- Chemoselective one-pot access to benzo[e]indole-4,5-diones and naphtho[2,1-b]thiophene-4,5-diones via copper-catalyzed oxidative [3 + 2] annulation of α-oxoketene N,S-acetals/β-ketothioamides with α-/β-naphthols
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An operationally simple and efficient one-pot method for the synthesis of 1-aroyl (or alkanoyl)-2-thioalkyl-3-aryl (or alkyl)-3H-benzo[e]indole-4,5-diones and naphtho[2,1-b]thiophene-4,5-diones has been devised by copper-catalyzed cross-coupling of α-oxoketene N,S-acetals/β-ketothioamides with α-/β-naphthols in open air for the first time. The key to the success of this transformation is the room temperature oxidation of α-/β-naphthol to 1,2-naphthoquinone as a reactive species, which undergoes formal [3 + 2] annulation with α-oxoketene N,S-acetals/β-ketothioamides via cascade sequence of Michael addition/tautomerization/oxidation/cyclization/aromatization reactions, enabling addition of a pyrrole/thiophene ring onto naphthoquinone moiety. Further, benzo[e]indole-4,5-diones were transformed to pentacyclic fused phenazine derivatives under solvent-free conditions. Based on our experimental outcomes, a tentative mechanistic rationale for this chemoselective protocol is proposed, which is well validated and supported by the control experiments.
- Yadav, Dhananjay,Shukla, Gaurav,Ansari, Monish A.,Srivastava, Abhijeet,Singh, Maya Shankar
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p. 5920 - 5931
(2018/08/29)
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- One-pot multistep synthesis of bipolar carbazolo-phenazines: Hydrogen bond control of Diels-Alder cycloaddition and application for fluoride sensing
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Access to novel bipolar carbazolo-phenazines is demonstrated by one-pot IBX-initiated multistep cascade, which involves oxidation of 2-naphthols to 1,2-naphthoquinones, Diels-Alder cycloaddition, aerial dehydroaromatization and cyclocondensation. With unprotected dienic indolylacrylates, N[sbnd]H?O hydrogen bonding in the transition state controls the product selectivity almost exclusively in favor of Diels-Alder cycloaddition over the competing Michael addition. The utility of one of the carbazolo-phenzines as applied to selective naked-eye sensing of fluoride is demonstrated.
- Mishra, Abhaya Kumar,Mukhopadhyay, Arindam,Moorthy, Jarugu Narasimha
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p. 2210 - 2216
(2017/03/24)
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- O-Iodoxybenzoic Acid-Initiated One-Pot Synthesis of 4-Arylthio-1,2-naphthoquinones, 4-Arylthio-1,2-diacetoxynaphthalenes, and 5-Arylthio-/5-Aminobenzo[a]phenazines
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1,2-Naphthoquiones and their derivatives constitute an important category of compounds of relevance in pharmaceutical and material chemistry. It is shown that 1,2-naphthoquinones generated by o-iodoxybenzoic acid-mediated oxidation of 2-naphthols can be subjected to a cascade of reactions, namely oxidation, Michael addition, reduction, acetylation, and cyclocondensation, in the same pot to afford diverse 4-arylthio-1,2-naphthoquinones 2, 4-arylthio-1,2-diacetoxynaphthalenes 3, and 5-arylthio-/5-aminobenzo[a]phenazines 4 in very good isolated yields. The multistep single-pot synthesis occurs smoothly in DMF at rt.
- Mishra, Abhaya Kumar,Moorthy, Jarugu Narasimha
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p. 6472 - 6480
(2016/08/16)
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- An efficient synthesis of 5, 6-dimethoxy 1- and 2-naphthols via Teuber reaction
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Based on the oxidation of 1, 5-naphthalenediol (4) and 6-bromo-2-naphthol (9) via Teuber reaction, an efficient synthesis of 5, 6-dimethoxy-1-naphthol (1) and 5, 6-dimethoxy-2-naphthol (2) was achieved with high overall yield (16% for 1 and 25% for 2). The key steps of the synthetic strategy involved the oxidation of naphthols (4 and 9) to the corresponding naphthoquinones (5 and 10) and the conversion of 5, 6-dimethoxy- 2-naphthaldehyde to 5, 6-dimethoxy-2-naphthol formate through Baeyer-Villiger oxidation-rearrangement.
