- Formation of Nucleophilic Allylboranes from Molecular Hydrogen and Allenes Catalyzed by a Pyridonate Borane that Displays Frustrated Lewis Pair Reactivity
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Here we report the in situ generation of nucleophilic allylboranes from H2 and allenes mediated by a pyridonate borane that displays frustrated-Lewis-pair reactivity. Experimental and computational mechanistic investigations reveal that upon H2 activation, the covalently bound pyridonate substituent becomes a datively bound pyridone ligand. Dissociation of the formed pyridone borane complex liberates Piers borane and enables a hydroboration of the allene. The allylboranes generated in this way are reactive towards nitriles. A catalytic protocol for the formation of allylboranes from H2 and allenes and the allylation of nitriles has been devised. This catalytic reaction is a conceptually new way to use molecular H2 in organic synthesis.
- Ahles, Sebastian,Averdunk, Arthur,Becker, Jonathan,Gellrich, Urs,Hasenbeck, Max
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- Acid-catalyzed conversion of 7-ethynyl- and 7-vinyleyclohepta-1,3, 5-trienes to substituted benzene derivatives
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The acid-catalyzed rearrangement in THF/TFA (5:1, v/v) of cyclohepta-1,3,5-trienes containing an α,β-unsaturated substituent at C-7 was investigated. 7-Ethynylcyclohepta-1,3,5-triene (1a) and its 1,4-di-tert-butyl (1b), 1,5-di-tert-butyl (1c), and 2,5-di-tert-butyl (1d) derivatives underwent isomerization to phenylallenes 2, 3, 7, and 3, respectively. 2,5-Di-tert-butyl-7-vinylcyclohepta-1,3,5-triene (17) gave a mixture (66:34) of (E)- and (Z)-1,4-di-tert-butyl-2-(1-propenyl)benzene (20). A mechanism involving the protonation of the norcaradiene tautomer (NCD), which is in equilibrium with cycloheptatriene (CHT) 1 or 17, followed by the cleavage of a three-membered ring to give an arenium ion, is proposed. In contrast, 2,5-di-tert-butyl-7-cyanocyclohepta-1,3,5-triene (12) and bis(cyclohepta-2,4,6-trien-1-yl)ethyne (21) did not give the expected products, probably due to the unfavorable energetics of the ring-opening step. A thermal 1,5-hydrogen shift predominates in these cases. Kinetic studies indicated that the rearrangement of 1a is significantly accelerated by the presence of tert-butyl groups on the seven-membered ring. The order of reactivity, 1a 〈 1b 〈 1c 〈 1d, is in agreement with the population of NCD forms at equilibrium, as estimated by the calculated CHT-NCD energy-difference and the 13C NMR chemical shifts of 1a-d, indicating the importance of the equilibrium concentration of the norcaradiene form as a rate-controlling factor. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Minegishi, Shinya,Kamada, Jun,Takeuchi, Ken'ichi,Komatsu, Koichi,Kitagawa, Toshikazu
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- Zinc promoted asymmetric propargylation of N-(2-chlorotetrafluoroethanesulfin)imines
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Zinc promoted asymmetric Barbier-type homopropargylation of aldimines is demonstrated. 2-Chlorotetrafluoroethanesulfinamide was used as the chiral auxiliary and the corresponding homopropargylamines were obtained in good yields with up to 98% diastereosel
- Liu, Li-Juan,Liu, Jin-Tao
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- Nickel-catalyzed coupling of terminal allenes, aldehydes, and silanes
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The development of a nickel-catalyzed coupling of terminal allenes, aldehydes, and silanes is described. This transformation selectively provides 1,1-disubstituted allylic alcohols, protected as a silyl ether. The choice of the reducing agent is essential
- Ng, Sze-Sze,Jamison, Timothy F.
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- Acid-catalyzed rearrangement of ethynylcycloheptatriene to phenylallene
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7-Ethynylcycloheptatriene (1) cleanly isomerizes to phenylallene in the presence of acid A machanism involving the protonation of ethynylnorcaradiene, which is in equilibrium with 1, followed by the cleavage of a three-membered ring to give an arenium ion, is proposed. The rearrangement is accelerated by a factor of 370 by introducing tert-butyl groups on C-2 and C-5, indicating the importance of the equilibrium concentration of the norcaradiene form as a rate-controlling factor.
- Kitagawa, Toshikazu,Kamada, Jun,Minegishi, Shinya,Takeuchi, Ken'ichi
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- Photoredox Catalyzed Sulfonylation of Multisubstituted Allenes with Ru(bpy)3Cl2 or Rhodamine B
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A highly regio- and stereoselective sulfonylation of allenes was developed that provided direct access to α, β-substituted unsaturated sulfone. By means of visible-light photoredox catalysis, the free radicals produced by p-toluenesulfonic acid reacted with multisubstituted allenes to obtain Markovnikov-type vinyl sulfones with Ru(bpy)3Cl2 or Rhodamine B as photocatalyst. The yield of this reaction could reach up to 91%. A series of unsaturated sulfones would be used for further transformation to some valuable compounds.
