- THE FACILE REARRANGEMENT OF 1-PHENYL-INDENE TO 3-PHENYL-INDENE INDUCED BY (CH3CN)3Cr(CO)3
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The rearrangement of 1-phenyl-indene to 3-phenyl-indene takes place at room temperature in THF if assisted by (CH3CN)3Cr(CO)3
- Berno, Piero,Ceccon, Alberto,Gambaro, Alessandro,Venzo, Alfonso
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Read Online
- Transfer of Chirality in the Rhodium-Catalyzed Chemoselective and Regioselective Allylic Alkylation of Hydroxyarenes with Vinyl Aziridines
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By taking advantage of chirality-transfer strategy, a chemo- and regioselective allylic alkylation of naphthols and phenols with vinylaziridines provides an atom-economic and efficient method for the synthesis of enantioenriched 2-vinyl-2-arylethylamine derivatives. Use of readily available starting materials, a broad substrate scope, high selectivity, mild reaction conditions, as well as versatile functionalizations of the aromatic ethylamine products make this approach very practical and attractive.
- Lin, Tao-Yan,Wu, Hai-Hong,Feng, Jian-Jun,Zhang, Junliang
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Read Online
- 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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Read Online
- Zinc-Catalyzed Alkene Cyclopropanation through Zinc Vinyl Carbenoids Generated from Cyclopropenes
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The zinc-catalyzed reaction of cyclopropenes with alkenes leading to vinylcyclopropane derivatives is reported. A broad range of alkenes (including highly substituted or functionalized alkenes) is compatible with this protocol. On the basis of trapping experiments and computational studies, this cyclopropanation reaction is proposed to proceed through initial formation of an electrophilic zinc vinyl carbenoid intermediate, which may be involved in a concerted cyclopropanation reaction. The reported protocol represents an unprecedented and simple strategy for the catalytic generation of zinc vinyl carbenoids, which are promising intermediates in organic synthesis.
- González, María J.,González, Javier,L?pez, Luís A.,Vicente, Rubén
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Read Online
- Stereospecific Ring-Opening Metathesis Polymerization of Norbornene Catalyzed by Iron Complexes
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Developing well-defined iron-based catalysts for olefin metathesis would be a breakthrough achievement in the field not only to replace existing catalysts by inexpensive metals but also to attain a new reactivity taking advantage of the unique electronic
- Belov, Dmitry S.,Mathivathanan, Logesh,Beazley, Melanie J.,Martin, William Blake,Bukhryakov, Konstantin V.
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Read Online
- 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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- The intramolecular reaction of acetophenoneN-tosylhydrazone and vinyl: Br?nsted acid-promoted cationic cyclization toward polysubstituted indenes
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In the presence of TsNHNH2, a Br?nsted acid-promoted intramolecular cyclization ofo-(1-arylvinyl) acetophenone derivatives was developed, leading to polysubstituted indenes with complexity and diversity in moderate to excellent yields. In sharp contrast with either the radical or carbene involved cyclization of aldehydicN-tosylhydrazone with vinyl, a cationic cyclization pathway was involved, whereN-tosylhydrazone served as an electrophile and alkylation reagent during this transformation.
- Wang, Zhixin,Li, Yang,Chen, Fan,Qian, Peng-Cheng,Cheng, Jiang
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p. 1810 - 1813
(2021/02/27)
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- Exploring the Labile Nature of 2,4,6-Trimethoxyphenyl Moiety in Allylic Systems under Acidic Conditions
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An investigation of the unexpected lability of the Csp3–Csp2 bond connecting 2,4,6-trimethoxyphenyl group and an allylic moiety is carried out. We observed that the catalytic presence of either Lewis or Br?nsted acid can render such 2,4,6-trimethoxyphenyl group labile. Several nucleophiles were found to substitute the labile C–C bond in mild reaction conditions resulting in very good yields of the allylated products. Even in the absence of a nucleophile, intramolecular cyclization of the parent substrate under acidic activation caused the labile C–C bond to cleave. A major motivation of this study is to understand the lability of electron-rich aryl group in acidic medium, employing 2,4,6-trimethoxyphenyl moiety as a case study. A plausible mechanism is proposed after carrying out several control reactions as well as UV/Vis and 1H NMR spectroscopic studies. This work provides an insight into the activation of electron-rich arenes as a labile entity in acidic medium while also adding a conceptually novel C–C bond breaking approach to the vast literature of allylation of arenes.
