- Electrochemically Induced Chain Reactions: The Electrochemical Behavior of Nitrosobenzene in the Presence of Proton Donors in Tetrahydrofuran
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The electrochemical reduction of nitrosobenzene in tetrahydrofuran with tetrabutylammonium hexafluorophosphate as the supporting electrolyte and in the presence of fluorene or indene at room temperature gives a mixture of an anil (1 or 3), a nitrone (2 or 4), and azoxybenzene and requires only a catalytic amount of electricity.Lowering the temperature and/or increasing the proportion of proton donor favors the formation of the anil at the expense of the nitrone and azoxybenzene: a 97percent yield of anil 1 was obtained from an electrolysis carried out at -30 deg C using 5 equiv of fluorene.The possible steps of the chain reactions involved are discussed on the basis of electrochemical and chemical data and digital simulation.With phenylacetylene as the proton donor, there is no reaction between nitrosobenzene and phenylacetylene and azoxybenzene is the main product formed.
- Mugnier, Yves,Gard, Jean-Christophe,Huang, Youqin,Couture, Yvon,Lasia, Andrzej,Lessard, Jean
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- Insights into the effect of ketylimine, aldimine, and vinylene group attachment and regiosubstitution on the fluorescence deactivation of fluorene
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The spectroscopic and electrochemical properties of a 9-substituted fluorene ketylimine (3) were investigated and compared with those of its vinylene analogue (4) to determine the origins of the quenched fluorescence of these compounds. The predominate mo
- Dufresne, Stephane,Skalski, Thomas,Skene
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- Generation and characterization of the selenocysteinyl radical: Direct evidence from time-resolved UV/Vis, electron paramagnetic resonance, and fourier transform infrared spectroscopy
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The selenocysteinyl radical 1 has been generated for the first time by laser flash photolysis (λexc = 266 nm) of dimethyl bis(N-tert-butoxycarbonyl)-L-selenocystine 2 and of [(9-fluorenylideneamino)- oxycarbonyl]methyl(N-tert-butoxycarbonyl)-L-selenocysteine 3 in acetonitrile and characterized by time-resolved (TR) UV/Vis, Fourier transform infrared (FTIR), and electron paramagnetic spectroscopy in combination with theoretical methods. A detailed product study was conducted using gas chromatography and one- and two-dimensional NMR spectroscopy. In the case of [(9-fluorenylideneamino) oxycarbonyl]methyl(N-tert-butoxycarbonyl)-L-selenocysteine 3, the (9-fluorenylideneamino)oxycarbonyl moiety serves as a photolabile protection group providing a caged selenocysteinyl radical suitable for biophysical applications. Cleavage of the diselenide bridge or the selenium-carbonyl bond by irradiation is possible in high quantum yields. Because of the lack of a good IR chromophore in the mid-IR region, the selenocysteinyl radical 1 cannot be monitored directly by TR FTIR spectroscopy. TR UV/Vis spectroscopy revealed the formation of the selenocysteinyl radical 1 from both precursors. The selenocysteinyl radical 1 has a lifetime τ ≈ 63 μs and exhibits a strong band located at λmax = 335 nm. Calculated UV absorptions of the selenocysteinyl radical (UB3LYP/6-311G(d,p)) are in good agreement with the experimental results. The use of TR UV/Vis spectroscopy permitted the determination of the decay rates of the selenocysteinyl radical in the presence of two quenchers. The product studies demonstrated the reversible photoreaction of dimethyl bis(N-tert-butoxycarbonyl) -L-selenocystine 2. Products of the photolysis of the caged selenocysteinyl radical precursor 3 are dimethyl bis(N-tert- butoxycarbonyl)-L-selenocystine 2, carbon dioxide, and some further smaller fragments. In addition, the photo-decomposition of the (9-fluorenylideneamino) oxycarbonyl moiety produced 9-fluorenone-oxime 4, 9-fluoren-imine 5, and 6 and 7 as products of the dimerization of two 9-fluorenoneiminoxy radicals 8.