- Chen, Jingyun,Chen, Shufang,Jiang, Jun,Lu, Qianqian,Shi, Liyang,Xu, Zekun,Yimei, Zhao
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supporting information
(2021/11/09)
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- Polymerization of Allenes by Using an Iron(II) β-Diketiminate Pre-Catalyst to Generate High Mn Polymers
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Herein, we report an iron(II)-catalyzed polymerization of arylallenes. This reaction proceeds rapidly at room temperature in the presence of a hydride co-catalyst to generate polymers of weight up to Mn=189 000 Da. We have determined the polymer structure and chain length for a range of monomers through a combination of NMR, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) analysis. Mechanistically, we postulate that the co-catalyst does not react to form an iron(II) hydride in situ, but instead the chain growth is proceeding via a reactive Fe(III) species. We have also performed kinetic and isotopic experiments to further our understanding. The formation of a highly unusual 1,3-substituted cyclobutane side-product is also investigated.
- Durand, Derek J.,Webster, Ruth L.,Woof, Callum R.
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p. 12335 - 12340
(2021/07/19)
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- Enantioselective Addition of α-Nitroesters to Alkynes
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By using Rh–H catalysis, we couple α-nitroesters and alkynes to prepare α-amino-acid precursors. This atom-economical strategy generates two contiguous stereocenters, with high enantio- and diastereocontrol. In this transformation, the alkyne undergoes isomerization to generate a RhIII–π-allyl electrophile, which is trapped by an α-nitroester nucleophile. A subsequent reduction with In powder transforms the allylic α-nitroesters to the corresponding α,α-disubstituted α-amino esters.
- Davison, Ryan T.,Parker, Patrick D.,Hou, Xintong,Chung, Crystal P.,Augustine, Sara A.,Dong, Vy M.
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supporting information
p. 4599 - 4603
(2021/01/18)
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- Copper(ii)-catalyzed protoboration of allenes in aqueous media and open air
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A method has been developed for the facile Cu(ii)-catalyzed protoboration of monosubstituted allenes in aqueous media under atmospheric conditions. The reaction occurs site selectively, favoring internal alkene protoboration to afford 1,1-disubstituted vinylboronic acid derivatives (up to 93?:?7) with modest to good yields. The method has been applied to a variety of phenylallene derivatives as well as alkyl-substituted allenes. This journal is
- Nekvinda, Jan,Santos, Webster L.,Snead, Russell F.
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p. 14925 - 14931
(2021/09/04)
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- Photoredox-Catalyzed α-Aminoalkylcarboxylation of Allenes with CO2
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The photoredox-catalyzed α-aminoalkylcarboxylation of aryl allenes with CO2 and N,N-dimethylanilines is reported for the first time (26 examples, up to 96% yield). In the case of electron-deficient allenes, good regioselectivity was observed (up to 94:6), exclusively generating kinetic products over thermodynamic products. This protocol is a novel synthetic method for highly functionalized β,γ-unsaturated γ-aminobutyric esters.
- Hahm, Hyungwoo,Baek, Doohyun,Kim, Dowon,Park, Seongwook,Ryoo, Jeong Yup,Hong, Sukwon
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p. 3879 - 3884
(2021/05/29)
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- Preparation of (E)-1,3-Enyne Derivatives through Palladium Catalyzed Hydroalkynylation of Allenes
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A general and efficient palladium catalyzed hydroalkynylation of allenes was developed to produce synthetically versatile (E)-1,3-enyne derivatives with high regio- and stereoselectivity. This catalytic system proceeded under mild conditions and was compatible with a broad range of substrates, especially for allenes without electron-bias groups. This work further broadens the synthetic potential of these scaffolds in organic synthesis and medicinal chemistry.
- Liu, Zhi-Kai,Yang, Ying,Zhan, Zhuang-Ping
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supporting information
(2022/01/20)
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- Indene formation upon borane-induced cyclization of arylallenes, 1,1-carboboration, and retro-hydroboration
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We herein report the reaction of arylallenes with tris(pentafluorophenyl)borane that yields pentafluorophenyl substituted indenes. The tris(pentafluorophenyl)borane induces the cyclization of the allene and transfers a pentafluorophenyl ring in the course of this reaction. A Hammett plot analysis and DFT computations indicate a 1,1-carboboration to be the C-C bond-forming step.
- Hasenbeck, Max,Wech, Felix,Averdunk, Arthur,Becker, Jonathan,Gellrich, Urs
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supporting information
p. 5518 - 5521
(2021/06/12)
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- Diboration of 3-substituted propargylic alcohols using a bimetallic catalyst system: access to (Z)-allyl, vinyldiboronates
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The diboration of substituted propargylic alcohols has been achieved using a bimetallic Pd/Cu catalyst system. Thein situformation of a pentrafluoroboronic acid intermediate sufficiently activates the C-O bond towards dual catalysis affording (Z)-allyl, vinyldiboronates stereoselectively.
- Peck, Cheryl L.,Nekvinda, Jan,Santos, Webster L.
