- 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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supporting information
p. 12335 - 12340
(2021/07/19)
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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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supporting information
p. 14925 - 14931
(2021/09/04)
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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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- 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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supporting information
p. 3879 - 3884
(2021/05/29)
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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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- Stereoselective Functionalization of Racemic Cyclopropylzinc Reagents via Enantiodivergent Relay Coupling
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Efficient construction of optically pure molecules from readily available starting materials in a simple manner is an ongoing goal in asymmetric synthesis. As a straightforward route, transition-metal-catalyzed enantioconvergent coupling between widely available secondary alkyl electrophiles and organometallic nucleophiles has emerged as a powerful strategy to construct chiral center(s). However, the scope of racemic secondary alkylmetallic nucleophiles for this coupling remains limited in specific substrates because of the difficulties in stereoselective formation of the key alkylmetal intermediates. Here, we report an enantiodivergent strategy to efficiently achieve an array of synthetically useful chiral cyclopropanes, including chiral fluoroalkylated cyclopropanes and enantiomerically enriched cyclopropanes with chiral side chains, from racemic cyclopropylzinc reagents. This strategy relies on a one-pot, two-step enantiodivergent relay coupling process of the racemic cis-cyclopropylzinc reagents with two different electrophiles, which involves kinetic resolution of racemic cis-cyclopropylzinc reagents through a nickel-catalyzed enantioselective coupling with alkyl electrophiles, followed by a stereospecific relay coupling of the remaining enantiomeric cyclopropylzinc reagent with various electrophiles, to produce two types of functionalized chiral cyclopropanes with opposite configurations on the cyclopropane ring. These chiral cyclopropanes are versatile synthons for diverse transformations, rendering this strategy effective for obtaining structurally diversified molecules of medicinal interest.
- An, Lun,Tong, Fei-Fei,Zhang, Shu,Zhang, Xingang
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supporting information
p. 11884 - 11892
(2020/08/06)
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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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- 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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supporting information
p. 23885 - 23891
(2020/10/26)
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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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- 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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- 4-Phenylspiro[2.2]pentane-1,1-dicarboxylate: synthesis and reactions with EtAlCl2 and 4,5-diazaspiro[2.4]hept-4-ene derivative
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Cyclopropanation of 1-methylidene-2-phenylcyclopropane with dimethyl diazomalonate affords new dimethyl 4-phenyl-spiro[2.2]pentane-1,1-dicarboxylate. On contact with EtAlCl2, this compound undergoes opening of both cyclopropane rings to give dimethyl (2-chloromethyl-3-phenylallyl)malonate. Its EtAlCl2-assisted reaction with methyl 5′-methylspiro[cyclo-propane-1,3′-pyrazoline]-5′-carboxylate proceeds as the 1,3:1′,5′-addition to afford mainly 3-(2-chloroethyl)-1-cyclo-propylmethyl-1H-pyrazoline derivative.
- Denisov, Dmitry A.,Borisov, Denis D.,Potapov, Konstantin V.,Novikov, Roman A.,Tomilov, Yury V.
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p. 417 - 418
(2019/08/20)
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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.
- -
-
Paragraph 0023-0025
(2019/03/28)
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- Stereoselective Desymmetrization of gem-Diborylalkanes by “Trifluorination”
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An efficient and general method for the chemoselective synthesis of unsymmetrical gem-diborylalkanes is reported. This method is based on a late-stage desymmetrization through nucleophilic “trifluorination”, providing chiral gem-diborylalkanes bearing a trifluoroborate group. The reaction offers a highly modular and diastereoselective approach towards the synthesis of gem-diborylcyclopropanes. The utility of the gem-diborylalkane building blocks was demonstrated by selective post-functionalization of the trifluoroborate group. These functionalizations include inter- and intra- Pd-catalyzed Suzuki–Miyaura coupling reactions.