- Kolano, Christoph,Bucher, Goetz,Schade, Olaf,Grote, Dirk,Sander, Wolfram
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- Reaction of arynes with trifluoroacetylated β-diketones: Novel formation of isocoumarins and phenanthrenes
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Polysubstituted isocoumarins were synthesized by the reaction of substituted 2-(trimethylsilyl)aryl triflates with trifluoromethylated β-diketones in the presence of CsF. The reaction proceeded through carbon-carbon bond insertion of aryne and intramolecular cyclization to form intermediates of alcohol anions, which extruded trifluoromethyl anion to afford isocoumarins. By using CuBr as a catalyst, 2 eq. of aryne reacted with β-diketones to afford phenanthrenes and 1,2-diarylethanones. Although reaction of 2-(trimethylsilyl)phenyl triflate with 1,1,1-trifluoro-4′-methylbenzoylacetone in the presence of CsF gave 3-(4′-methylphenyl)isocoumarin in 67% yield, addition of 0.2 eq. of CuCN resulted in the formation of 9-(4-methylbenzoyl)-10-trifluoromethylphenanthrene in 35% yield.
- Okuma, Kentaro,Tanabe, Yukiko,Fukami, Takuto,Ishibashi, Yuto
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- Selective, Oxophilic Imination of Ketones with Bis(dichloroaluminum) Phenylimide
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Bis(dichloroaluminum) phenylimide, which can be readily prepared from ethylaluminum dichloride and aniline, is shown to be a highly selective iminating agent for aldehydes, ketones, and acid chlorides.Especially the transformation of α,β-unsaturated keton
- Eisch, John J.,Sanches, Ramiro
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- Bildung von 1,2,4-Trithiolanen in Dreikomponenten-Gemischen aus Phenyl-azid, aromatischen Thioketonen und 2,2,4,4-Tetramethylcyclobutan-thionen: Eine Schwefel-Transfer-Reaktion unter Bildung von 'Thiocarbonyl-thiolaten' ((Alkylidensulfonio)thiolaten) als
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The reaction of PhN3 and aromatic thioketones 18 (two-component reaction) at 80 degree yields only the corresponding imines 22, S, and N2.Under similar conditions, in the presence of sterically crowded 2,2,4,4-tetramethyl-cyclobutanethiones 19 (three-comp
- Mloston, Grzegorz,Heimgartner, Heinz
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- Photoredox-Catalyzed Synthesis of α-Amino Acid Amides by Imine Carbamoylation
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An operationally simple protocol for the photocatalytic carbamoylation of imines is reported. Easily available, bench-stable 4-amido Hantzsch ester derivatives serve as precursors to carbamoyl radicals that undergo rapid addition to N-aryl imines. The reaction proceeds under blue light irradiation in the presence of the photocatalyst 3DPAFIPN and Br?nsted/Lewis acid additives. Mechanistic studies indicated a photoredox mechanism that involves carbamoyl radicals.
- Cardinale, Luana,Schmotz, Mattis-Ole W. S.,Konev, Mikhail O.,Jacobi von Wangelin, Axel
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supporting information
p. 506 - 510
(2022/01/20)
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- Photoredox Radical/Polar Crossover Enables Construction of Saturated Nitrogen Heterocycles
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Photoredox-mediated radical/polar crossover (RPC) processes offer new avenues for the synthesis of cyclic molecules. This process has been realized for the construction of medium-sized saturated nitrogen heterocycles. Photocatalytically generated alkyl ra
- Pantaine, Lo?c R.E.,Milligan, John A.,Matsui, Jennifer K.,Kelly, Christopher B.,Molander, Gary A.