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supporting information
p. 10313 - 10316
(2020/09/16)
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- Intermolecular Allene Functionalization by Silver-Nitrene Catalysis
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Under silver catalysis conditions, using [Tp*,BrAg]2 as the catalyst precursor, allenes react with PhI═NTs in the first example of efficient metal-mediated intermolecular nitrene transfer to such substrates. The nature of the substituent at the allene seems crucial for the reaction outcome since arylallenes are converted into azetidine derivatives, whereas methylene aziridines are the products resulting from alkylallenes. Mechanistic studies allow proposing that azetidines are formed through unstable cyclopropylimine intermediates, which further incorporate a second nitrene group, both processes being silver-mediated. Methylene aziridines from alkylallenes derive from catalytic nitrene addition to the allene double bonds. Both routes have resulted to be productive for further synthetic transformations affording aminocyclopropanes.
- Rodríguez, Manuel R.,Besora, María,Molina, Francisco,Maseras, Feliu,Díaz-Requejo, M. Mar,Pérez, Pedro J.
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supporting information
p. 13062 - 13071
(2020/09/01)
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- An Electroreductive Approach to Radical Silylation via the Activation of Strong Si-Cl Bond
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The construction of C(sp3)-Si bonds is important in synthetic, medicinal, and materials chemistry. In this context, reactions mediated by silyl radicals have become increasingly attractive but methods for accessing these intermediates remain limited. We present a new strategy for silyl radical generation via electroreduction of readily available chlorosilanes. At highly biased potentials, electrochemistry grants access to silyl radicals through energetically uphill reductive cleavage of strong Si-Cl bonds. This strategy proved to be general in various alkene silylation reactions including disilylation, hydrosilylation, and allylic silylation under simple and transition-metal-free conditions.
- Lu, Lingxiang,Siu, Juno C.,Lai, Yihuan,Lin, Song
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supporting information
p. 21272 - 21278
(2020/12/21)
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- Vanadium complex catalyst containing phenoxy ligand and preparation method and application of vanadium complex catalyst
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The invention discloses a vanadium complex catalyst containing a phenoxy ligand. The structural general formula of the vanadium complex catalyst containing the phenoxy ligand is shown in the specification, wherein R1, R2, R3, R4, R5, R'1, R'2, R'3, R'4 an
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Paragraph 0048-0050
(2020/11/12)
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- Gold-Catalyzed Carbazolation Reactions of Alkynes
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Herein, we report on a Au(I)-catalyzed reaction of alkynes with carbazoles that enables a one-step synthesis of vinyl carbazoles that are important molecules for applications as photoluminescent materials. This reaction proceeds under mild conditions at r
- He, Feifei,Jana, Sripati,Koenigs, Rene M.
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supporting information
(2020/07/03)
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- Enantioselective Copper-Catalyzed Three-Component Carboboronation of Allenes: Access to Functionalized Dibenzo [b,f][1,4]oxazepine Derivatives
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A copper-catalyzed enantioselective three-component difunctionalization of allenes with seven-membered cyclic imines and bis(pinacolato)diboron (B2(Pin)2) to approach functionalized dibenzo[b,f][1,4]oxazepine derivatives is developed. The chiral products are obtained in up to 81% yield, >20:1 dr, and 98% ee when either a chiral diphosphine ligand or a chiral ferrocenyl-based P,N-ligand is used. Furthermore, the reaction exhibits reversed diastereoselectivities when the chiral diphosphine ligand and the chiral P,N-ligand are used respectively. (Figure presented.).
- Deng, Hao,Meng, Ziwei,Wang, Sifan,Zhang, Zheming,Zhang, Yaqi,Shangguan, Yu,Yang, Fazhou,Yuan, Dekai,Guo, Hongchao,Zhang, Cheng
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supporting information
p. 3582 - 3587
(2019/07/17)
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- Trifluoromethylation of Allenes: An Expedient Access to α-Trifluoromethylated Enones at Room Temperature
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A silver(I) catalyzed regioselective trifluoromethylation of allenes using Langlois's salt (NaOSOCF3) is demonstrated. This transformation enables direct expedient access to α-trifluoromethylated acroleins, which are valuable synthons for a number of pharmaceuticals and agrochemicals containing vinyl-CF3 moieties. Versatility of this trifluoromethylation method has been established with good yield and excellent regioselectivity. Preliminary experiments and computational studies were carried out to elucidate the mechanistic insight of this protocol.
- Brochetta, Massimo,Borsari, Tania,Gandini, Andrea,Porey, Sandip,Deb, Arghya,Casali, Emanuele,Chakraborty, Arka,Zanoni, Giuseppe,Maiti, Debabrata
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supporting information
p. 750 - 753
(2019/01/04)
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- A 1, 1 - disubstituted [...] compound synthesis method
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The invention discloses a 1, 1 - disubstituted [...] compound synthesis method, the catalyst cuprous chloride, carbene precursor, the tertiary butyl alcohol potassium is added in the Schlenk reaction tube, vacuum, in an inert gas conditions, adding tetrahydrofuran, stir; then the [...][...], type I shown and methanol is dissolved in the tetrahydrofuran zincon after, in the Schlenk reaction tube of the instillment to states, for 25 °C stirring for 1 - 5 hours, the resulting reaction solution after treatment of formula II shown in 1, 1 - disubstituted [...] compound. Synthesis method of the invention has catalyst is cheap and easy to obtain and the low toxicity, high selectivity, environment friendly, mild reaction conditions, functional group universal good and simple operation and the like.
