- A practical synthesis of substituted benzo[c]cinnoline- N,N′-dioxides and N-oxides
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A practical synthesis of variously substituted benzo[c]cinnoline-N,N′-dioxides and N-oxides is described, based on the reduction of the appropriate o,o′-dinitrobiphenyl compound with KOH in refluxing 2-propanol.
- Paradisi, Cristina,Gonzalez-Trueba, Guadalupe,Scorrano, Gianfranco
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- Chemoselective electrochemical reduction of nitroarenes with gaseous ammonia
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Valuable aromatic nitrogen compounds can be synthesized by reduction of nitroarenes. Herein, we report electrochemical reduction of nitroarenes by a protocol that uses inert graphite felt as electrodes and ammonia as a reductant. Depending on the cell voltage and the solvent, the protocol can be used to obtain aromatic azoxy, azo, and hydrazo compounds, as well as aniline derivatives with high chemoselectivities. The protocol can be readily scaled up to >10 g with no decrease in yield, demonstrating its potential synthetic utility. A stepwise cathodic reduction pathway was proposed to account for the generations of products in turn.
- Chang, Liu,Li, Jin,Wu, Na,Cheng, Xu
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supporting information
p. 2468 - 2472
(2021/04/02)
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- NOVEL PREPARATION METHOD OF QUINOLINE N-OXIDE DERIVATIVE WITH AMIDE GROUP
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Provided are a preparation method of a quinoline N-oxide derivative with an amide group capable of easily introducing the amide group into the quinoline N-oxide derivative by simplified processes and mild reaction conditions, and a quinoline N-oxide derivative with an amide group prepared by using the same.
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Paragraph 168-170
(2015/11/09)
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- Regioselective introduction of heteroatoms at the C-8 position of quinoline N-oxides: Remote C-H activation using N-oxide as a stepping stone
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Reported herein is the metal-catalyzed regioselective C-H functionalization of quinoline N-oxides at the 8-position: direct iodination and amidation were developed using rhodium and iridium catalytic systems, respectively. Mechanistic study of the amidation revealed that the unique regioselectivity is achieved through the smooth formation of N-oxide-chelated iridacycle and that an acid additive plays a key role in the rate-determining protodemetalation step. While this approach of remote C-H activation using N-oxide as a directing group could readily be applied to a wide range of heterocyclic substrates under mild conditions with high functional group tolerance, an efficient synthesis of zinquin ester (a fluorescent zinc indicator) was demonstrated.
- Hwang, Heejun,Kim, Jinwoo,Jeong, Jisu,Chang, Sukbok
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supporting information
p. 10770 - 10776
(2014/08/18)
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- Transition-Metal-Free Cross-Coupling Reactions by Single Electron Transfer (SET)
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A facile, efficient, single-step protocol for the synthesis of cinnoline derivatives by a transition-metal-free coupling between amino- and nitroaryl compounds by single electron transfer (SET) has been developed. Direct carbon-carbon bond formation was achieved from nonfunctionalized aromatic carbon atoms. A plausible mechanism has been proposed.
- Sythana, Suresh Kumar,Unni, Santhosh,Kshirsagar, Yogesh M.,Bhagat, Pundlik R.
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p. 311 - 314
(2015/10/05)
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- Transition-metal-free cross-coupling reactions by single electron transfer (SET)
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A facile, efficient, single-step protocol for the synthesis of cinnoline derivatives by a transition-metal-free coupling between amino- and nitroaryl compounds by single electron transfer (SET) has been developed. Direct carbon-carbon bond formation was achieved from nonfunctionalized aromatic carbon atoms. A plausible mechanism has been proposed. Direct carbon-carbon bond formation between nonfunctionalized carbon atoms (C-H) in the presence of KOtBu for the synthesis of cinnoline derivatives was achieved. Copyright
- Sythana, Suresh Kumar,Unni, Santhosh,Kshirsagar, Yogesh M.,Bhagat, Pundlik R.
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p. 311 - 314
(2014/01/23)
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- 1,2-Eliminations in a novel reductive coupling of nitroarenes to give azoxy arenes by sodium bis(trimethylsilyl)amide
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(Chemical Equation Presented) Symmetric azoxy arenes were successfully prepared in one step from 2 equiv of the corresponding nitroarenes by use of sodium bis-(trimethylsilyl)amide as the deoxygenating agents in THF at 150°C in a sealed tube.
