- Supported palladium nanoparticle-catalysed Suzuki–Miyaura cross-coupling approach for synthesis of aminoarylbenzosuberene analogues from natural precursor
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A semi-synthetic method has been developed for the synthesis of aminoarylbenzosuberenes (AABs) from naturally occurring himachalenes, an isomeric mixture of sesquiterpenes present in Cedrus deodara oil. Polymer-stabilized Pd(0) nanoparticle-catalysed Suzu
- Bharti, Richa,Bal Reddy,Kumar, Sandeep,Das, Pralay
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Read Online
- Bathocuproine-Enabled Nickel-Catalyzed Selective Ullmann Cross-Coupling of Two sp 2-Hybridized Organohalides
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Cross-coupling reactions are essential for the synthesis of complex organic molecules. Here, we report a nickel-catalyzed Ullmann cross-coupling of two sp 2-hybridized organohalides, featuring high cross-selectivity when the two coupling partners are used in a 1:1 ratio. The high chemoselectivity is governed by the bathocuproine ligand. Moreover, the mild reductive reaction conditions allow that a wide range of functional groups are compatible in this Ullmann cross-coupling.
- Li, Yuqiang,Yin, Guoyin
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supporting information
p. 1657 - 1661
(2021/09/13)
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- Rh(II)-Catalyzed Alkynylcyclopropanation of Alkenes by Decarbenation of Alkynylcycloheptatrienes
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Alkynylcyclopropanes have found promising applications in both organic synthesis and medicinal chemistry but remain rather underexplored due to the challenges associated with their preparation. We describe a convenient two-step methodology for the alkynyl
- Echavarren, Antonio M.,Mato, Mauro,Montesinos-Magraner, Marc,Sugranyes, Arnau R.
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supporting information
p. 10760 - 10769
(2021/07/28)
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- Alumina-Mediated π-Activation of Alkynes
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The ability to induce powerful atom-economic transformation of alkynes is the key feature of carbophilic π-Lewis acids such as gold- and platinum-based catalysts. The unique catalytic activity of these compounds in electrophilic activations of alkynes is explained through relativistic effects, enabling efficient orbital overlapping with π-systems. For this reason, it is believed that noble metals are indispensable components in the catalysis of such reactions. In this study, we report that thermally activated γ-Al2O3activates enynes, diynes, and arene-ynes in a manner enabling reactions that were typically assigned to the softest π-Lewis acids, while some were known to be triggered exclusively by gold catalysts. We demonstrate the scope of these transformations and suggest a qualitative explanation of this phenomenon based on the Dewar-Chatt-Duncanson model confirmed by density functional theory calculations.
- Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
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p. 15420 - 15426
(2021/09/30)
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- Small Gold(I) and Gold(I)–Silver(I) Clusters by C?Si Auration
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Auration of o-trimethylsilyl arylphosphines leads to the formation of gold and gold–silver clusters with ortho-metalated phosphines displaying 3c–2e Au?C?M bonds (M=Au/Ag). Hexagold clusters [Au6L4](X)2 are obtained by reaction of (L?TMS)AuCl with AgX, whereas reaction with AgX and Ag2O leads to gold–silver clusters [Au4Ag2L4](X)2. Oxo-trigold(I) species [Au3O]+ were identified as the intermediates in the formation of the silver-doped clusters. Other [Au5], [Au4Ag], and [Au12Ag4] clusters were also obtained. Clusters containing PAu?Au?AuP structural motif display good catalytic activity in the activation of alkynes under homogeneous conditions.
- Pei, Xiao-Li,Pereira, Ana,Smirnova, Ekaterina S.,Echavarren, Antonio M.
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supporting information
p. 7309 - 7313
(2020/05/18)
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- Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non-radiative Decay Pathway
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To broaden the application of aggregation-induced emission (AIE) luminogens (AIEgens), the design of novel small-molecular dyes that exhibit high fluorescence quantum yield (Φfl) in the solid state is required. Considering that the mechanism of
- Igawa, Kazunobu,Iwai, Riki,Konishi, Gen-ichi,Morokuma, Keiji,Sairi, Amir Sharidan,Sasaki, Shunsuke,Suenobu, Tomoyoshi,Suzuki, Satoshi
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supporting information
p. 10566 - 10573
(2020/04/15)
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- Conversion of Carbonyl Compounds to Olefins via Enolate Intermediate
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A general and efficient protocol to synthesize substituted olefins from carbonyl compounds via nickel catalyzed C—O activation of enolates was developed. Besides ketones, aldehydes were also suitable substrates for the presented catalytic system to produce di- or tri- substituted olefins. It is worth noting that this approach exhibited good tolerance to highly reactive tertiary alcohols, which could not survive in other reported routes for converting carbonyl compounds to olefins. This method also showed good regio- and stereo-selectivity for olefin products. Preliminary mechanistic studies indicated that the reaction was accomplished through nickel catalyzed C—O activation of enolates, thus offering helpful contribution to current enol chemistry.