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Paragraph 0023-0025
(2019/03/28)
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- Reactivity of [TismPriBenz]MgMe towards secondary amines and terminal alkynes: Catalytic dehydrocoupling with hydrosilanes to afford Si–N and Si–C bonds
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The magnesium hydride and methyl compounds, [TismPriBenz]MgX (X = H, Me), react with diphenylamine (Ph2NH)and pyrrolidine (C4H8NH)to afford the amide derivatives, [TismPriBenz]MgNPh2 and [TismPriBenz]MgNC4H8, while reactions with the terminal alkynes, PhC[tbnd]CH and BunC[tbnd]CH, afford the corresponding acetylide derivatives, [TismPriBenz]MgC[tbnd]CPh and [TismPriBenz]MgC[tbnd]CBun. The Mg[sbnd]N bond of [TismPriBenz]MgNR2 may be cleaved by hydrosilanes, such that [TismPriBenz]MgMe is an effective precatalyst for the dehydrocoupling of hydrosilanes and amines. For example, [TismPriBenz]MgMe enables the conversion of a 1:1 mixture of Ph2SiH2 and C4H8NH at room temperature to the silazane, Ph2SiH(NC4H8). [TismPriBenz]MgH and [TismPriBenz]MgMe are also capable of dehydrocoupling PhC[tbnd]CH and PhSiH3 to form PhSiH2C[tbnd]CPh. In addition to dehydrocoupling of terminal alkynes, [TismPriBenz]MgMe is also capable of achieving the isomerization 3-phenyl-1-propyne to phenylallene.
- Rauch, Michael,Roberts, Renee C.,Parkin, Gerard
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p. 271 - 279
(2019/07/02)
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- Direct Synthesis of 1-Arylprop-1-ynes with Calcium Carbide as an Acetylene Source
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A simple method is described for the synthesis of 1-arylprop-1-ynes directly from aromatic aldehyde p -tosylhydrazones by using calcium carbide as an acetylene source. The salient features of this protocol are its use of a readily available and easily handled source of acetylene, its operational simplicity, its high yield, and its broad substrate scope.
- Gao, Lei,Li, Zheng
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supporting information
p. 1580 - 1584
(2019/08/20)
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- A convenient access to allylic triflones with allenes and triflyl chloride in the presence of (EtO)2P(O)H
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A simple method for the preparation of allylic triflones from allenes and triflyl chloride in the presence of (EtO)2P(O)H has been developed. The features of this reaction are catalyst-free and simple starting substrates. This method tolerates diverse functional groups and substituted allylic triflones are obtained in moderate to good yields.
- Ni, Jixiang,Jiang, Yong,An, Zhenyu,Lan, Jingfeng,Yan, Rulong
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supporting information
p. 7343 - 7345
(2019/06/27)
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- Copper-Catalyzed Difunctionalization of Allenes with Sulfonyl Iodides Leading to (E)-α-Iodomethyl Vinylsulfones
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A highly regioselective iodosulfonylation of allenes in the presence of CuI and 1,10-phenanthroline has been developed for the synthesis of various useful (E)-α-iodomethyl vinylsulfones in moderate to excellent yields. This practical reaction is fast, operationally simple, and in particular, proceeds under very mild conditions to afford the target products with high regio- and stereoselectivity. The selectivity was illustrated by a conceptual DFT analysis.
- Lu, Ning,Zhang, Zhiguo,Ma, Nana,Wu, Conghui,Zhang, Guisheng,Liu, Qingfeng,Liu, Tongxin
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supporting information
p. 4318 - 4322
(2018/07/29)
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- Borane-Induced Dimerization of Arylallenes
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A series of arylallenes react with HB(C6F5)2 in a 2:1 molar ratio to give the tail-to-tail 1,6-diaryl-2-boryl-hexa-1,5-diene coupling products. The reaction of the phenylallene substrate with HB(C6F5)
- Tao, Xin,Daniliuc, Constantin G.,Dittrich, Dustin,Kehr, Gerald,Erker, Gerhard
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supporting information
p. 13922 - 13926
(2018/10/05)
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- Palladium-catalyzed allylic alkylation with internal alkynes to construct C-C and C-N bonds in water
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A palladium-catalyzed system enabled efficient allylic alkylation with alkynes in water has been developed. This reaction presents an environmentally friendly strategy for constructing lots of allylic compounds with indolinones, ketones, amines as well as electron-rich aromatic compounds as nucleophiles. Moreover, the in situ formed arylallene intermediate adopting alkynes as starting materials omits the need for leaving groups and extra oxidants, showing high atom economy. The versatility of the developed reaction also lends itself to the incorporation of deuteriums by simply replacing H2O with D2O.
