- New synthesis of 2-aryl- and 2-hetarylpyrroles from 1-propargylbenzotriazole
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1-(3-Lithiopropargyl)benzotriazole reacts with N-tosylarylimines to give adducts which undergo cycloelimination on treatment with ethanolic sodium hydroxide to afford 2-aryl- and 2-hetarylpyrroles in 45-60% yields. Treatment of 1-(1,3-dilithiopropargyl)benzotriazole successively with 1 equivalent of an alkyl halide followed by N-tosyl(1-naphthyl)imine and then ethanolic sodium hydroxide gives the corresponding 5-alkyl-2-(1-naphthyl)pyrroles in 43-56% yields.
- Katritzky,Li,Gordeev
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Read Online
- σ-Bond initiated generation of aryl radicals from aryl diazonium salts
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σ-Bond nucleophiles and molecular oxygen transform aryl diazonium salts into aryl radicals. Experimental and computational studies show that Hantzsch esters transfer hydride to aryl diazonium species, and that oxygen initiates radical fragmentation of the diazene intermediate to produce aryl radicals. The operational simplicity of this addition-fragmentation process for the generation of aryl radicals, by a polar-radical crossover mechanism, has been illustrated in a variety of bond-forming reactions.
- Chan, Bun,McErlean, Christopher S. P.,Nashar, Philippe E.,Tatunashvili, Elene
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supporting information
p. 1812 - 1819
(2020/03/17)
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- Transformation of the non-selective aminocyclohexanol-based Hsp90 inhibitor into a Grp94-seletive scaffold
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Glucose regulated protein 94 kDa, Grp94, is the endoplasmic reticulum (ER) localized isoform of heat shock protein 90 (Hsp90) that is responsible for the trafficking and maturation of toll-like receptors, immunoglobulins, and integrins. As a result, Grp94 has emerged as a therapeutic target to disrupt cellular communication, adhesion, and tumor proliferation, potentially with fewer side effects compared to pan-inhibitors of all Hsp90 isoforms. Although, the N-terminal ATP binding site is highly conserved among all four Hsp90 isoforms, recent cocrystal structures of Grp94 have revealed subtle differences between Grp94 and other Hsp90 isoforms that has been exploited for the development of Grp94-selective inhibitors. In the current study, a structure-based approach has been applied to a Grp94 nonselective compound, SNX 2112, which led to the development of 8j (ACO1), a Grp94-selective inhibitor that manifests -440 nM affinity and ≥200-fold selectivity against cytosolic Hsp90 isoforms.
- Mishra, Sanket J.,Ghosh, Suman,Stothert, Andrew R.,Dickey, Chad A.,Blagg, Brian S. J.
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p. 244 - 253
(2017/12/30)
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- Radical Arylation of Anilines and Pyrroles via Aryldiazotates
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The radical arylation of anilines and pyrroles can be achieved under transition-metal- and catalyst-free conditions by using aryldiazotates in strongly alkaline aqueous solutions. The aryldiazotates act as protected diazonium ions, which do not undergo azo coupling with electron-rich aromatic substrates, but can still serve as an aryl radical source at slightly elevated temperatures. Based on an improved preparation of aryldiazotates in aqueous solution, homolytic aromatic substitutions of anilines and pyrroles were conducted with good overall yields and high regioselectivity. Moreover, DFT calculations provided further mechanistic insights.
- Hofmann, Josefa,Gans, Eva,Clark, Timothy,Heinrich, Markus R.
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p. 9647 - 9656
(2017/07/22)
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- Synthesis of 5-Arylpyrrole-2-carboxylic Acids as Key Intermediates for NBD Series HIV-1 Entry Inhibitors
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5-Arylpyrrole-2-carboxylic acids are important key intermediates in the synthesis of HIV-1 entry inhibitors (such as NBD-11021 and NBD-14010). Here we present a general method for the synthesis of some 5-arylpyrrole-2-carboxylic acids in three steps starting from pyrrole. By this method, the compounds could be prepared on gram scale and without chromatographic purification.