- Cao, Zhi-Chao,Xu, Pei-Lin,Luo, Qin-Yu,Li, Xiao-Lei,Yu, Da-Gang,Fang, Huayi,Shi, Zhang-Jie
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supporting information
p. 781 - 785
(2019/06/24)
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- Rhodium(II)- or Copper(I)-Catalyzed Formal Intramolecular Carbene Insertion into Vinylic C(sp2)?H Bonds: Access to Substituted 1H-Indenes
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A rhodium(II)- or copper(I)-catalyzed formal intramolecular carbene insertion into vinylic C(sp2)?H bonds is reported herein. This method provides straightforward access to 1H-indenes with high efficiency and excellent functional-group compatibility. Mechanistically, the reaction is proposed to involve the following sequence: metal carbene formation, intramolecular nucleophilic addition of the double bond to the electron-deficient carbene carbon atom, dearomatization, and finally a 1,5-H shift.
- Zhou, Qi,Li, Shichao,Zhang, Yan,Wang, Jianbo
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p. 16013 - 16017
(2017/11/27)
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- Dissymmetric ansa zirconocene complexes with di- and trisubstituted indenyl ligands as catalysts for homogeneous ethylene homo- and ethylene/1-hexene copolymerization reactions
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Different routes for the synthesis of 1,2- and 1,2,3-substituted indene derivatives are described. Representative substituents are: Me, Ph, PhCH2, PhCH2CH2, PhCH2CH2CH2, CH2CH?=?CH2. Subsequent deprotonation of these substituted indenes and reaction with indenyl zirconium trichloride gave the corresponding dissymmetric bis(indenyl) zirconium complexes. After activation with methylaluminoxane (MAO) these complexes show high activities both in ethylene homopolymerisation and ethylene/1-hexene copolymerisation. The rate of comonomer incorporation can reach 33.3% (15/MAO). The copolymers exhibit lower melting points than the homopolymers and their crystallinities α are lower compared with the homopolymers.
- Rimkus, Andrea M.,Alt, Helmut G.
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- 2 - aryl indene catalyst composition and method of manufacturing the compound
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PROBLEM TO BE SOLVED: To provide a method for producing a 2-aryl-indene compound from safe raw materials with high yield and good purity and to provide a catalyst composition used for the same.SOLUTION: There is provided a method for producing a 2-aryl-in
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Paragraph 0067; 0068
(2017/09/02)
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- Fluorine-containing diaryliodonium salt and application thereof
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The invention relates to fluorine-containing diaryliodonium salt as well as a preparation method and an application thereof. The fluorine-containing diaryliodonium salt has a structure represented as a formula I and is taken as an arylation reagent. The fluorine-containing diaryliodonium salt has the advantages that the preparation is easy, when the fluorine-containing diaryliodonium salt is applied to an arylation reaction, the arylation reaction condition is relatively mild, the selectivity of an arylation product is good and the like; in the formula I shown in the specification, R1 represents an aromatic ring group or a heteroaromatic ring group or represents a substituted aromatic ring group or a substituted heteroaromatic ring group, and Y represents a univalent organic or inorganic acid radical anion.
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Paragraph 0112; 0113; 0114; 0115; 0116
(2017/01/02)
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- Synthesis of Barbaralones and Bullvalenes Made Easy by Gold Catalysis
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The gold(I)-catalyzed oxidative cyclization of 7-ethynyl-1,3,5-cycloheptatrienes gives 1-substituted barbaralones in a general manner, which simplifies the access to other fluxional molecules. As an example, we report the shortest syntheses of bullvalene, phenylbullvalene, and disubstituted bullvalenes, and a readily accessible route to complex cage-type structures by further gold(I)-catalyzed reactions.
- Ferrer, Sofia,Echavarren, Antonio M.