- Gao, Shang,Liu, Hao,Wu, Zijun,Yao, Hequan,Lin, Aijun
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supporting information
p. 1861 - 1865
(2017/06/09)
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- Highly 2,3-Selective Polymerization of Phenylallene and Its Derivatives with Rare-Earth Metal Catalysts: From Amorphous to Crystalline Products
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Rare-earth metal complexes (Flu-CH2-Py)Ln(CH2SiMe3)2(THF)n (Ln=Sc(1), Lu(2), Tm(3), Y(4) and Gd(5)), upon the activation of [Ph3C][B(C6F5)4] and AliBu3, were employed to catalyze the polymerization of allene derivatives under mild conditions. The Gd, Y, Tm, Lu metal based precursors exhibited distinguished 2,3-selectivity (>99.9 %) for phenylallene (PA) polymerization, whereas the smallest Sc metal based precursor showed a moderate 2,3-selectivity. The activity increased with the central metal size following the trend of Gd(5)>Tm(4)>Y(3)>Lu(2)>Sc(1). Moreover, Gd(5) also realized the purely 2,3-selective polymerizations of polar or nonpolar allene derivatives, para-methylphenylallene, para-flourophenylallene and para-methoxyphenylallene, regardless of electron-donating or -withdrawing substituents. Owing to the highly regular backbones, these polymers (except PPA) were crystalline, thus being the first crystalline polymers based on allene derivatives.
- Lin, Fei,Liu, Zhaohe,Wang, Tiantian,Cui, Dongmei
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supporting information
p. 14653 - 14657
(2017/10/18)
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- Photoredox-catalyzed oxytrifluoromethylation of allenes: Stereoselective synthesis of 2-trifluoromethylated allyl acetates
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We have developed novel oxytrifluoromethylation of aryl-substituted allenes by photoredox catalysis. The present photocatalytic system allows direct and stereoselective synthesis of 2-CF3-allyl acetates bearing tetrasubstituted CF3-a
- Tomita, Ren,Koike, Takashi,Akita, Munetaka
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supporting information
p. 4681 - 4684
(2017/07/10)
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- Stereoselective annulation between an allene, an alkene, and two nitrosoarenes to access bis(isoxazoliodine) derivatives
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This work reports metal-free annulations between one allene, two nitrosoarenes and one electron-deficient alkene to afford bis(isoxazolidine) derivatives stereoselectively. This process involves an initial formation of isoxazolidin-4-imine oxides, followe
- Sharma, Pankaj,Jadhav, Prakash D.,Skaria, Manisha,Liu, Rai-Shung
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supporting information
p. 9389 - 9397
(2017/11/22)
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- Propargylic C(sp3)-H Bond Activation for Preparing η3-Propargyl/Allenyl Complexes of Yttrium
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Propargylic C(sp3) - H bond activation of 1-substituted-1-propynes, such as 1-trimethylsilyl-1-propyne, 2-hexyne, and 1-phenyl-1-propyne, was achieved by treatment with an alkylyttrium complex 8 bearing an ene-diamido ligand to give the corresponding (η3-propargyl/allenyl)yttrium complexes 7a-c. A unique delocalized η3-propargyl/allenyl structure of these three complexes was revealed by NMR spectroscopy and X-ray single crystal analyses. To elucidate the reactivity of the η3-propargyl/allenyl unit of complexes 7a-c, we conducted two reactions with N-methylaniline and N,N′-dicyclohexylcarbodiimine. For protonation by N-methylaniline, we found that the product distribution of monosubstituted internal alkynes and allenes depended on the substituent on the η3-propargyl/allenyl moiety: 7a and 7b afforded the corresponding internal alkynes as the major products, whereas the major protonation product of 7c was phenylallene. For the insertion of N,N′-dicyclohexylcarbodiimine, complex 7a selectively yielded η3-{N,N′-dicyclohexyl-2-(3-trimethylsilylpropargyl)amidinate}yttrium 12a, while complex 7c produced η3-{N,N′-dicyclohexyl-2-(1-phenylallenyl)amidinate}yttrium complex 13c, though complex 7b gave a mixture of η3-{N,N′-dicyclohexyl-2-(3-normalpropylpropargyl)amidinate}yttrium complex 12b and η3-{N,N′-dicyclohexyl-2-(1-normalpropylallenyl)amidinate}yttrium 13b in an 83:17 ratio. On the basis of the product distributions in these two-types of reactions, (η3-propargyl/allenyl)yttrium complexes were shifted into preferentially favorable η1-allenyl species or η1-propargyl species depending on the substituents prior to the reaction with electrophiles via a four-membered cyclic mechanism.
- Nagae, Haruki,Kundu, Abhinanda,Tsurugi, Hayato,Mashima, Kazushi
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p. 3061 - 3067
(2017/09/05)
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- Iodothiocyanation/Nitration of Allenes with Potassium Thiocyanate/Silver Nitrite and Iodine
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Direct strategies for the iodothiocyanation and iodonitration of allenes have been developed. In this process, potassium thiocyanate/silver nitrite and molecular iodine are used as the source of SCN, ONO2and iodine to provide the desired products in moderate to good yields with high stereoselectivity. (Figure presented.).
- Yang, Xiaodong,She, Yue,Chong, Ya,Zhai, Huichun,Zhu, He,Chen, Baohua,Huang, Guosheng,Yan, Rulong
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supporting information
p. 3130 - 3134
(2016/10/09)
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- Synthesis of Terminal Allenes via a Copper-Catalyzed Decarboxylative Coupling Reaction of Alkynyl Carboxylic Acids
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Synthesis of terminal allenes via a copper-catalyzed decarboxylative coupling reaction was developed. Aryl alkynyl carboxylic acid, paraformaldehyde, and dicyclohexylamine were reacted with CuI (20 mol %) in diglyme at 100°C for 2 h to produce the terminal allene in moderate to good yields. The method showed good functional group tolerance.