- Jih, Ru Hwu,Das, Asish R.,Chia, Wei Yang,Huang, Jiann-Jyh,Hsu, Ming-Hua
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p. 3211 - 3214
(2007/10/03)
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- Investigations of a novel process to the framework of benzo[c]cinnoline
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A novel synthetic process leading to the framework of benzo[c]cinnoline has been discovered and investigated. The process is composed of two separate reactions, the first of which is a partial reduction of the nitro groups of the 2,2′-dinitrobiphenyl, a process that we believe proceeds via a SET mechanism to yield the hydroxyamino and nitroso groups. In the following step the cyclization takes place under formation of the -N=N- bond. We believe that this process take place via a radical mechanism through the nitroso radical anion. The novel process affords either benzo[c]cinnoline or benzo[c]cinnoline N-oxide, both in high yields, 93% and 91%, respectively. To obtain benzo[c]cinnoline, the reaction is conducted with an alcohol as solvent and an alkoxide as the base, while for benzo[c]cinnoline N-oxide, water is used as solvent with sodium hydroxide as the base. To establish the latter procedure, statistical experimental design and multivariate modeling were utilized to reveal the response surface for the reaction and to determine the optimal conditions for the reaction. A proposal for the complex reaction mechanism is given. During the corroboration of the mechanism, a new deoxygenation reaction for converting benzo[c]cinnoline N-oxide into benzo[c]cinnoline was discovered. The reaction is conducted by treating the N-oxide with sodium ethoxide at elevated temperature to achieve near-quantitative conversion into benzo[c]cinnoline in a yield of 96%.
- Bjorsvik, Hans-Rene,Gonzalez, Raquel Rodriguez,Liguori, Lucia
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p. 7720 - 7727
(2007/10/03)
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- The newborn surface of dull metals in organic synthesis. Bismuth-mediated solvent-free one-step conversion of nitroarenes to azoxy- and azoarenes
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When milled together with bismuth shots, nitroarenes are readily converted to azoxy- and/or azoarenes depending on substrates and conditions employed. Simple extraction with organic solvent followed by evaporation of the resulting dark pasty solid gave the product in good yield.
- Wada, Shinobu,Urano, Mika,Suzuki, Hitomi
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p. 8254 - 8257
(2007/10/03)
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- Bi-KOH. An efficient reagent for the coupling of nitroarenes to azo and azoxy compounds
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A simple and inexpensive procedure for the coupling of nitroarenes to azoxy compounds with bismuth and potassium hydroxide in methanol at ambient temperature is achieved. When carried out under microwave irradiation it gives exclusively azo compounds in excellent yields.
- Laskar, Dhrubojyoti Dey,Prajapati, Dipak,Sandhu, Jagir S.
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- Anti-androgenic activity of substituted azo- and azoxy-benzene derivatives.
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Substituted phenylazo and phenylazoxy compounds were systematically prepared and their anti-androgenic activity was measured in terms of (1) the growth-inhibiting effect on an androgen-dependent cell line, SC-3, and (2) the binding affinity to nuclear androgen receptor. Generally, azo/azoxy compounds showed cell toxicity, and the growth-inhibiting effects on SC-3 cells correlated with the toxicity. However, some compounds, including 4,4'-dinitroazobenzene (25), 4,4'-dimethoxyazobenzene (33), and 2,2'-dichloroazoxybenzene (47), possessed potent anti-androgenic activity without apparent cell toxicity.
- Takahashi,Ishioka,Koiso,Sodeoka,Hashimoto
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p. 1387 - 1390
(2007/10/03)
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- Thermal- and photo-induced transformations of N-aryl-N-nitroso-hydroxylamine ammonium salts to azoxy compounds
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Heating of an ethanolic solution containing N-aryl-N-nitrosohydroxylamine ammonium salts at 78°C produced the desired azoxy compounds in 80-93% yields. Furthermore, irradiation with UV light (κ ≤300 nm) of ethanolic solutions of those ammonium salts at room temperature also provided the desired azoxy compounds in 51-72% yields.
- Hwu, Jih Ru,Yau, Chii Shyang,Tsay, Shwu-Chen,Ho, Tong-Ing
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p. 9001 - 9004
(2007/10/03)
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- Cadmium chloride-zinc catalysed selective reduction of nitro aromatics to azoxy compounds
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Treatment of aromatic nitro compounds with cadmium chloride-metallic zinc combination systems has been shown to display a good reaction selectivity in the formation of symmetrical azoxy compounds in high yields.
- Baruah, Bipul,Boruah, Anima,Prajapati, Dipak,Sandhu, Jagir S.
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p. 351 - 352
(2007/10/03)
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- Bismuth(III) Chloride-Zinc Promoted Selective Reduction of Aromatic Nitro Compounds to Azoxy Compounds
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In the presence of bismuth(III)chloride-metalllic zinc aromatic nitro compounds have been found to be selectively reduced inter and intramolecularly to the corresponding N-oxides at ambient temperature in high yields.