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supporting information
p. 11178 - 11182
(2016/10/13)
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- CoIII-Carbene Radical Approach to Substituted 1H-Indenes
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A new strategy for the catalytic synthesis of substituted 1H-indenes via metalloradical activation of o-cinnamyl N-tosyl hydrazones is presented, taking advantage of the intrinsic reactivity of a CoIII carbene radical intermediate. The reaction uses readily available starting materials and is operationally simple, thus representing a practical method for the construction of functionalized 1H-indene derivatives. The cheap and easy to prepare low spin cobalt(II) complex [CoII(MeTAA)] (MeTAA = tetramethyltetraaza[14]annulene) proved to be the most active catalyst among those investigated, which demonstrates catalytic carbene radical reactivity for a nonporphyrin cobalt(II) complex, and for the first time catalytic activity of [CoII(MeTAA)] in general. The methodology has been successfully applied to a broad range of substrates, producing 1H-indenes in good to excellent yields. The metallo-radical catalyzed indene synthesis in this paper represents a unique example of a net (formal) intramolecular carbene insertion reaction into a vinylic C(sp2)-H bond, made possible by a controlled radical ring-closure process of the carbene radical intermediate involved. The mechanism was investigated computationally, and the results were confirmed by a series of supporting experimental reactions. Density functional theory calculations reveal a stepwise process involving activation of the diazo compound leading to formation of a CoIII-carbene radical, followed by radical ring-closure to produce an indanyl/benzyl radical intermediate. Subsequent indene product elimination involving a 1,2-hydrogen transfer step regenerates the catalyst. Trapping experiments using 2,2,6,6-tetra-methylpiperidine-1-oxyl (TEMPO) radical or dibenzoylperoxide (DBPO) confirm the involvement of cobalt(III) carbene radical intermediates. Electron paramagnetic resonance spectroscopic spin-trapping experiments using phenyl N-tert-butylnitrone (PBN) reveal the radical nature of the reaction.
- Das, Braja Gopal,Chirila, Andrei,Tromp, Moniek,Reek, Joost N. H.,De Bruin, Bas
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p. 8968 - 8975
(2016/07/30)
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- Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand
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Sarcosine was discovered to be an excellent ligand for cobalt-catalyzed carbon-carbon cross-coupling of Grignard reagents with allylic and vinylic bromides. The Co(II)/sarcosine catalytic system is shown to perform efficiently when phenyl and benzyl Grignards are coupled with alkenyl bromides. Notably, previously unachievable Co-catalyzed coupling of allylic bromides with Grignards to linearly coupled α-products was also realized with Co(II)/sarcosine catalyst. This method was used for efficient preparation of the key intermediate in an alternative synthesis of the antihyperglycemic drug sitagliptin.
- Frlan, Rok,Sova, Matej,Gobec, Stanislav,Stavber, Gaj,?asar, Zdenko
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p. 7803 - 7809
(2015/08/18)
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- D-Glucosamine in iron-catalysed cross-coupling reactions of Grignards with allylic and vinylic bromides: Application to the synthesis of a key sitagliptin precursor
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A sustainable D-glucosamine ligand is successfully introduced into iron-catalysed C-C cross-coupling reactions for the first time. The Fe(acac)2/D-glucosamine·HCl/Et3N catalytic system was effective at 5 mol% loading in coupling reactions of Grignard reagents with organic bromides. Moderate to high efficiency was achieved with preserved stereochemistry when allyl (Csp3) or alkenyl (Csp2) bromides were coupled with phenylmagnesium (Csp2) or benzylmagnesium (Csp3) bromides. The catalytic system developed was also successfully applied for the novel and economic preparation of a Michael-acceptor-like starting material used in an alternative synthesis of the drug sitagliptin, a known blockbuster for the treatment of type II diabetes mellitus.
- Sova, Matej,Frlan, Rok,Gobec, Stanislav,Stavber, Gaj,asar, Zdenko
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p. 528 - 535
(2015/08/04)
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- C15H10 and C15H12 Thermal Chemistry: Phenanthrylcarbene Isomers and Phenylindenes by Falling Solid Flash Vacuum Pyrolysis of Tetrazoles
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2-Phenyl-5-(phenylethynyl)tetrazole 44 provides a new entry to the C15H10 energy surface. Flash vacuum pyrolysis of 44 using the falling solid flash vacuum pyrolysis (FS-FVP) method afforded cyclopenta[def]phenanthrene 31 and cyclope
- Wentrup, Curt,Becker, Jürgen,Diehl, Manfred
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p. 7144 - 7149
(2015/07/28)
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- Gold(I) carbenes by retro-buchner reaction: Generation and fate
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The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent. Indenes and fluorenes are obtained by intramolecular reaction of highly electrophilic gold(I) carbenes with alkenes and arenes. According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon-carbon cleavages occur on a rather flat potential energy surface.
- Wang, Yahui,McGonigal, Paul R.,Herle, Bart,Besora, Maria,Echavarren, Antonio M.
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p. 801 - 809
(2014/02/14)
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- Selective arylation at the vinylic site of cyclic olefins
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Cyclic olefins usually give Heck products having an aryl ring residing at the allylic or homoallylic position. We describe herein a new method that allows arylation at the vinylic position of various cyclic olefins.