- Lim, Jeongah,Choi, Jinseop,Kim, Han-Sung,Kim, In Seon,Nam, Kye Chun,Kim, Jimin,Lee, Sunwoo
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p. 303 - 308
(2016/01/15)
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- Highly Regio- and Enantioselective Alkoxycarbonylative Amination of Terminal Allenes Catalyzed by a Spiroketal-Based Diphosphine/Pd(II) Complex
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An enantioselective alkoxycarbonylation-amination cascade process of terminal allenes with CO, methanol, and arylamines has been developed. It proceeds under mild conditions (room temperature, ambient pressure CO) via oxidative Pd(II) catalysis using an aromatic spiroketal-based diphosphine (SKP) as a chiral ligand and a Cu(II) salt as an oxidant and affords a wide range of α-methylene-β-arylamino acid esters (36 examples) in good yields with excellent enantioselectivity (up to 96% ee) and high regioselectivity (branched/linear > 92:8). Preliminary mechanistic studies suggested that the reaction is likely to proceed through alkoxycarbonylpalladation of the allene followed by an amination process. The synthetic utility of the protocol is showcased in the asymmetric construction of a cycloheptene-fused chiral β-lactam.
- Liu, Jiawang,Han, Zhaobin,Wang, Xiaoming,Wang, Zheng,Ding, Kuiling
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supporting information
p. 15346 - 15349
(2015/12/26)
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- Ligandless Regioselective Hydrosilylation of Allenes Catalyzed by Gold Nanoparticles
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The first example of Au-catalyzed hydrosilylation of allenes is presented using recyclable gold nanoparticles as catalyst, without the requirement of any external ligands or additives. The hydrosilane addition takes place on the more substituted double bond of terminal allenes in a highly regioselective manner. The observed regioselectivity/reactivity modes are attributed to steric and electronic factors.
- Kidonakis, Marios,Stratakis, Manolis
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supporting information
p. 4538 - 4541
(2015/09/28)
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- Organomagnesium-catalyzed isomerization of terminal alkynes to allenes and internal alkynes
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Organomagnesium complexes 2 were synthesized from N,N-dialkylamineimine ligands 1 and dibenzylmagnesium by benzylation of the imine moiety. 3-Aryl-1-propynes reacted with 2 to form the corresponding tetraalkynyl complexes, which acted as catalysts for the transformation of these terminal alkynes into allenes and further to internal alkynes under mild conditions. To the best of our knowledge, this example is the first of an organomagnesium-catalyzed isomerization of alkynes. Notably, the reactions proceeded through temporally separated autotandem catalysis, thus allowing the isolation of the allene or internal alkyne species in good yields. Mechanistic experiments suggested that the catalytically active tetraalkynyl complexes consist of a tautomeric mixture of alkynyl-, allenyl-, and propargylmagnesium species.
- Rochat, Rapha?l,Yamamoto, Koji,Lopez, Michael J.,Nagae, Haruki,Tsurugi, Hayato,Mashima, Kazushi
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supporting information
p. 8112 - 8120
(2015/05/27)
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- Total synthesis of (-)-ophiodilactone A and (-)-ophiodilactone B
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The first asymmetric total synthesis of (-)-ophiodilactone A and (-)-ophiodilactone B, isolated from the ophiuroid (Ophiocoma scolopendrina), is reported. The key features of the synthesis include the highly stereocontrolled construction of the structurally congested γ-lactone/δ-lactone skeleton through an asymmetric epoxidation, diastereoselective iodolactonization, and intramolecular epoxide-opening with a carboxylic acid, and biomimetic radical cyclization of ophiodilactone A to ophiodilactone B. Bioinspired synthesis: The first total synthesis of the title compounds has been accomplished in a highly stereocontrolled manner. Key features of the synthesis include an asymmetric epoxidation, a diastereoselective iodolactonization, an intramolecular epoxide opening with a carboxylic acid, and a biomimetic radical cyclization of ophiodilactone A to ophiodilactone B. Copyright
- Matsubara, Takaaki,Takahashi, Keisuke,Ishihara, Jun,Hatakeyama, Susumi
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supporting information
p. 757 - 760
(2014/01/23)
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- Palladium-catalyzed insertion of an allene into an aminal: Aminomethylamination of allenes by C-N bond activation
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A new and atom-economic palladium-catalyzed aminomethylamination of allenes with aminals by C-N bond activation is described. This direct and operationally simple method provides a fundamentally novel approach for the synthesis of 1,3-diamines. Mechanistic studies suggest that a unique cationic π-allylpalladium complex containing an aminomethyl moiety is generated as a key intermediate through the carbopalladation of the allene with a cyclometalated palladium-alkyl species.
- Hu, Jianhua,Xie, Yinjun,Huang, Hanmin
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supporting information
p. 7272 - 7276
(2014/07/21)
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- A new gold-catalysed azidation of allenes
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A new gold-catalysed azidation reaction of allenes is presented as a new highly modular approach for the synthesis of substituted allyl derivatives containing nitrogen from simple precursors. This journal is The Royal Society of Chemistry.
