- Adenine supported hydroxyl-bridged dicopper core as a catalytically competent unit for phenol oxidation
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This communication describes crystallographic investigation of a dicopper complex of modified adenine nucleobase containing a Cu2O2 core. This arrangement is remarkably similar to active sites present in some copper-containing redox enzymes. Interestingly, this complex is also competent in catalyzing redox reactions, suggesting the possibility of catalytically competent primitive metal-nucleobase systems.
- Mishra, Ashutosh Kumar,Prajapati, Rajneesh Kumar,Verma, Sandeep
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- An umpolung strategy for rapid access to thermally activated delayed fluorescence (TADF) materials based on phenazine
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Herein, Ag(I)-promoted regioselective intramolecular radical nucleophilic addition/rearrangement of 2-aryl diazaboroles has been accomplished for the first time to construct phenazine structures. This protocol is an umpolung strategy based on the classical electrophilic mechanism, and therefore, a reversed regioselectivity was observed, which provides an opportunity to prepare sterically hindered phenazines. The resulting thermally activated delayed fluorescence (TADF) materials based on phenazine exhibit emission bands from green to red with high quantum yields and moderate fluorescence lifetimes as solid films.
- Cheng, Hu,Guo, Qiang,Lan, Jingbo,Ran, Chunhao,Wu, Di,Zhang, Huaxing
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supporting information
p. 1581 - 1584
(2022/02/10)
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- Direct synthesis of novel quinoxaline derivativesviapalladium-catalyzed reductive annulation of catechols and nitroarylamines
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Here, a palladium-catalyzed new hydrogenative annulation reaction of catechols and nitroarylamines, allowing straightforward access to two classes of novel quinoxaline derivatives, is reported. The reaction proceeds with operational simplicity, an easily available catalyst system, and a broad substrate scope, and without the need for pre-functionalization, which offers the potential for further design of new reductive transformations of renewable resources into value-added products.
- Xie, Feng,Li, Yibiao,Chen, Xiuwen,Chen, Lu,Zhu, Zhongzhi,Li, Bin,Huang, Yubing,Zhang, Kun,Zhang, Min
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supporting information
p. 5997 - 6000
(2020/06/04)
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- Rhodium-Catalyzed Reaction of Azobenzenes and Nitrosoarenes toward Phenazines
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A rhodium-catalyzed annulative reaction between azobenzenes and nitrosoarenes has been developed, leading to a series of phenazines in moderate to good yields. This procedure proceeds with sequential chelation-assisted addition of aryl C-H to nitrosoarenes and ring closure by electrophilic attack of azo group to aryl. During this transformation, the azo group served as not only a traceless directing group but also a building block in the final products.
- Xiao, Yan,Wu, Xiaopeng,Wang, Hepan,Sun, Song,Yu, Jin-Tao,Cheng, Jiang
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p. 2565 - 2568
(2019/04/30)
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- Reactivity and substituent effects in the cyclization of N-aryl-2-nitrosoanilines to phenazines
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Reactivity of variously substituted N-aryl-2-nitrosoanilines in the reaction of cyclization leading to phenazine derivatives, carried out in the presence of N,O-bis(trimethylsilyl)acetamide (BSA), was estimated on the base of the observed reaction times. A strong opposite effect of substituents located at position para to the nitroso group and those located para to the amino group in the side ring was observed. Mechanistic explanation, based on the electronic properties of the substituents and their mesomeric effects, was presented. The usefulness of the obtained data for the designed syntheses of phenazines was exposed.
- Wróbel, Zbigniew,Plichta, Karolina,Kwast, Andrzej
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p. 3147 - 3152
(2017/05/08)
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- Transition-metal-free tandem oxidative removal of benzylic methylene group by C-C and C-N bond cleavage followed by intramolecular new aryl C-N bond formation under radical conditions
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A novel tandem oxidative conversion of 10,11-dihydro-5H-dibenzo[b,e][1,4]diazepines to phenazines has been achieved under transition-metal-free, mild conditions using K2S2O8 or DDQ as the oxidizing agent. The transformation proceeds through oxidative removal of a benzylic methylene group by C-C and C-N bond cleavage followed by a new aryl C-N bond formation under radical conditions.
