- Wittig Olefination Using Phosphonium Ion-Pair Reagents Incorporating an Endogenous Base
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Despite common perception, the use of strong bases in Wittig chemistry is utterly unnecessary: we report a series of novel ion-pair phosphonium carboxylate reagents which are essentially "storable ylides". These reagents are straightforwardly prepared in excellent yields, and their fluxional nature permits clean olefination of a broad range of aldehydes and even hemiacetals.
- Vetter, Anna C.,Gilheany, Declan G.,Nikitin, Kirill
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p. 1457 - 1462
(2021/03/08)
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- Ready approach to poly(vinyldiphenylphosphine): A novel soluble polymer for conveniently conducting Wittig reactions
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The novel poly(vinyldiphenylphosphine) could be easily prepared by using the reactions of the cheap poly(vinyl chloride) with sodium phosphides. Poly(vinyldiphenylphosphine) is soluble in common solvents while its corresponding phosphine oxide is hardly soluble in the solvents. Taking advantage of this different solubility, poly(vinyldiphenylphosphine) could be used as a soluble phosphinopolymer for the Wittig reactions. The reactions could take place efficiently to produce the corresponding olefins while the isolation of the products were simple since the resulted poly(vinyldiphenylphosphine oxide) was not soluble in the solvent and could be easily removed by filtration.
- Ye, Jing-Jing,Han, Li-Biao
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supporting information
(2021/01/25)
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- E, Z -Selectivity in the reductive cross-coupling of two benzaldehydes to stilbenes under substrate control
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Unsymmetrical E- and Z-stilbenes can be synthesized from two differently substituted benzaldehydes in a MesP(TMS)Li-promoted reductive coupling sequence. Depending on the order of addition of the two coupling partners, the same olefin can be produced in either E- or Z-enriched form under identical reaction conditions. A systematic study of the correlation between the stereochemical outcome of the reaction and the substitution pattern at the two aldehydes is presented. The results can be used as guidelines to predict the product stereochemistry. This journal is
- Arkhypchuk, Anna I.,D'Imperio, Nicolas,Ott, Sascha
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p. 6171 - 6179
(2020/10/21)
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- Syntheses of diarylethenes by perylene-catalyzed photodesulfonylation from ethenyl sulfones
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Diarylethenes were obtained from the corresponding ethenyl sulfones by photocatalyzed desulfonylation using UV or blue LEDs. When perylene and i-Pr2NEt were used as a photocatalyst and a sacrificing reagent, respectively, this desulfonylation proceeded smoothly to afford the desired ethenes with the functional groups such as chloro, alkoxy and heteroaromatic rings remaining untouched. The use of a flow photoreactor enabled this desulfonylation to proceed more rapidly to finish in an hour of residence time.
- Adachi, Kazumasa,Dakegata, Aki,Fukuyama, Takahide,Okuda, Yasuhiro,Orita, Akihiro,Ryu, Ilhyong,Takemoto, Mai,Wakamatsu, Kan,Watanabe, Hikaru
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supporting information
p. 409 - 412
(2020/04/27)
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- A Bidentate Ru(II)-NC Complex as a Catalyst for Semihydrogenation of Alkynes to (E)-Alkenes with Ethanol
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Four Ru(II)-NC complexes were tested as catalysts for semihydrogenation of internal alkynes to (E)-alkenes with ethanol, and the complex {(C5H4N)(C6H4)}RuCl(CO)(PPh3)2 (1a) showed the highest activity. The reactions proceeded well with 1 mol % catalyst loading and 0.1 equiv of t-BuONa at 110 °C for 1 h, and 32 alkenes were synthesized with excellent E:Z selectivity. This is the first ruthenium-catalyzed semihydrogenation of internal alkynes to (E)-alkenes using ethanol as the hydrogen donor.