- Hurtado-Rodrigo, Cesar,Hoehne, Stefanie,Munoz, Maria Paz
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supporting information
p. 1494 - 1496
(2014/02/14)
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- Highly regio- and stereoselective synthesis of alkylidenecyclopropanes via Ru(II)-pheox catalyzed asymmetric inter- and intramolecular cyclopropanation of allenes
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An efficient protocol for the synthesis of optically active alkylidenecyclopropanes (ACPs) via the Ru(II)-Pheox catalyzed asymmetric cyclopropanation of allenes has been established. This catalytic system proceeded with high regioselectivity to give the A
- Chanthamath, Soda,Chua, Hao Wei,Kimura, Seiya,Shibatomi, Kazutaka,Iwasa, Seiji
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supporting information
p. 3408 - 3411
(2014/07/08)
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- Nickel-catalyzed substitution reactions of propargyl halides with organotitanium reagents
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A simple and mild catalytic coupling reaction of propargyl halides with organotitanium reagents is reported. The reaction of propargyl bromide with organo-titanium reagents mediated by NiCl2(2 mol%) and PCy3(4 mol%) in CH2
- Li, Qing-Han,Liao, Jung-Wei,Huang, Yi-Ling,Chiang, Ruei-Tang,Gau, Han-Mou
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p. 7634 - 7642
(2014/12/11)
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- Highly selective copper-catalyzed hydroboration of allenes and 1,3-dienes
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The highly selective copper-catalyzed hydroboration of allenes has been developed. Allylboranes and alkenylboranes were selectively prepared by the judicious choice of catalytic species (copper hydride and boryl copper). Furthermore, two types of alkenylboranes could be selectively synthesized by the choice of an appropriate ligand. Mechanistic studies confirmed that the protonation of a (Z)-σ-allyl copper species, which was isolated and structurally characterized by single-crystal X-ray diffraction, was a key step in these reactions. Besides allenes, this method is also applicable to the selective hydroboration of 1,3-diene derivatives to afford allylboranes and homoallylboranes. Copyright
- Semba, Kazuhiko,Shinomiya, Masataka,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
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supporting information
p. 7125 - 7132
(2013/07/04)
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- Stereocontrol in palladium-catalyzed propargylic substitutions: Kinetic resolution to give enantioenriched 1,5-enynes and propargyl acetates
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Kinetic resolution during the catalytic allyl-propargyl cross-coupling with chiral starting materials can be accomplished with a chiral palladium catalyst. These reactions offer ready access to enantiomerically enriched enyne products from simple, readily
- Ardolino, Michael J.,Eno, Meredith S.,Morken, James P.
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supporting information
p. 3413 - 3419
(2013/12/04)
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- Theoretical support for the involvement of a radical pathway in the formation of allenylzincs from propargyl iodides and dialkylzincs: Influence of zinc coordination
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Propargyl iodides are good precursors for allenylzincs via reaction with diethylzinc, even in nondegassed medium. These reactions proceed via zinc/iodine exchange. Owing to the previously reported detection of propargyl radical by ESR experiments, in this process a radical mechanism was suspected. Calculations of the C-Zn BDEs in allenyl- and propargylzinc species were performed with the CBS-QB3 method to demonstrate that propargyl radicals could undergo homolytic substitution at zinc. The stabilization of allenylzinc derivatives by chelation, made possible by the selection of appropriate ortho-substituted 3-phenylalkynyl iodides as precursors, was shown to influence the regioselectivity of their addition to aldehydes and ketones. The more stabilized the chelated allenylzinc intermediate, the higher the ratio of homopropargylic alcohols.
- Jammi, Suribabu,Mouysset, Dominique,Siri, Didier,Bertrand, Michèle P.,Feray, Laurence
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p. 1589 - 1603
(2013/04/10)
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- Some reactions of gem-dibromocyclopropanes and metal carbonyls
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A series of gem-dibromocyclopropanes were treated with various metal complexes. Among the metal complexes, Ru(CO)2(PPh3) 3, Ru(CO)3(PPh3)2, and Mo(CO) 6 were able to remove a bro
- Lin, Shaw-Tao,Lee, Chuan-Chen,Ding, Mei-Fang,Liang, David W.,Jeng, An-Ting
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scheme or table
p. 529 - 534
(2012/08/08)
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- Synthesis of allenes via Nickel-catalyzed cross-coupling reaction of propargylic bromides with grignard reagents
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We describe a convenient method for the synthesis of terminal allenes from cross-coupling of propargylic bromide with Grignard reagent. The reaction of propargylic bromide with 1.2 equivalents of Grignard reagent mediated by Ni(acac)2 (2 mol%) and Ph3P (4 mol%) in THF may produce terminal allenes in good yields and high regioselectivities at room temperature. Georg Thieme Verlag Stuttgart · New York.
- Li, Qinghan,Gau, Hanmou
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experimental part
p. 747 - 750
(2012/06/29)
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- Regioselective radical bromoallylation of allenes leading to 2-bromo-substituted 1,5-dienes
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The regioselective radical bromoallylation of allenes proceeded efficiently in the presence of AIBN as a radical initiator to give 2-bromo-substituted 1,5-dienes in excellent yields. The addition of a bromine radical took place regioselectively onto the central carbon of allenes generating a stable allyl radical, which underwent addition/β-fragmentation reactions with allylbromides. The products could be further functionalized by Pd-catalyzed coupling reactions.