- Kumar, Nivesh,Reddy, Reddy Rajasekhar,Masarwa, Ahmad
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supporting information
p. 8008 - 8012
(2019/05/28)
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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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- Hydrodebromination of allylic and benzylic bromides with water catalyzed by a rhodium porphyrin complex
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Hydrodebromination of allylic and benzylic bromides was successfully achieved by a rhodium porphyrin complex catalyst using water as the hydrogen source without a sacrificial reductant. Mechanistic investigations suggest that bromine atom abstraction via a rhodium porphyrin metalloradical operates to give the rhodium porphyrin alkyl species and the subsequent hydrolysis of the rhodium porphyrin alkyl species to a hydrocarbon product is a key step to harness the hydrogen from water.
- Yang, Wu,Chen, Chen,Chan, Kin Shing
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supporting information
p. 12879 - 12883
(2018/10/02)
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- A Modular Approach to the Synthesis of gem-Disubstituted Cyclopropanes
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A diastereoselective, Pd-catalyzed Suzuki-Miyaura coupling reaction of geminal bis(boryl)cyclopropanes has been developed. The reaction offers a highly modular approach to the synthesis of tertiary cyclopropylboronic esters. The resulting boronic esters may be further functionalized to afford a range of gem-disubstituted cyclopropanes, which represent an important structural motif in the pharmaceutical industry. Sequential Suzuki-Miyaura cross-coupling reactions of gem-bis(boryl)cyclopropanes are also reported. The coupling protocols are compatible with a broad range of functionalized aryl and heteroaryl bromides.
- Harris, Michael R.,Wisniewska, Hanna M.,Jiao, Wenhua,Wang, Xiaochun,Bradow, James N.
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supporting information
p. 2867 - 2871
(2018/05/29)
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- Synthesis of Substituted Cyclopropanecarboxylates via Room Temperature Palladium-Catalyzed α-Arylation of Reformatsky Reagents
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The room temperature palladium-catalyzed cross-coupling of aromatic and heteroaromatic halides with Reformatsky reagents derived from 1-bromocyclopropanecarboxylates provides an exceptionally mild method for enolate α-arylation. The method is tolerant of a wide range of functionalities and dramatically shortens many of the existing routes to access widely used 1,1-disubstituted cyclopropanecarboxylate derivatives.
- Greszler, Stephen N.,Halvorsen, Geoff T.,Voight, Eric A.
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supporting information
p. 2490 - 2493
(2017/05/24)
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- Structure activity relationship and modeling studies of inhibitors of lysine specific demethylase 1
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Post-translational modifications of histone play important roles in gene transcription. Aberrant methylation of histone lysine sidechains have been often found in cancer. Lysine specific demethylase 1 (LSD1), which can demethylate histone H3 lysine 4 (H3K4) and other proteins, has recently been found to be a drug target for acute myeloid leukemia. To understand structure activity/selectivity relationships of LSD1 inhibitors, several series of cyclopropylamine and related compounds were synthesized and tested for their activities against LSD1 and related monoamine oxidase (MAO) A and B. Several cyclopropylamine containing compounds were found to be highly potent and selective inhibitors of LSD1. A novel series cyclopropylimine compounds also exhibited strong inhibitory activity against LSD1.Structure activity relationships (SAR) of these compounds are discussed. Docking studies were performed to provide possible binding models of a representative compound in LSD1 and MAO-A. Moreover, these modeling studies can rationalize the observed SARs and selectivity.
- Zhou, Chao,Wu, Fangrui,Lu, Lianghao,Wei, Liping,Pai, Eric,Yao, Yuan,Song, Yongcheng
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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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- 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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- 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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- A Convenient Stereoselective Reduction of Gem-Dibromides with a Combination of Dimethyl Phosphite and Potassium Carbonate
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An efficient and highly stereoselective reduction of a gem-dibromocyclopropane to the corresponding monobromocyclopropane under mild reaction conditions was developed using a combination of dimethyl phosphite and potassium carbonate. This reaction provided a simple and practical way for the synthesis of the valuable monobromocyclopropanes and β-monobromoalkenes.
