Photoinduced heterocyclic rearrangements of O–N bond-containing azoles have been claimed in the synthesis of target fluorinated heterocyclic compounds. In this context, the photochemical behavior of some fluorinated 1,2,4-oxadiazoles has been investigated. Irradiations of 3-amino-5-perfluoroalkyl-1,2,4-oxadiazoles at 313 nm in methanol gave open-chain products arising from a reaction of the nucleophilic solvent with either the first formed ring-photolytic species or with a nitrilimine moiety generated from it. Differently, irradiations in methanol with the presence of triethylamine (TEA) followed competing phototransposition pathways leading to the ring-isomers 2-amino-5-perfluoroalkyl-1,3,4-oxadiazoles (major component) and the ring degenerate isomers 5-amino-3-perfluoroalkyl- 1,2,4-oxadiazoles (minor component). On the other hand, 3-amino-5-polyfluorophenyl-1,2,4-oxadiazoles underwent ring-photoisomerization into 1,3,4-oxadiazoles when irradiations were carried out at 254 nm. In turn, the irradiation of the 3-phenyl-5-perfluoroheptyl-1,2,4- oxadiazole at 254 nm in methanol gave the solvolysis product, but no ring-isomerization was observed. Some mechanistic considerations are reported, and some applications in the synthesis of target fluorinated 1,3,4-oxadiazoles are claimed.
|Data di pubblicazione:||2004|
|Titolo:||Fluorinated heterocyclic compounds: an assay on photochemistry of some fluorinated 1-oxa-2-azoles: an expedient route to fluorinated heterocycles|
|Autori:||BUSCEMI S; PACE A; PIBIRI I; VIVONA N; CARONNA T|
|Tipologia:||Articolo su rivista|
|Citazione:||BUSCEMI S, PACE A, PIBIRI I, VIVONA N, & CARONNA T (2004). Fluorinated heterocyclic compounds: an assay on photochemistry of some fluorinated 1-oxa-2-azoles: an expedient route to fluorinated heterocycles. JOURNAL OF FLUORINE CHEMISTRY, 125, 165-173.|
|Digital Object Identifier (DOI):||10.1016/j.jfluchem.2003.07.006|
|Appare nelle tipologie:||01 - Articolo su rivista|