78414-72-9Relevant academic research and scientific papers
Photoinduced molecular rearrangements. The photochemistry of some 1,2,4-oxadiazoles in the presence of nitrogen nucleophiles. Formation of 1,2,4-triazoles, indazoles, and benzimidazoles
Buscemi, Silvestre,Vivona, Nicolo,Caronna, Tullio
, p. 8397 - 8401 (2007/10/03)
The photochemistry of some 3,5-disubstituted 1,2,4-oxadiazoles in the presence of nitrogen nucleophiles [external, such as added amines or hydrazines, or internal, such as an o-aminophenyl moiety at C(3) of the oxadiazole ring] has been investigated. In the irradiation of 5-amino-(or 5-N-substituted amino) 3-phenyl-1,2,4-oxadiazoles in the presence of aliphatic primary amines (or ammonia), photolytic species arising from heterolytic cleavage of the ring O-N bond capture the nucleophilic reagent to give open-chain intermediates, which develop into 1,2,4-triazolin-5-ones. Similarly, irradiations of 3,5-diphenyl-, 3-methoxy-5-phenyl-, and 5-methyl-3-phenyl-1,2,4-oxadiazoles gave 1,2,4-triazoles. In the same context, irradiations of representative substrates in the presence of hydrazines have been also investigated. In the irradiation of 3-(o-aminophenyl)-5-methyl-, 3-[o-(methylamino)phenyl]-5-methyl-, and 3-(o-aminophenyl)-5-phenyl-1,2,4-oxadiazoles, concomitant formation of indazoles and benzimidazoles, presumably arising from a common photolytic species, has been observed. Some mechanistic aspects have been considered, and possible applications in synthesis have been pointed out.
Thermal Behaviour of 3-Phenyl-1,2,4-oxadiazol-5-ylhydrazines
Adembri, Giorgio,Camparini, Alfredo,Ponticelli, Fabio,Tedeschi, Piero
, p. 1703 - 1706 (2007/10/02)
Depending on the substitution on the hydrazine moiety, thermolysis of 3-phenyl-1,2,4-oxadiazol-5-ylhydrazines (1)-(5) gives variable amounts of 1-amino-Δ2-1,2,4-triazolin-5-ones (13) or (17), Δ2- or Δ3-1,2,4-triazolin-5-ones (12), (18), or (19), and the s-triazine (20).A possible mechanism accounting for the products and the effects is discussed.A diradical intermediate and a hydrogen transfer from the reaction medium are suggested on the basis of the effect of benzoyl peroxide on the reaction and on the behaviour of the hydrazines (1)-(4) towards catalytic hydrogenation.
