- Electrochemical-Oxidation-Promoted Direct N-ortho-Selective Difluoromethylation of Heterocyclic N-Oxides
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An efficient and green electrochemical N-ortho-selective difluoromethylation method of various quinoline and isoquinoline N-oxides has been developed. In this method, sodium difluoromethanesulfinate (HCF2SO2Na) was used as the source of the difluoromethyl moiety, and various N-ortho-selective difluoromethylation quinoline and isoquinoline N-oxides were obtained in good to excellent yields under a constant current. In addition, the reaction was easy to scale up and maintained a good yield. Preliminary mechanism studies suggested that the reaction undergoes a free-radical addition and hydrogen elimination pathway.
- Zhang, Dong,Cai, Jinlin,Du, Jinze,Wang, Qingdong,Yang, Jinming,Geng, Rongqing,Fang, Zheng,Guo, Kai
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supporting information
p. 1434 - 1438
(2022/03/01)
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- Copper/manganese oxide catalyzed regioselective amination of quinoline N-oxides: An example of synergistic cooperative catalysis
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An atom economical and efficient protocol for C-2 amination of quinoline N-oxides using our synthesized recyclable heterogeneous Cu–MnO catalyst has been reported here. Direct C[sbnd]H aminations of heterocyclic N-oxides with secondary amine were carried out under base, and ligand-free conditions in good to excellent yields. The major advantage is that air is used as a sole oxidant and our catalyst is recycled several times.
- Sahoo, Tapan,Thakur, Dinesh,Panda, Asit Baran,Ghosh, Subhash Chandra
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supporting information
(2021/09/29)
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- Co(III)-Catalyzed C-H Amidation of Nitrogen-Containing Heterocycles with Dioxazolones under Mild Conditions
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A cobalt(III)-catalyzed C-8 selective C-H amidation of quinoline N-oxide using dioxazolone as an amidating reagent under mild conditions is disclosed. The reaction proceeds efficiently with excellent functional group compatibility. The utility of the current method is demonstrated by gram scale synthesis of C-8 amide quinoline N-oxide and by converting this amidated product into functionalized quinolines. Furthermore, the developed catalytic method is also applicable for C-7 amidation of N-pyrimidylindolines and ortho-amidation of benzamides.
- Dhiman, Ankit Kumar,Thakur, Ankita,Kumar, Inder,Kumar, Rakesh,Sharma, Upendra
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p. 9244 - 9254
(2020/08/14)
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- Simple and scalable electrochemical synthesis of 2,1-benzisoxazoles and quinoline: N -oxides
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Cathodic reduction of the nitro moiety and subsequent intramolecular cyclization affords different substituted 2,1-benzisoxazoles and quinoline N-oxides. This methodology allows the synthesis of two different types of heterocycles from common simple starting materials, using electrons as a sole reagent for this transformation. The electrolysis can be conducted in a very simple undivided electrolysis cell under constant current conditions. This permits working on a larger scale compared to other electrochemical methodologies and represents a significant advantage.
- Rodrigo, Eduardo,Baunis, Haralds,Suna, Edgars,Waldvogel, Siegfried R.
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p. 12255 - 12258
(2019/10/22)
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- Cu-Catalyzed carbamoylation: Versus amination of quinoline N -oxide with formamides
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An efficient, direct carbamoylation and amination of quinoline N-oxides with formamides to access 2-carbamoyl and 2-amino quinolines has been developed through copper-catalyzed C-C and C-N bond formations via cross-dehydrogenative coupling reactions. The reaction proceeds smoothly over a broad range of substrates with excellent functional group tolerance under mild conditions. Mechanistic studies suggest that the reaction is initiated by formamide radical or decarbonylative aminyl radical formation in the presence of TBHP, according to the different substituent on the N atom of formamide.