- Paul, Dipankar,Chatterjee, Paresh Nath
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supporting information
p. 4705 - 4712
(2020/07/28)
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- C 1-Symmetric Si-bridged (2-indenyl)(1-indenyl) ansa -metallocenes as efficient ethene/1-hexene copolymerization catalysts
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In the search for more efficient single-center ethene/α-olefin copolymerization catalysts, metallocenes bearing a 2-indenyl substituent pattern have largely been ignored in the past. Here, we show that such a structural motif yields competent linear low-density polyethylene (LLDPE) catalysts. They are also relatively easy to synthesize, allowing for a wide structural amplification. A screening of 28 catalysts reveals that the lead catalyst in this study displays high comonomer affinity and molecular weight capability at industrially relevant temperatures. QSAR models show that steric factors likely contribute stronger than electronic factors to the observed substituent trends, both for comonomer affinity and MW capability.
- Borisov, Ilya S.,Busico, Vincenzo,Cipullo, Roberta,Ehm, Christian,Friederichs, Nic,Guzeev, Bogdan A.,Hendriksen, Coen,Mladentsev, Dmitry Y.,Uborsky, Dmitry V.,Vittoria, Antonio,Voskoboynikov, Alexander Z.
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supporting information
p. 3015 - 3025
(2020/03/13)
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- DIMETHYL-SILYL-BRIDGED-1-SUBSTITUTED-2-INDENYL METALLOCENE COMPLEXES FOR OLEFIN POLYMERIZATION
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The invention relates to a metallocene complex according to formula A, wherein R1-R10 are independently selected from H, C1-C10 alkyl, C7-C20 Aralkyl groups, and C1-C10 alkoxy groups; wherein R11 is selected from methyl, ethyl, propyl, isopropyl, butyl, phenyl; wherein R1 and R2, R3 and R4, R4 and R5, R5 and R6, R7 and R8, R8 and R9, and/or R9 and R10 can be connected to form a ringstructure; wherein R0 is selected from a C1-C10 alkyl group or an aryl group wherein M is selected from Ti, Zr and Hf, X is an anionic ligand to M, z is the number of X groups and equals the valence of M minus 2. The invention further relates to a catalyst for preparing polyolefins, a process for polymerizing olefins and to polymers prepared by said catalyst system.
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Paragraph 0130-0132
(2020/05/02)
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- Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
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A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
- Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
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supporting information
p. 1778 - 1781
(2020/03/11)
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- Hydroarylation of Alkenes by Protonation/Friedel-Crafts Trapping: HFIP-Mediated Access to Per-aryl Quaternary Stereocenters
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Upon treatment with a combination of HFIP and an organic sulfonic acid, alkenes behave as Br?nsted bases and protonate to give carbocations which can be trapped by electron-rich arenes. The reaction constitutes a Friedel-Crafts hydroarylation which procee
- Nielsen, Christian D.-T.,White, Andrew J. P.,Sale, David,Bures, Jordi,Spivey, Alan C.