- Borah, Harsha N.,Prajapati, Dipak,Sandhu, Jagir S.,Ghosh, Anil C.
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p. 3167 - 3170
(2007/10/02)
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- Reduction of Nitroarenes Using an Activated Catalyst Prepared by the Reduction of Nickel Nitrate with Excess Zinc in the Presence of Hydrazine Monohydrate
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An activated catalyst prepared from a mixture of nickel nitrate hexahydrate with zinc in dry ethanol under reflux showed exceptional catalytic activity for the reduction of nitroarenes to the corresponding azoxy compounds exclusively in the presence of hydrazine monohydrate.However when nickel nitrate hexahydrate was replaced by nickel chloride dihydrate with zinc, only the aminoarenes were formed in high yields.With unactivated catalyst, the reduction reaction from a mixture of nitroarenes, nickel nitrate or chloride, excess zinc and hydrazine monohydrate gave the corresponding azo, azoxy and amino compounds in much lower yields.
- Yun, Tae Ho,Park, Moon Keu,Han, Byung Hee
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p. 2774 - 2788
(2007/10/02)
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- Metathesis and reduction reactions of nitroso compounds with metal carbenes and metal carbonyls
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Reaction of nitroso compounds with metal-carbene complexes and metal carbonyls has been investigated.These reactions lead to reduction of the nitroso compounds, primarily to the corresponding azo- and azoxy compounds.Metal-nitrene complexes have been proposed as intermediates in these reactions.These intermediates couple rapidly with the unreacted nitroso compound, or enter into nitrene-like reactions with external or internal trapping agents.Reaction of metal carbonyls with nitrosoarenes and photolysis has been found to be an effective method for the reduction of nitrosoarenes to azoxyarenes, with few problems resulting from overreduction to amines or azo compounds.
- Herndon, James W.,McMullen, Leonard A.
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- Heterocyclic mesomeric betaines. Part 2. Synthesis of a hetero derivative of the benzo[b]phenalenide anion
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Reductive cyclization of 2,4-dimethyl-8-(2-nitrophenyl)quinoline with hot triethyl phosphite afforded 2,4-dimethyl-7H-pyrido[3,2-c]carbazole (10) and 4,6-dimethyl-6aλ5,7-diazabenz[de]anthracen-6a-ium-7-ide (4; R = Me). The latter is the first example of a conjugated heterocyclic mesomeric betaine isoconjugate with the benzo[b]phenalenide anion.
- Ollis, W. David,Stanforth, Stephen P.,Ramsden, Christopher A.
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p. 953 - 956
(2007/10/02)
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- Observations on the Reduction of Aryl Nitro Groups with Palladium-Sodium Borohydride
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The reduction of aryl nitro groups by the palladium-sodium borohydride system can be controlled in some instances to give products differing from those of catalytic hydrogenation.With six equivalents of borohydride added to the catalyst 2,2'-dinitrobiphenyl formed only 2,2'-diaminobiphenyl.With added sodium hydroxide and varying amounts of borohydride and catalyst, the reduction can be controlled to give benzocinnoline, benzocinnoline 5-oxide or benzocinnoline 5,6-dioxide.In a closed system, the reagents reduce both the nitro and olefin functional groups in 6-nitro-5,8-dimethoxy-1,4-dihydro-1,4-ethanonaphtalene.In an open flask flushed with argon, the reduction is confirmed to the nitro group.Reduction of 2-chloro and 4-chloronitrobenzene with palladium-borohydride gives substantial yields of the appropriate chloroanilines.In contrast, hydrogen and palladium give aniline as the major product from each of these.These results suggest that the addition of sodium borohydride to palladium on carbon produces a reductive entity differing from that of catalytic hydrogenation.
- Smith, William B.
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p. 745 - 748
(2007/10/02)
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- 1,3-Dipolar Cycloadditions, 86. Aromatic Azoxy Compounds and Strained Cycloalkenes
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4,4'-Dicyano- and 4,4'-dinitroazoxybenzene as well as benzocinnoline N-oxide combine with (E)-cyclooctene or (1E,5Z)-1,5-cyclooctadiene to give bicyclic 1,2,3-oxadiazolidines which undergo in situ 1,3-dipolar cycloreversion with opening of both rings.Azomethine imines are formed which are connected by a hexamethylene chain with an aldehyde function.These new 1,3-dipoles add to a second molecule of the strained cycloalkene and furnish derivatives of cyclooctapyrazole as 1:2 adducts in high yields.A 1,4 H-shift of the intermediate azomethine imine competes at low concentration of the (E)-cyclooctene and produces an 8-hydrazino-7-octenal as a 1:1 product.
- Huisgen, Rolf,Gambra, Francisco Palacios
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p. 2242 - 2255
(2007/10/02)
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