- Zhang, Yan,Zhang, Shiwei,Xu, Guangxing,Li, Min,Tang, Chunlei,Fan, Weizheng
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supporting information
p. 309 - 314
(2019/01/10)
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- Regioselective Cyanation of Six-Membered N-Heteroaromatic Compounds Under Metal-, Activator-, Base- and Solvent-Free Conditions
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A regioselective cyanation of heteroaromatic N-oxides with trimethylsilyl cyanide has been developed to obtain 2-substituted N-heteroaromatic nitrile without the requirement of any external activator-, metal-, base-, and solvent. The present protocol is a straightforward, one-pot heteroaromatic C?H cyanation process, and proceeds smoothly in conventional heating but also under microwave irradiation with shorter reaction times. This approach now allows access to a broad class of quinoline N-oxides and other heteroarene N-oxides with high to good yields and can also be scaled up to obtain gram quantities. Further application of this process was observed and utilized in late-stage cyanation of the anti-malarial drug quinine as well as transformation of the 2-cyanoazines to a series of biologically important molecules. Based on the experimental observations, a plausible mechanism has also been proposed highlighting the dual role of trimethylsilyl cyanide as a nitrile source and as an activating agent. (Figure presented.).
- Sarmah, Bikash Kumar,Konwar, Monuranjan,Bhattacharyya, Dipanjan,Adhikari, Priyanka,Das, Animesh
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supporting information
p. 5616 - 5625
(2019/11/22)
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- Synthesis of heteroaromatic trifluoromethyl ethers with trifluoromethyl triflate as the source of the trifluoromethoxy group
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A series of nitrogen-heterocycles have been transformed to the corresponding trifluoromethyl or higher perfluoroalkyl ethers by reaction of the corresponding N-oxides with trifluoromethyl or higher perfluoroalkyl triflate. Trifluoromethyl triflate, which has generally been used as a precursor to [OCF3]?, is used here as a bifunctional reagent to render the heteroarene more electrophilic and to deliver the trifluoromethoxy group. This reagent was easily prepared on a large scale (>100 grams) and is stable in either pure form or as a stock solution. Applications and limitations of this method are reported.
- Zhang, Qing-Wei,Hartwig, John F.
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supporting information
p. 10124 - 10127
(2018/09/18)
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- Transition-Metal-Free Regioselective Alkylation of Quinoline N-Oxides via Oxidative Alkyl Migration and C?C Bond Cleavage of tert-/sec-Alcohols
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An unprecedented C2-alkylation of quinoline N-oxide derivatives via C?C bond activation of tert- and sec-alkyl alcohol is described using hypervalent iodine (III) reagent PhI(OAc)2 (PIDA). This regioselective alkylation using mild hypervalent iodine reagents is more practical, operationally simple and transition metal free. The reaction proceeds efficiently with a broad range of substrates including quinoline, isoquinoline, and pyridine N-oxides using a variety of tert-/sec- alcohols. From experimental outcome, we also propose a rationalized mechanism, mediated by PIDA. (Figure presented.).
- Sen, Chiranjit,Ghosh, Subhash C.
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supporting information
p. 905 - 910
(2018/01/11)
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- Dehydrogenative etherification homocoupling of heterocyclic N-oxides
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A novel approach was developed for the dehydrogenative etherification homocoupling of heterocyclic N-oxides in the presence of silver oxide and PyBroP. Various substrates were well tolerated and the desired products were obtained in moderate to good yields. Generally, this reaction features excellent functional group compatibility, broad substrate scope and good regioselectivity.
- Zhang, Dong,Qiao, Kai,Yuan, Xin,Zheng, Mingwei,Fang, Zheng,Wan, Li,Guo, Kai
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supporting information
p. 1752 - 1756
(2018/04/10)
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- Visible Light-Mediated Decarboxylative Alkylation of Pharmaceutically Relevant Heterocycles
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A net redox-neutral method for the decarboxylative alkylation of heteroarenes using photoredox catalysis is reported. Additionally, this method features the use of simple, commercially available carboxylic acid derivatives as alkylating agents, enabling the facile alkylation of a variety of biologically relevant heterocyclic scaffolds under mild conditions.
- Sun, Alexandra C.,McClain, Edward J.,Beatty, Joel W.,Stephenson, Corey R. J.