- Chen, Dafa,Gong, Dawei,Hu, Bowen,Kong, Degong,Xia, Haiping,Yang, Weiwei
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- New 1,2,3-triazole based bis- And trisphosphine ligands: Synthesis, transition metal chemistry and catalytic studies
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The syntheses and transition metal chemistry of triazole-based bis- and tris-phosphines, 5-(diphenylphosphanyl)-1-(2-(diphenylphosphanyl)phenyl)-4-phenyl-1H-1,2,3-triazole (2), 5-(diphenylphosphanyl)-4-(2-(diphenylphosphanyl)phenyl)-1-phenyl-1H-1,2,3-tria
- Balakrishna, Maravanji S.,Butcher, Ray J.,Kunchur, Harish S.,Namdeo, Pavan K.,Radhakrishna, Latchupatula
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p. 3434 - 3449
(2020/03/27)
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- Ynamide Smiles Rearrangement Triggered by Visible-Light-Mediated Regioselective Ketyl-Ynamide Coupling: Rapid Access to Functionalized Indoles and Isoquinolines
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In the past decades, significant advances have been made on radical Smiles rearrangement. However, the eventually formed radical intermediates in these reactions are limited to the amidyl radical, except for the few examples initiated by a N-centered radical. Here, a novel and practical radical Smiles rearrangement triggered by photoredox-catalyzed regioselective ketyl-ynamide coupling is reported, which represents the first radical Smiles rearrangement of ynamides. This method enables facile access to a variety of valuable 2-benzhydrylindoles with broad substrate scope in generally good yields under mild reaction conditions. In addition, this chemistry can also be extended to the divergent synthesis of versatile 3-benzhydrylisoquinolines through a similar ketyl-ynamide coupling and radical Smiles rearrangement, followed by dehydrogenative oxidation. Moreover, such an ynamide Smiles rearrangement initiated by intermolecular photoredox catalysis via addition of external radical sources is also achieved. By control experiments, the reaction was shown to proceed via key ketyl radical and α-imino carbon radical intermediates.
- Chen, Yang-Bo,Sun, Zhou,Wang, Ze-Shu,Ye, Long-Wu,Zhang, Hao-Wen,Zhu, Chunyin
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supporting information
p. 3636 - 3644
(2020/03/06)
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- Novel Carbazole-Based N-Heterocyclic Carbene Ligands to Access Synthetically Relevant Stilbenes in Pd-Catalyzed Coupling Processes
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A series of new carbazole-based N-heterocyclic carbene (NHC) ligands have been synthesized in a simple and facile synthetic route and subsequently used in a Pd/carbazole-based NHC catalytic system, which was found to be effective in catalyzing Heck reactions to provide substituted stilbene derivatives in good yields. Several bioactive stilbenes, including pterostilbene, pinosylvin, trimethoxy resveratrol, and resveratrol, were synthesized in good yields, and a 10 mmol scale-up was also performed for trimethoxy resveratrol. The synthetic application was also extended by performing a double-tandem chemoselective Heck reaction followed by Miyaura borylation in a one-pot procedure to give single-step access to synthetically useful stilbenyl boronate esters. Similarly, a unique triple-tandem protocol of a chemoselective Heck reaction/Miyaura borylation/Suzuki–Miyaura coupling reaction sequence was performed for the one-pot modification of biologically relevant molecules.
- Girase, Tejpalsingh Ramsingh,Kapdi, Anant R.
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supporting information
p. 2611 - 2619
(2019/07/05)
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- Catalytic Asymmetric Synthesis of Atropisomeric Quinolines through the Friedl?nder Reaction
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A phosphoric acid catalyzed atroposelective Friedl?nder reaction was developed in which acetylacetone and a variety of 2′-substituted 2-Aminobenzophenones were successfully employed to give optically active biaryl quinolines in good yields and with high enantioselectivities.
