19155-86-3Relevant articles and documents
A Common, Facile and Eco-Friendly Method for the Reduction of Nitroarenes, Selective Reduction of Poly-Nitroarenes and Deoxygenation of N-Oxide Containing Heteroarenes Using Elemental Sulfur
Cerecetto, Hugo,Romero, Angel H.
supporting information, (2020/03/23)
A transition metal-free, environment-friendly and practical protocol was developed either for the reduction of nitroarenes or for the deoxygenation of N-oxide containing heteroarenes. The reaction proceeded with the use of a non-toxic and cheap feedstock as elemental sulfur in aqueous methanol under relatively mild conditions. Green chemistry credentials were widely favorable compared to traditional and industrial protocols with good E-factors and a low production of waste. The strategy allowed the efficient reduction of a large variety of substituted-nitroarenes including various o-nitroanilines as well as selective reduction of various poly-nitroarenes in excellent yields with a broad substrate scope. The protocol was successfully extended to the deoxygenation of some N-oxide containing heteroarenes, like benzofuroxans, phenazine N,N'-dioxides, pyridine N-oxides, 2H-indazole N1-oxides, quinoxaline N1,N4-dioxides and benzo[d]imidazole N1,N3-dioxides. A gram-scale example for the synthesis of luminol, in green conditions, was reported. A solid mechanism of reaction was proposed from experimental evidences.
Cu-Catalyzed π-Core Evolution of Benzoxadiazoles with Diaryliodonium Salts for Regioselective Synthesis of Phenazine Scaffolds
Sheng, Jinyu,He, Ru,Xue, Jie,Wu, Chao,Qiao, Juan,Chen, Chao
, p. 4458 - 4461 (2018/08/09)
The Cu-catalyzed regioselective synthesis of phenazine N-oxides was realized from benzoxadiazoles and diaryliodonium salts. The process was initiated by the electrophilic arylation of benzoxadiazoles with diaryliodonium salts and followed by benzocyclization reactions. The further reduction of N-oxides in situ to phenazine scaffolds and deviation to organic fluorescent materials were readily accomplished.
Molybdenum-Catalyzed Deoxygenation of Heteroaromatic N-Oxides and Hydroxides using Pinacol as Reducing Agent
Rubio-Presa, Rubén,Fernández-Rodríguez, Manuel A.,Pedrosa, María R.,Arnáiz, Francisco J.,Sanz, Roberto
supporting information, p. 1752 - 1757 (2017/05/22)
A molybdenum-catalyzed deoxygenation of pyridine N-oxides and N-hydroxybenzotriazoles, as well as other azole N-oxides, has been developed using pinacol as an environmentally friendly oxo-acceptor. The only by-products are acetone and water making the process a convenient alternative to established protocols in terms of waste generation. The reaction is highly chemoselective and a variety of functional groups are tolerated. The processes are usually very clean allowing the isolation of the pure deoxygenated products after a simple extraction in most cases. (Figure presented.).
σ-Adduct formation and oxidative substitution in the reactions of 4-nitrobenzofurazan and some derivatives with hydroxide ions in water
Crampton, Michael R.,Lunn, Rachel E.A.,Lucas, David
, p. 3438 - 3443 (2007/10/03)
The reactions of hydroxide ions with 4-nitrobenzofurazan, 1a, 4-nitrobenzofuroxan, 1b, and with three 4-nitro-7-substituted benzofurazans have been examined using 1H NMR and UV-visible spectroscopies. In each case initial reaction is at the 5-position to give an anionic σ-adduct. Kinetic and equilibrium results are reported. NMR spectra show that in the case of la oxidation of the anionic adduct yields 4-nitro-5-hydroxybenzofurazan. In the case of 1b rearrangement of the 5-hydroxy adduct to the thermodynamically more stable 7-hydroxy adduct, possibly by a Boulton-Katritzky mechanism, precedes oxidation. When the 7-substituent in the 4-nitrobenzofurazan is Cl, OMe or OPh the eventual product is 7-hydroxy-4-nitrobenzofurazan produced by nucleophilic displacement of the substituent.
Vergleichende Untersuchungen zur Arylaminierung von Benzofuroxan-Derivaten
Goehrmann, B.,Niclas, H.-J.
, p. 1054 - 1060 (2007/10/02)
The amination of benzofuroxan 2a and monosubstituted benzofuroxans 2b-e with alkali metal salts of formanilides 1 and sodium acetanilides 6 is described.Thus, the reaction of 2a with 6a-d gives the benzotriazole 1-oxides 3a-d.The benzofuroxans 2b and 2c react with sodium formanilides to give the isomeric mixtures 3f/3g and 3h/3i.Potassium 4-nitroformanilide reduces 2a furnishing benzofurazan 7.Nitrosubstituted benzofuroxans such as 2d and 2e undergo a carbocyclic amination leading to the benzofurazans 8 and 9.