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supporting information
p. 2317 - 2321
(2019/03/26)
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- Preparation method of 10H-spiro[acridine-9,9'-fluorene] and derivative thereof
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The invention provides a preparation method of 10H-spiro[acridine-9,9'-fluorene] and a derivative thereof, and belongs to the technical field of organic synthesis. According to the invention, an iminecompound, potassium fluoride, 18-corona-6 and methanesu
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Paragraph 0065-0068
(2019/04/06)
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- Structure and Reactivity of Half-Sandwich Rh(+3) and Ir(+3) Carbene Complexes. Catalytic Metathesis of Azobenzene Derivatives
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Traditional rhodium carbene chemistry relies on the controlled decomposition of diazo derivatives with [Rh2(OAc)4] or related dinuclear Rh(+2) complexes, whereas the use of other rhodium sources is much less developed. It is now shown that half-sandwich carbene species derived from [Cp?MX2]2 (M = Rh, Ir; X = Cl, Br, I, Cp? = pentamethylcyclopentadienyl) also exhibit favorable application profiles. Interestingly, the anionic ligand X proved to be a critical determinant of reactivity in the case of cyclopropanation, epoxide formation and the previously unknown catalytic metathesis of azobenzene derivatives, whereas the nature of X does not play any significant role in 'OH insertion reactions. This perplexing disparity can be explained on the basis of spectral and crystallographic data of a representative set of carbene complexes of this type, which could be isolated despite their pronounced electrophilicity. Specifically, the donor/acceptor carbene 10a derived from ArC( - N2)COOMe and [Cp?RhCl2]2 undergoes spontaneous 1,2-migratory insertion of the emerging carbene unit into the Rh-Cl bond with formation of the C-metalated rhodium enolate 11. In contrast, the analogous complexes 10b,c derived from [Cp?RhX2]2 (X = Br, I) as well as the iridium species 13 and 14 derived from [Cp?IrCl2]2 are sufficiently stable and allow true carbene reactivity to be harnessed. These complexes are competent intermediates for the catalytic metathesis of azobenzene derivatives, which provides access to α-imino esters that would be difficult to make otherwise. Rather than involving metal nitrenes, the reaction proceeds via aza-ylides that evolve into diaziridines; a metastable compound of this type has been fully characterized.
- Tindall, Daniel J.,Werlé, Christophe,Goddard, Richard,Philipps, Petra,Farès, Christophe,Fürstner, Alois
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supporting information
p. 1884 - 1893
(2018/02/17)
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- Photocatalytic and Chemoselective Transfer Hydrogenation of Diarylimines in Batch and Continuous Flow
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A visible-light photocalytic method for the chemoselective transfer hydrogenation of imines in batch and continuous flow is described. The reaction utilizes Et3N as both hydrogen source and single-electron donor, enabling the selective reduction of imines derived from diarylketimines containing other reducible functional groups including nitriles, halides, esters, and ketones. The dual role of Et3N was confirmed by fluorescence quenching measurements, transient absorption spectroscopy, and deuterium-labeling studies. Continuous-flow processing facilitates straightforward scale-up of the reaction.
- Van As, Dean J.,Connell, Timothy U.,Brzozowski, Martin,Scully, Andrew D.,Polyzos, Anastasios
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supporting information
p. 905 - 908
(2018/02/22)
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- Visible-Light-Mediated Umpolung Reactivity of Imines: Ketimine Reductions with Cy2NMe and Water
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A novel carbanionic reactivity of imines mediated by photoredox catalysis is demonstrated. The umpolung imine reactivity is exemplified by proton abstraction from water as a key step in the reduction of benzophenone ketimines to amines (up to 98% yield). Deuterium is introduced into amines efficiently using D2O as an inexpensive deuterium source (≥95% D ratio). The mechanism of this unusual transformation is probed.
- Wang, Rui,Ma, Mengyue,Gong, Xu,Panetti, Grace B.,Fan, Xinyuan,Walsh, Patrick J.
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supporting information
p. 2433 - 2436
(2018/04/27)
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- Cycloaddition of Fluorenone N-Aryl Nitrones with Methylenecyclopropanes and Sequential 1,3-Rearrangement: An Entry to Synthesis of Spirofluorenylpiperidin-4-ones
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A facile synthesis of various spirofluorenylpiperidin-4-ones has been achieved in good yields from fluorenone N-aryl nitrones and methylenecyclopropanes. This method involved an initial cycloaddition to form a 5-spirocyclopropane-isoxazoline, which underwent a highly selective 1,3-rearrangement to give the desired product. The stereochemistry of the spirofluorenylpiperidin-4-one could be controlled by the cycloaddition and sequential rearrangement strategy. Furthermore, the spirofluorenylpiperidin-4-ones could be not only prepared in one-pot procedure but also converted to useful scaffolds by reduction or oxidation conditions.