- Hu, Xingena,Jiang, Jun,Lan, Yunjun,Li, Juan,Li, Xinhua,Liu, Hongxin,Wan, Junlin,Xiao, Hong-Ping
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p. 2198 - 2202
(2019/11/25)
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- Synthesis of divergent benzo[b]fluorenones through cycloaromatization reactions of 1,5-enynols and 1,5-diynols
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A facile and efficient synthesis of divergent benzo[b]fluorenones is described through the use of dichlorobenzoquinone-promoted oxidative cycloaromatization reactions of acyclic 1,5-enynols and 1,5-diynols. The success of these cascade reactions depends on the chemoselectivity of the initial Meyer-Schuster rearrangement to produce allenol intermediate, which is followed by regioselective Schmittel cyclization and the subsequent Friedal-Crafts alkylation or radical attack at the terminal Ar moiety. Only an oxidant and a solvent were required in the reaction, thus delivering a small library of the expected polycarbocyclic products with excellent functional group tolerance under metal-free conditions. The absorption and photoluminescence properties of the selected benzo[b] fluorenones were also investigated. The results indicated that the compound (2h) which contained an electron-donating 4-OMe group at the phenyl moiety displayed deep green color emission (491 nm).
- Yan, Bingyu,Fu, Yang,Zhu, Hui,Chen, Zhiyuan
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p. 4246 - 4262
(2019/03/26)
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- Br?nsted Acid-Catalyzed Carbonyl-Olefin Metathesis inside a Self-Assembled Supramolecular Host
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Carbonyl–olefin metathesis represents a powerful yet underdeveloped method for the formation of carbon–carbon bonds. So far, no Br?nsted acid based method for the catalytic carbonyl–olefin metathesis has been described. Herein, a cocatalytic system based on a simple Br?nsted acid (HCl) and a self-assembled supramolecular host is presented. The developed system compares well with the current benchmark catalyst for carbonyl–olefin metathesis in terms of substrate scope and yield of isolated product. Control experiments provide strong evidence that the reaction proceeds inside the cavity of the supramolecular host. A mechanistic probe indicates that a stepwise reaction mechanism is likely.
- Catti, Lorenzo,Tiefenbacher, Konrad
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supporting information
p. 14589 - 14592
(2018/01/27)
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- Metal-free denitrative arylation of β-nitrostyrenes using benzoyl peroxide: An easy access to: Trans -stilbenes
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A simple, novel and stereoselective synthesis of trans-stilbenes has been described using denitrative arylation of β-nitrostyrenes in the presence of benzoyl peroxide under metal-free conditions. The reaction is assumed to involve homolytic cleavage of benzoyl peroxide followed by decarboxylation to generate a phenyl radical, which brings about ipso-substitution of the nitro group of nitrostyrenes to afford trans-stilbenes.
- Yadav, Arvind Kumar,Singh, Krishna Nand
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supporting information
p. 14914 - 14917
(2017/12/15)
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- Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl-Olefin Metathesis
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Polycyclic aromatic hydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry, and materials science. The development of a new synthetic strategy toward these compounds is described based on the design principle of iron(III)-catalyzed carbonyl-olefin metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility, and regioselectivity while relying on FeCl3 as an environmentally benign, earth-abundant metal catalyst. Experimental evidence for oxetanes as reactive intermediates in the catalytic carbonyl-olefin ring-closing metathesis has been obtained.
- McAtee, Christopher C.,Riehl, Paul S.,Schindler, Corinna S.
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supporting information
p. 2960 - 2963
(2017/03/11)
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- Synthesis of stilbene derivatives via visible-light-induced cross-coupling of aryl diazonium salts with nitroalkenes using-NO2 as a leaving group
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The straightforward visible-light-induced synthesis of stilbene compounds via the cross-coupling of nitroalkenes and diazonium tetrafluoroborates under transition-metal-free conditions is described. The protocol uses green LEDs as light sources and eosin Y as an organophotoredox catalyst. Broad substrate scope and exclusive selectivity for the (E)-configuration of stilbenes are observed. This protocol proceeds via a radical pathway, with nitroalkenes serving as the radical acceptor, and the nitro group is cleaved during the process.