- Zhao, Yalei,Chen, Tieqiao,Wang, Xiang-Bo,Han, Li-Biao
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p. 1820 - 1827
(2015/12/12)
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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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- 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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p. 757 - 760
(2014/01/23)
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- Preparative resolution of bromocyclopropylcarboxylic acids
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A general and efficient method for the preparative resolution of α- and β-bromocyclopropylcarboxylic acids has been developed. This protocol involves a sequence of two crystallizations with pseudo-enantiomeric amines, cinchonine, and cinchonidine, which yield both enantiomers of the acid in highly enriched form. Both alkaloids can be easily recovered and reused multiple times without any loss of efficacy.
- Edwards, Andrew,Ryabchuk, Pavel,Barkov, Alexey,Rubina, Marina,Rubin, Michael
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p. 1537 - 1549
(2015/02/02)
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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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- Spectroscopic analysis of the products of the cycloaddition reaction of 1-Aryl-2-chlorocyclopropenes and cyclopentadiene
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The treatment of a series of 1-aryl-2,2-dihalocyclopropanes with t-BuOK at -10 °C produces the corresponding 1-aryl-2-halocyclopropenes, which react with cyclopentadiene to produce fairly good yield of [4+2]-cycloaddition products with more than 90% of the endo-isomer. The higher yield obtained from hexane medium then from methanol and ionic liquid demonstrates that the reaction is a nonpolar process. The treatment of a series of 1-aryl-2,2- dihalocyclopropanes with t-BuOK at -10 °C produces the corresponding 1-aryl-2-halocyclopropenes, which react with cyclopentadiene to produce fairly good yield of [4+2]-cycloaddition products with more than 90% of the endo-isomer. The higher yield obtained from hexane medium then from methanol and ionic liquid demonstrates that the reaction is a nonpolar process. Copyright
- Ding, Mei-Fang,Lee, Chuan-Chen,Lin, Lian-Chun,Lin, Shaw-Tao
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p. 285 - 289
(2014/05/06)
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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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- Probes for narcotic receptor mediated phenomena. 41. Unusual inverse μ-agonists and potent μ-opioid antagonists by modification of the N-substituent in enantiomeric 5-(3-hydroxyphenyl)morphans
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Conformational restraint in the N-substituent of enantiomeric 5-(3-hydroxyphenyl)morphans was conferred by the addition of a cyclopropane ring or a double bond. All of the possible enantiomers and isomers of the N-substituted compounds were synthesized. Opioid receptor binding assays indicated that some of them had about 20-fold higher μ-affinity than the compound with an N-phenylpropyl substituent (Ki = 2-450 nM for the examined compounds with various N-substituents). Most of the compounds acted unusually as inverse agonists in the [35S]GTP-γ-S functional binding assay using nondependent cells that stably express the cloned human μ-opioid receptor. Two of the N-substituted compounds with a cyclopropane ring were very potent μ-opioid antagonists ((+)-29, Ke = 0.17 and (-)-30, Ke =0.3) in the [35S]GTP-γ-S functional binding assay. By comparison of the geometry-optimized structures of the newly synthesized compounds, an attempt was made to rationalize their μ-opioid receptor affinity in terms of the spatial position of N-substituents. This article not subject to U.S. Copyright. Published 2011 by the American Chemical Society.
- Cheng, Kejun,Lee, Yong Sok,Rothman, Richard B.,Dersch, Christina M.,Bittman, Ross W.,Jacobson, Arthur E.,Rice, Kenner C.
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experimental part
p. 957 - 969
(2011/04/24)
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- Copper-catalyzed trifluoromethylation of unactivated olefins
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Activating the inactive: A copper-catalyzed allylic trifluoromethylation of unactivated terminal olefins proceeds under mild conditions to produce linear allylic trifluoromethylated products with high E/Z selectivity (see scheme). The reaction can be applied to a range of substrates bearing numerous functional groups. Furthermore, the reaction is scalable and amenable to a benchtop setup. Copyright
- Parsons, Andrew T.,Buchwald, Stephen L.
