- 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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- 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
p. 1589 - 1597
(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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p. 5518 - 5521
(2021/06/12)
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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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- 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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- 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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- Access to Stereodefined (E)-2-Silylallylboronates via Regioselective Chloroboration of Allenylsilanes
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A catalyst-free method for the highly regioselective chloroboration of allenylsilanes is described. In the presence of BCl3 and 2,6-lutidine, chloroboration of allenylsilanes proceeds smoothly without any catalyst, and the product could be treated with pinacol to afford the corresponding pinacol borates in one-pot reaction. This reaction provides a direct approach to construct valuable 2-silylallylboronate frameworks with operational simplicity and high atom-economy.
- Yang, Zhantao,Liu, Tingjie,Chen, Xixi,Wan, Ranran,Li, Yang,Wang, Xianzhen,Yang, Chun-Hua,Chang, Junbiao
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supporting information
p. 9541 - 9544
(2019/11/20)
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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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- 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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- Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: Synthesis of vicinal-dichlorides and chlorodienes
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Allyl and vinyl chlorides represent important structural motifs in organic chemistry. Herein is described the chemoselective and regioselective reaction of aryl- and α-substituted phenylallenes with the hypervalent iodine (HVI) reagent 1-chloro-1,2-benz-iodoxol-3-one. The reaction typically results in vicinal dichlorides, except with proton-containing α-alkyl substituents, which instead give chlorinated dienes as the major product. Experimental evidence suggests that a radical mechanism is involved.
- Zhao, Zhensheng,Murphy, Graham K.
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p. 796 - 802
(2018/04/16)
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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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- 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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- Fluorinative Rearrangements of Substituted Phenylallenes Mediated by (Difluoroiodo)toluene: Synthesis of α-(Difluoromethyl)styrenes
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Phenylallenes undergo fluorinative rearrangement upon the action of (difluoroiodo)toluene in the presence of 20 mol % BF3?OEt2 to yield α-difluoromethyl styrenes. This unprecedented reaction was entirely chemoselective for the internal allene π bond, and showed remarkable regioselectivity during the fluorination event. Substituted phenylallenes, phenylallenes possessing both phenyl- and α-allenyl substituents, and diphenylallenes were investigated, and good functional-group compatibility was observed throughout. The ease with which allenes can be prepared on a large scale, and the operational simplicity of this reaction allowed us to rapidly access fluorine-containing building blocks that have not been accessed by conventional deoxyfluorination strategies.
- Zhao, Zhensheng,Racicot, Léanne,Murphy, Graham K.
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p. 11620 - 11623
(2017/09/11)
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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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- 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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- 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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- 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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- 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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- 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 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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- 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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- 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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- 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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- 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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- Practical iron-catalyzed allylations of aryl grignard reagents
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An operationally simple iron-catalyzed reductive cross-coupling reaction between aryl halides and allyl electrophiles has been developed. The underlying domino process exhibits high versatility with respect to the allylic leaving group (acetate, tosylate, diethyl phosphate, methyl carbonate, trimethylsilanolate, methanethiolate, chloride, bromide) and high economic and environmental sustainability with respect to the catalyst system (0.2-5 mol% tris(acetylacetonato)iron(III), ligand-free) and reaction conditions (tetrahydrofuran, 0°C, 45 min).
- Mayer, Matthias,Czaplik, Waldemar M.,Von Wangelin, Axel Jacobi
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supporting information; experimental part
p. 2147 - 2152
(2010/12/18)
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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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- Asymmetric dihydroxylation of allenes
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We have used asymmetric dihydroxylation (AD) of allenes in order to synthesize chiral α-hydroxy ketones. This methodology has been applied to several aryl-substituted allenes. We have found that electron donating groups on the aromatic ring increase the efficiency of the reaction.
- Fleming, Steven A.,Carroll, Sean M.,Hirschi, Jennifer,Liu, Renmao,Pace, J. Lee,Redd, J. Ty
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p. 3341 - 3343
(2007/10/03)
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- Unusual, strained heterocycles: 3-Alkylidene-2-methyleneoxetanes from Morita-Baylis-Hillman-type adducts
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(Matrix presented) 3-Alkylidene-2-methyleneoxetanes have been prepared by treating α-alkylidene-β-lactones, derived from Morita-Baylis-Hillman-type adducts, with dimethyltitanocene. Preliminary studies of the reactivity of these little known, strained het
- Martinez, Isamir,Andrews, Alexander E.,Emch, Joseph D.,Ndakala, Albert J.,Wang, Jun,Howell, Amy R.
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p. 399 - 402
(2007/10/03)
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- Highly chemoselective coupling of allenylstannanes with organic iodides promoted by Pd(PPh3)4/LiCl: An efficient method for the synthesis of substituted allenes
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An efficient method for the preparation of various monosubstituted arylallenes, disubstituted allenes and alkenylallenes via palladium-catalyzed coupling of allenylstannanes with aryl iodides or alkenyl iodides is described. The coupling reaction was carr
- Huang, Chih-Wei,Shanmugasundaram, Muthian,Chang, Hao-Ming,Cheng, Chien-Hong
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p. 3635 - 3641
(2007/10/03)
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