- Wu, Xiaojin,Zhou, Jianrong
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supporting information
p. 4794 - 4796
(2013/06/05)
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- Copper-catalyzed alkene arylation with diaryliodonium salts
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Alkenes and arenes represent two classes of feedstock compounds whose union has fundamental importance to synthetic organic chemistry. We report a new approach to alkene arylation using diaryliodonium salts and Cu catalysis. Using a range of simple alkenes, we have shown that the product outcomes differ significantly from those commonly obtained by the Heck reaction. We have used these insights to develop a number of new tandem and cascade reactions that transform readily available alkenes into complex arylated products that may have broad applications in chemical synthesis.
- Phipps, Robert J.,McMurray, Lindsay,Ritter, Stefanie,Duong, Hung A.,Gaunt, Matthew J.
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supporting information; experimental part
p. 10773 - 10776
(2012/08/07)
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- Formation of five- and seven-membered rings enabled by the triisopropylsilyl auxiliary group
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A highly convenient synthetic pathway to 2-indanones from aldehydes was established. The introduction of a triisopropylsilyl group greatly facilitated Meinwald rearrangement of the intermediate epoxides and alleviated the necessity of polysubstitution for the clean formation of indenes and cyclopentadienes via cyclodehydration of allylic alcohols; unprecedented freedom with respect to the product structure was thus achieved. The developed methodology could also be applicable to the formation of seven-membered rings leading to dibenzo[7]annulenes and dibenzosuberones.
- Usanov, Dmitry L.,Yamamoto, Hisashi
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p. 414 - 417
(2012/02/15)
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- Gold(I)-catalyzed cyclodehydration enabled by the triisopropylsilyl group: A synthetically versatile methodology
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Introduction of a triisopropylsilyl group into allyl and allenyl carbinols greatly enhances the efficiency of gold(I)-catalyzed cyclodehydration, which can provide rapid access to a library of various compounds including 1H-indenes (Table 2 and Scheme 5), benzofulvenes (Table 3), indan-2-ones (Scheme 2), fulvenes (Table 4), cyclopentadienes (Table 4), 5H-dibenzo[a,c][7]annulenes (Scheme 6) and dibenzosuberones (Scheme 6). The developed method enables unprecedented product generality for several classes of cyclodehydration reactions, which is particularly notable for the preparation of 1H-indenes. The first synthesis of non-benzo-fused fulvenes via cyclodehydration of allenyl vinyl carbinols could be accomplished. The protocol is remarkable for mild conditions, operational convenience, and easy access to starting materials. Copyright
- Usanov, Dmitry L.,Naodovic, Marina,Brasholz, Malte,Yamamoto, Hisashi
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p. 1773 - 1789,17
(2012/12/12)
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- Gold for the generation and control of fluxional barbaralyl cations
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Fluxional molecules which rapidly pass back and forth between a large number of constitutional isomers through low-energy rearrangements have fascinated chemists owing to their role in the study of fundamental theoretical concepts[ 2] and their potential to adapt their chemical structures in response to their environment or to act as prototypical molecular transport systems. They represent a facet of systems chemistry that is relatively unexplored, in which a dynamic structural library can be contained within a single molecule. The 9-barbaralyl cation (1) is a hugely fluxional C9H9 + hydrocarbon that exists as a mixture of 181 400 degenerate forms which interconvert rapidly at temperatures as low as -135 °C-each carbon atom may exchange with every other carbon atom in the structure through a series of pericyclic reactions. Unlike the neutral homologues semibullvalene (2; two degenerate tautomers) and bullvalene (3; 1209600 degenerate tautomers), which are stable compounds under ambient conditions, 1 is highly reactive and undergoes irreversible rearrangement to 1,4-bishomotropylium cation (4) above -125 °C. Functionalized barbaralanes may be suitable candidates for switchable, fluxional molecules. However, the difficulty in handling these compounds coupled with the low-yielding, multistep syntheses and harsh reaction conditions (typically featuring strongly or super acidic media) employed in the generation of 1 and its derivatives have so far limited the extent to which the chemistry of this fascinating dynamic carbon skeleton has been explored.
- McGonigal, Paul R.,De Leon, Claudia,Wang, Yahui,Homs, Anna,Solorio-Alvarado, Cesar R.,Echavarren, Antonio M.
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p. 13093 - 13096
(2013/03/13)
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- Studies in Acyl C-H activation via aryl and alkyl to acyl "through space" migration of palladium
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Examples of the 1,4-migration of a palladium moiety in aryl- and alkylpalladium intermediates to the acyl position of an aldehyde or formamide have been observed. The resulting acylpalladium intermediate can undergo ester or carbamate formation by reaction with an alcohol; decarbonylation, followed by β hydride elimination to an alkene; reaction with an organomercurial to form an ester; or alkene insertion. Deuterium-labeling studies have been used to confirm the palladium migration mechanism.