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p. 14965 - 14973
(2019/11/13)
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- [Pd]-Catalyzed Intermolecular Coupling and Acid Mediated Intramolecular Cyclodehydration: One-Pot Synthesis of Indenes
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An efficient one-pot synthesis of indenes from simple starting materials is presented. This process involves a dual C–C bond formation through an intermolecular Heck coupling reaction followed by acid-mediated intramolecular cyclodehydration. The strategy
- Niharika, Pedireddi,Satyanarayana, Gedu
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supporting information
p. 971 - 979
(2018/02/22)
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- Cyclopropenylgold(I) Complexes as Aurated Carbenoids or Quasi-Carbenes
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Highly strained hydrocarbons have always been a research target of high interest. Due to their untypical electronic structure, they show interesting reactivity patterns and can easily be activated by π-coordination to or insertion reactions with metal complexes. Herein we report the synthesis of a range of 3,3-disubstituted cyclopropenylgold(I) complexes. The synthesis of such compounds with a metal, which usually easily activate cyclopropenes is a double-edged sword. We found σ-bound vinylic gold to generally have a strong stabilizing effect in terms of ring strain. The complexes show a strong distortion, preactivating the cyclopropenyls towards the ring-opening mode which thermally generates 1-aurated vinylcarbenes which is reflected by a much faster conversion (Ea of 10 kcal/mol instead of 40 kcal/mol, the reaction proceeds at temperatures as low as ?20 °C instead of 200 °C reported in the literature). In 3-phenyl-cyclopropenyl complexes, these could be trapped intramolecularly to give indenylgold(I) complexes. The properties of these highly strained complexes were investigated, utilizing a range of analytical and experimental procedures and Kohn-Sham density functional theoretic methods. (Figure presented.).
- Mulks, Florian F.,Antoni, Patrick W.,Rominger, Frank,Hashmi, A. Stephen K.
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p. 1810 - 1821
(2018/03/21)
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- Catalytic Enantioselective [10+4] Cycloadditions
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The first peri- and stereoselective [10+4] cycloaddition between catalytically generated amino isobenzofulvenes and electron-deficient dienes is described. The highly stereoselective catalytic [10+4] cycloaddition exhibits a broad scope with high yields,
- Donslund, Bjarke S.,Jessen, Nicolaj Inunnguaq,Bertuzzi, Giulio,Giardinetti, Maxime,Palazzo, Teresa A.,Christensen, Mette Louise,J?rgensen, Karl Anker
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supporting information
p. 13182 - 13186
(2018/09/12)
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- High-enantioselectivity 1,1-diarylboroalkanes and preparation method thereof
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The invention provides high-enantioselectivity 1,1-diarylboroalkanes and a preparation method thereof, belonging to the technical field of organic synthetic chemistry. The structural general formula of the compounds is disclosed as Formula I. The invention also provides a preparation method of the high-enantioselectivity 1,1-diarylboroalkanes. The method comprises the following steps: carrying out reaction on a copper salt and an alkali under the catalytic action of an alkali to generate a tert-butyl oxy copper intermediate, and reacting with pinacol biborate to generate a copper-boron material, inserting C-C double bonds, and obtaining the hydrogen bononization products under the action of alcohol. The 1,1-diarylboroalkanes have high enantioselectivity; and the high performance liquid chromatography experiment proves that the ee value can reach 90% or above.
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Paragraph 0129; 0130; 0131; 0132
(2017/07/21)
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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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supporting information
p. 16013 - 16017
(2017/11/27)
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- Palladium-Catalyzed Formal [4 + 1] Annulation via Metal Carbene Migratory Insertion and C(sp2)-H Bond Functionalization
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A highly efficient and operationally simple palladium-catalyzed formal [4 + 1] annulation reaction has been developed. The reaction is featured by the formation of two different C-C bonds on a carbenic center. It represents a concise method for the synthesis of a wide range of polycyclic aromatic hydrocarbons (PAHs) and 1H-indenes with easily available (trimethylsilyl)diazomethane as the carbene source. Metal carbene migratory insertion and C(sp2)-H bond activation are proposed as the key steps in this transformation. The reaction further demonstrates the versatility of the carbene-based coupling in combination with various transition-metal-catalyzed transformations.
- Xu, Shuai,Chen, Ri,Fu, Zihao,Zhou, Qi,Zhang, Yan,Wang, Jianbo
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p. 1993 - 1997
(2017/08/14)
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- AlBr3-mediated tandem cyclizationcarboxylation of allenylbenzenes with CO2 in the presence of pyridines
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Indene-2-carboxylic acids are prepared from allenylbenzenes and CO2 by an AlBr3-mediated tandem reaction consisting of intramolecular FriedelCrafts alkylation of allenylbenzenes and subsequent carbonation of the resulting indenylaluminum species. The reaction requires 2,6- di-tert-butylpyridine or 2,6-diiodopyridine to neutralize an acidic by-product without deactivating the Lewis acid.
