- Nickel/Photoredox-Catalyzed Methylation of (Hetero)aryl Chlorides Using Trimethyl Orthoformate as a Methyl Radical Source
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Methylation of organohalides represents a valuable transformation, but typically requires harsh reaction conditions or reagents. We report a radical approach for the methylation of (hetero)aryl chlorides using nickel/photoredox catalysis wherein trimethyl orthoformate, a common laboratory solvent, serves as a methyl source. This method permits methylation of (hetero)aryl chlorides and acyl chlorides at an early and late stage with broad functional group compatibility. Mechanistic investigations indicate that trimethyl orthoformate serves as a source of methyl radical via β-scission from a tertiary radical generated upon chlorine-mediated hydrogen atom transfer.
- Kariofillis, Stavros K.,Shields, Benjamin J.,Tekle-Smith, Makeda A.,Zacuto, Michael J.,Doyle, Abigail G.
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supporting information
p. 7683 - 7689
(2020/04/22)
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- Homogeneous Nickel-Catalyzed Sustainable Synthesis of Quinoline and Quinoxaline under Aerobic Conditions
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Dehydrogenative coupling-based reactions have emerged as an efficient route toward the synthesis of a plethora of heterocyclic rings. Herein, we report an efficacious, nickel-catalyzed synthesis of two important heterocycles such as quinoline and quinoxaline. The catalyst is molecularly defined, is phosphine-free, and can operate at a mild reaction temperature of 80 °C. Both the heterocycles can be easily assembled via double dehydrogenative coupling, starting from 2-aminobenzyl alcohol/1-phenylethanol and diamine/diol, respectively, in a shorter span of reaction time. This environmentally benign synthetic protocol employing an inexpensive catalyst can rival many other transition-metal systems that have been developed for the fabrication of two putative heterocycles. Mechanistically, the dehydrogenation of secondary alcohol follows clean pseudo-first-order kinetics and exhibits a sizable kinetic isotope effect. Intriguingly, this catalyst provides an example of storing the trapped hydrogen in the ligand backbone, avoiding metal-hydride formation. Easy regeneration of the oxidized form of the catalyst under aerobic/O2 oxidation makes this protocol eco-friendly and easy to handle.
- Bains, Amreen K.,Singh, Vikramjeet,Adhikari, Debashis
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p. 14971 - 14979
(2020/11/30)
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- Nature of the Nucleophilic Oxygenation Reagent Is Key to Acid-Free Gold-Catalyzed Conversion of Terminal and Internal Alkynes to 1,2-Dicarbonyls
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2,3-Dichloropyridine N-oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.
- Dubovtsev, Alexey Yu.,Shcherbakov, Nikolay V.,Dar'in, Dmitry V.,Kukushkin, Vadim Yu.
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p. 745 - 757
(2020/02/04)
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- Potassium tert-Butoxide-Promoted Acceptorless Dehydrogenation of N-Heterocycles
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Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of six- and five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas. (Figure presented.).
- Liu, Tingting,Wu, Kaikai,Wang, Liandi,Yu, Zhengkun
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supporting information
p. 3958 - 3964
(2019/08/01)
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- Iron-catalyzed Minisci acylation of N-heteroarenes with α-keto acids
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An efficient and mild protocol has been developed for the Minisci acylation reactions of nitrogen-containing heteroarenes with α-keto acids. Distinct from the conventional Minisci acylation conditions, the chemistry was performed using non-noble metal Fe(II), instead of expensive Ag(I) salt, as catalyst. A wide range of substrates, including aliphatic or aromatic α-keto acids, as well as various N-heteroarenes, proved to be compatible with the protocol. Scale-up experiment also demonstrates the practicality of the approach.
- Wang, Xiu-Zhi,Zeng, Cheng-Chu
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supporting information
p. 1425 - 1430
(2019/02/01)
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- Rapid, efficient and eco-friendly procedure for the synthesis of quinoxalines under solvent-free conditions using sulfated polyborate as a recyclable catalyst
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An efficient and inexpensive sulfated polyborate catalyst was applied for the rapid synthesis of quinoxaline derivatives from various substituted o-phenylenediamines and 1,2-diketones/α-hydroxy ketones using sulfated polyborate is described. The catalyst has the advantage of Lewis as well as Bronsted acidity and recyclability without significant loss in catalytic activity. The key advantages of the present method are high yields, short reaction times, solvent-free condition, easy workup, and ability to tolerate a variety of functional groups, which give economical as well as ecological rewards. [Figure not available: see fulltext.]