- Cui, Jia-Hua,Li, Shao-Shun
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p. 1163 - 1168
(2013/10/22)
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- Multiple oxo-vanadium schiff base containing cyclotriphosphazene as a robust heterogeneous catalyst for regioselective oxidation of naphthols and phenols to quinones
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Grafting of multiple oxo-vanadium Schiff base moieties to cyclotriphosphazene provided an efficient and recyclable heterogeneous catalyst for the regioselective oxidation of naphthols and phenols to quinones by using tbutylhydroperoxide as oxidant. One of the main advantages of the developed catalyst was the presence of multiple oxovanadium moieties in close proximity which made the developed catalyst more active as compared to its homogeneous oxo-vanadium Schiff base. After the reaction, the catalyst was easily recovered from the reaction mixture by simple filtration and reused for five runs without loss in activity.
- Khatri, Praveen K.,Jain, Suman L.
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p. 1020 - 1025
(2012/10/29)
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- A new class of phenazines with activity against a chloroquine resistant plasmodium falciparum strain and antimicrobial activity
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New phenazines were synthesized by oxygenation of 1- and 2-naphthol with transition metal peroxo complexes and in situ reaction with 1,2-diamines. The title compounds were evaluated for in vitro antimalarial activity against Plasmodium falciparum and chloroquine-resistant strains. Phenazines 12, 27, and 28 were most prominent in growth inhibition. In vivo protection against cerebral malaria was observed with the phenazines 11, 12, 20, and 27, whereas partial protection was provided by 19.
- Hussain, Hidayat,Specht, Sabine,Sarite, Salem R.,Saeftel, Michael,Hoerauf, Achim,Schulz, Barbara,Krohn, Karsten
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supporting information; experimental part
p. 4913 - 4917
(2011/09/15)
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- Indole Derivatives With Antitumor Activity
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3H-Benzo[e]indol-4,5-dione derivatives with antitumor activity, the processes for the preparation thereof and pharmaceutical compositions containing them.
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Page/Page column 4
(2009/04/24)
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- Selective arylation, alkenylation, and cyclization of dibromonaphthols, using visible light, via carbene intermediates
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(Chemical Equation Presented) The photoreactivity of several 3-substituted-1,6-dibromo-2-naphthols has been investigated in neat acetonitrile in the presence of diluted Et3N and in aqueous buffered acetonitrile (pH 8, phosphate buffered), using visible light (450 nm). Hydrobromic acid loss in the presence of the base, for the unsubstituted naphthol, or heterolytic C-Br cleavage directly from the naphtholates, for the more acid 3-substutited naphthols (R = COOCH3, CONH2, CONMe2), generates electrophilic carbene intermediates, which have been successfully trapped by molecular oxygen, pyrrole, acrylonitrile, ethyl vinyl ether, and allyltrimethylsilane. Product distribution analysis reveals three types of products arising from (i) arylation, (ii) alkenylation, and (iii) cyclization reactions. The generation and the reactivity of α-ketocarbene intermediates, as electrophilc diradicals, has been supported by laser flash photolysis, with the detection of both the carbene (λmax 510 nm) and 1,2-naphthoquinone-O-oxide (R = CONMe2, λ max 600 nm) in the presence of O2.
- Verga, Daniela,Doria, Filippo,Mella, Mariella,Freccero, Mauro
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body text
p. 5311 - 5319
(2009/11/30)
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- New compounds with antiglutamatergic properties and uses thereof
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The present invention provides new compounds displaying antiglutamatergic properties. It also provides the use of such compounds for the treatment and/or prophylaxis of conditions and diseases linked to abnormalities in glutamatergic transmission. It further provides a pharmaceutical composition for the treatment and/or prophylaxis of acute and chronic neurodegenerative conditions and disorders.
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Page/Page column 10-11
(2008/12/08)
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- INDOLE DERIVATIVES WITH ANTITUMOR ACTIVITY
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3H-Benzo[e]indol-4,5-dione derivatives with antitumor activity, the processes for the preparation thereof and pharmaceutical compositions containing them.
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Page/Page column 10-11
(2008/06/13)
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- Transition metal catalyzed oxidations; 4. Improved method for the oxidation of 1- and 2-naphthols to 1,2-naphthoquinones
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A specific oxidation of 1- and 2-naphthols to the corresponding 1,2-naphthoquinones can be achieved by slow addition of the preformed complex of the naphthols with titanium tetraisopropylate with a syringe pump to excess tert-butyl hydroperoxide (TBHP). A previously described method gave mainly coupling products from the Michael reaction.
- Krohn,Rieger,Bruggmann
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p. 1141 - 1143
(2007/10/02)
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