- Coupling of Reformatsky Reagents with Aryl Chlorides Enabled by Ylide-Functionalized Phosphine Ligands
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The coupling of aryl chlorides with Reformatsky reagents is a desirable strategy for the construction of α-aryl esters but has so far been substantially limited in the substrate scope due to many challenges posed by various possible side reactions. This limitation has now been overcome by the tailoring of ylide-functionalized phosphines to fit the requirements of Negishi couplings. Record-setting activities were achieved in palladium-catalyzed arylations of organozinc reagents with aryl electrophiles using a cyclohexyl-YPhos ligand bearing an ortho-tolyl-substituent in the backbone. This highly electron-rich, bulky ligand enables the use of aryl chlorides in room temperature couplings of Reformatsky reagents. The reaction scope covers diversely functionalized arylacetic and arylpropionic acid derivatives. Aryl bromides and chlorides can be converted selectively over triflate electrophiles, which permits consecutive coupling strategies.
- Hu, Zhiyong,Wei, Xiao-Jing,Handelmann, Jens,Seitz, Ann-Katrin,Rodstein, Ilja,Gessner, Viktoria H.,Goo?en, Lukas J.
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supporting information
p. 6778 - 6783
(2021/02/01)
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- Halogen-Bridged Methylnaphthyl Palladium Dimers as Versatile Catalyst Precursors in Coupling Reactions
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Halogen-bridged methylnaphthyl (MeNAP) palladium dimers are presented as multipurpose Pd-precursors, ideally suited for catalytic method development and preparative organic synthesis. By simply mixing with phosphine or carbene ligands, they are in situ converted into well-defined monoligated complexes. Their catalytic performance was benchmarked against state-of-the-art systems in challenging Buchwald–Hartwig, Heck, Suzuki and Negishi couplings, and ketone arylations. Their use enabled record-setting activities, beyond those achievable by optimization of the ligand alone. The MeNAP catalysts permit syntheses of tetra-ortho-substituted arenes and bulky anilines in near-quantitative yields at room temperature, allow mono-arylations of small ketones, and enable so far elusive cross-couplings of secondary alkyl boronic acids with aryl chlorides.
- Doppiu, Angelino,Goo?en, Lukas J.,Hu, Zhiyong,Pirkl, Nico,Sivendran, Nardana
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supporting information
p. 25151 - 25160
(2021/10/19)
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- Iron-Catalyzed Isopropylation of Electron-Deficient Aryl and Heteroaryl Chlorides
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Traditional methods for the preparation of secondary alkyl-substituted aryl and heteroaryl chlorides challenge both selectivity and functional group tolerance. This contribution describes the use of statistical design of experiments to develop an effective procedure for the preparation of isopropyl-substituted (hetero)arenes with minimal isopropyl to n-propyl isomerization. The reaction tolerates electronically diverse aryl chloride coupling partners, with excellent conversion observed for strongly electron-deficient aromatic rings, such as esters and amides. Electron-rich systems, including methyl- and methoxy-substituted aryl chlorides, were found to be less reactive. Furthermore, the reaction was found to be most successful when heteroaryl chlorides were submitted to the cross-coupling protocol. By mapping substituent effects on reaction selectivity, we were able to show that electron-deficient aryl chlorides are essential for efficient coupling, and use electronic structure calculations to predict the likelihood of successful coupling through the estimation of the electron affinity of each aryl chloride. Moderate isolated yields were achieved with selected aryl chlorides, and moderate to good isolated yields were obtained for all the heteroaryl chlorides coupled. Excellent selectivity was observed when a 2,6-dichloroquinoline was used, allowing mono-substitution on a challenging substrate. (Figure presented.).
- Sanderson, James N.,Dominey, Andrew P.,Percy, Jonathan M.
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p. 1007 - 1017
(2017/03/27)
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- Pd-PEPPSI-IPent-SiO2: A Supported Catalyst for Challenging Negishi Coupling Reactions in Flow
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A silica-supported precatalyst, Pd-PEPPSI-IPent-SiO2, has been prepared and evaluated for its proficiency in the Negishi cross-coupling of hindered and electronically deactivated coupling partners. The precatalyst Pd-PEPPSI-IPent loaded onto packed bed columns shows high catalytic activity for the room-temperature coupling of deactivated/hindered biaryl partners. Also for the first time, the flowed Csp3–Csp2 coupling of secondary alkylzinc reagents to (hetero)aromatics has been achieved with high selectivity with Pd-PEPPSI-IPent-SiO2. These couplings required residence times as short as 3 minutes to effect completion of these challenging transformations with excellent selectivity for the nonrearranged product.