- Kesharwani, Tanay,Verma, Akhilesh K.,Emrich, Daniel,Ward, Jeffrey A.,Larock, Richard C.
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supporting information; experimental part
p. 2591 - 2593
(2009/10/23)
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- Cross-coupling of aryl/alkenyl pivalates with organozinc reagents through nickel-catalyzed C-O bond activation under mild reaction conditions
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Finding the right partner: The catalyst system [NiCl2(PCy 3)2] mediates the title transformation with high efficiency and allows aryl-aryl and vinyl-aryl coupling to proceed. The first example of catalytic cross-coupling u
- Li, Bi-Jie,Li, Yi-Zhou,Lu, Xing-Yu,Liu, Jia,Guan, Bing-Tao,Shi, Zhang-Jie
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supporting information; experimental part
p. 10124 - 10127
(2009/05/30)
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- Nickel-catalyzed carboannulation reaction of o-bromobenzyl zinc bromide with unsaturated compounds
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(Chemical Equation Presented) A number of indenes have been prepared in good yields by treating o-bromobenzyl zinc bromide 1 with various terminal and internal alkynes in the presence of a nickel catalyst. The nickel-catalyzed carboannulation reaction was successfully extended to the synthesis of indane derivatives by reaction of 1 with acrylates and styrene.
- Deng, Ruixue,Sun, Liangdong,Li, Zhi
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p. 5207 - 5210
(2008/09/17)
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- Low-valent niobium-mediated synthesis of indenes: Intramolecular coupling reaction of CF3 group with alkene C-H bond
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CF3 group of o-alkenyl-α,α,α-trifluorotoluenes underwent intramolecular coupling reaction with the alkene C-H bond under NbCl5/LiAlH4 system. Substituted indenes were obtained in good yields. Copyright
- Fuchibe, Kohei,Mitomi, Ken,Akiyama, Takahiko
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- Joining the rings: The preparation of 2- and 3-indenyl-triptycenes, and curious related processes
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The indenyltriptycenes, 1 and 2, where the 3- or 2-indenyl, respectively, is attached at the 9-position of the triptycene, are attractive prototypes of molecular gearing systems that can also incorporate a brake. These molecules have been prepared from their respective indenylanthracenes, 3 and 4, by the [4 + 2] cycloaddition of benzyne to the anthracene fragment, and the rotational barriers about the indenyl-triptycenyl single bonds in 1 (12 kcal mol -1) and 2 (-1) have been measured. The precursor anthracenes, 3 and 4, were prepared by using palladium-catalysed coupling reactions. Unexpectedly, the Heck-type reaction of 9-bromoanthracene, 5, with indene leads to the formation of 3-indenylanthracene 3; moreover, this process is accompanied by a novel palladium-catalysed carbocyclisation reaction leading to the indenophenanthrylene 9. The addition of benzyne to 9-(3-indenyl)anthracene, 3, yields the corresponding indenyltriptycene, 1, and, surprisingly, the anthracenyl methano-bridged phenanthrene 16. It has been demonstrated that 2-arylindenes can act as 1,3-dienes in the [4 + 2] cycloadditions of benzyne. The products 2, 7a, 9 and 16 have been characterised by X-ray crystallography. The Royal Society of Chemistry.
- Nikitin, Kirill,Mueller-Bunz, Helge,Ortin, Yannick,McGlinchey, Michael J.
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p. 1952 - 1960
(2008/02/10)
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- Catalysts for thermoplastic elastomeric olefin polymers
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This invention is directed to novel catalysts the structure and activity of which can be controlled to produce a wide range of alpha olefin polymers and co-polymers, and preferably for the production of stereoblock poly alpha olefins comprising a wide ran
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- New method for the synthesis of indenes
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A new two-step method was developed for the synthesis of 2-sulfonyl-substituted indenes from aromatic aldehydes. The reactions of 1-phenylsulfonyl-1-(trimethylsilyl)ethylene with ortho-lithiated derivatives of aromatic and heteroaromatic aldehydes afford conjugate addition products whose subsequent cyclization gives substituted 2-sulfonylindenes in preparative yields. The reactions of 2-(phenylsulfonyl)indenes with Grignard reagents were studied. It was shown that the sulfonyl group can be replaced in the presence of iron(III) acetylacetonate.
- Nenajdenko,Denisenko,Balenkova
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p. 2090 - 2096
(2007/10/03)
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- Palladium-catalyzed cross coupling of Grignard reagents with in situ-derived enol phosphates
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A useful, one-pot protocol has been developed for the conversion of enolizable ketones to alkylated or arylated olefins by Pd-catalyzed cross coupling of in situ-generated enol phosphate intermediates with Grignard reagents.
