16322-19-3Relevant articles and documents
The N-alkylation of 4-nitrobenzochalcogenadiazoles: Synthesis and theoretical approach
Salah, Saida B.,Zaier, Rania,Ayachi, Sahbi,Goumont, Régis,Boubaker, Taoufik
, p. 80 - 86 (2019/07/18)
A facile synthetic method for N-alkylated substituted benzochalcogenadiazoles is described. When treated with Meerwein salt, the 4-nitrobenzochalcogenadiazoles have undergone an N-alkylation to afford the expected salts as a mixture of two N1/N3 isomers in toluene. The regioselectivity of the alkylation reaction was then confirmed by spectroscopic data as well as theoretical calculations.
Porphyrins with exocyclic rings. Part 20: Synthesis and spectroscopic characterization of porphyrins with fused 2,1,3-benzoxadiazole and 2,1,3-benzoselenadiazole moieties
Cillo, Catherine M.,Lash, Timothy D.
, p. 11615 - 11627 (2007/10/03)
Porphyrins with fused 2,1,3-benzoxadiazole and 2,1,3-benzoselenadiazole units were prepared by the '3+1' MacDonald-type methodology. 4-Nitro-2,1,3-benzoxadiazole, 6-chloro-4-nitro-2,1,3-benzoxadiazole and 4-nitro-2,1,3-benzoselenadiazole condensed with isocyanoacetates in the presence of the non-nucleophilic base DBU to give tricyclic pyrrole derivatives in excellent yields. Further cleavage of the ester moieties and decarboxylation afforded α-unsubstituted pyrroles and these were further condensed with 2 equiv of an acetoxymethylpyrrole tert-butyl ester to give crude preparations of tripyrranes. The tert-butyl ester protective groups were cleaved with TFA and following dilution with dichloromethane, '3+1' condensation with a pyrrole dialdehyde, and oxidation with ferric chloride, the heterocyclic ring fused porphyrins were obtained in moderate yields. The yields were lower than expected because of difficulties in preparing required tripyrranes due to the reduced reactivity of the pyrrolic intermediates. The UV-vis spectra of these new porphyrin systems were highly modified showing broadened split Soret bands. In addition, the nickel(II), copper(II) and zinc complexes gave unusual UV-vis spectra with weakened split Soret bands and strong Q-type absorptions above 600 nm. These modified structures show some potential for applications as photosensitizers in photodynamic therapy.
Kinetic and equilibrium studies of the reactions of 4-nitrobenzo-furazan and some derivatives with sulfite ions in water. Evidence for the Boulton-Katritzky rearrangement in a σ-adduct
Crampton, Michael R.,Pearce, Lyndsey M.,Rabbitt, Lynsey C.
, p. 257 - 261 (2007/10/03)
The reactions with sulfite ions in water of 4-nitrobenzofurazan, 1, 4-nitrobenzofuroxan, 2, and three 4-nitro-7-substituted benzofurazans have been examined by 1H NMR spectroscopy and stopped-flow spectrophotometry. For each substrate the initial reaction occurs at the 5-position to give σ-adducts which have considerably higher thermodynamic stability than the corresponding adduct of 1,3,5-trinitrobenzene. In the cases of 1 and 2 isomerisation of the 5-adducts occurs slowly to yield adducts carrying sulfite at the 7-position. 1H NMR measurements on 2 labelled with 15N provide evidence that here the rearrangement involves an intramolecular Boulton-Katritzky mechanism.