- Indalkar, Krishna S,Khatri, Chetan K,Chaturbhuj, Ganesh U
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p. 141 - 148
(2017/02/23)
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- Ruthenium(II) η6-arene complexes containing a dinucleating ligand based on 1,8-naphthyridine
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Ruthenium arene complexes, [(η6-p-cymene)2Ru2(L)Cl2](PF6)2 [3b, L = 2, 7-bis(di-2-pyridinyl)-1,8-naphthyridine] and [(η6-p-cymene)Ru(L′)Cl](PF6) [4, L′ = tri(2-pyridinyl)amine], were synthesized and characterized by spectroscopic and analytical techniques. The molecular structure of [(η6-p-cymene)2Ru2(L)Cl2]Cl2 (3a) was further determined by single-crystal X-ray analysis. The use of these ruthenium complexes as pre-catalysts for oxidative coupling of 1,2-diols/1,2-aminoalcohol with o-phenylenediamines leading to quinoxalines was investigated. Complex 3b appeared to be a good catalyst for this transformation.
- Tang, Wei-Hung,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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- Acceptorless dehydrogenation of nitrogen heterocycles with a versatile iridium catalyst
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Gas up: A cyclometalated iridium complex is found to catalyze the dehydrogenation of various benzofused N-heterocycles, thus releasing H 2. Driven by as low as 0.1 mol % catalyst, the reaction affords quinolines, indoles, quinoxalines, isoquinolines, and β-carbolines in high yields. Copyright
- Wu, Jianjun,Talwar, Dinesh,Johnston, Steven,Yan, Ming,Xiao, Jianliang
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supporting information
p. 6983 - 6987
(2013/07/26)
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- A green synthesis of quinoxalines and 2,3-dihydropyrazines
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Quinoxaline and dihydropyrazine derivatives were obtained in high yields by simple addition of 1,2-diamines and 1,2-dicarbonyl compounds in water. In some cases, the products spontaneously precipitated from the reaction mixture, making it possible to recover and reuse the mother liquor for further condensations. The very mild reaction conditions, the high yields of the products, and the absence of any catalyst make this methodology an efficient and green route to quinoxalines and dihydropyrazines. Georg Thieme Verlag Stuttgart New York.
- Delpivo, Camilla,Micheletti, Gabriele,Boga, Carla
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p. 1546 - 1552
(2013/06/27)
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- Biomass into chemicals: One-pot two- and three-step synthesis of quinoxalines from biomass-derived glycols and 1,2-dinitrobenzene derivatives using supported gold nanoparticles as catalysts
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An efficient and selective one-pot two-step method, for the synthesis of quinoxalines by oxidative coupling of vicinal diols with 1,2-phenylenediamine derivatives, has been developed by using gold nanoparticles supported on nanoparticulated ceria (Au/CeO2) or hydrotalcite (Au/HT) as catalysts and air as oxidant, in the absence of any homogeneous base. Reaction kinetics shows that the reaction controlling step is the oxidation of the diol to α-hydroxycarbonyl compound. Furthermore, a one-pot three-step synthesis of 2-methylquinoxaline starting from 1,2-dinitrobenzene and 1,2-propanediol has been successfully carried out with 98% conversion and 83% global yield to the final product.
- Climent,Corma,Hernandez,Hungria,Iborra,Martinez-Silvestre
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experimental part
p. 118 - 129
(2012/10/08)
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- Polystyrene-supported AlCl3 as a highly active and reusable heterogeneous lewis acid catalyst for the one-pot synthesis of quinoxalines
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A new and environmentally benign protocol for the synthesis of quinoxaline derivatives through the condensation reactions of 1,2-diketones and 1,2-phenylenediamines using cross-linked polystyrene-supported aluminum chloride (PS/AlCl3) as a highly active and reusable heterogeneous Lewis acid catalyst is described. This polymeric catalyst is stable and can be easily recovered and reused without appreciable change in its efficiency. Copyright
- Rahmatpour, Ali
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p. 472 - 477
(2012/10/29)
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- Synthesis of libraries of quinoxalines through eco-friendly tandem oxidation-condensation or condensation reactions
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A facile and expeditious solid-phase synthesis of libraries of quinoxalines promoted on KF-alumina surface via tandem oxidation-condensation or condensation reactions is reported. The reaction protocol is operationally simple and mild. Moreover, solvent-free reaction condition makes the reaction procedure eco-friendly and economically viable.
