- Nickel-Catalyzed Formal Homocoupling of Methoxyarenes for the Synthesis of Symmetrical Biaryls via C-O Bond Cleavage
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A new method has been developed for the nickel-catalyzed homocoupling of methoxyarenes via C-O bond cleavage using a diboron reagent. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand was found to be critical to the success of the reaction. This new method allows the synthesis of a wide range of biaryl compounds.
- Nakamura, Keisuke,Tobisu, Mamoru,Chatani, Naoto
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- Homocoupling of arylboronic acids catalyzed by 1,10-phenanthroline-ligated copper complexes in air
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The efficient homocoupling of arylboronic acids was achieved by using the catalytic combination of inexpensive copper salts and 1,10-phenanthroline as aligand. The homocoupling reaction proceeds at ambient temperature in air without any additives such as base or oxidant. This method tolerates various substituents on the arylboronic acids such as halogens, carbonyls, and a nitro group. As a result, 25 symmetrical biaryls were obtained from readily available arylboronic acids in 19-92% isolated yields. A binuclear (μ- hydroxido)copper complex is assumed as the catalytically active species, which undergoes efficient transmetalation with arylboronic acids to produce dinuclear arylcopper complexes. The binuclear structure is assumed to be essential for the bimetallic reductive elimination of biaryls as well as the oxidative restoration of the catalyst. Wiley-VCH Verlag GmbH & Co, KGaA.
- Kirai, Naohiro,Yamamoto, Yoshihiko
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- Reductive Coupling of Aryl Halides via C—H Activation of Indene
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This paper describes the first case of a reductive coupling reaction with indene, a non-heteroatom olefin used as a reducing agent. The scope of the substrate is wide. The homo-coupling, cross-coupling, and synthesis of 12 and 14-membered rings were realized. The control experiment, indene-product curve and density functional theory calculations showed that the η3-palladium indene intermediate was formed by C—H activation in the presence of cesium carbonate. We speculate that the final product was obtained through a Pd (IV) intermediate or aryl ligand exchange. In addition, we excluded the formation of palladium anion (Pd(0)?) intermediates.
- Zhang, Bo-Sheng,Yang, Ying-Hui,Wang, Fan,Gou, Xue-Ya,Wang, Xi-Cun,Liang, Yong-Min,Li, Yuke,Quan, Zheng-Jun
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- Synthesis of biaryl compounds via Suzuki homocoupling reactions catalyzed by metal organic frameworks encapsulated with palladium nanoparticles
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Heterogeneous homocoupling reactions of phenylboronic acids were greatly accelerated via Suzuki homocoupling reactions. In this work, a tandem route was designed which firstly one part of phenylboronic acids reacted with iodine to form iodobenzenes, then another part of phenylboronic acids coupled with iodobenzenes to produce biaryl compounds. The tandem reaction were catalyzed by a bifunctional heterogeneous catalyst of metal organic frameworks encapsulated with palladium nanoparticles (Pd?MOFs). This strategy for forming symmetric C-C bond between benzene rings has obvious advantages such as high efficiency, easy separation, good recyclability and no addition of toxic halogenated benzene.
- Bao, Yan-Sai,Cui, Xin-Yu,Han, Zheng-Bo,Li, Xin,Tang, Hong,Yang, Ming,Zhang, Yu-Yang,Zhao, Kun,Zhou, Mei-Li
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- Synthesis of Enaminone-Pd(II) Complexes and Their Application in Catalysing Aqueous Suzuki-Miyaura Cross Coupling Reaction
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A series of Pd(II)-enaminone complexes, termed Pd(eao)2, have been synthesized and characterized. The investigation on the catalytic activities of these new Pd(II)-reagents has proved that the Pd(eao)2-1 possesses excellent catalytic activity for the Suzuki- Miyaura cross coupling reactions of aryl bromides/chlorides with aryl/vinyl boronic acids in the environmentally benign media of aqueous PEG400 at low loading (5 mol‰). The superiority of this Pd(II)-reagent to those commercial Pd(II) and Pd(0) catalysts in catalyzing the reactions has been confirmed by parallel experiments. What's more, Pd(eao)2-2 has been found as a practical catalyst for the homo-coupling reactions of aryl boronic acids.
- Fu, Leiqing,Cao, Xiaoji,Wan, Jie-Ping,Liu, Yunyun
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p. 254 - 258
(2020/01/25)
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- Acid-catalyzed rearrangements in arenes: Interconversions in the quaterphenyl series
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Arenes undergo rearrangement of phenyl, alkyl, halogen and other groups through the intermediacy of ipso arenium ions in which a proton is attached at the same carbon as the migrating substituent. Interconversions among the six quaterphenyl isomers have b
- Skraba-Joiner, Sarah L.,Holt, Carter J.,Johnson, Richard P.
