- Chiral (Macrocyclic) Sulphides as Ligands for Nickel Catalysed Carbon-Carbon Bond Formation
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Various sulphide combinations have been synthesized and examined as ligands for the NiII catalysed cross coupling of α-phenylethylmagnesium chloride and vinyl bromide; good yields and, in some cases, modest enantiomeric excesses can be obtained
- Lemaire, Marc,Buter, Jan,Vriesema, Bindert K.,Kellogg, Richard M.
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Read Online
- Contra-Thermodynamic Positional Isomerization of Olefins
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A light-driven method for the contra-thermodynamic positional isomerization of olefins is described. In this work, stepwise PCET activation of a more substituted and more thermodynamically stable olefin substrate is mediated by an excited-state oxidant an
- Zhao, Kuo,Knowles, Robert R.
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supporting information
p. 137 - 144
(2022/01/19)
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- Rhodium-Catalyzed Regiodivergent Synthesis of Alkylboronates via Deoxygenative Hydroboration of Aryl Ketones: Mechanism and Origin of Selectivities
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Here, we report an efficient rhodium-catalyzed deoxygenative borylation of ketones to synthesize alkylboronates, in which the regioselectivity can be switched by the choice of the ligand. The linear alkylboronates were obtained exclusively in the presence of P(nBu)3, and PPh2Me favored the formation of branched alkylboronates. The protocol also allows access to 1,1,2-triboronates from the readily available ketones. Mechanistic studies suggest that this Rh-catalyzed deoxygenative borylation of ketones goes through an alkene intermediate, which undergoes regiodivergent hydroboration to afford linear and branched alkylboronates. The different steric effects of PPh2Me and P(nBu)3 were found to be responsible for product selectivity by density functional theory calculations. The alkene intermediate can alternatively undergo sequential dehydrogenative borylation and hydroboration to deliver the triboronates.
- Zhang, Bing,Xu, Xin,Tao, Lei,Lin, Zhenyang,Zhao, Wanxiang
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p. 9495 - 9505
(2021/08/04)
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- Cobalt(II)-Catalyzed Stereoselective Olefin Isomerization: Facile Access to Acyclic Trisubstituted Alkenes
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Stereoselective synthesis of trisubstituted alkenes is a long-standing challenge in organic chemistry, due to the small energy differences between E and Z isomers of trisubstituted alkenes (compared with 1,2-disubstituted alkenes). Transition metal-catalyzed isomerization of 1,1-disubstituted alkenes can serve as an alternative approach to trisubstituted alkenes, but it remains underdeveloped owing to issues relating to reaction efficiency and stereoselectivity. Here we show that a novel cobalt catalyst can overcome these challenges to provide an efficient and stereoselective access to a broad range of trisubstituted alkenes. This protocol is compatible with both mono- and dienes and exhibits a good functional group tolerance and scalability. Moreover, it has proven to be a useful tool to construct organic luminophores and a deuterated trisubstituted alkene. A preliminary study of the mechanism suggests that a cobalt-hydride pathway is involved in the reaction. The high stereoselectivity of the reaction is attributed to both a π-πstacking effect and the steric hindrance between substrate and catalyst.
- Zhang, Sheng,Bedi, Deepika,Cheng, Lu,Unruh, Daniel K.,Li, Guigen,Findlater, Michael
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supporting information
p. 8910 - 8917
(2020/12/23)
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- Palladium-catalyzed tandem isomerization/hydrothiolation of allylarenes
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Herein we report a tandem olefin migration/hydrothiolation of allyl benzenes facilitated by an in situ generated palladium hydride. A catalyst system composed of palladium acetate and bidentate ligand dtbpx (1,2-bis(di-tert-butylphosphinomethyl)benzene in the presence of catalytic amounts of triflic acid led to the tandem transformation, which furnished benzylic thioethers. The reaction exhibits high regioselectivity and can be conducted under mild conditions. The robustness of the catalyst is displayed through reactions with coordinating thiols.
- Kathe, Prasad M.,Fleischer, Ivana
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supporting information
p. 2213 - 2217
(2019/03/26)
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- Photocatalytic Synthesis of γ-Lactones from Alkenes: High-Resolution Mass Spectrometry as a Tool to Study Photoredox Reactions
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A mild photocatalytic manifold for the synthesis of γ-lactones has been developed. Utilizing Ru(bpy)3Cl2 as the photocatalyst, a cheap and reproducible synthetic protocol for γ-lactones has been introduced. Mechanistic studies revealed the successful monitoring of photocatalytic reactions and radical intermediates via high-resolution mass spectrometry.
- Triandafillidi, Ierasia,Kokotou, Maroula G.,Kokotos, Christoforos G.
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supporting information
p. 36 - 39
(2018/01/17)
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- Palladium-Catalyzed Oxidative Borylation of Allylic C-H Bonds in Alkenes
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This communication describes an efficient palladium pincer complex-catalyzed allylic C-H borylation of alkenes. The transformation exhibits high regio- and stereoselectivity with a variety of linear alkenes. A synthetically useful feature of this allylic C-H borylation method is that all allyl-Bpin products can be isolated in usually high yields. Preliminary mechanistic studies indicate that this C-H borylation reaction proceeds via Pd(IV) pincer complex intermediates.