- Miller, Joseph A.
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p. 7111 - 7114
(2007/10/03)
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- A facile synthesis of 2-arylindenes by Pd-catalyzed direct arylation of indene with aryl iodides
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A series of 2-arylindenes were prepared by the reaction of aryl iodides with indene in the presence of a catalytic amount of Pd(OAc)2.
- Nifant'ev, Ilya E,Sitnikov, Alexander A,Andriukhova, Nonna V,Laishevtsev, Ilya P,Luzikov, Yuri N
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p. 3213 - 3215
(2007/10/03)
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- Flash vacuum pyrolysis over solid catalysts. 2. Pyrazoles over hydrotalcites
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Flash vacuum pyrolysis (fvp) reactions of NH-pyrazole (1) and 3,5-diphenylpyrazole (2) were investigated in the presence of anionic clays having hydrotalcite structure (HT). Solid catalysts with Mg:Al ratio equal to 2:1 containing carbonate (HT-1), nitrate (HT-2), and silicate (HT-3) as interlayer anions were employed. Between 400 and 600 °C, compound 1 remained almost unchanged and only unidentified volatile products were detected in small amounts. In contrast, 2 afforded benzonitrile (3) and phenylacetonitrile (4) by a ring fragmentation reaction at 450 °C. At a higher temperature (660 °C), the same products obtained in homogeneous fvp reactions, i.e., 2-phenylindene (5) and 3-phenylindene (6), were obtained showing no catalysis by HT under these conditions. Results showed that the yield is strongly dependent on the nature of the interlayer anion in the hydrotalcite structure. In comparison with reactions of 2 over zeolites, HTs exhibit selectivity for ring fragmentation reaction.
- Moyano, Elizabeth L.,Del Arco, Margarita,Rives, Vicente,Yranzo, Gloria I.
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p. 8147 - 8150
(2007/10/03)
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- Process for preparing 2-aryl-substituted indenes
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A process is disclosed for preparing 2-aryl-substituted indenes by reacting an indene with an arene compound substituted with an halogen atom, preferably a iodine atom, or with an organosulphonate group, said reaction being carried out in a basic medium i
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- Unbridged metallocene dichloride complexes with mono-substituted indenyl ligands and their application for the polymerization of propene
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The synthesis of unbridged metallocene dichloride complexes of the type Ind′2ZrCl2 (Ind′ = 2-alkyl- or arylalkyl-substituted indenyl) is described. The complexes are characterized by 1H- and 13C-NMR spectroscopy and mass spectrometry. After activation with methylalumoxane these complexes can be used for propene polymerization; they produce block copolymers consisting of alternating isotactic and atactic blocks. The polymerization results and the polymer properties are presented. The influence of the catalyst structure on the polymerization behaviour is discussed.
- Schmidt, Roland,Alt, Helmut G.
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p. 304 - 309
(2007/10/03)
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- Flash vacuum pyrolysis over solid catalysts. 1. Pyrazoles over zeolitest
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Flash vacuum pyrolysis (fvp) reactions of 1H-pyrazole (1), 3,5-dimethylpyrazole (2), and 3,5-diphenylpyrazole (3) were carried out over zeolites. Reactions were performed using ZCOY-7, NH4-Y, and Na-Y zeolites. Reaction temperatures of heterogeneous reactions were lower than the corresponding temperatures in the homogeneous system, showing a catalytic effect of the zeolites. Compounds 1-3 afforded nitrogen extrusion in homogeneous fvp reactions while in the heterogeneous ones different reactions were present. Compounds 1 and 2 also afforded nitrogen extrusion; products arising from ring fragmentation were found in reactions of 2 and 3 while an isomeric imidazole was isolated in reactions of 3. Isomerization of 3 is attributed to a transition-state selectivity by the catalyst due to the relation between the size of the molecule and the cavity of the zeolite. This isomerization reaction was present only when zeolites with active Broensted sites were used.
- Moyano,Yranzo
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p. 2943 - 2947
(2007/10/03)
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- Zirconium bis-indenyl compounds. Synthesis and X-ray crystallography study of 1- and 2-substituted bis(R-indenyl)zirconium dichloride metallocenes
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A series of 1- and 2-substituted indenyl ligands were prepared and used in the synthesis of [1-R-Ind]2ZrCl2 [R = Me (2b), Et (4b), iPr (5b), tBu (6b), SiMe3 (8b), Ph (10b), Bz (12b), 1-Naph (14b)] and [2-R-Ind]2ZrCl2 [R = Me (1b), Et (3b), SiMe3 (7b), Ph (9b), Bz (11b), 1-Naph (13b)] metallocenes. An X-ray crystallographic study of 4b and 10b showed the complexes to be the racemic diastereomers (4b, both the R,R and S,S-enantiomers and 10b, the S,S-enantiomer). The X-ray data together with NMR spectral data revealed that the size of the substituent influenced the orientation the two indenyl ligands of the metallocenes. The 4b diastereomers are both found to crystallize with their ethyl groups syn (bis-central) with respect to each other whereas the larger phenyl groups in 10b results in an anti (bis-lateral) orientation of the indenyl ligands.