- Tanaka, Shinya,Chiba, Masafumi,Saito, Yuki,Yamamoto, Takaya,Hattori, Tetsutaro
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p. 419 - 421
(2017/06/14)
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- Nickel-Catalyzed Direct Synthesis of Aryl Olefins from Ketones and Organoboron Reagents under Neutral Conditions
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Nickel-catalyzed addition of arylboron reagents to ketones results in aryl olefins directly. The neutral condition allows acidic protons of alcohols, phenols, and malonates to be present, and fragile structures are also tolerated.
- Lei, Chuanhu,Yip, Yong Jie,Zhou, Jianrong Steve
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supporting information
p. 6086 - 6089
(2017/05/08)
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- Silver-Catalyzed Allylation of Ketones and Intramolecular Cyclization through Carbene Intermediates from Cyclopropenes under Ambient Conditions
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Tandem C-C bond formation was achieved through silver-catalyzed ring-opening of cyclopropenes via carbene intermediates. The reaction of cyclopropenes in the presence of a silver catalyst gave indene derivatives under ambient conditions. In contrast, the
- Nakano, Takeo,Endo, Kohei,Ukaji, Yutaka
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p. 713 - 721
(2016/03/09)
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- Transition-Metal-Free Self-Hydrogen-Transferring Allylic Isomerization
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Phenanthroline and tert-butoxide have been established as powerful radical initiators in reactions such as the SRN1-type coupling reactions due to the cooperation of large heteroarenes and a special feature of tert-butoxide. The first phenanthroline-tert-butoxide-catalyzed transition-metal-free allylic isomerization is described. The resulting ketones are key intermediates for indenes. The control experiments rule out the base-promoted allylic anion pathway. The radical pathway is supported by experimental evidence that includes kinetic study, kinetic isotope effect, isotope-labeling experiments, trapping experiments, and EPR experiments.
- Zheng, Hong-Xing,Xiao, Zu-Feng,Yao, Chuan-Zhi,Li, Qiang-Qiang,Ning, Xiao-Shan,Kang, Yan-Biao,Tang, Yong
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supporting information
p. 6102 - 6105
(2016/01/09)
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- Cyclodehydrations leading to indene products having n-heterocyclic substituents
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In this Note, we describe superacid-promoted cyclodehydrations leading to functionalized indenes. The product indenes are synthesized having N-heterocyclic substituents, including pyridyl, imidazolyl, pyrimdyl, and other groups. A mechanism is proposed in
- Boblak, Kenneth N.,Klumpp, Douglas A.
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p. 5852 - 5857
(2014/07/08)
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- Synthesis of indenes via aluminum chloride-promoted tandem Friedel-Crafts alkylation of arenes and cinnamaldehydes
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A series of substituted indenes were synthesized from arenes and cinnamaldehydes via aluminum chloride-promoted tandem Friedel-Crafts alkylation. The scope and limitation of the tandem reaction were explored. A plausible reaction mechanism is also discuss
- Kheira, Haiouani,Li, Pingfan,Xu, Jiaxi
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p. 168 - 174
(2014/06/09)
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- Synthesis of substituted 4-aroyl-1-indanone and 5-aroyl-1-tetralone
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Several substituted 4-aroyl-1-indanones 2 and 5-aroyl-1-tetralones 3 were prepared in good yields from 1-indanones 1 via a series of reasonable transformations.
- Chang, Meng-Yang,Lee, Nien-Chia
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scheme or table
p. 306 - 308
(2011/10/19)
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- Dications of 3-phenyl-indenylidene dibenzo[ a. d ]cycloheptene: The role of charge in the antiaromaticity of cationic systems
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Dications of 9-(3-phenyl-1H-inden-1-ylidene)-5H-dibenzo[a,d]cycloheptene, 52+, were prepared by oxidation with SbF5 in SO 2ClF, and their magnetic behavior was compared to dications of 9-(3-phenyl-1H-inden-1-ylidene)-9H-fl
- Mills, Nancy S.,Cheng, Francine E.,Baylan, Joseph M.,Tirla, Cornelia,Hartmann, Jennifer L.,Patel, Kiran C.,Dahl, Bart J.,McClintock, Sean P.
