- Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
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A uniqueN,O-bidentate ligand 6-oxo-1,6-dihydro-pyridone-2-carboxylic acid dimethylamide (L1) catalyzed direct C(sp2)-H (intra/intermolecular) arylation of unactivated arenes has been developed to expedite access to (Het)biaryl scaffolds under UV-irradiation at room temperature. The protocol tolerated diverse functional groups and substitution patterns, affording the target products in moderate to excellent yields. Mechanistic investigations were also carried out to better understand the reaction pathway. Furthermore, the synthetic applicability of this unified approach has been showcasedviathe construction of biologically relevant 4-quinolone, tricyclic lactam and sultam derivatives.
- Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
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p. 208 - 218
(2021/12/29)
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- Organocatalyst in Direct C(sp2)-H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C-H Bond Activation
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This article describes the identification of 1-(2-hydroxyethyl)-piperazine as a new, cost-effective, highly efficient organocatalyst, which promotes both inter- A nd intra-molecular direct C(sp2)-H arylations of unactivated arenes in the presence of potassium tert-butoxide. While the inter-molecular C-H arylation of unactivated benzenes with aryl halides (Ar-X; X = I, Br, Cl) toward biaryl syntheses underwent smoothly in the presence of only 10 mol percent organocatalyst, the intra-molecular C-H arylation catalytic system composed of 40 mol percent each of the catalyst and the additive (4-dimethylaminopyridine (DMAP)). The novel catalyst was also able to perform both inter- A nd intra-molecular direct arylations simultaneously in a single pot. The mechanistic studies confirmed the involvement of aryl radical anions and proceeded via a single-electron-transfer (SET) mechanism. The large substrate scope, high functional group tolerance, competition experiments, gram-scale synthesis, and kinetic studies further highlight the importance and versatile nature of the methodology as well as the compatibility of the new catalyst. To the best of our knowledge, this is the first report on any organocatalyst that reported detailed investigations of both inter- A nd intra-molecular direct C(sp2)-H arylations of unactivated arenes in a single representation.
- Yadav, Lalit,Tiwari, Mohit K.,Shyamlal, Bharti Rajesh Kumar,Chaudhary, Sandeep
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p. 8121 - 8141
(2020/07/16)
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- Rhodium(I)-Catalyzed Aryl C-H Carboxylation of 2-Arylanilines with CO2
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An unprecedented Rh(I)-catalyzed, amino-group-assisted C-H carboxylation of 2-arylanilines with CO2 under redox-neutral conditions has been developed. This reaction was promoted by a phosphine ligand with t-BuOK as the base and did not require the use of additional strong organometallic reagent. It enabled an efficient direct conversion of a broad range of 2-(hetero)arylanilines including electron-deficient heteroarenes to various phenanthridinones. Possible intermediates of the reaction were also evaluated in the preliminary mechanistic studies.
- Gao, Yuzhen,Cai, Zhihua,Li, Shangda,Li, Gang
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supporting information
p. 3663 - 3669
(2019/05/17)
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- Palladium-catalyzed intramolecular C-H arylation of 2-halo-: N -Boc- N -arylbenzamides for the synthesis of N-H phenanthridinones
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A palladium catalyzed synthesis of N-H phenanthridinones was developed via C-H arylation. The protocol gives phenanthridinones regioselectively by one-pot reaction without deprotection. It exhibits broad substrate scope and affords targets in up to 95% yields. Importantly, it could be applied for the less reactive o-chlorobenzamides.
- Hu, Quan-Fang,Gao, Tian-Tao,Shi, Yao-Jie,Lei, Qian,Yu, Luo-Ting
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p. 13879 - 13890
(2018/04/25)
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- Palladium-Catalyzed C-H Activation and Cyclization of Anilides with 2-Iodoacetates and 2-Iodobenzoates: An Efficient Method toward Oxindoles and Phenanthridones
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A concise approach to the synthesis of oxindoles and phenanthridones from anilides is described. In the presence of catalytic amount of Pd(OAc)2, 2-iodoacetates and 2-iodobenzoates can be used to functionalize ortho C-H bond of anilides, which subsequently undergo intramolecular cyclization to give the products. A possible reaction mechanism that involves a PdII/PdIV catalytic cycle is proposed with the support of detailed mechanistic studies.