- Grimmer, Neil E.,Coville, Neil J.,De Koning, Charles B.,Smith, Jeremy M.,Cook, Leanne M.
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p. 112 - 127
(2007/10/03)
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- Highly active Pd(II) cyclometallated imine catalysts for the Heck reaction
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The new cyclopalladated, phosphine-free imine complexes 1-3 are exceptional catalysts for the Heck arylation, leading to more than a million turnovers in some cases; the catalysts are very thermally and air stable and are recovered unchanged after the catalysis.
- Ohff, Manuela,Ohff, Andreas,Milstein, David
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p. 357 - 358
(2007/10/03)
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- Flash vacuum pyrolysis of pyrazoles as an alternative way to study vinylcarbenes
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Flash vacuum pyrolysis (FVP) reactions of 3,5-diphenylpyrazole (1) and 3(5)-methyl-5(3)-phenylpyrazole (2) were carried out. The reaction products expected for nitrogen extrusion were formed through different rearrangements in the vinylcarbene intermediate. Kinetic parameters for nitrogen extrusion from 1 are reported. To show that FVP reactions of pyrazoles are useful to obtain vinylcarbenes, the reactions of other pyrazoles previously studied are also discussed.
- Moyano, Elizabeth L.,Yranzo, Gloria I.,Elguero, Jose
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p. 8188 - 8191
(2007/10/03)
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- Addition and Cyclization Reactions in the Thermal Conversion of Hydrocarbons with Enyne Structure, I. Detailed Analysis of the Reaction Products of Ethynylbenzene
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The pyrolysis of ethynylbenzene (C8H6, 1) was studied in a flow system between 700 and 1100 deg C (reaction time about 0.3 s) by using a mixture of 5 mol-percent of 1 in nitrogen and also in hydrogen at 700 deg C.The products were analyzed gas chromatogra
- Hofmann, Joerg,Zimmermann, Gerhard,Guthier, Klaus,Hebgen, Peter,Homann, Klaus-Heinrich
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p. 631 - 636
(2007/10/02)
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- Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
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Disclosed is a process for preparing a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, comprising reacting (i) a lithium, sodium or potassium salt of a cyclopentadiene derivative with (ii) a silicon halide compound or a germanium halide compound in the presence of a cyanide or a thiocyanate. The cyanide or the thiocyanate is preferably a copper salt. According to the process of the invention, a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, which is very useful for the preparation of a metallocene complex catalyst component, can be prepared in a high yield for a short period of time.
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- CRYPTATE ACIDITY SCALES. VI. EFFECT OF POLARITY OF THE MEDIUM ON CRYPTATE ION-PAIR ACIDITY
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A thermodynamic analysis was made of the effects of various types of solvation interactions on ion-pair acidity.It was shown that the polarity of the medium does not have an effect on the relative cryptate acidity of organic compounds.
- Antipin, I. S.,Vedernikov, A. N.,Solomonov, B. N.,Konovalov, A. I.
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p. 1861 - 1865
(2007/10/02)
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- CRYPTATE ACIDITY SCALES. V. EQUILIBRIUM ACIDITY OF INDICATOR CH-ACIDS IN TETRAHYDROFURAN
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A scale of equilibrium cryptate acidity in tetrahydrofuran is constructed.Its distinguishing feature is the constancy of the contribution from ionic association.A method is proposed for determination of the constants for the association of the ions into ion pairs in dimethyl sulfoxide.
- Antipin, I. S.,Gareev, R. F.,Vedernikov, A. N.,Konovalov, A. I.
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p. 1039 - 1044
(2007/10/02)
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- α,β-UNSATURATED THIO COMPOUNDS. REDUCTION OF 3-HETEROSUBSTITUTED 2-ARYL-1-INDENETHIONES
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3-Amino-, 3-mercapto-, and 3-alkylthio-substituted 2-aryl-1-indenethiones react readily with sodium borohydride or S-nucleophiles, forming 2-aryl-3-indenethiols. 2-Phenyl-3-indenethiol in the thioketone tautomeric form is reduced by cyanide ion in DMFA to
- Petriashvili, K. A.,Usov, V. A.,Protasova, L. E.,Shagun, V. A.,Sidorkin, V. F.,Voronkov, M. G.