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experimental part
p. 645 - 653
(2011/03/19)
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- Highly enantioselective hydrogenation of quinolines using phosphine-free chiral cationic Ruthenium catalysts: Scope, mechanism, and origin of enantioselectivity
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Asymmetric hydrogenation of quinolines catalyzed by chiral cationic η6-arene-N-tosylethylenediamine-Ru(II) complexes have been investigated. A wide range of quinoline derivatives, including 2-alkylquinolines, 2-arylquinolines, and 2-functionalized and 2,3-disubstituted quinoline derivatives, were efficiently hydrogenated to give 1,2,3,4-tetrahydroquinolines with up to >99% ee and full conversions. This catalytic protocol is applicable to the gram-scale synthesis of some biologically active tetrahydroquinolines, such as (-)-angustureine, and 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline, a key intermediate for the preparation of the antibacterial agent (S)-flumequine. The catalytic pathway of this reaction has been investigated in detail using a combination of stoichiometric reaction, intermediate characterization, and isotope labeling patterns. The evidence obtained from these experiments revealed that quinoline is reduced via an ionic and cascade reaction pathway, including 1,4-hydride addition, isomerization, and 1,2-hydride addition, and hydrogen addition undergoes a stepwise H+/H- transfer process outside the coordination sphere rather than a concerted mechanism. In addition, DFT calculations indicate that the enantioselectivity originates from the CH/π attraction between the η6-arene ligand in the Ru-complex and the fused phenyl ring of dihydroquinoline via a 10-membered ring transition state with the participation of TfO- anion.
- Wang, Tianli,Zhuo, Lian-Gang,Li, Zhiwei,Chen, Fei,Ding, Ziyuan,He, Yanmei,Fan, Qing-Hua,Xiang, Junfeng,Yu, Zhi-Xiang,Chan, Albert S. C.
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supporting information; experimental part
p. 9878 - 9891
(2011/08/10)
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- Iodine/Et3SiH: A novel reagent system for the synthesis of 3-aryl-1H-indenes from 1,3-diaryl propargyl alcohols
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1,3-Diaryl propargyl alcohols undergo smooth intramolecular Friedel-Crafts cyclization with triethylsilane in the presence of 10 mol % iodine 3-aryl-1H-indene derivatives in good yields in short reaction times. This is the first example on the synthesis of substituted indenes from 1,3-diaryl propargyl alcohols. The use of inexpensive and readily available molecular iodine makes this method quite simple, more convenient, and practical.
- Reddy, B.V. Subba,Reddy, B. Brahma,Rao, K.V. Raghavendra,Yadav
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experimental part
p. 5697 - 5700
(2010/11/05)
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- Efficient synthesis of indenes by FeCl3·6H2O-catalyzed intramolecular Friedel-Crafts reaction of aryl-substituted allylic alcohols
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An efficient procedure for the synthesis of substituted indenes through the FeCl3·6H2O-catalyzed intramolecular Friedel-Crafts cyclization of aryl-substituted allylic alcohols has been developed. This method features the easily avail
- Wang, Jialiang,Zhang, Lixin,Jing, Yufeng,Huang, Wen,Zhou, Xigeng
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experimental part
p. 4978 - 4982
(2009/12/01)
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- Palladium(II)-catalyzed intramolecular addition of arylboronic acids to ketones
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A palladium(II)-catalyzed intramolecular addition of arylboronic acids to ketones was developed. Compared to Pd(OAc)2 catalysis system, cationic palladium complex with dppp as the ligand has higher catalytic activity and efficiency for wider sc
- Liu, Guixia,Lu, Xiyan
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p. 7324 - 7330
(2008/12/20)
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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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- Iodine induced transformations of alcohols under solvent-free conditions
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Iodine has been shown to be an efficient catalyst for transformations of alcohols under solvent-free conditions. In the presence of 5% of iodine, tertiary alcohols underwent dehydration forming the corresponding alkenes, while in the case of 2-phenylpropane-2-ol cyclodimerisation to 1,1,3-trimethyl-3-phenylindane took place. Secondary and primary benzyl alcohols under the same conditions gave the corresponding ethers.