- Price, Gregory A.,Hassan, Abbas,Chandrasoma, Nalin,Bogdan, Andrew R.,Djuric, Stevan W.,Organ, Michael G.
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supporting information
p. 13347 - 13350
(2017/10/17)
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- Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents
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Palladium-catalysed cross-coupling of secondary C(sp3) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C-C bond formation with organolithium reagents, herein we present a Pd-catalysed cross-coupling of secondary alkyllithium reagents with aryl and alkenyl bromides. The reaction proceeds at room temperature and on short timescales with high selectivity and yields. This methodology is also applicable to hindered aryl bromides, which are a major challenge in the field of metal catalysed cross-coupling reactions.
- Vila, Carlos,Giannerini, Massimo,Hornillos, Valentin,Fananas-Mastral, Martin,Feringa, Ben L.
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p. 1361 - 1367
(2014/03/21)
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- Stereospecific Pd-catalyzed cross-coupling reactions of secondary alkylboron nucleophiles and aryl chlorides
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We report the development of a Pd-catalyzed process for the stereospecific cross-coupling of unactivated secondary alkylboron nucleophiles and aryl chlorides. This process tolerates the use of secondary alkylboronic acids and secondary alkyltrifluoroborates and occurs without significant isomerization of the alkyl nucelophile. Optically active secondary alkyltrifluoroborate reagents undergo cross-coupling reactions with stereospecific inversion of configuration using this method.
- Li, Ling,Zhao, Shibin,Joshi-Pangu, Amruta,Diane, Mohamed,Biscoe, Mark R.
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supporting information
p. 14027 - 14030
(2015/01/08)
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- Evaluation of adenine as scaffold for the development of novel P2X3 receptor antagonists
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Ligands that selectively block P2X3 receptors localized on nociceptive sensory fibres may be useful for the treatment of chronic pain conditions including neuropathic pain, migraine, and inflammatory pain. With the aim at exploring the suitability of aden
- Lambertucci, Catia,Sundukova, Mayya,Kachare, Dhuldeo D.,Panmand, Deepak S.,Dal Ben, Diego,Buccioni, Michela,Marucci, Gabriella,Marchenkova, Anna,Thomas, Ajiroghene,Nistri, Andrea,Cristalli, Gloria,Volpini, Rosaria
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supporting information
p. 41 - 50
(2013/10/01)
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- Amino acid intercalated layered double hydroxide catalyzed chemoselective methylation of phenols and thiophenols with dimethyl carbonate
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Sixteen different amino acids are intercalated into Mg-Al layered double hydroxides (LDHs) by the reconstruction method and are characterized by powder XRD and FT-IR. The intercalated amino acid-LDHs (AA-LDHs) are used as catalysts for chemoselective O-methylation of phenol and S-methylation of thiophenol with dimethyl carbonate (DMC) as a green methylating agent. The intercalation behavior of various amino acids is influenced by various structural features of amino acids, namely, carbon chain length, structure, and physicochemical properties. In particular, amino acids possessing a hydrophobic side-chain show higher catalytic activity. A suitable reaction mechanism is proposed. The catalyst can also be recycled.
- Subramanian, Thirumeni,Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
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p. 7167 - 7170
(2013/12/04)
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- Pd-PEPPSI-IPentCl: A highly effective catalyst for the selective cross-coupling of secondary organozinc reagents
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No migration? No problem. A series of new N-heterocyclic carbene based Pd complexes has been created and evaluated in the Negishi cross-coupling of aryl and heteroaryl chlorides, bromides, and triflates with a variety of secondary alkylzinc reagents (see scheme). The direct elimination product is nearly exclusively formed; in most examples there is no migratory insertion at all. Copyright
- Pompeo, Matthew,Hadei, Niloufar,Organ, Michael G.,Froese, Robert D. J.
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supporting information
p. 11354 - 11357,4
(2012/12/12)
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- Pd-PEPPSI-IPentCl: A highly effective catalyst for the selective cross-coupling of secondary organozinc reagents
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No migration? No problem! A series of new N-heterocyclic carbene based Pd complexes has been created and evaluated in the Negishi cross-coupling of aryl and heteroaryl chlorides, bromides, and triflates with a variety of secondary alkylzinc reagents (see scheme). The direct elimination product is nearly exclusively formed; in most examples there is no migratory insertion at all. Copyright
- Pompeo, Matthew,Froese, Robert D. J.,Hadei, Niloufar,Organ, Michael G.