- Zhang, Na,Quan, Zheng-Jun,Zhang, Zhang,Da, Yu-Xia,Wang, Xi-Cun
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supporting information
p. 14234 - 14237
(2016/12/14)
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- Palladium-Catalysed Desulfitative Heck Reaction Tolerant to Aryl Carbon-Halogen Bonds for Access to (Poly)halo-Substituted Stilbene or Cinnamate Derivatives
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The palladium-catalysed desulfitative Heck type reaction of (poly)halo-substituted benzenesulfonyl chlorides with alkenes was investigated. Styrene or acrylates in the presence of bromo- or iodobenzenesulfonyl chlorides and a phosphine-free palladium catalyst were found to afford the expected β-arylated Heck type products with complete regio- and stereoselectivities. The reaction tolerates a variety of substituents on the halobenzenesulfonyl chloride. Moreover, no cleavage of the C-Br and C-I bonds was observed in the course of these reactions, allowing further transformations. Using 4-bromobenzenesulfonyl chloride as the central unit, consecutive desulfitative Heck type reaction followed by palladium-catalysed direct arylation allowed to prepare heteroarylated stilbene derivatives in only two steps.
- Skhiri, Aymen,Salem, Ridha Ben,Soulé, Jean-Francois,Doucet, Henri
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p. 3097 - 3106
(2016/09/09)
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- Air-Driven Potassium Iodide-Mediated Oxidative Photocyclization of Stilbene Derivatives
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A new method has been developed for the potassium iodide-mediated oxidative photocyclization of stilbene derivatives. Compared with conventional iodine-mediated oxidative photocyclization reactions, this new method requires shorter reaction times and affords cyclized products in yields of 45-97%. This reaction proceeds with a catalytic amount of potassium iodide and works in an air-driven manner without the addition of an external scavenger. The radical-mediated oxidative photocyclization of stilbene derivatives using TEMPO was also investigated.
- Matsushima, Tomoya,Kobayashi, Sayaka,Watanabe, Soichiro
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p. 7799 - 7806
(2016/09/09)
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- Stereoretentive Pd-catalyzed kumada-corriu couplings of alkenyl halides at room temperature
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Stereoselective palladium-catalyzed Kumada-Corriu reactions of functionalized alkenyl halides and a variety of Grignard reagents, including those bearing β-hydrogen atoms and sensitive functional groups, can be carried out at room temperature using a new combination of reagents.
- Krasovskiy, Arkady L.,Haley, Stephen,Voigtritter, Karl,Lipshutz, Bruce H.
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supporting information
p. 4066 - 4069
(2014/10/15)
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- Palladium-catalyzed annulation of diarylamines with olefins through C-H activation: Direct access to N-arylindoles
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A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.
- Sharma, Upendra,Kancherla, Rajesh,Naveen, Togati,Agasti, Soumitra,Maiti, Debabrata
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supporting information
p. 11895 - 11899
(2015/01/09)
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- Iridium-catalyzed borylation of secondary benzylic C-H bonds directed by a hydrosilane
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Most functionalizations of C-H bonds by main-group reagents occur at aryl or methyl groups. We describe a highly regioselective borylation of secondary benzylic C-H bonds catalyzed by an iridium precursor and 3,4,7,8-tetramethyl-1, 10-phenanthroline as the ligand. The reaction is directed to the benzylic position by a hydrosilyl substituent. This hydrosilyl directing group is readily deprotected or transformed to other functional groups after the borylation reaction, providing access to a diverse set of secondary benzylboronate esters by C-H borylation chemistry.
- Cho, Seung Hwan,Hartwig, John F.
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supporting information
p. 8157 - 8160
(2013/07/05)
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- Oxidative Mizoroki-Heck-type reaction of arylsulfonyl hydrazides for a highly regio- and stereoselective synthesis of polysubstituted alkenes
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A useful source: Arylsulfonyl hydrazides have been identified as synthetically useful aryl sources for the Pd(OAc)2 catalyzed oxidative Mizoroki-Heck-type reaction under molecular oxygen to provide a convenient access to polysubstituted alkenes in a highly regio- and stereoselective manner (see scheme). The reaction well tolerates various functional groups such as alkoxy, halo, alcohol, carboxylic acid, ester, amide, sulfonamide, and sulfone. Copyright
- Yang, Fu-Lai,Ma, Xian-Tao,Tian, Shi-Kai
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p. 1582 - 1585
(2012/03/11)
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- Unequivocal experimental evidence for a unified lithium salt-free wittig reaction mechanism for all phosphonium ylide types: Reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products
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The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.