- Kippo, Takashi,Fukuyama, Takahide,Ryu, Ilhyong
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supporting information; experimental part
p. 3864 - 3867
(2011/09/15)
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- Highly selective cobalt-mediated [6 + 2] cycloaddition of cycloheptatriene and allenes
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[6 + 2] Cycloadditions between cycloheptatrienes with allenes have been investigated. Cobalt salts were found to promote this transformation efficiently. Moreover, this reaction was found to be highly selective since only one regioisomer was obtained with an excellent E/Z-selectivity.
- Clavier, Herve,Jeune, Karel Le,Riggi, Innocenzo De,Tenaglia, Alphonse,Buono, Gerard
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supporting information; experimental part
p. 308 - 311
(2011/04/15)
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- Lewis acid promoted reactions of ethenetricarboxylates with allenes: Synthesis of indenes and γ-lactones via conjugate addition/cyclization reaction
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(Figure presented) Indenes are important core structures in organic chemistry. Few simple arylallenes have been used to construct indene skeletons by Friedel-Crafts reaction. Lewis acid catalyzed reaction of ethenetricarboxylates 1 and arylallenes has been examined in this study. The reaction of arylallenes and ethenetricarboxylate triesters with SnCl4 gave indene derivatives efficiently, via a conjugate addition/Friedel-Crafts cyclization reaction. On the other hand, the reactions of 1,1-diethyl 2-hydrogen ethenetricarboxylate and arylallenes or alkylallenes with SnCl4 at -78 °C or room temperature and subsequent treatment with Et3N gave γ-lactones. The reactions of triethyl ethenetricarboxylate and 1,1-dialkylallenes with SnCl4 at room temperature also gave γ-lactones.
- Yamazaki, Shoko,Yamamoto, Yuko,Fukushima, Yugo,Takebayashi, Masachika,Ukai, Tetsuma,Mikata, Yuji
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supporting information; experimental part
p. 5216 - 5222
(2010/09/05)
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- Regioselective silylzincation of phenylallene derivatives
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This paper deals with our new approach for regio-controlled synthesis of exo/endo-vinylsilanes through silylzincation as a key reaction, using newly developed silylzinc reagents. In this system, by choosing appropriate zinc reagents, either exo-vinylsilane or endo-vinylsilane can be synthesized with good regioselectivity, using the same phenylallene substrates. (Chemical equation presented).
- Yonehara, Mitsuhiro,Nakamura, Shinji,Muranaka, Atsuya,Uchiyama, Masanobu
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supporting information; experimental part
p. 452 - 455
(2010/09/08)
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- Gold(I)-catalyzed rearrangement of propargyl benzyl ethers: A practical method for the generation and in situ transformation of substituted allenes
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A series of benzyl propargyl ethers react with a gold(I) catalyst to furnish variously substituted allenes via a 1,5-hydride shift/fragmentation sequence. This transformation is rapid and practical. It can be performed under very mild conditions (room temperature or 60 °C) using terminal as well as substituted alkyne substrates bearing a primary, secondary, or tertiary benzyl ether group. The allenes thus formed can be reacted in situ with an internal or external nucleophile, corresponding to an overall reductive substitution process, to produce more functionalized compounds.
- Bolte, Benoit,Odabachian, Yann,Gagosz, Fabien
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supporting information; experimental part
p. 7294 - 7296
(2010/08/05)
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- Iron-catalyzed carbolithiation of alkynes having no heteroatoms
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Alkyl- and aryllithium compounds were found to add to alkynes having no heteroatoms in the presence of an iron or iron-copper catalyst to give various trisubstituted vinyllithium compounds.
- Shirakawa, Eiji,Ikeda, Daiji,Ozawa, Tsubasa,Watanabe, Shogo,Hayashi, Tamio
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body text
p. 1885 - 1887
(2009/10/17)
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- Synthesis of mono- and 1,3-disubstituted allenes from propargylic amines via palladium-catalysed hydride-transfer reaction
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Mono- and 1,3-disubstituted allenes were synthesized from the corresponding propargylamines via palladium-catalysed hydride-transfer reaction. In the current transformation, propargylic amines can be handled as allenyl anion equivalents and introduced int
- Nakamura, Hiroyuki,Ishikura, Makoto,Sugiishi, Tsuyuka,Kamakura, Takaya,Biellmann, Jean-Francois
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scheme or table
p. 1471 - 1477
(2008/10/09)
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- Cobalt/rhodium heterobimetallic nanoparticle-catalyzed carbonylative [2+2+1] cycloaddition of allenes and bisallenes to Pauson-Khand-type reaction products
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The first catalytic intra- and intermolecular [2+2+1] cocyclization reactions of allenes and carbon monoxide have been developed. In the Co 2Rh2 heterobimetallic nanoparticle-catalyzed carbonylative [2+2+1] cycloaddition of allenes a
- Park, Ji Hoon,Kim, Eunha,Kim, Hyeong-Mook,Choi, Soo Young,Chung, Young Keun
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supporting information; body text
p. 2388 - 2390
(2009/02/03)
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