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supporting information
p. 11354 - 11357
(2013/01/15)
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- Negishi cross-coupling of secondary alkylzinc halides with aryl/heteroaryl halides using Pd-PEPPSI-IPent
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Pd-PEPPSI-IPent has proven to be an excellent catalyst for the Negishi cross-coupling reaction of secondary alkylzinc reagents with a wide variety of aryl/heteroaryl halides. Importantly, β-hydride elimination/migratory insertion of the organometallic leading to the production of isomeric coupling products has been significantly reduced using the highly-hindered Ipent ligand.
- Alimsiz, Seluk,Organ, Michael G.
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supporting information; experimental part
p. 5181 - 5183
(2011/06/09)
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- Sequential Birch reaction and asymmetric Ir-catalyzed hydrogenation as a route to chiral building blocks
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A range of 1,2,4-trisubstituted cyclohexadienes obtained from the Birch reaction were hydrogenated asymmetrically to produce synthetically valuable chiral compounds in high enantio- and diastereoselectivity. The Royal Society of Chemistry.
- Paptchikhine, Alexander,Itto, Kaori,Andersson, Pher G.
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supporting information; experimental part
p. 3989 - 3991
(2011/06/09)
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- Synthesis of novel structurally simplified estrogen analogues with electron-donating groups in ring A
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A library of 25 novel estrogen analogues were prepared in five to eight steps from mostly commercially available substituted anisoles via bromination, formylation, Corey-Fuchs reaction, elimination, and Sonogashira reaction. Georg Thieme Verlag Stuttgart.
- Tietze, Lutz F.,Vock, Carsten A.,Krimmelbein, Ilga K.,Nacke, Linda
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experimental part
p. 2040 - 2060
(2009/12/27)
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- Rare earth(III) perfluorooctanesulfonates catalyzed Friedel-Crafts alkylation in fluorous biphase system
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The catalyst of rare earth(III) perfluorooctanesulfonates (RE(OSO 2C8F17)3, RE = Sc, Y, La-Lu) were prepared from either rare earth chlorides(III) or oxides and perfluorooctanesulfonic acid. The perflates thus obtained act as novel catalysts for Friedel-Crafts alkylation in fluorous biphasic system. Perfluorohexane (C6F14), perfluoromethylcyclohexane (C7F 14), perfluorotoluene (C7F8), perfluorooctane (C8F18), perfluorooctyl bromide (C8F 17Br) and perfluorodecalin (C10F18, cis- and trans-mixture) can be used as fluorous solvents for this reaction. By simple separation of the fluorous phase containing only catalyst, alkylation can be repeated many times.
- Yi, Wen-Bin,Cai, Chun
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p. 831 - 833
(2007/10/03)
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- 2-Hydroxy-4-isopropylbenzaldehyde, a potent partial tyrosinase inhibitor
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Chamaecin (2-hydroxy-4-isopropylbenzaldehyde) was synthesized and tested for its tyrosinase inhibitory activity. It partially inhibits the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase with an IC50 of 2.3 μ
- Nihei, Ken-Ichi,Yamagiwa, Yoshiro,Kamikawa, Tadao,Kubo, Isao
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p. 681 - 683
(2007/10/03)
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- Compounds having activity as inhibitors of cytochrome P450RAI
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Compounds having Formula 1 wherein the symbols have the meaning defined in the specification are inhibitors of the cytochrome P450RAI (retinoic acid inducible) enzyme, and are used for treating diseases responsive to treatment by retinoids.
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Page column 123
(2010/01/31)
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- Compounds having activity as inhibitors of cytochrome P450RAI
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Compounds having Formula 2 wherein the symbols have the meaning defined in the specification are inhibitors of the cytochrome P450RAI (retinoic acid inducible) enzyme, and are used for treating diseases responsive to treatment by retinoids.
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Page column 121
(2010/01/31)
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- Compounds having activity as inhibitors of cytochrome P450RAI
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Compounds having Formula 8 wherein the symbols have the meaning defined in the specification are inhibitors of the cytochrome P450RAI (retinoic acid inducible) enzyme, and are used for treating diseases responsive to treatment by retinoids.
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Page column 45, 122
(2010/11/29)
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- Compounds having activity as inhibitors of cytochrome P450RAI
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Compounds having Formula 1 wherein the symbols have the meaning defined in the specification are inhibitors of the cytochrome P450RAI (retinoic acid inducible) enzyme, and are used for treating diseases responsive to treatment by retinoids.