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supporting information
p. 3487 - 3490
(2018/06/26)
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- Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts
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We report the first reductive coupling of unactivated alkenes with N-methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts under hydrogen atom transfer (HAT) conditions, and an expanded scope for the coupling of alkenes with N-methoxy pyridinium salts. N-Methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts are accessible in 1-2 steps from the commercial arenes or arene N-oxides (25-99%). N-Methoxy imidazolium salts are accessible in three steps from commercial amines (50-85%). In total 36 discrete methoxyheteroarenium salts bearing electron-donating, electron-withdrawing, alkyl, aryl, halogen, and haloalkyl substituents were prepared (several in multigram quantities) and coupled with 38 different alkenes. The transformations proceed under neutral conditions at ambient temperature, provide monoalkylation products exclusively, and form a single alkene addition regioisomer. Preparatively useful and complementary site selectivities in the addition of secondary and tertiary radicals to pyidinium salts are documented: harder secondary radicals favor C-2 addition (2->10:1), while softer tertiary radicals favor bond formation to C-4 (4.7->29:1). A diene possessing a 1,2-disubstituted and 2,2-disubstituted alkene undergoes hydropyridylation at the latter exclusively (61%) suggesting useful site selectivities can be obtained in polyene substrates. The methoxypyridinium salts can also be employed in dehydrogenative arylation, borono-Minisci, and tandem arylation processes. Mechanistic studies support the involvement of a radical process.
- Ma, Xiaoshen,Dang, Hester,Rose, John A.,Rablen, Paul,Herzon, Seth B.
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supporting information
p. 5998 - 6007
(2017/05/04)
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- Copper-Catalyzed Direct, Regioselective Arylamination of N-Oxides: Studies to Access Conjugated π-Systems
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An efficient copper(I)-catalyzed direct regioselective arylamination of various heterocyclic N-oxides was achieved successfully under redox-neutral conditions using anthranils as arylaminating reagents. The developed protocol is simple, straightforward, and economic with a broad range substrate scope. The dual functional groups in the final molecules were utilized to construct structurally and functionally diverse nitrogen-containing organic π-conjugated systems.
- Biswas, Aniruddha,Karmakar, Ujjwal,Nandi, Shiny,Samanta, Rajarshi
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p. 8933 - 8942
(2017/09/11)
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- Regioselective Chlorination of Quinoline N-Oxides and Isoquinoline N-Oxides Using PPh3/Cl3CCN
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A novel method for the regioselective C2-chlorination of heterocyclic N-oxides has been developed. PPh3/Cl3CCN were used as chlorinating reagents and the desired N-heterocyclic chlorides were obtained smoothly in satisfactory yields. The reactions proceeded in a highly efficient and selective manner across a broad range of substrates demonstrating excellent functional group tolerance. In addition, this chlorination reaction can be used for the modification of N-heterocyclic scaffolds of appealing ligands and pharmaceuticals.
- Qiao, Kai,Wan, Li,Sun, Xiaoning,Zhang, Kai,Zhu, Ning,Li, Xin,Guo, Kai
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p. 1606 - 1611
(2016/04/05)
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- Benzylation of heterocyclic N-oxides via direct oxidative cross-dehydrogenative coupling with toluene derivatives
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A novel cross-dehydrogenative coupling (CDC) of heterocyclic N-oxides with toluene derivatives has been discussed, allowing for the facile synthesis of a broad range of structurally diverse C1-benzyl quinoline N-oxides, isoquinoline N-oxides and pyridine N-oxides, including two methylated quinoline N-oxides in particular. This protocol not only extends the application of toluenes in synthetic organic chemistry, but also offers an alternative method to prepare benzylated heterocyclic N-oxides without any metal involved, which is important in medicinal chemistry.
- Wan,Qiao,Sun,Di,Fang,Li,Guo
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supporting information
p. 10227 - 10232
(2016/12/07)
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- Synthesis of pyridine N-oxide-BF2CF3 complexes and their fluorescence properties
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Pyridine N-oxide-BF2CF3 and-BF2C 2F5 complexes and their derivatives were synthesized. Most of the complexes show fluorescence both in solution and in the solid state. By expanding the π-conjugated skeleton, the color of the fluorescence could be changed dramatically. A fluorophore with a high solvent dependency could also be produced. Since such compounds can be synthesized on a gram scale in high yield, and are stable to oxygen, water, and heat, the complexes hold great potential as organic functional materials. Too complex for simple answers: Complexes of pyridine N-oxide with BF2CF3 and BF 2C2F5, and their derivatives were synthesized. Most of the complexes fluoresce, both in solution and in the solid state. By expanding the π-conjugated skeleton, the color of the fluorescence could be changed dramatically. Owing to their properties such complexes hold potential as organic functional materials.