- Byrne, Peter A.,Gilheany, Declan G.
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p. 9225 - 9239
(2012/07/14)
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- Potassium tert-butoxide promoted intramolecular arylation via a radical pathway
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Potassium tert-butoxide mediated intramolecular cyclization of aryl ethers, amines, and amides was efficiently performed under microwave irradiation to provide the corresponding products in high regioisomeric ratios. The reaction proceeds via single-electron transfer to initiate the formation of an aryl radical, followed by a kinetically favored 5-exo-trig and subsequent ring expansion.
- Roman, Daniela Sustac,Takahashi, Yoko,Charette, Andre B.
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supporting information; experimental part
p. 3242 - 3245
(2011/08/02)
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- O -amino conjugation effect on the photochemistry of trans -aminostilbenes
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The excited-state behavior of a series of trans-2-(N-arylamino)stilbenes (aryl = phenyl (o1H), 4-methylphenyl (o1Me), 4-methoxyphenyl (o1OM), and 4-cyanophenyl (o1CN)) and trans-2-(N,N-diphenylamino)stilbene (o2) in both nonpolar and polar solvents is rep
- Lin, Cheng-Kai,Prabhakar,Yang, Jye-Shane
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scheme or table
p. 3233 - 3242
(2011/06/10)
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- A class of benzene backbone-based olefin-sulfoxide ligands for Rh-catalyzed enantioselective addition of arylboronic acids to enones
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A class of readily available and easily tunable benzene backbone-based olefin-sulfoxide ligands was developed for the rhodium-catalyzed asymmetric conjugate addition reaction of arylboronic acids to enones with up to 97% yield and 97% ee.
- Xue, Feng,Li, Xincheng,Wan, Boshun
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experimental part
p. 7256 - 7262
(2011/10/09)
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- Novel cyclization cascades to functionalized indanes and tetrahydronaphthalenes
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Cyclization cascades involving C-C bond formations followed by lactonization reactions provide fast access to structurally complex tricyclic indane and tetrahydronaphthalene derivatives. Crown Copyright
- Khan, Zulfiqar A.,Iwaoka, Michio,Wirth, Thomas
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experimental part
p. 6639 - 6646
(2010/10/19)
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- Palladium-catalyzed oxidative activation of arylcyclopropanes
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(Diagram presented) Palladium chloride-catalyzed intramolecular activation of electroneutral cyclopropane derivatives results in cleavage of the cyclopropane ring followed by formation of heterocyclic derivatives. Phenols, carboxylic acids, and amide groups were considered as substituents ortho to the cyclopropane ring in this catalytic activation chemistry. The regioselectivity observed in the case of amide-containing substrates was different from that of carboxylic acid-containing substrates, ruling out simple cyclopropane isomerization followed by a Wacker oxidation as the mechanistic pathway.
- He, Zhi,Yudin, Andrei K.
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p. 5829 - 5832
(2007/10/03)
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- Co-operative ortho-effects on the Wittig reaction. Interpretation of stereoselectivity in the reaction of ortho-halo-substituted benzaldehydes and benzylidenetriphenylphosphoranes
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The E/Z ratios of the stilbenes 1 formed in the Wittig reaction of ortho-halo substituted benzyltriphenylphosphonium salts 2 and benzaldehydes 3 were determined. It was found that there is a co-operative effect of one ortho-halo group on each of the two reacting partners which increases Z-selectivity, but two such groups on the same reactant gives high E-selectivity. The effects are strong enough to be preparatively significant in certain cases and can be interpreted within the modern framework of the Wittig mechanism established by Vedejs and co-workers.