- Ma, Xiao-Pan,Zhu, Jie-Feng,Wu, Si-Yi,Chen, Chun-Hua,Zou, Ning,Liang, Cui,Su, Gui-Fa,Mo, Dong-Liang
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p. 502 - 511
(2017/04/26)
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- Metal-free synthesis of highly substituted quinolines under mild conditions Dedicated to Professor Jonathan S. Lindsey on his sixtieth birthday
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Starting from easily accessible nitrones and acetylenes, a simple, metal free synthesis of substituted quinolines under mild conditions with high atom efficiency has been developed. Our method is flexible enough to introduce substituents regiospecifically
- Natarajan, Rakesh,Unnikrishnan, Peruparambil A.,Radhamani, Sandhya,Rappai, John P.,Prathapan, Sreedharan
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p. 2981 - 2984
(2016/07/06)
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- A copper-catalyzed one-pot, three-component diastereoselective synthesis of 3-spiroazetidinimine-2-oxindoles and their synthetic transformation into fluorescent conjugated indolones
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A facile and efficient copper(I)-catalyzed one-pot, three-component diastereoselective synthesis that provides new 3-spiroazetidinimine-2-oxindoles in excellent yield has been accomplished. The 3-spiroazetidinimine-2-oxindoles underwent a facile ring-open
- Periyaraja, Somasundharam,Shanmugam, Ponnusamy,Mandal, Asit Baran
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p. 954 - 965
(2014/03/21)
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- A Copper-Catalyzed One-Pot, Three-Component Diastereoselective Synthesis of 3-Spiroazetidinimine-2-oxindoles and Their Synthetic Transformation into Fluorescent Conjugated Indolones
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A facile and efficient copper(I)-catalyzed one-pot, three-component diastereoselective synthesis that provides new 3-spiroazetidinimine-2-oxindoles in excellent yield has been accomplished. The 3-spiroazetidinimine-2-oxindoles underwent a facile ring-opening reaction of the spiroazetidinimine unit by treatment with KOH/MeOH and p-thiocresol under basic conditions to afford two new classes of fluorescent conjugated indolones. This method has general applications with regard to the imines that are derived from 9-fluorenone, 1,2-diketones, and 1,2,3-triketones. A facile and efficient copper(I)-catalyzed one-pot, three-component diastereoselective synthesis that provides new 3-spiroazetidinimine-2-oxindoles in excellent yield has been accomplished. The ring-opening reaction of the 3-spiroazetidinimine-2-oxindoles has also been described. This method has general applications with regard to the imines of 9-fluorenone, 1,2-diketones, and 1,2,3-triketones.
- Periyaraja, Somasundharam,Shanmugam, Ponnusamy,Mandal, Asit Baran
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p. 954 - 965
(2015/10/05)
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- Facile synthesis of triarylmethanimine promoted by a lewis acidbase pair: Theoretical and experimental studies
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An efficient method for triarylmethanimine synthesis promoted by a Lewis acidbase pair (AlCl3Et3N) was designed using mechanistic analysis with the aid of density functional theory. A series of triarylmethanimines were successfully prepared under mild con
- Liu, Yan,Yang, Qiwu,Hao, Dongling,Zhang, Wenqin
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p. 1390 - 1395,6
(2020/09/02)
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- Transition Metal-Catalyzed C-H Amination Using Unactivated Amines
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One aspect of the invention relates to a method of animation or amidation, comprising the step of combining a substrate, comprising a reactive C—H bond, and an amine or amide, comprising a reactive N—H bond, in the presence of an oxidizing agent and a metal-containing catalyst, thereby forming a product with a covalent bond between the carbon of the reactive C—H bond and the nitrogen of the reactive N—H bond.