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p. 513 - 517
(2007/10/02)
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- SYNTHESIS OF INDENES FROM PHENYLPROPANONES USING ALUMINA CATALYST
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1,3-Diphenylpropan-2-one undergoes dehydration over alumina at around 400 deg C to form 1,3-diphenylallene which cyclizes to 2-phenylindene.Since the parent ketone can be obtained under the reaction conditions from phenylacetic acid, the present reaction forms a one step syntheses of 2-phenylindene from phenylacetic acid. 3- and 4-methylphenylacetic acids also give the corresponding indenes. 1,3-Diphenylpropan-1-ones also give phenylindenes, presumably by a direct cyclodehydration reaction.
- Jayamani, M.,Pant, Nalin,Ananthan, S.,Narayanan, K.,Pillai, C. N.
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p. 4325 - 4332
(2007/10/02)
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- Reactions of Tropone Tosylhydrazone Sodium Salt with Anthracene, 1,3-Diphenylisobenzofuran, and Phenylacetylene: and Type Cycloaddition Reactions of Cycloheptatrienylidene or 1,2,4,6-Cycloheptatetraene
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The reaction of tropone tosylhydrazone sodium salt (1) with anthracene gave a -type adduct and the reaction of 1 with 1,3-diphenylisobenzofuran afforded endo- and exo--type adducts as well as a heptafulvene derivative.The reaction of 1 with phenylacetylene yielded a -type adduct, which rearranged into 2-phenylindene upon heating.The addition reactions are thought to proceed via the allene intermediate, 1,2,4,6-cycloheptatetraene, which is a valence-bond isomer of the carbene intermediate, cycloheptatrienylidene, initially generated by the pyrolysis of 1.The photoreaction of adduct 3 with a high-pressure mercury lamp afforded a ring-closure product via the photobicyclization reaction of the cycloheptatriene moiety of the adduct.Thermal interconversions between the three products of the reaction of 1 with 1,3-diphenylisobenzofuran were investigated.
- Saito, Katsuhiro,Omura, Yoichi,Mukai, Toshio
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p. 1663 - 1668
(2007/10/02)
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- Carbon Acidity. 67. The Indicator Scale of Cesium Ion Pairs in Tetrahydrofuran
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An equilibrium cesium ion-pair indicator scale relative to 9-phenylfluorene at pKa = 18.49 has been established for 22 hydrocarbons in tetrahydrofuran.Comparison of this scale to those developed in Me2So and DME shows the scale to be independent of solvent.Visible absorbance spectral characteristics of the indicator anions are also reported and discussed in relation to other solvents.Thermodynamic studies of the equilibrium reactions were carried out over a temperature range of -20 to 25 deg C and reveal the importance of internal rotation on the entropy of reactions.Thermodynamic constants found for reaction between fluorenes show a complex behavior and are generally not interpretable at this time.
- Bors, Daniel A.,Kaufman, Michael J.,Streitwieser, Andrew Jr.
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p. 6975 - 6982
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF 2-PHENYLINDENE
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A benzene solution of phenylacetic acid when passed over alumina at 420 deg C gave 2-phenylindene.
- Jayamani, M.,Pillai, C. N.
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p. 535 - 542
(2007/10/02)
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- SYNTHESIS OF MESO-SUBSTITUTED TRICARBOCYANINE DYES WITH AN ORTHO-PHENYLENE BRIDGE IN THE CHROMOPHORE
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The synthesis of derivatives of glutaconaldehyde containing an ortho-phenylene bridge in the chain of conjugation was realized by the reaction of the complex of dimethylformamide and phosphorus oxychloride with 2-ethoxy- and 2-phenylidene.Their condensation with the quaternary salts of heterocyclic bases containing an active methyl group gave the corresponding meso-ethoxy- and meso-phenyl-substituted tricarbocyanine dyes.
- Sosnovskii, G. M.,Lugovskii, A. P.,Tishchenko, I. G.
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p. 1861 - 1864
(2007/10/02)
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- Response of Acidity and Magnetic Rtesonance Properties to Aryl Substitution in Carbon Acids and Derived Carbanions: 2- and 3-Arylindenes
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Substitution in the aryl ring of 2- and 3-arylindenes has been used to examine the acidity of these hydrocarbons and the charge density and ion pair structure of their anions.Acidities were measured for the 2-arylindenes both in pure Me2SO and in Me2SO-H2
- Greifenstein, Linda G.,Lambert, Joseph B.,Nienhuis, Ronald J.,Fried, Herbert E.,Pagani, Giorgio A.
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p. 5125 - 5132
(2007/10/02)
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