- Dunne, Eoin C,Coyne, éamonn J,Crowley, Peter B,Gilheany, Declan G
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p. 2449 - 2453
(2007/10/03)
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- ANTHRACENE DERIVATIVES AND ORGANIC ELECTROLUMINESCENT DEVICES MADE BY USING THE SAME
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An anthracene derivative represented by general formula (I): wherein X and Y represent a trifunctional aromatic ring group or the like, (1) A1 to A4 represent an aryl group or a monovalent heterocyclic group or (2) A1 and
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- Stereocontrolled synthesis of carbon-carbon double bond locked analogues of strobilurins which are characterized by a trans-1,2-disubstituted cyclopropane ring
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The racemic forms of four new carbon-carbon double bond locked analogues of strobilurins, which are characterized by a trans-1,2-disubstituted cyclopropane ring, have been synthesized according to a strategy which involves palladium-catalyzed cross-coupli
- Rossi,Carpita,Ribecai,Mannina
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p. 2847 - 2856
(2007/10/03)
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- Heck Reactions under Microwave Irradiation in Solvent-Free Conditions
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Palladium-catalyzed vinylation of organic halides can be carried out under microwave irradiation in the absence of solvent in 22 minutes with excellent yields.
- Díaz-Ortiz, ángel,Prieto, Pilar,Vázquez, Ester
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p. 269 - 270
(2007/10/03)
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- Palladium-catalyzed cross-coupling reactions of arenediazonium tetrafluoroborates with aryl- And alkeriylboronic acids
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Arcnediazonium tetrafluoroborates undergo a facile and efficient palladium-catalyzed cross-coupling reaction with aryl- and alkenylboronic acids at ambient temperature, without addition of base. The reaction described is characterized by a high chemoselectivity because bromide and trifiate functional groups are tolerated. Eisevier,.
- Darses, Sylvain,Jeffery, Tuyet,Jean-Louis,Demoute, Jean-Pierre,Genet, Jean-Pierre
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p. 1095 - 1102
(2007/10/03)
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- Fungicides
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This invention relates to derivatives of acrylic acid useful as fungicides, to processes for preparing them, to fungicidal compositions containing them, and to methods of combating fungi, especially fungal infections in plants, using them.
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- An Intramolecular Arene-Triflate Coupling Reaction for the Regiospecific Synthesis of Substituted Benzofluoranthenes
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An intramolecular triflate-arene coupling reaction mediated by bis(triphenylphosphine)palladium(II) chloride has been developed for the synthesis of each of the isomeric benzofluoranthenes.This reaction, which results in formation of a new five-membered ring, proceeds in highest yields when performed using 0.1 equiv of the palladium catalyst, 3 eqiv of lithium chloride, and 1.2 eqiv of 1,8-diazabicycloundec-7-ene in N,N-dimethylformamide at 140 deg C.The biaryl precursors needed for the coupling reaction can be prepared by nickel(II) chloride catalyzed coupling of an aryl bromide with an magnesium bromide (prepared by ortho-lithiation of an aryl methoxymethyl ether followed by transmetalation with magnesium bromide).Using this procedure benzofluoranthene, benzofluoranthene, benzofluoranthene, and benzofluoranthene were prepared in yields of 84percent, 85percent, 93percent and 64percent, respectively.The reaction to prepare benzofluoranthene was regiospecific and afforded none of the six-membered ring product, perylene.This method was extended to the preparation of benzofluoranthene (BbF) derivatives with fluoro or methoxy groups on the benzo ring.The cyclization of compounds posessing a methoxy group on the same ring as the triflate required the addition of 0.4 equiv of triphenylphosphine to the reaction mixture.Strategies are reported for the regiospecific preparation of 4-, 5-, 6-, and 7-substituted benzofluoranthenes.Evidence is presented wich suggests the intermediacy of radicals in the oxidative-addition of aryl triflates to the palladium catalyst.