- Stavber, Gaj,Zupan, Marko,Stavber, Stojan
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p. 8463 - 8466
(2007/10/03)
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- GASTRIN AND CHOLECYSTOKININ RECEPTOR LIGANDS
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This invention relates to a compound of formula (I) wherein the variables are as defined in the specification. The compound is useful for the treatment of gastrin related disorders.
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Page/Page column 26-27
(2010/11/30)
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- Dications of 3-phenylindenylidenefluorenes: Evaluation of antiaromaticity of indenyl and fluorenyl cations by magnetic measures
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Dications of p-substituted 3-phenylindenylidenefluorenes were prepared to examine the response of the resulting indenyl and fluorenyl cationic systems to magnetic measures of antiaromaticity. All measures, 1H NMR shifts, nucleus independent che
- Mills, Nancy S.,Llagostera, Kathleen B.,Tirla, Cornelia,Gordon, Stacey M.,Carpenetti, Donald
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p. 7940 - 7946
(2007/10/03)
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- A new synthesis of 3-substituted-1H-indenes through reaction of o-(β-magnesioalkyl)phenylmagnesium dihalides with carboxylate esters
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A new synthesis of 3-substituted-1H-indenes has been developed through the reaction of o-(β-magnesioalkyl)phenylmagnesium dihalides with carboxylate esters, followed by dehydration of the intermediate 1-substituted-1-indanols. Di-Grignard reagents allowing the synthesis of 3-substituted-, 2-methyl-3-substituted-, and 4-methyl-3-substituted-1H-indenes have been prepared, with overall yields for the two-step sequence ranging from 45 to 95%.
- Baker, Robert W.,Foulkes, Michael A.,Griggs, Michael,Nguyen, Bao N.
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p. 9319 - 9322
(2007/10/03)
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- Dynamic kinetic resolution-asymmetric transfer hydrogenation of 1-aryl-substituted cyclic ketones
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A range of 1-aryl-2-tetranols, and 1-phenyl-2-indanol, have been generated in high yield and enantiomeric excess from the corresponding racemic ketones, via a dynamic kinetic resolution-transfer hydrogenation process, using Ru(II)-TsDPEN in formic acid/triethylamine (5:2). This provides a potential entry to an asymmetric total synthesis of benzazepines such as Sch 39166.
- Alcock, Nathaniel J.,Mann, Inderjit,Peach, Philip,Wills, Martin
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p. 2485 - 2490
(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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- A novel tandem [2 + 2] cycloaddition-Dieckmann condensation with ynolate anions. Efficient synthesis of substituted cycloalkenones and naphthalenes via formal [n + 1] cycloaddition
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A novel tandem [2 + 2] cycloaddition-Dieckmann condensation via ynolate anions is described. Ynolate anions are useful for the formation of reactive β-lactone enolates via a pathway not involving the enolization of the corresponding β-lactones. The [2 + 2] cycloaddition of ynolate anions with δ- or σ-keto esters, followed by Dieckmann condensation, gives bicyclic β-lactones, which are easily decarboxylated to produce synthetically useful 2,3-disubstituted cyclopentenones and cyclohexenones in one pot. This tandem reaction was applied to a novel, one-pot synthesis of highly substituted naphthalenes.