- Belov, Dmitry S.,Ivanov, Vladimir N.,Curreli, Francesca,Kurkin, Alexander V.,Altieri, Andrea,Debnath, Asim K.
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p. 3692 - 3699
(2017/08/15)
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- Chromoselective Photocatalysis: Controlled Bond Activation through Light-Color Regulation of Redox Potentials
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Catalysts that can be regulated in terms of activity and selectivity by external stimuli may allow the efficient multistep synthesis of complex molecules and pharmaceuticals. Herein, we report the light-color regulation of the redox potential of a photocatalyst to control the activation of chemical bonds. Light-color control of the redox power of a photocatalyst introduces a new selectivity parameter to photoredox catalysis: Instead of changing the catalyst or ligand, alteration of the color of the visible-light irradiation adjusts the selectivity in catalytic transformations. By using this principle, the selective activation of aryl–halide bonds for C?H arylation and the sequential conversion of functional groups with different reduction potentials is possible by simply applying different colors of light for excitation of the photocatalyst.
- Ghosh, Indrajit,K?nig, Burkhard
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supporting information
p. 7676 - 7679
(2016/07/07)
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- Direct synthesis of aryl substituted pyrroles from calcium carbide: An underestimated chemical feedstock?
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In this work, a novel synthetic methodology for the preparation of aryl pyrroles directly from the reaction of calcium carbide with oxime is reported. Various pyrrole derivatives are generated from the corresponding oximes in satisfactory yields (49–88%) under the optimized conditions. The one-pot synthesis of aryl pyrrole from widely available ketone is also successfully developed. A new near-infrared fluorescent BODIPY dye containing a phenyl substitution at the C-3 position is expediently prepared from the aryl pyrrole derived from this methodology. The key benefit of this methodology is the use of an inexpensive and less hazardous primary chemical feedstock, calcium carbide, in a wet solvent without any metal catalysts. This process offers a novel cost-efficient route for the synthesis of functionalized pyrrole.
- Kaewchangwat, Narongpol,Sukato, Rangsarit,Vchirawongkwin, Viwat,Vilaivan, Tirayut,Sukwattanasinitt, Mongkol,Wacharasindhu, Sumrit
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p. 460 - 465
(2018/04/16)
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- Structure-Based Design of a Small Molecule CD4-Antagonist with Broad Spectrum Anti-HIV-1 Activity
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Earlier we reported the discovery and design of NBD-556 and their analogs which demonstrated their potential as HIV-1 entry inhibitors. However, progress in developing these inhibitors has been stymied by their CD4-agonist properties, an unfavorable trait for use as drug. Here, we demonstrate the successful conversion of a full CD4-agonist (NBD-556) through a partial CD4-agonist (NBD-09027), to a full CD4-antagonist (NBD-11021) by structure-based modification of the critical oxalamide midregion, previously thought to be intolerant of modification. NBD-11021 showed unprecedented neutralization breath for this class of inhibitors, with pan-neutralization against a panel of 56 Env-pseudotyped HIV-1 representing diverse subtypes of clinical isolates (IC50 as low as 270 nM). The cocrystal structure of NBD-11021 complexed to a monomeric HIV-1 gp120 core revealed its detail binding characteristics. The study is expected to provide a framework for further development of NBD series as HIV-1 entry inhibitors for clinical application against AIDS.
- Curreli, Francesca,Kwon, Young Do,Zhang, Hongtao,Scacalossi, Daniel,Belov, Dmitry S.,Tikhonov, Artur A.,Andreev, Ivan A.,Altieri, Andrea,Kurkin, Alexander V.,Kwong, Peter D.,Debnath, Asim K.
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p. 6909 - 6927
(2015/09/22)
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- Expedient one-pot synthesis of pyrroles from ketones, hydroxylamine, and 1,2-dichloroethane
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2- and 2,3-Substituted pyrroles are readily synthesized in a one-pot procedure from ketones, hydroxylamine hydrochloride, and 1,2-dichloroethane in the KOH/DMSO system (120 °C, 2-4 h), the yields of pyrroles ranging 11-85%. Aliphatic, cycloaliphatic, aromatic, and heteroaromatic ketones tolerate the reaction conditions.