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p. 2655 - 2663
(2019/12/11)
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- Role of the base and control of selectivity in the suzuki-miyaura cross-coupling reaction
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The outcome of the Suzuki-Miyaura cross-coupling for the direct competition reaction between two boronic acids was evaluated under routine synthesis conditions. The reaction selectivity was found to depend on the amount of the base used, with fewer bases
- Lima, Carlos F. R. A. C.,Rodrigues, Ana S. M. C.,Silva, Vera L. M.,Silva, Artur M. S.,Santos, Luis M. N. B. F.
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p. 1291 - 1302
(2014/05/20)
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- Active-alkali metal promoted reductive desulfurization of dibenzothiophene and its hindered analogues
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Dibenzothiophene and some related organosulfur compounds are efficiently reductively desulfurized under mild reaction conditions, with Na and/or Li metal in the presence of a catalytic amount of tetraphenylethylene in THF at room temperature. This simple methodology was applied to the synthesis of several substituted biphenyls, thus realizing a connection between the directing properties of the sulfur atom of dibenzothiophene and the efficiency of 1,2-dianions of tetraphenylethane as homogenous electron transfer reagents.
- Pittalis, Mario,Azzena, Ugo,Pisano, Luisa
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p. 207 - 211
(2013/01/15)
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- Syntheses and Spectral Characteristics of Seven Polyphenyls Containing Highly Branched para-Phenylene Ring(s)
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Seven polyphenyls, including four new compounds, 2,2',6'- (2) and 3,2',6'-triphenyl-p-terphenyl (3), 3',5'-diphenyl-p-quarterphenyl (4), and 2-phenyl-3'-(2-biphenylyl)-p-terphenyl (7), were synthesized by the Ullmann coupling reaction of aryl iodide(s) or by the Kharash type coupling reaction of aryl Grignard reagent with an aryl iodide catalyzed by bis(acetylacetonato)-nickel(II).Infrared spectral studies of the polyphenyls showed that the range of 730-770 cm-1, generally accepted as the position of the out-of-plane C-H bending bands of the phenyl ring, should be widened slightly to 730-786 cm-1.The high frequency bands were confirmed to be correlated closely to the overcrowding by terminal rings in the complex structures.Proton magnetic resonance spectral studies indicated that he characteristic spectral features of the branched polyphenyls were consistent with their conformational aspects deduced from stereomodels.In the ultraviolet spetcral studies the polyphenyls containing highly branched p-phenylene ring(s) showed intense K-bands or shoulders at locations very similar to those of the corresponding linear polyphenyls containing the same number of p-phenylene rings. Keywords -- Ullmannn reaction; Ni-complex-catalyzed cross-coupling; quinquephenyl; sexiphenyl; octiphenyl; IR; UV; 1H-NMR
- Fujioka, Yasuhiro,Ozasa, Shigeru,Sato, Kazumi,Ibuki, Eiichi
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- Syntheses and Spectral Properties of several Branched-chain Polyphenyls containing 1,2,3-Trisubstituted Ring(s)
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Nine polyphenyls, including six new compound, 3'-phenyl-o-quaterphenyl (3), 2,6-diphenyl-m- (4), 2,6-diphenyl-p-terphenyl (5), 2,6,5'-triphenyl-m-terphenyl (6), 2',2''-diphenyl-m-quaterphenyl (8), and 2'-(phenyl-d5)-m-terphenyl (9), were synthesized by the Ullmann coupling reaction of aryl iodide(s) or by the Karash-type coupling reaction of deuterated aryl Grignard reagent with aryl iodide catalyzed by bis(acetylacetonato)-nickel(II).Infrared studies of the polyphenyls showed that the range 730-770 cm-1, generally accepted as the position of the C-H out-of-plane bending bands of phenyl rings, should be widened slightly to 730-781 cm-1.The high frequency bands were found to be correlated closely to the sterically overcrowded structure of terminal rings.Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the polyphenyls containing 1,2,3-trisubstituted ring(s) were fully consistent with their conformational aspects deduced from stereomodels.Ultraviolet spectral data suggeted that the most probable conformation of the highly crowded 3',6''-diphenyl-o-quaterphenyl (1) is one in which the interplanar angles of the pivot bonds between the 1,2,3-trisubstituted ring and three benzene rings are rather smaller than those of the less crowded 2'-phenyl-m-terphenyl (2).Keywords - Ullmann reaction; nickel-complex-catalyzed cross-coupling; quaterphenyl; deuterated quaterphenyl; quinquephenyl; sexiphenyl; polyphenyl; IR; UV; 1H-NMR
- Ozasa, Shigeru,Fujioka, Yasuhiro,Kikutake, Jun-ichiro,Ibuki, Eiichi