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Page/Page column 3
(2011/09/20)
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- Hydride, hydrogen, proton, and electron affinities of imines and their reaction intermediates in acetonitrile and construction of thermodynamic characteristic graphs (TCGs) of imines as a molecule ID card
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(Chemical Equation Presented) A series of 61 imines with various typical structures were synthesized, and the thermodynamic affinities (defined as enthalpy changes or redox potentials in this work) of the imines to abstract hydride anions, hydrogen atoms, and electrons, the thermodynamic affinities of the radical anions of the imines to abstract hydrogen atoms and protons, and the thermodynamic affinities of the hydrogen adducts of the imines to abstract electrons in acetonitrile were determined by using titration calorimetry and electrochemical methods. The pure heterolytic and homolytic dissociation energies of the C=N π-bond in the imines were estimated. The polarity of the C=N double bond in the imines was examined using a linear free-energy relationship. The idea of a thermodynamic characteristic graph (TCG) of imines as an efficient Molecule ID Card was introduced. The TCG can be used to quantitatively diagnose and predict the characteristic chemical properties of imines and their various reaction intermediates as well as the reduction mechanism of the imines. The information disclosed in this work could not only supply a gap of thermodynamics for the chemistry of imines but also strongly promote the fast development of the applications of imines. 2009 American Chemical Society.
- Zhu, Xiao-Qing,Liu, Qiao-Yun,Chen, Qiang,Mei, Lian-Rui
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scheme or table
p. 789 - 808
(2010/04/29)
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- An aryl to imidoyl palladium migration process involving intramolecular C-H activation
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Biologically interesting fluoren-9-one and xanthen-9-one derivatives have been prepared by a novel aryl to imidoyl palladium migration, followed by intramolecular arylation. The fluoren-9-one synthesis appears to involve both a palladium migration mechanism and a C-H activation process proceeding through an unprecedented organopalladium(IV) hydride intermediate. The results from deuterium labeling experiments are consistent with the proposed dual mechanism.
- Zhao, Jian,Yue, Dawei,Campo, Marino A.,Larock, Richard C.
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p. 5288 - 5295
(2008/02/02)
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- N-substituted imines by the copper-catalyzed N-imination of boronic acids and organostannanes with O-acyl ketoximes
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Catalytic quantities of copper(I) or copper(II) sources catalyze the N-imination of boronic acids and organostannanes through reaction with oxime O-carboxylates under nonbasic conditions. This method tolerates various functional groups and takes place efficiently using aryl, heteroaryl, and alkenyl boronic acids and stannanes.
- Liu, Songbai,Yu, Ying,Liebeskind, Lanny S.
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p. 1947 - 1950
(2008/02/02)
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- Sulfur centered 1,3-dipoles. An efficient trapping of adamantanethione-S-sulfide generated in the reaction of adamantanethione with organic azides
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The reaction of adamantanethione (1) and an organic azide at 80°C ("two-component reaction") yields the symmetrical 1,2,4-trithiolane 9 and the corresponding adamantylidene imine 10 in nearly equal amounts. Under the same conditions, the "three-component reaction" with 1, phenyl azide and an aromatic thioketone gives the unsymmetrical 1,2,4-trithiolane 12 as the major product, and 9 and imine 13 as by-products. A 1,3-dipolar cycloaddition of an intermediate thiocarbonyl-S-sulfide and a thioketone is proposed as the mechanism for the formation of the trithiolanes. The structure of trithiolane 12a has been established by X-ray crystallography.
- Mloston,Romanski,Heimgartner
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p. 437 - 445
(2007/10/03)
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- SULFUR TRANSFER IN A THREE-COMPONENT SYSTEM INCLUDING PHENYL AZIDE, AROMATIC THIONE AND STERICALLY CROWDED TETRAMETHYLCYCLOBUTANETHIONE
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A new access to thiosulfines generated in a reaction system containing thiocarbonyl compounds and phenyl azide is described.
- Mloston, Grzegorz,Heimgartner, Heinz
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p. 355 - 358
(2007/10/02)
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- Azophilic Addition of Alkyllithium Reagents to Fluorenimines. The Synthesis of Secondary Amines
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N-Alkyl- and N-arylfluorenimines undergo azophilic addition with n-BuLi to give N-butyl-N-alkyl- or N-butyl-N-aryl-9-aminofluorene systems.The fluorenyl group can then be hydrogenolyzed, furnishing the secondary amine.The selectivity for azophilic (vs carbophilic) addition ranges from 80 to 100percent for the N-alkylfluorenimines to 24-29percent for the N-arylfluorenimines.The decreased azophilic selectivity of the N-arylfluorenimines can be rationalized on the basis of frontier molecular orbital interactions as well as steric effects.Other related imines, that would appear toprovide an inverse polarization similar to that of the fluorenimines, do not give satisfactory yields of azophilic addition products.