- Paul, Susmita,Basu, Basudeb
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experimental part
p. 6597 - 6602
(2012/01/03)
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- Nano-TiO2: An eco-friendly alternative for the synthesis of quinoxalines
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Nano-TiO2 as an eco-friendly and efficient nanocatalyst was applied for quinoxaline preparation with improved yield. In this protocol, diketones and 1,2-diamines were condensed in the presence of catalyst at room temperature.
- Mirjalili, Bi Bi Fatemeh,Akbari, Ali
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experimental part
p. 753 - 756
(2012/01/05)
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- Ag-TiO2/clay composite photocatalyst for the oxidation-cyclization of 1,2-diamine compounds with propylene glycol or alcohols
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Silver-loaded TiO2 (Ag-TiO2) and acidic clay (K10 montmorillonite) composite photocatalyst has been successfully applied for the light-induced conversion of o-phenylenediamine (OPD) and its derivatives to substituted benzimidazoles with various alcohols in acetonitrile using UV-A and solar light. The influence of the various photocatalysts, solvents, and substituents on the yield and selectivity of the products has been investigated. The mechanism of photocatalysis is proposed. Loading silver on TiO2 enhances product yield and selectivity both in UV and solar light. In the presence of primary alcohols, 2-aminothiophenol forms only disulfide and hence Ag-TiO2/ clay can be used as a green catalyst for the synthesis of disulfides.
- Selvam, Kaliyamoorthy,Annadhasan, Mari,Velmurugan, Rengasamy,Swaminathan, Meenakshisundaram
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experimental part
p. 831 - 837
(2010/09/06)
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- Furazan ring opening upon treatment of benzofurazan with ethanolamine to yield quinoxalines
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Heating of benzofurazans with ethanolamine in the presence of catalytic amount of p-toluenesulfonic acid leads to quinoxalines.
- Samsonov
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experimental part
p. 2510 - 2512
(2009/02/05)
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- NOVEL CHEMICAL COMPOUNDS
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This invention relates to newly identified compounds for inhibiting hYAK3 proteins and methods for treating diseases associated with hYAK3 activity.
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Page/Page column 112
(2008/06/13)
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- (5Z)-5-(6-QUINOXALINYLMETHYLIDENE)-2-[(2,4,6-TRICHLOROPHENYL)AMINO]-1,3-THIAZOL-4(5H)-ONE
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Invented is the compound (5Z)-5-(6-quinoxalinylmethylidene)-2-[(2,4,6-trichlorophenyl)amino]-1 ,3-thiazol-4(5H)-one, and pharmaceutically acceptable salts, hydrates, solvates and pro-drugs thereof. Also invented are pharmaceutical compositions containg this compound, methods of preparing this compound and pharmaceutically acceptable salts, hydrates, solvates and pro-drugs thereof. Also invented are methods of using this compound as an inhibitor of hYAK3 proteins.
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Page/Page column 7
(2008/06/13)
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- Benzooxazole and benzothiazole antagonists of gonadotropin releasing hormone receptor
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The present invention relates to Gonadotropin Releasing Hormone (GnRH, also known as Luteinizing Hormone Releasing Hormone) receptor antagonists.
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Page/Page column 37
(2008/06/13)
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- Piperazinylimidazopyridine and piperazinyltriazolopyridine antagonists of gonadotropin releasing hormone receptor
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The present invention relates to Gonadotropin Releasing Hormone (GnRH, also known as Luteinizing Hormone Releasing Hormone) receptor antagonists.
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Page/Page column 39
(2008/06/13)
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- Processes for preparing gonadotropin releasing hormone receptor antagonists
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The present invention relates to methods of making Gonadotropin Releasing Hormone (“GnRH”) (also known as Leutinizing Hormone Releasing Hormone) receptor antagonists.
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Page/Page column 17-18
(2008/06/13)
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- Elemental fluorine. Part 10.1 Selective fluorination of pyridine, quinoline and quinoxaline derivatives with fluorine-iodine mixtures
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Selective fluorination of a range of pyridine and quinoline substrates to give corresponding 2-fluoro-derivatives can be readily achieved in high yield at room temperature using elemental fluorine-iodine mixtures. Reaction of fluorine with iodine forms, in situ, systems that function like sources of both iodonium and fluoride ions and fluorination of heterocyclic derivatives is suggested to proceed by fluoride ion attack on intermediate W-iodo-heterocyclic species. Quinoxaline derivatives react under similar conditions to give either the 2-fluoro- or 2,3-difluoro-quinoxaline derivatives depending on the ratio of fluorine passed through the solution. In related processes, pyridine can be alkoxylated upon reaction of an appropriate alcohol and fluorine.