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p. 1572 - 1581
(2007/10/02)
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- Syntheses and Spectral Properties of Several Branched-chain Polyphenyls containing 1,3,5-Trisubstituted Ring(s)
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Six polyphenyls, including four new compounds, 5',5''-di(2-biphenylyl)-2,2'''-diphenyl-m-quaterphenyl (3), 2,5',2''-triphenyl-m-terphenyl (4), 3,5-di(2-biphenylyl)-o-terphenyl (5), and 5''-(3-biphenylyl)-m-quinquephenyl (6), were synthesized by the Ullmann coupling reaction of iodo compounds.Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the polyphenyls containing 1,3,5-trisubstituted ring system(s) were fully compatible with their conformational aspects deduced from stereomodels.Ultraviolet spectral data indicated that the dihedral angle of the pivot bond of the branched ring in the polyphenyls in solution is very similar to that of biphenyl.Keywords - Ullmann reaction; quinquephenyl; sexiphenyl; septiphenyl; decaphenyl; polyphenyl; IR; UV; 1H-NMR
- Ozasa, Shigeru,Fujioka, Yasuhiro,Hashino, Hiromi,Kimura, Naoko,Ibuki, Eiichi
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p. 2313 - 2320
(2007/10/02)
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- Cross-coupling Reaction of Aryl Grignard Reagents with Aromatic Halides catakyzed by Bis(acetylacetonato)nickel(II)
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A series of cross-coupling reactions of aryl Grignard reagents with aromatic iodides catalyzed by bis(acetylacetonato)nickel(II) was studied to establish reaction conditions under which the cross-coupling proceeded selectively and quantitatively.Under the standard conditions thus selected, the coupling reactions proceeded within a few hours by a simple procedure and gave very pure product in high yield.Thus, the Kharash-type cross-coupling reaction was found to be very useful for the synthesis of a variety of polyphenyls.With some reactants of more or less crowded geometry, the reaction resulted in rather low yields of polyphenyls.This cross-coupling was successfully applied to the synthesis of a new compound, 2,6,2',6'-tetraphenylbiphenyl, having a highly non-planar arrangement of ?-systems.
- Ibuki, Eiichi,Ozasa, Shigeru,Fujioka, Yasuhiro,Yanagihara, Yoshihiko
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p. 802 - 809
(2007/10/02)
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- Syntheses and Spectral Properties of Several Unsymmetrical Sexiphenyls
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Six sexiphenyls, including four new isomers, 2,3'-di(4-biphenylyl)biphenyl (2), 4-(2-biphenylyl)-o- (4), 4-(2-biphenylyl)-m-quaterphenyl (5), and 2-phenyl-p-quinquephenyl (6), were synthesized by the Ullmann cross-coupling of iodobiphenyl and diiodobiphenyl or of two kinds of iodoterphenyls.The characteristic bands of the infrared spectra (680-920 cm-1) and signals of the proton magnetic resonance spectra of the sexiphenyls were assigned tentatively and are discussed briefly.The remarkable high field shifts of the p-phenylene proton signals in 4 (1.23 and 0.89 ppm) as compared with that of p-terphenyl (δ 7.68) presumably reflect the ring current effects caused by the presence of adjacent o-phenylene rings.Ultraviolet spectral studies indicated that the absorption curves of the sexiphenyls were related closely to those of the polyphenyls corresponding to their partial structures.Keywords-Ullmann reaction; IR; UV; 1H-NMR; sexiphenyls; polyphenyls
- Ozasa, Shigeru,Fujioka, Yasuhiro,Ibuki, Eiichi
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p. 2698 - 2704
(2007/10/02)
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- Preparation and Conformational Properties of Several 1,8-Diarylnaphthalenes
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Six new 1,8-diarylnaphthalenes, each having closely held parallel aromatic rings, were synthesized by a Kharash-type Grignard cross-coupling of arylmagnesium iodide and 1,8-diiodonaphthalene in the presence of N,N'-bis(1-methyl-3-oxobutylidene)ethylenediaminatonickel(II) as a catalyst.Among them, 1,8-di(1-naphthyl)naphthalene was obtained as cis and trans rotamers, caused by the restricted rotation at the 1,8-position.Interconversion between the rotamers on heating above their melting points was confirmed by differential scanning calorimetry.The proton magnetic resonance spectral studies of the 1,8-diarylnaphthalenes indicated the presence of a face-to-face arrangement of aromatic rings in the peri-position.Two new 8,8'-diaryl-1,1'-binaphthyls, each having two sets of closely held parallel aromatic rings, were isolated as minor coupling products.Trans-trans conformations were proposed for them on the basis of their thermal behavior.Several nickel(II) complexes were found to be effective catalysts for preparative Grignard cross-coupling reaction involving closely crowded geometry.