- Rice, Joseph E.,Cai, Zhen-Wei
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p. 1415 - 1424
(2007/10/02)
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- Fungicides
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Compounds of formula: ψψ and stereoisomers thereof, wherein X, Y and Z, which may be the same or different, are hydrogen or halogen atoms, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted aryl, optionally substituted alkynyl, haloalkyl, alkoxy, haloalkoxy, optionally substituted aryloxy, optionally substituted arylalkoxy, optionally substituted acyloxy, optionally substituted amino, optionally substituted arylazo, acylamino, nitro, nitrile, -CO2R3, -CONR4R5, -COR6, -CR7=NR8, or -N=CR9R10 groups; or the groups X and Y, when they are in adjacent positions on the phenyl ring, may join to form a fused ring, either aromatic or aliphatic, optionally containing one or more heteroatoms; and R1, Ry, R3, R4, R5, R6, R7, R8, R9 and R10, which may be the same or different, are hydrogen atoms or alkyl, cycloalkyl, alkenyl, alkynyl, optionally substituted aryl, optionally substituted aralkyl, or cycloalkylalkyl groups; and metal complexes thereof.ψ
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- 1,7-Electrocyclisation and Carbene Reactions of o-Alkenylaryldiazoalkanes: The Effect of Alkene Configuration on the Mode of Reaction
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The 1,7-8?-electron electrocyclisation of o-alkenylaryldiazoalkanes (1) to give 1H-2,3-benzodiazepines (3) takes place readily for substrates with a cis-hydrogen atom at the cyclisation site, but is blocked by phenyl or methyl groups at that position.Such
- Munro, David P.,Sharp, John T.
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p. 849 - 858
(2007/10/02)
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- Synthesis of Triphenylphosphane-en-ynes and Phosphindoles as well as X-Ray Analyses of two Phosphindoles
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By means of aminochlorophenylphosphanes triphenylphosphanes are prepared, in which the o-positions are optionally substituted by trans-phenylethenyl and phenylethinyl groups (4a - c and 5a - c).Surprisingly, the intermediate chlorophosphanes 3a and c can
- Butters, Thomas,Winter, Werner
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p. 990 - 1002
(2007/10/02)
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- Photochemistry of chloro-2-vinylstilbenes
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Short irradiation at 300 nm of α-chloro- and β-chloro-2-vinylstilbene (20 and 21) leads to a mixture of 2-vinyltolane (35) and 2-vinylstilbene (1) accompanied by the cis- and trans-isomers of the starting compounds.Evidence is found for the occurrence of an ionic intermediate during the photolysis of 20 in methanol.At 360 nm, an additional, small amount of 1-chloro-endo- and 1-chloro-exo-6-phenylbenzobicyclohex-2-ene (39) is formed formed from 20.The elimination of hydrogen chloride also occurs during the irradiation of 2-(2-chlorovinyl)stilbene (23) and leads to 2-ethynylstilbene (41).The acetylenic compounds are photocyclized into 2-phenylnaphthalene (38).However, 2-(1-chlorovinyl)stilbene (22) reacts without loss of chlorine to give 1-chloro-exo-5-phenylbenzobicyclo-hex-2-ene (40).This exceptional reaction mode is due to a much higher rate of photocyclization resulting from less distortion in the stilbene moiety and a preference for a conformation better suited to the reaction of the 2-(1-chlorovinyl)stilbene molecule.It is shown that both isomers of 22 can photocyclize into 40.
- Brouw, P. M. op den,Laarhoven, W. H.
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- Iminyls. Part 9. Intramolecular Addition of an Iminyl to an Alkene
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Phenyl o-styrylphenyl iminyl, generated by oxidation of the corresponding O-carboxymethyloxime with persulphate and by thermolysis of the perester of that acid, cyclises to give a mixture of isoquinoline and 1H-isoindole derivatives.The intermediate radicals have been investigated by e.s.r.
- Atmaram, Shiravante,Forrester, Alexander R.,Gill, Melvin,Thomson, Ronald H.
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p. 1721 - 1724
(2007/10/02)
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