- Chambers, Richard D.,Parsons, Mandy,Sandford, Graham,Skinner, Christopher J.,Atherton, Malcolm J.,Moilliet, John S.
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p. 803 - 810
(2007/10/03)
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- Photoinduced Nitro-Nitrite Rearrangement of 5-Nitroquinoxalines
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Unlike known o-nitro methyl derivatives of aromatic compounds, 6-methyl-5-nitro-, 2,3,6-trimethyl-5-nitro-, and 7-methyl-6-nitroquinoxaline and 1,6-dimethyl-5-nitroquinoxalinium perchlorate do not exhibit photochromism in aqueous-ethanolic solutions under conditions of flash photolysis with a time resolution of 50 μs. Under conditions of continuous photolysis, these 5-nitromethylquinoxaline derivatives and also 5-nitroquinoxaline undergo nitro-nitrite rearrangement to give 5-quinoxalinol derivatives with quantum yields ranging from 1 × 10-4 to 3 × 10-3; the efficiency of the photochemical reaction increases when irradiation is performed with a shorter-wave light. 6-Nitro derivatives do not form stable products of photochemical transformations under the same conditions.
- El'tsov,Selitrenikov,Rtishchev
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p. 285 - 294
(2007/10/03)
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- The Thermolysis of Polyazapentadienes. Part 2. Formation of Quinoxalines from 5-Aryl-1-phenyl-1,2,5-triazapentadienes
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Thermolysis in the gas phase of 5-(p-substituted phenyl)-1-phenyl-1,2,5-triazapentadienes at 600 deg C and 10-2 Torr gives 6-substituted quinoxalines.The yield is ca. 30 percent, and is independent of the electronic nature of the substituent.The corresponding 5-(o-substituted) derivatives give 5-substituted quinoxalines, though the yield is lower, and quinoxaline itself is a major contaminant, due to ipso attack and ejection of the substituent. 5-(m-Substituted) derivatives give mixtures of 5- and 6-substituted quinoxalines on pyrolysis.The 5-isomer is dominant for compounds with m-alkyl substituents, while the 6-isomer is the major product for those with electron-withdrawing or electron-donating m-substituents.
- McNab, Hamish
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p. 1941 - 1946
(2007/10/02)
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- 13C Nuclear Magnetic Resonance Spectra of Quinoxaline Derivatives
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The 13C n.m.r. spectra of a series of 5-, 6-, and 2-substituted quinoxalines have been analysed by consideration of their 1H coupled spectra.Typical values of the coupling constants are: C(2,3), 1JCH 181.9, 2JCH 11.4, C(5,8), 1JCH 162.6, 3JCH 6.5, C(6.7), 1JCH 159.4, 3JCH 9.1; C(9), 3JCH(2) = 3JCH(7) = 10.0, 3JCH(5) 5.4; C(10), 3JCH(3) = 3JCH(6) = 10.0, 3JCH(8) 5.4 Hz.The magnitudes of the coupling constants in the benzenoid ring are similar to these for the corresponding positions in naphthalene, but application of naphthalene chemical shift substitutions effects leads in some cases to the wrong peak sequence in the related quinoxalines.Within the quinoxaline series itself, however, acceptable additivity of substituent effects is found (+/- 0.8 p.p.m.), provided that the reference compounds are carefully chosen.Analysis of mixtures of quinoxalines from substituted o-phenylenediamines and α-oxo-aldehydes is possible by consideration of the multiplicity of the ring-junction quaternary carbon signals in the fully coupled spectra.
- McNab, Hamish
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p. 357 - 364
(2007/10/02)
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- The Thermolysis of Polyazapentadienes. Part 1. 1,5-Diaryl-1,2,5-triaza-derivatives
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Flash vacuum pyrolysis of the title compounds at 600 deg C gives quinoxalines and arylamines, together with small quantities of nitriles, diarylamines, azobenzenes, and formamidines.The mechanism involves homolytic cleavage of the N-N bond to generate a conjugated iminyl radical, which can either cyclise to a quinoxaline, or fragment to simpler radicals which lead to the minor products by coupling reactions.
- McNab, Hamish
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p. 2200 - 2204
(2007/10/02)
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