- Ibuki, Eiichi,Ozasa, Shigeru,Fujioka, Yasuhiro,Mizutani, Hiroshi
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p. 845 - 851
(2007/10/02)
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- Syntheses and Physical Properties of Several Octiphenyls and a Septiphenyl
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Six symmetrical linear octiphenyls were synthesized by the Ullmann homo-coupling reaction of iodoquaterphenyl.Another satisfactory method for synthesizing octiphenyls is also described, i.e., a Kharash-type Grignard cross-coupling of biphenylylmagnesium bromide and diiodoquaterphenyl in the presence of bis(acetylacetonato)nickel(II).Moreover, m-septiphenyl was succesfully synthesized by deamination of the corresponding amino compound.Infrared studies of the polyphenyls indicated that the fine-structure bands in the regions of 770-810 and 870-915 cm-1 may be considered as indicators of the presence of consecutive m-phenylene rings, regardless of the existence of o- or p-phenylene rings.The ultraviolet spectra of the octiphenyls, which contain two kinds of linkages, showed absorption curves closely related to those of quaterphenyls corresponding to the structural units of the former compounds.The nuclear magnetic resonance spectra of the polyphenyls without an o-phenylene ring showed multiplet peaks due to the resonances of an isolated m-phenylene proton at the lowest field within a narrow region (δ 7.81-7.95).Hueckel molecular orbital calculations of the longest wavelength absorption bands of ten polyphenyls were carried out.The calculated and observed wavelengths were in rather good agreement except for the cases of three compounds.Keywords - Ullmann reaction; Ni-complex-catalyzed cross-coupling; octiphenyls; septiphenyls; IR; UV; NMR; MO; quaterphenyl derivatives; polyphenyls
- Ozasa, Shigeru,Fujioka, Yasuhiro,Fujiwara, Michiko,Ibuki, Eiichi
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p. 3210 - 3222
(2007/10/02)
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- Studies of Polyphenyls and Polyphenylenes. II. The Synthesis and Physical Properties of Polyphenyls Containing Para Linkage
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Twelwe linear polyphenyls, including quinque- to octiphenyl, were synthesized by the Ullmann cross-coupling reaction of iodobiphenyl with diiodobenzene or iodoterphenyl.Ultraviolet spectral studies of the polyphenyls indicated that the positions of the K-bands above ca.260 nm, regardless of the presence of o- or m-phenylene unit(s), may be considered to be an indication of the approximate number of consecutive p-phenylene units.Infrared studies also showed that the locations of strong or medium bands in the 815-850 cm-1 region may give the same information.The HMO calculations of the longest wavelength absorption bands of twenty-four polyphenyls were carried out.A comparison between the calculated and observed wavelengths gave rather good agreement, except in the cases of two compounds.The signals of the proton magnetic resonanse spectra of eighteen polyphenyls were assigned tentatively.The correlations between the arrangement of the benzene rings and the spectral patterns are discussed.
- Ozasa, Shigeru,Hatada, Noriko,Fujioka, Yasuhiro,Ibuki, Eiichi
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p. 2610 - 2617
(2007/10/02)
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- Syntheses and Physical Properties of Several Symmetrical Sexiphenyls
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Seven sexiphenyls, including three new isomers, 3,4,3',4'-tetraphenylbiphenyl (Id), 2,5,2',5'-tetraphenylbiphenyl (IIId), and 2,2'-di(3-biphenylyl)biphenyl (Vd), were synthesized by Ullmann homo-coupling of iodoterphenyl.The characteristic band of the infrared spectra (675-920 cm-1) and signals of the nuclear magnetic resonance spectra of the sexiphenyls were assigned tentatively and are discussed briefly.Infrared studies indicated that the range 730-770 cm-1, generally accepted as the position of the C-H out-of-plane bending bands of phenyl rings, should be widened slightly to 730-782 cm-1.The ultraviolet spectra commonly displayed an intense E-band in the narrow region of 192-207 nm.The prominent K-band above ca. 260 nm of branched sexiphenyls was taken as indicative of the presence of one or more p-linkages, as in the case of linear compounds.Keywords - polyphenyls; Ullmann reaction; infrared spectra; ultraviolet spectra; NMR spectra; iodoterphenyls
- Ibuki, Eiichi,Ozasa, Shigeru,Fujioka, Yasuhiro,Kitamura, Hirohiko
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p. 1468 - 1476
(2007/10/02)
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