadiazoles are reported. Irradiation of 3-benzoylamino-5-methyl-1,2,4-oxadiazole at λ= 254 nm in methanol involves excitation of the benzoylamino group chromophore to a triplet state species and induces a 6π electrocyclic closure to a tricyclic intermediate. On the other hand, irradiation of 3-acetylamino-5-phenyl-1,2,4-oxadiazole at λ= 254 nm involves excitation of a 5-phenyl-substituted oxadiazole chromophore which leads to the photolysis of the ring O–N bond in a singlet state species. Furthermore, irradiation of some selected 5-phenyl substituted oxadiazoles in the presence of a triplet sensitizer produces an excited triplet state species which collapses in a ring closure reaction involving the C5-phenyl moiety.Keywords
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