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supporting information; experimental part
p. 9120 - 9123
(2011/10/13)
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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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- 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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- An efficient synthesis of cyclopropyl silyl ketones
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The reaction of silylcyclopropyl bromides with dichloromethyl methyl ether in the presence of n-butyllithium is investigated. Under basic reaction conditions, the corresponding cyclopropylidene derivatives are exclusively obtained. The resulting cyclopropylidene compounds are subjected to protonolysis or trapping with electrophiles in a one-pot to give the cyclopropyl silyl ketone derivatives in good yields. Acidic treatment of derived cyclopropyl silyl ketone allows isomerization to give the thermodynamically favorable trans form exclusively.
- Honda, Mitsunori,Nakae, Kenta,Nishizawa, Toshiaki,Suda, Mitsuhiro,Kunimoto, Ko-Ki,Segi, Masahito
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body text
p. 9500 - 9508
(2012/01/02)
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- PROCESSES FOR THE PREPARATION OF SGLT2 INHIBITORS
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Provided are processes for the preparation of complexes that are useful in purifying compounds having an inhibitory effect on sodium-dependent glucose cotransporter SGLT. The processes can reduce the number of steps needed to obtain the target compounds and the complexes formed in the processes are typically provided in a crystalline form.
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Page/Page column 42-43
(2010/04/03)
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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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- Ionic liquids accelerating cycloaddition between 1-aryl-2-halocyclopropenes and furan
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Treatment of a series of 1-aryl-2,2-dihalocyclopropanes with t-BuOK at-10 °C gave the corresponding 1-aryl-2-halocyclopropenes, which react with furan in a RTIL to give a fair good yield of the [4+2]-cycloadducts with more than 90% of the exo-isomer. The imidazolium type ionic liquids are able to accelerate this cycloaddition process with high steric selectivity. Neither pyrrole nor thiophene undergoes the cycloaddition with cyclopropene to form the [4+2]-cycloadduct. 1-Aryl-3,3-difluoro-2-halocyclopropenes are inert towards furan even at a temperature higher than 100 °C.
- Ding, May-Fan,Lin, Shaw-Tao,Chang, Woan-Ju
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experimental part
p. 240 - 247
(2010/09/16)
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- Is a phase transfer catalyst really needed for gem-dihalocyclopropanation of alkenes with haloforms in the presence of alkali metal hydroxide?
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Chloroform, bromoform and dibromochloromethane react with alkenes in the presence of cone. aq. sodium hydroxide, without phase-transfer catalyst, giving gem-dihalocyclopropanes. The process is particularly useful for preparation of gem-bromochlorocyclopropanes which are formed in good yields and in high selectivity.
- Karwowska,Jonczyk
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- Can relief of ring-strain in a cyclopropylmethyllithium drive the Brook rearrangement?
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α-Cyclopropyl-α-trialkylsilyl alkoxides were formed either by addition of cyclopropyllithiums to acylsilanes or by addition of organolithiums to a cyclopropylformylsilane. [1,2]-Brook rearrangement led to α-silyloxy organolithiums which on warming underwent cyclopropane ring opening and [1,5]-retro-Brook rearrangement to yield γ-silyl ketones. Despite the favourability of the cyclopropane ring opening, the Brook rearrangement still required the presence of an anion stabilising group to proceed. β-Silylketones were similarly formed by Brook-retro-Brook rearrangement on warming acylsilanes with a vinyllithium.
- Clayden, Jonathan,Watson, David W.,Chambers, Mark
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p. 3195 - 3203
(2007/10/03)
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- gem-Dihalocyclopropane formation by iron/copper activation of tetrahalomethanes in the presence of nucleophilic olefins. Evidence for a carbene pathway
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The activation of CBr4 and CCl4 by a bimetallic iron/copper couple in acetonitrile is a new, inexpensive, nontoxic and efficient procedure for gem-dibromo- and gem-dichloromethylenation of nucleophilic alkenes. This new route to gem-dihalocyclopropanes involves dihalocarbene species.