- Trofimov, Boris A.,Mikhaleva, Al'Bina I.,Ivanov, Andrei V.,Shcherbakova, Viktoria S.,Ushakov, Igor A.
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p. 124 - 128
(2015/02/02)
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- Copper-catalyzed 5-endo-trig cyclization of ketoxime carboxylates: A facile synthesis of 2-arylpyrroles
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A novel and facile copper-catalyzed 5-endo-trig cyclization of ketoxime carboxylates for the synthesis of 2-arylpyrroles has been developed. The reaction tolerates a range of functional groups and is a practical procedure for rapid synthesis of 2-arylpyrroles in high yields under mild conditions. the Partner Organisations 2014.
- Du, Wei,Zhao, Mi-Na,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
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supporting information
p. 7437 - 7439
(2014/07/07)
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- Synthesis and optical properties of difluorobora-s-diazaindacene dyes with trifluoromethyl meso-substituents
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A series of meso-CF3-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes with aryl and hetaryl substituents at the C-3 and C-5 positions, both symmetric and asymmetric, have been synthesized in 36-90 % yields by a new strategy involving as the key step the condensation of 2,2,2-trifluoro-1-(5- arylpyrrol-2-yl)-1-ethanols with diverse 2-arylpyrroles. The starting 2,2,2-trifluoro-1-(5-arylpyrrol-2-yl)-1-ethanols are easily prepared by reduction of the available 2-trifluoroacetyl-5-arylpyrroles. The synthesized dyes fluoresce in a longer wavelength region (626-698 nm) with high quantum yield (0.84-0.99). A new strategy for the synthesis of highly efficient symmetric and asymmetric BODIPY fluorophores that combine trifluoromethyl and 3,5-aryl substituents has been developed. The key step is the P 2O5-promoted condensation of 2,2,2-trifluoro-1-(5- arylpyrrol-2-yl)-1-ethanols with diverse 2-arylpyrroles. Copyright
- Sobenina, Lyubov N.,Petrova, Olga V.,Petrushenko, Konstantin B.,Ushakov, Igor A.,Mikhaleva, Albina I.,Meallet-Renault, Rachel,Trofimov, Boris A.
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p. 4107 - 4118
(2013/07/19)
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- Direct arylation of arene and N -heteroarenes with diaryliodonium salts without the use of transition metal catalyst
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A novel and simple transition metal-free direct arylation of arene and N-heteroarenes with diaryliodonium salts has been developed. This cross-coupling reaction is promoted only by base and gives the desired products in moderate to good yields.
- Wen, Jun,Zhang, Ruo-Yi,Chen, Shan-Yong,Zhang, Ji,Yu, Xiao-Qi
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experimental part
p. 766 - 771
(2012/02/16)
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- Catalytic C-H arylation of unactivated heteroaromatics with aryl halides by cobalt porphyrin
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Direct C-H arylation of unactivated heteroaromatics with aryl halides catalyzed by cobalt porphyrin is reported. The reaction is proposed to go through a homolytic aromatic substitution reaction. The aryl radical is electrophilic and a SOMO-HOMO interaction is predominant in the aryl radical addition process.
- Qian, Ying Ying,Wong, Ka Lai,Zhang, Meng Wen,Kwok, Tsz Yiu,To, Ching Tat,Chan, Kin Shing
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supporting information; experimental part
p. 1571 - 1575
(2012/04/11)
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- Convenient access to 2-arylpyrroles from 2-lithio-N,N- dibenzylcyclopropylamine and nitriles
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N,N-Dibenzylaminocyclopropyl ketimines formed as intermediates upon treatment of 2-lithiated N,N-dibenzylcyclopropylamines with nitriles, being donor-acceptor-substituted cyclopropanes, immediately underwent ring-enlarging rearrangement and 1,2-elimination of dibenzylamine to produce 2-substituted pyrroles in good yields (14 examples, 55-80%). Georg Thieme Verlag Stuttgart.