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- Methods of providing and using compounds having activity as inhibitors of cytochrome P450RAI
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Novel compounds having the Formulas 1 through 8, wherein the symbols have the meaning defined in the specification, and certain previously known compounds have been discovered to act as inhibitors of the cytochrome P450RAI (retinoic acid inducible) enzyme, and are used for treating diseases responsive to treatment by retinoids. The compound can also be used in co-treatment with retinoids.
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- Use of conjugated dienones in cyclialkylations: The total syntheses of (±)-barbatusol, (±)-pisiferin, (±)-deoxofaveline, (±)-xochitlolone, and (±)-faveline
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Concise syntheses of five tricyclic diterpenoids are reported. The key reaction in each synthesis is a cyclialkylation of a functionalized arene with a Lewis acid-activated conjugated dienone to generate a 6,7,6-fused tricycle.
- Majetich, George,Hicks, Rodgers,Zhang, Yong,Tian, Xinrong,Feltman, Terry Lee,Fang, Jing,Duncan Jr., Sam
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p. 8169 - 8185
(2007/10/03)
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- An expedient synthesis of isopropyl anisoles and veratroles
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Isopropyl-substituted anisoles and veratroles were obtained in high yields (89-93%) on the aqueous work-up of the reaction of 3-(methoxyphenyl)-2-oxopropanoic acids with iodomethane and potassium hydroxide in dimethyl sulfoxide.
- Yli-Kauhaluoma, Jari T.,Janda, Kim D.
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p. 4509 - 4510
(2007/10/02)
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- FRIEDEL-CRAFTS ALKYLATION OF ANISOLE AND ITS COMPARISON WITH TOLUENE. PREDOMINANT ORTHO-PARA SUBSTITUTION UNDER KINETIC CONDITIONS AND THE EFFECT OF THERMODYNAMIC ISOMERIZATIONS
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The AlCl3 and BF3, as well as 65percent HPF6, catalyzed Friedel-Crafts alkylation of anisole with alkyl halides and alkohols was investigated.The alkylation of anisole with lower catalyst concentrations under mild conditions shows predominant ortho/para directing effect generally with a ratio of c.a. 2:1, with the amount of meta isomer uniformly less than 3percent.With "swamping" catalyst conditions the amount of meta substitution in methylation and ethylation can substantially increase.The isomer distribution in tert-butylation changes with time due to rapid ortho-para interconversion.Consequently, the AlCl3-catalyzed isomerization of isomeric alkylanisoles was also studied.In case of tert-butylanisoles, the ortho isomer shows relatively rapid conversion into para followed by much slower isomerization to meta.The para and meta isomers show isomerization to meta-para mixtures.Isomerization of ethyl-, isopropyl-, and benzylanisoles is generally slow whereas methylanisoles do not isomerize.Comparing results of the alkylation of anisole with toluene leads to the conclusion that the latter are readily affected by concurrent (and in some cases consecutive) isomerization.As the barrier for isomerization in the benzenium ion intermediates of the alkylations is higher in the case of CH3O- than CH3-substituted systems, anisole tends to give the kinetically controlled ortho-para alkylation products and the amount of meta isomer is low.Study of alkylation of 3,5-di- and 2,4,6-trideuterated toluene and anisole and comparing retained deuterium contents with isomer distributions shows that alkylated product formation in case of toluene, but not of anisole, is proceeded by intramolecular, 1,2-alkyl, and hydrogen-deuterium shifting resulting also in increased meta substitution.This effect is most predominant in methylation and ethylation where the alkyl shifts are intramolecular but not in tert-butylation and benzylation, where alkyl transfer is intermolecular.Isopropylation is intermediate in nature.No simple selectivity-reactivity relationship is indicated in the studied alkylation reactions.As shown in benzylations with increasingly electron-donating and -withdrawing substituted benzyl chlorides overall rate (i.e., substrate selectivity) and isomer distributions (i.e., regioselectivity) are not determined in the same step as significantly decreased substrate selectivity is not accompanied by loss of positional selectivity.Previously reported alkylations showing high degree of meta substitution therefore, must have been affected by thermodynamically controlled rearrangement processes, including intramolecular alkyl and hydrogen shifts in the arenium ion intermediates of the alkylation reactions.These are to be differentiated from possible subsequent product isomerizations.Under predominantly kinetic conditions anisole as well as toluene are substantially ortho-para directing in alkylations, as in other electrophilic aromatic substitutions.
- Olah, George A.,Olah, Judith A.,Ohyama, Toshiyuki
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p. 5284 - 5290
(2007/10/02)
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