- Dai, Wei,Srinivasan, Rajgopal,Katzenellenbogen, John A.
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p. 2204 - 2208
(2007/10/02)
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- Electron transfer reactions. Reaction of nitrones with potassium
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Treatment of nitrones (1a-d, 26a,b, 34, 49) with potassium in tetrahydrofuran (THF) gives rise to radical anion (2a-d, 27a,b, 35, 50) and dianion intermediates (3a-d, 28a,b, 36) through electron transfer reactions.These intermediates undergo further transformations to give a variety of products.Thus, the aldehydonitrones (1a-d) give the corresponding aldehydes (10a-c), carboxylic acids (25a-c), and azobenzenes (19a,d), whereas the ketonitrones (26a,b) give deoxygenation products (31a,b).The nitrone 34 gave a mixture of products consisting of benzoic acid (25a), dibenzyl (48), the dimeric product 38, and tetraphenylpyrazine (46), whereas 49 did not give any isolable product.Cyclic voltammetric studies have been employed to measure the reduction potentials for both one-electron and two-electron transfer processes, leading to the radical anions and dianions respectively.These intermediates have been characterized through their electronic spectra and they were quenched by oxygen.Pulse radiolysis of the nitrones 1a-d, 26a,b, 34, and 49 also gave the corresponding radical anions 2a-d, 27a,b, 35, and 50, characterized by their spectra.
- Ashok, Konda,Scaria, Pallikkaparambil M.,Kamat, Prashant V.,George, Manapurathu V.
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p. 2039 - 2049
(2007/10/02)
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- Reaction entre solvant et especes intermediaires apparues lors de l'electroreduction-acylation de la fluorenone et de la fluorenone-anil dans l'acetonitrile
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The electrogenerated anions CH2CN- induce the conversion of the various reduction-acylation products of fluorenone 1a and its anil 1b in acetonitrile into 1a and 1b; this phenomenon is controlled by the fortuitous introduction of molecular oxygen.The CH2CN- anions catalyse the transformation of 1a and 1b into fluorenylideneacetonitrile (FlC=CHCN) 17, convertible into the nitriles FlC=CH(CN)=C(NH2)CH3 8, FlC=C(CN)CHFl 10, and FlC(CN)CH2CN 11.These observations allow us to interpret the formation of the products appearing during the electrolysis of fluorenone in acetonitrile in the presence of an equivalent of chloride or anhydride of ω-chloro acid.The products of reduction-acylation appear successively, followed by the nitriles, FlC(OH)CH2CH2CN 3a, 10, FlC(OH)CH2CN 24, and polymers.Because of its basicity the fluorenone radical anion promotes reactions with the solvent, olefin 17 being a preferred intermediate.Bis-fluorenol, fluorenol, and finally fluorene and found with 1a and the above products.
- Degrand, Chantal,Belot, Gerard,Compagnon, Paul-Louis,Gasquez, Francoise
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p. 2581 - 2589
(2007/10/02)
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- EXTREMELY REACTIVE CARBON-CARBON DOUBLE BONDS-I; REACTIONS WITH 2-(9-XANTHYLIDENE)-, 2-(9-THIOXANTHYLIDENE)-, AND 2-(9-FLUORENYLIDENE)-INDANE-1,3-DIONE. A CONTRIBUTION ON THE STRUCTURE AND REACTIVITY OF NON-PLANAR C-C DOUBLE BONDS
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The compounds in the title (cf 1a, 1b and 2) react with various reagents, often under mild conditions, mostly by breaking of the central double bond.According to X-ray diffraction the central double bond of 2-(9-xanthylidene)indane-1,3-dione is inclined by 47.2 deg.The relationship between the structure and reactivity of the compounds in the title is discussed.
- Schoenberg, Alexander,Singer, Erich,Stephan, Werner,Sheldrick, William S.
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p. 2429 - 2438
(2007/10/02)
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