- Shindo,Sato,Shishido
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p. 7818 - 7824
(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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- Efficient synthesis of 2- and 3-substituted indenes from 2-bromobenzyl bromide through an enolate alkylation/Cr(II)/Ni(II)-mediated carbonyl addition sequence
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An efficient new synthesis of 2- and 3-substituted indenes has been developed based on the nickel-catalyzed chromium(II)-promoted addition of aryl bromides to a tethered ketone carbonyl. Several tethered bromoaryl ketones were prepared through enolate alk
- Halterman, Ronald L.,Zhu, Chengian
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p. 7445 - 7448
(2007/10/03)
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- Nonlinear solvent water effects in the excited-state (formal) intramolecular proton transfer (ESIPT) in m-hydroxy-1,1-diaryl alkenes: Efficient formation of m-quinone methides
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The photohydration of hydroxy-substituted 1,1-diaryl alkenes 1-3 has been studied in aqueous CH3CN solution. Evidence for formation of quinone methide intermediates was provided by product studies and by observation of its absorption spectrum by laser flash photolysis. For the meta isomers, the proposed mechanism of m-quinone methide formation probably involves a solvent-mediated ("proton-relay") excited-state (formal) intramolecular proton transfer (ESIPT) from the phenol hydroxyl group to the β-carbon of the alkene moiety in neutral aqueous CH3CN solution, either in a concerted manner or via two very fast steps. The m-quinone methides are then trapped by water to form the corresponding diaryl ethanol product with high overall quantum yield. Evidence for the ESIPT pathway was provided by fluorescence and LFP measurements. The addition of small amounts of water (3CN) decreased the fluorescence emissions of 1 and 2 with a concomitant increase in production of m-quinone methides. Stem-Volmer analyses of fluorescence data revealed a dynamic and a minor static quenching component, both of which involved a water trimer cluster. The degree of charge transfer from the phenol (phenolate) oxygen to the alkene β-carbon, which may be thought of as the driving force for this efficient ESIPT, is pronounced for the meta isomer in the excited state, consistent with Zimmerman's "meta-ortho effect". Alkenes 1 and 2 were shown to be more efficient in m-quinone methide photogeneration than the hydroxy-substituted benzyl alcohol 8, which required conditions of higher water content for similar quantum yields.
- Fischer, Maike,Wan, Peter
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p. 4555 - 4562
(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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- CALCULATION OF THE LUMO ENERGY OF THE SUBSTITUTION PRODUCT OF THE AROMATIC SRN1 REACTION
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Comparison of the efficiency of twentytwo Y- species in their nucleophilic substitution reaction on PhI has been undertaken under Fe(II)- and photo-induction.Both these initiation procedures result to benefit from a higher electron-donor capacity of Y-.A key intermediate of the SRN1 reaction is the radical anion of the substitution product (i.e., PhYradical anion).It is formed in the propagation chain by addition of the nucleophile to phenyl radical.Information on the energy of the MO where the odd electron of PhYradical anion resides is inferred by calculating the LUMO energy of the PhY product.This appears to be an useful tool for predicting SRN1 reactivity trends for structurally homogeneous compounds.
- Galli, Carlo,Gentili, Patrizia,Guarnieri, Alessandra
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p. 159 - 164
(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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- Photochemistry of Organic Molecules Entwined in Spiderwebs; The Use of Poly(methyl methacrylate) Glass for Restricting Excited-State Motion
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A study of several unimolecular photochemical rearrangements in poly(methyl methacrylate) glass was carried out with the intent of comparing the behavior of excited-state species trapped in a polymer matrix with both the corresponding solution photochemistry and that in crystal lattices.Three reactants were studied: (a) 4,5,5-triphenylcyclohex-2-en-1-one, (b) 1,1-dicyano-3,3,5,5-tetraphenyl-1,4-pentadiene, and (c) 2,2-dimethyl-1,1-diphenyl-3-(2,2-diphenylvinyl)cyclopropane.The solution photochemistry of the three compounds had previously been studied in our laboratory, and the photochemistry in the crystal lattice had been similarly investigated for the first two.The crystal lattice photochemistry of the last of the three was investigated in the present study.For each of the three reactants, different photochemical behavior was observed depending on the environment-polymer glass, solution, or crystal lattice.The experimental behavior correlated nicely with theoretical assessment of molecular motion of the component atoms in proceeding onward from that point along the reaction coordinate where multiple reaction pathways are available.The preferred reaction pathway proved consistently to require the least motion and the minimum molecular volume displacement.A concept of least motion dependent on its application to the "branch point" rather than the entire conversion of reactant to product was established.