- Tanguy, Chloé,Bertus, Philippe,Szymoniak, Jan,Larionov, Oleg V.,De Meijere, Armin
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p. 2339 - 2341
(2007/10/03)
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- 2-Bromo-N-(p-toluenesulfonyl)pyrrole: A Robust Derivative of 2-Bromopyrrole
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2-Bromo-AL(p-toluenesulfonyl)pyrrole (2), a crystalline stable derivative of 2-bromopyrrole (1) has been prepared in 80% yield by bromination of pyrrole, followed by conversion to the N-(p-toluenesulfonyl) derivative. This compound is stable indefinitely at ambient temperature. Compound 2 is an excellent substrate for Suzuki coupling with arylboronic acids.
- Knight, Lea W.,Huffman, John W.,Isherwood, Matthew L.
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p. 1993 - 1996
(2007/10/03)
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- Palladium (0)-catalysed arylations using pyrrole and indole 2-boronic acids
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A versatile synthesis of 2-arylpyrroles and 2-arylindoles is described based on the use of either N-(Boc) pyrrole-2-boronic acid or N-(Boc) indole-2-boronic acid as components for Suzuki coupling.
- Johnson, Christopher N.,Stemp, Geoffrey,Anand, Neel,Stephen, Susanna C.,Gallagher, Timothy
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p. 1025 - 1027
(2007/10/03)
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- NUCLEOPHILIC ADDITION TO ALKYNES IN SUPERBASIC CATALYTIC SYSTEMS. V. VINYLATION OF KETOXIMES
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The nucleophilic addition of the oximes of aliphatic, aromatic, and heteroaromatic ketones to acetylene in the superbasic heterophase potassium hydroxide-DMSO system was studied.The vinylation of ketoximes not containing a CH2 group at the α position to the oxime function goes well, and the yields of the O-vinyloximes are 38-72percent.With such a group and with electronegative substituents in the aromatic ring of the ketoxime rapid heterocyclization of the O-vinyloximes occurs under the reaction conditions, giving the corresponding 2-substituted pyrroles.
- Tarasova, O. A.,Korostova, S. E.,Mikhaleva, A. I.,Sobenina, L. N.,Nesterenko, R. N.,et al.
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p. 863 - 869
(2007/10/02)
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- PYRROLES FROM KETOXIMES AND ACETYLENE. 1,2-DICHLOROETHANE IN PLACE OF ACETYLENE IN THE SYNTHESIS OF 2-ARYLPYRROLES
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In reaction with 1,2-dichloroethane in the potassium hydroxide-DMSO system 100-125 deg C methyl allyl ketone oximes form 2-arylpyrroles with yields of up to 69percent.The yield of the simultaneously formed N-vinyl derivatives is not greater than 12percent.
- Korostova, S. E.,Mikhaleva, A. I.,Sobenina, L. N.,Shevchenko, S. G.,Polovnikova, R. I.
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p. 436 - 438
(2007/10/02)
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- PYRROLES FROM KETOXIMES AND ACETYLENE. 30. THE SYNTHESIS OF 3-ALKYL-2-ARYLPYRROLES
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Conditions were found for the synthesis of 3-alkyl-2-arylpyrroles using the Trofimov reaction at 50-70 deg C both at elevated and atmospheric pressure.O-Vinyloximes and 3H-5-hydroxy-4,5-dihydropyrroles were isolated as intermediates.
- Korostova, S. E.,Mikhaleva, A. I.,Sobenina, L. N.,Shevchenko, S. G.,Shcherbakov, V. V.
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p. 1238 - 1241
(2007/10/02)
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- PYRROLES FROM KETOXIMES AND ACETYLENE. XXVI. THE SYNTHESIS OF NEW 2-ARYLPYRROLES
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New representatives of the 2-arylpyrrole series were obtained with yields of 36-90percent from the oximes of alkyl aryl ketones by the Trofimov reaction.When vinyl chloride was used instead of acetylene under the same conditions (potassium hydroxide-DMSO, 80-100 deg C), the pyrroles were obtained with yields of 2-7percent.
- Korostova, S. E.,Sobenina, L. N.,Nesterenko, R. N.,Aliev, I. A.,Mikhaleva, A. I.
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p. 1790 - 1793
(2007/10/02)
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