- Léonel, Eric,Lejaye, Michael,Oudeyer, Sylvain,Paugam, Jean Paul,Nédélec, Jean-Yves
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p. 2635 - 2638
(2007/10/03)
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- Reactions of gem-dibromo compounds with trialkylmagnesate reagents to yield alkylated organomagnesium compounds
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The reaction of gem-dibromocyclopropanes 5 with nBu3MgLi affords butylated cyclopropylmagnesium species that can be trapped with various electrophiles. The reaction of dibromomethylsilanes 12 requires the addition of a catalytic amount of CuCN · 2 LiCl for smooth migration of the alkyl groups. The resultant α-silylpentylmagnesium compounds 16 react with electrophiles, such as acyl chlorides or α, β-unsaturated ketones to afford α- or γ-silyl ketones, respectively. Treatment of dibromodisilylmethanes with Me3MgLi yields 1-bromo- 1,1-disilylethanes 25 that can be converted into 1,1-disilylethenes 29 by dehydrobromination.
- Inoue, Atsushi,Kondo, Junichi,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 1730 - 1740
(2007/10/03)
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- The nickel and palladium catalyzed stereoselective cross coupling of cyclopropyl nucleophiles with aryl halides
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The reaction of 2-phenylcyclopropylzinc chloride with some substituted (het)aryl halides gave the corresponding coupling products with good yields and stereoselectivities under the influence of a catalytic amount of Pd(PPh3)4. Other Ni- and Pd-catalysts were less efficient. Alkyl-substituted cyclopropyl nucleophiles gave lower yields.
- De Lang,Brandsma
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p. 225 - 232
(2007/10/03)
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- Photochemical activation of metalloporphyrin carbene complexes
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While the photochemistry of simple metalloporphyrin complexes has been explored to some extent, the photoactivation of multiple-bonded axial ligands coordinated to metalloporphyrins has not been previously examined. We report here the photochemistry of several iron porphyrin carbene and vinylidene complexes. Irradiation of these complexes with visible light cleaves the iron-carbon double bond and produces a four coordinate iron(II) porphyrin and a free carbene, which can be trapped in high yield with a variety of alkenes. This photochemistry is unique among organo transition metal complexes of carbenes or alkylidenes. For these metalloporphyrin carbene complexes, the presence of the porphyrin ring alters the photoreactivity of the metal-carbon bond. This is probably due to the mixing between the π * orbitals of the porphyrin ring and the iron-carbon orbitals, which is also responsible for the hypso-type spectrum (i.e. blue-shifted) seen in these complexes. Hypso spectra are a common trait in other photodissociative porphyrin complexes, most notably CO complexes.
- Ziegler, Christopher J.,Suslick, Kenneth S.
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- Kupfer(II)-chlorid-katalysierte 'Carben-Dimerisierung' von 1-Halogeno-1-lithiocyclopropanen: Ein einfacher Zugang zu Bi(cyclopropylidenen)
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A series of 13 bi(cyclopropylidenes) 11 are prepared in a simple one-pot reaction by halogeno-lithio exchange between 1,1-dibromocyclopropanes 1a-n and BuLi, in most cases at -95 deg C, to give 1-bromo-1-lithiocyclopropanes 2a-n, followed by treatment with CuCl2 at low temperature and a simple workup at room temperature (Scheme 3c and Table 1).The yields of bi(cyclopropylidenes) 11 strongly depend on reaction parameters, as explicitly shown for the conversion 1f->-> 11f (Tables 2-8).Mixed couplings between two different carbenoids are possible (Scheme 4), while diastereoselectivity of the active transition-metal complex seems to be low.The structures of bi(cyclopropylidenes) 11 are confirmed by spectroscopic data as well as by X-ray analysis of an isolated crystalline diastereomer of 11k (Fig. 1).
- Loosli, Thomas,Borer, Markus,Kulakowska, Iga,Minger, Andrea,Neuenschwander, Markus,Engel, Peter
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p. 1144 - 1165
(2007/10/02)
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- A CONVENIENT METHOD FOR SYNTHESIS OF GEM-BROMOCHLOROCYCLOPROPANES
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Gem-bromochlorocyclopropanes can be prepared by a convenient method based on the reactions of the mixtures of haloforms and tetrahalomethanes or hexahaloethane with powdered sodium hydroxide.
- Xu, Linxiao,Tao, Fenggang
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p. 2117 - 2122
(2007/10/02)
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