- Zimmerman, Howard E.,O'Brien, Michael E.
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p. 1809 - 1816
(2007/10/02)
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- Friedel-crafts-type cyclodehydration of 1,3-diphenyl-1-propanones. Kinetic evidence for the involvement of dication
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The mechanism of intramolecular ketone-aromatic cyclodehydration of 1,3-diphenyl-1-propanones to give 1-phenyl-1H-indenes in trifluoromethanesulfonic acid (TFSA) was investigated. The rate of the reaction of the monoprotonated diphenylpropanone increased
- Saito, Shinichi,Sato, Yasuo,Ohwada, Tomohiko,Shudo, Koichi
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p. 2312 - 2317
(2007/10/02)
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- Friedel-Crafts-type reactions involving di- and tricationic species. Onium-allyl dications and O,O-diprotonated aci-nitro species bearing a protonated carbonyl group
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Stable carbocations do not react with nonactivated benzenes. For example, acetophenone does not react with benzene in the presence of trifluoromethanesulfonic acid (TFSA), while trifluoroacetophenone does do so under acidic conditions owing to activation of the electrophilicity of the hydroxycarbenium cation by the trifluoromethyl group. This and other studies suggest that an electron-withdrawing substituent on the cationic center increases the reactivity toward benzenes. In this paper, involvement of multiply positively charged (dicationic and tricationic) species, which have sufficient electrophilicity toward benzene, is demonstrated in the acid-catalyzed reactions of cinnamaldehyde and its derivatives and also in the acid-catalyzed reactions of nitromethanes. The species formed from cinnamaldehyde, cinnamaldimine, cinnamaldoxime, and their derivatives in TFSA or TFSA-SbF5 have an adequate reactivity toward benzene. O-Protonated cinnamaldehyde and its derivatives, N-protonated cinnamaldimine, and N,N-dimethylcinnamaldiminium salt do not react with benzene. Since a strong acid catalyst is required for the reactions, participation of doubly protonated species, onium-allyl dications, is proposed. Ab initio calculations of (1) the donor-acceptor interaction energies of a neutral donor (such as water and ammonia) and a doubly charged allyl dication and (2) proton affinities demonstrated that the ammonium-allyl dication is more stable than the oxonium-allyl dication, in accordance with the experimental observation. Nitronic acids also react with benzene at the ipso position with respect to the nitro group to give the phenylated oximes in the presence of TFSA. The reaction with benzene is not catalyzed by trifluoroacetic acid, which is sufficiently acidic to monoprotonate a nitronic acid to the protonated aci-nitro form. The reaction requires a stronger acid, trifluoromethanesulfonic acid, suggesting intervention of the dication formed by O,O-diprotonation of acinitroalkanes rather than the monoprotonated aci-nitroalkane. As a result of further study on the phenylation reactions, we found a facile phenylation reaction of nitromethanes substituted with an electron-withdrawing group, catalyzed by TFSA, to give phenylated α-carbonyloximes in high yields. A triply positively charged cation, an O,O-diprotonated aci-nitro species bearing a protonated ethoxycarbonyl group, which can react with nonactivated benzene, is proposed to be an intermediate in this reaction.
- Ohwada, Tomohiko,Yamagata, Naoko,Shudo, Koichi
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p. 1364 - 1373
(2007/10/02)
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- An Assortment of Highly Unusual Rearrangements in the Photochemistry of Vinylcyclopropanes. Mechanistic and Exploratory Organic Photochemistry
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The singlet and triplet photochemistry of 2,2-dimethyl-1,1-diphenyl-3-(2,2-diphenylvinyl)cyclopropane and 3-(2,2-dicyanovinyl)-2,2-dimethyl-1,1-diphenylcyclopropane was investigated.In the (diphenylvinyl)cyclopropane case, direct irradiation led via the s
- Zimmerman, Howard E.,Oaks, Frank L.,Campos, Pedro
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p. 1007 - 1018
(2007/10/02)
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