- Gandeepan, Parthasarathy,Rajamalli, Pachaiyappan,Cheng, Chien-Hong
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p. 1872 - 1879
(2016/06/15)
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- KOtBu mediated synthesis of phenanthridinones and dibenzoazepinones
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Synthesis of substituted phenanthridinones and dibenzoazepinones has been realized from 2-halo-benzamides in the presence of potassium tert-butoxide and a catalytic amount of 1,10-phenanthroline or AIBN. This new carbon-carbon bond forming reaction gives direct access to various biaryl lactams containing six- and seven-membered rings chemoselectively. Carbon-carbon coupling seems to proceed by the generation of a radical in the amide ring which leads to C-H arylation of aniline.
- Bhakuni, Bhagat Singh,Kumar, Amit,Balkrishna, Shah Jaimin,Sheikh, Javeed Ahmed,Konar, Sanjit,Kumar, Sangit
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supporting information; experimental part
p. 2838 - 2841
(2012/07/28)
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- General method for the synthesis of substituted phenanthridin-6(5H)-ones using a KOH-mediated anionic ring closure as the key step
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Substituted phenanthridin-6(5H)-ones were obtained in a two-step procedure involving a Suzuki cross-coupling reaction followed by a KOH-mediated anionic ring closure. The influence of the nature and the position of the substituents on the cyclization step were studied. This methodology offers a general and practical route to diversely substituted phenanthridin-6(5H)-ones.
- Dubost, Emmanuelle,Magnelli, Rosa,Cailly, Thomas,Legay, Rémi,Fabis, Frédéric,Rault, Sylvain
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experimental part
p. 5008 - 5016
(2010/08/13)
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- Synthesis and biological evaluation of novel 5(H)-phenanthridin-6-ones, 5(H)-phenanthridin-6-one diketo acid, and polycyclic aromatic diketo acid analogs as new HIV-1 integrase inhibitors
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A new series of phenanthridinone derivatives, and diketo acid analogs, as well as related phenanthrene and anthracene diketo acids have been synthesized and evaluated as HIV integrase (IN) inhibitors. Several new β-diketo acid analogs with the phenanthrid
- Patil, Shivaputra,Kamath, Shantaram,Sanchez, Tino,Neamati, Nouri,Schinazi, Raymond F.,Buolamwini, John K.
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p. 1212 - 1228
(2007/10/03)
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- Iron-catalyzed aryl-aryl cross-coupling reaction tolerating amides and unprotected quinolinones
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The iron(III)-catalyzed cross-coupling reaction between functionalized arylcopper reagents and aromatic iodides bearing an amide function or an unprotected quinolinone leads smoothly to polyfunctionalized biphenyls in excellent yields due to an intramolec
- Kofink, Christiane C.,Blank, Benoit,Pagano, Sandro,Goetz, Nadine,Knochel, Paul
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p. 1954 - 1956
(2008/02/07)
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- Photocyclization of Aryl Halides. Part 3. Phenanthridone Photosynthesis from 2-Halogenobenzanilides
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2-Chlorobenzanilides cyclize to phenanthridones in deaereted cyclohexane solution on 254 nm irradiation, whereas 2-bromo- and 2-iodo-benzanilides undergo dehalogenative reduction.These observations are understandable in terms of the assisted homolysis model as applied to configurationally flexible molecules.Cyclization in hydrocarbon media is retarted by triplet quenchers and fails in polar solvents.The cyclization can also be singlet and triplet sensitized. 4'-Substituents influence the cyclization quantum yield by altering the ?-donor ability of the aniline ring and the rotational barrier about the amide bond.
- Grimshaw, James,Silva, A. Prasanna de
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p. 857 - 866
(2007/10/02)
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- Photocyclisation of 2-Halogenobenzanilides: An Extreme Example of Halogen Atom, Solvent, and Isomer Dependence. A Practical Phenanthridine Synthesis
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2-Chlorobenzanilides photocyclise to phenanthridones by assisted homolysis of the carbon-chlorine bond.
- Grimshaw, James,Silva, A. Prasanna de
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p. 302 - 303
(2007/10/02)
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