- Nishida, Tomoaki,Fukazawa, Aiko,Yamaguchi, Eriko,Oshima, Hiroya,Yamaguchi, Shigehiro,Kanai, Motomu,Kuninobu, Yoichiro
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p. 1026 - 1030
(2014/04/17)
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- Iridium(iii) catalyzed trifluoroacetoxylation of aromatic hydrocarbons
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A tridentate, NNC-tb (where NNC-tb = 2-(pyridin-2-yl)benzo[h]quinoline) ligated IrIII complex (NNC-tb)Ir(Ph)(4-MePy)(TFA), 11 along with analogues are very active for CH activation as evidenced by rapid catalytic H/D exchange between benzene and trifluoroacetic acid-d1 (DTFA). The complexes were examined with a variety of oxidants for the catalytic conversion of benzene to phenyltrifluoroacetate. Herein, the synthesis and characterization of (NNC-tb)Ir complexes is described along with the reactivity of these complexes towards arenes and alkanes.
- Bischof, Steven M.,Hashiguchi, Brian G.,Lokare, Kapil S.,Gunsalus, Niles,Yousufuddin, Mohammed,Periana, Roy A.
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p. 35639 - 35648
(2014/12/10)
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- NOVEL ANTHRACENE DERIVATIVES AND ORGANIC ELECTRONIC DEVICE USING SAME
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The present invention provides a novel anthracene derivatives and an organic electronic device using the same. Thte organic electronic device according to the present invention shows excellent properties in terms of efficiency, a driving voltage, and a life span.
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Page/Page column 30
(2011/06/23)
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- Steric effects of the ligand in the enantioselective palladium-catalyzed allylic alkylation using chiral oxazolinylpyridines
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Eight new chiral oxazolinylpyridines were prepared and assessed in the enantioselective palladium-catalyzed allylic substitution of 1,3- diphenylprop-2-enyl acetate with dimethyl malonate. Catalytic activity and enantioselectivity were found to be highly
- Chelucci, Giorgio,Medici, Serenella,Saba, Antonio
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p. 543 - 550
(2007/10/03)
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- Novel potent and selective central 5-HT3 receptor ligands provided with different intrinsic efficacy. 1. Mapping the central 5-HT3 receptor binding site by arylpiperazine derivatives
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Synthesis and pharmacological evaluation of a series of condensed quinoline and pyridine derivatives bearing a N-methylpiperazine moiety attached to the 2-position of the quinoline or pyridine nucleus are described. 5-HT receptor binding studies revealed subnanomolar affinity for the 5-HT3 receptor subtype in some of the compounds under study. The most active compound (5b) displayed a K(i) value about 1 order of magnitude higher than that of quipazine along with a higher selectivity. The potential 5-HT3 agonist/antagonist activity of four selected compounds was assessed in vitro on 5-HT3 receptor-dependent [14C]guanidinium uptake in NG 108-15 cells. Compound 5j acted as a 5-HT3 agonist in this assay with an EC50 value close to that reported for quipazine, while 5b was a partial agonist with an EC50 value of about 0.25 nM, and compound 5c possessed antagonist properties with an IC50 value (?8 nM) in the same range as those of previously characterized 5-HT3 receptor antagonists. Qualitative and quantitative structure-affinity relationship studies carried out by making use of theoretical molecular descriptors allowed to elucidate the role of the main pharmacophoric components and to develop a model for the interaction of the 5-HT3 ligands related to quipazine with their receptor.
- Cappelli, Andrea,Anzini, Maurizio,Vomero, Salvatore,Mennuni, Laura,Makovec, Francesco,Doucet, Edith,Hamon, Michel,Bruni, Giancarlo,Romeo, Maria R.,Menziani, M. Cristina,De Benedetti, Pier G.,Langer, Thierry
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p. 728 - 741
(2007/10/03)
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- KINETICS OF N-OXIDATION OF COMPOUNDS OF THE QUINOLINE SERIES AND ISOMERIC BENZOQUINOLINES BY PERBENZOIC ACID IN CHLOROFORM AND AQUEOUS DIOXANE
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The kinetics of the N-oxidation with perbenzoic acid of 15 derivatives of quinoline and benzoquinoline in chloroform and 19 compounds in 50percent aqueous dioxane at 20, 25, 30, and 35 deg C were subjected to a comparative study.The rate constants, parameters of Arrhenius equation, and the activation energies for the N-oxidation of the indicated monoazines were determined.A scale of the reactivities of derivatives of the quinoline series and benzoquinolines was calculated within the framework of general perturbation theory.
- Lokhov, R. E.
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