- Laha, Joydev K.,Tummalapalli, K. S. Satyanarayana,Gupta, Ankur
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supporting information
p. 4392 - 4395
(2015/01/08)
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- Palladium-catalyzed domino double n-arylations (inter- and intramolecular) of 1,2-diamino(hetero)arenes with o,o-dihalo(hetero)arenes for the synthesis of phenazines and pyridoquinoxalines
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Domino reactions for the synthesis of phenazines have been developed that start from 1,2-diaminoarenes and 1,2-dihaloarenes and proceed through palladium-catalyzed double N-arylations (inter- and intramolecular) followed by an in situ oxidation. A variety of functional groups, which include base-sensitive groups, were well tolerated under the optimized reaction conditions to afford phenazines in good to excellent yields. The protocol was extended to the synthesis of pyridoquinoxalines by employing either o-phenylenediamines and 2,3-dihalopyridines or 1,2-diaminopyridines and 1,2-dihaloarenes. Domino reactions for the synthesis of phenazines have been developed that start from 1,2-diaminoarenes and 1,2-dihaloarenes and proceed through palladium-catalyzed double N-arylations (inter- and intramolecular) followed by an in situ oxidation. The protocol was extended to the synthesis of pyridoquinoxalines. Copyright
- Laha, Joydev K.,Tummalapalli, K.S. Satyanarayana,Gupta, Ankur
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p. 8330 - 8335
(2014/01/06)
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- N-Aryl-2-nitrosoanilines as intermediates in the synthesis of substituted phenazines from nitroarenes
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N-Aryl-2-nitrosoanilines, available from the reaction of nitroarenes with anilide anions, undergo cycliza-tion to furnish substituted phenazines. The reaction is promoted by potassium carbonate in methanol, N,O-bis(trimethylsilyl) acetamide (BSA) in aprotic solvents, and by acetic acid. The method is illustrated by the synthesis of 1-methoxyphenazine, a precursor of pyocyanine, starting from the appropriate nitro-arene-aniline pairs.
- Kwast, Andrzej,Stachowska, Karolina,Trawczyński, Adam,Wróbel, Zbigniew
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p. 6484 - 6488
(2011/12/16)
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- Potential chemopreventive agents based on the structure of the lead compound 2-bromo-1-hydroxyphenazine, isolated from streptomyces species, strain CNS284
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The isolation of 2-bromo-1-hydroxyphenazine from a marine Streptomyces species, strain CNS284, and its activity against NF-κB, suggested that a short and flexible route for the synthesis of this metabolite and a variety of phenazine analogues should be developed. Numerous phenazines were subsequently prepared and evaluated as inducers of quinone reductase 1 (QR1) and inhibitors of quinone reductase 2 (QR2), NF-κB, and inducible nitric oxide synthase (iNOS). Several of the active phenazine derivatives displayed IC50 values vs QR1 induction and QR2 inhibition in the nanomolar range, suggesting that they may find utility as cancer chemopreventive agents.
- Conda-Sheridan, Martin,Marler, Laura,Park, Eun-Jung,Kondratyuk, Tamara P.,Jermihov, Katherine,Mesecar, Andrew D.,Pezzuto, John M.,Asolkar, Ratnakar N.,Fenical, William,Cushman, Mark
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experimental part
p. 8688 - 8699
(2011/02/28)
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- Efficient methods for the synthesis of 2-hydroxyphenazine based on the Pd-catalyzed N-arylation of aryl bromides
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(Chemical Equation Presented) Substituted diphenylamines can be synthesized by Pd(0)-catalyzed N-arylation using o-nitroanilines and nitro-substituted aryl bromides for a substrate. Cyclization of the diphenylamines by various methods, including the intramolecular Pd(0)-catalyzed N-arylation, produces 2-methoxyphenazine which can easily be deprotected to give 2-hydroxyphenazine. This phenazine is required to synthesize methanophenazine, a novel redoxactive cofactor isolated from methanogenic archaea.
- Tietze, Mario,Iglesias, Alberto,Merisor, Elena,Conrad, Juergen,Klaiber, Iris,Beifuss, Uwe
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p. 1549 - 1552
(2007/10/03)
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- The Photo-Deoxygenation Of Heterocyclic N-Oxides
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2-Methoxy and 2-nitrophenazine 10-oxide are deoxygenated by irradiation in the presence of triethylamine, 2,3-dimethyl-2-butene and triethylphosphite via electron transfer to the singlet excited state, as shown by the comparison of reaction quantum yield and fluorescence quenching. 1,4-Dimethoxybenzene quenches the singlet, but causes no deoxygenation.The same mechanism operates in the photoreduction of benzocinnoline 5-oxide, but it is too slow to compete efficiently with the rearrangement in the case of quinoline 1-oxide.The photo-deoxygenation of the borontrifluoride ground state complexes of these substrate is in every case unefficient.
- Fasani, Elisa,Amer, Atef M.,Albini, Angelo
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p. 985 - 992
(2007/10/02)
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- Synthesis of Substituted Phenazines from Benzofurazanoxid and Hydroquinones
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The sterical course of the formation of substituted phenazines from benzofurazanoxid and hydroquinone derivatives was investigated.The additional functional group of the hydroquinone determines the substitution pattern and the product ratio of the phenazines formed. - Key words: Phenazine, Synthese, Hydrochinone
- Roemer, A.,Sammet, M.
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p. 866 - 872
(2007/10/02)
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