- Mao, Lujia,Bertermann, Rüdiger,Rachor, Simon G.,Szabó, Kálmán J.,Marder, Todd B.
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supporting information
p. 6590 - 6593
(2017/12/26)
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- CROSS METATHESIS OF POLY-BRANCHED POLY-OLEFINS
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This invention describes processes to make products by cross metathesis of functionalized or non-functionalized olefins with poly-branched poly-olefins such as terpenes (e.g., farnesene(s), α-farnesene, β-farnesene, β-myrcene, etc.) and compositions made
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Paragraph 0323; 0324
(2016/05/10)
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- Low-Pressure Cobalt-Catalyzed Enantioselective Hydrovinylation of Vinylarenes
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An efficient and practical protocol for the enantioselective cobalt-catalyzed hydrovinylation of vinylarenes with ethylene at low (1.2 bar) pressure has been developed. As precatalysts, stable [L2CoCl2] complexes are employed that are activated in situ with Et2AlCl. A modular chiral TADDOL-derived phosphine-phosphite ligand was identified that allows the conversion of a broad spectrum of substrates, including heterocyclic vinylarenes and vinylferrocene, to smoothly afford the branched products with up to 99 % ee and virtually complete regioselectivity. Even polar functional groups, such as OH, NH2, CN, and CO2R, are tolerated.
- Movahhed, Sohajl,Westphal, Julia,Dindaro?lu, Mehmet,Falk, Anna,Schmalz, Hans-Günther
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supporting information
p. 7381 - 7384
(2016/05/24)
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- Reactivity of mixed organozinc and mixed organocopper reagents: 14. Phosphine-nickel catalyzed aryl-allyl coupling of (n-butyl)(aryl)zincs. Ligand and substrate control on the group selectivity and regioselectivity
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The group selectivity and regioselectivity in the allylation of mixed (n-butyl)(aryl)zinc reagents in THF depends on the nickel catalyst type and also on nature of the allylic substrate. Allylation of (n-butyl)(phenyl)zinc reagent with alkyl substituted primary allylic chlorides and acetates in the presence of NiCl2(dppf) catalysis affords the phenyl coupling product with γ-selectivity. However, allylation with aryl substituted primary allylic substrates results in both phenyl- and alkyl-coupling products with medium α-selectivity in the presence of NiCl2(dppf) catalysis whereas phenyl coupling product is formed with α-selectivity in the presence of NiCl2(Ph3P)2 catalysis. This new NiCl2(dppf) catalyzed protocol for γ-selective aryl allylation of (n-butyl)(aryl)zinc reagents with alkyl substituted primary allylic chlorides in THF at room temperature provides an atom economic alternative to allylation of (aryl)2Zn reagents. A mechanism for the dependence of group selectivity and regioselectivity of Ni catalyzed allylation of (n-butyl)(aryl)zinc reagents on the catalyst ligand and the substrate was proposed.
- Kalkan, Melike,Erdik, Ender
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- Copper(I)-Catalyzed Allylic Substitutions with a Hydride Nucleophile
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An easily accessible copper(I)/N-heterocyclic carbene (NHC) complex enables a regioselective hydride transfer to allylic bromides, an allylic reduction. The resulting aryl- and alkyl-substituted branched α-olefins, which are valuable building blocks for synthesis, are obtained in good yields and regioselectivity. A commercially available silane, (TMSO)2Si(Me)H, is employed as hydride source. This protocol offers a unified alternative to the established metal-catalyzed allylic substitutions with carbon nucleophiles, as no adaption of the catalyst to the nature of the nucleophile is required.
- Nguyen, T. N. Thanh,Thiel, Niklas O.,Pape, Felix,Teichert, Johannes F.
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p. 2455 - 2458
(2016/06/09)
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- PREPARATION OF SURFACTANTS VIA CROSS-METATHESIS
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The present invention relates to compositions comprising 2-phenyl linear alkene benzenes or 2-phenyl linear alkene benzene sulfonates or 2-phenyl linear alkylbenzenes or 2-phenyl linear alkylbenzene sulfonates; where the benzene ring is optionally substituted with one or more groups designated R *, where R * is defined herein and to methods for making the same. This invention also relates to compositions, methods of making, use of, and articles of manufacuture comprising 2-ethoxylated hydroxymethylphenyl linear alkyl benzenes or 2-propoxylated hydroxymethylphenyl linear alkyl benzenes.
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Paragraph 000427
(2015/09/28)
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- Nickel-Catalyzed C-Br/C-H Bis-phenylation of Methyl 4-Bromocrotonate: A Stereoselective Entry to Methyl (E)-3,4-Diphenylbut-2-enoate
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A method for C-Br/C-H bis-phenylation of methyl 4-bromocrotonate via nickel-catalyzed cross-coupling reaction has been developed. This protocol involves commercially available catalyst components and furnishes a suitable doubly phenylated building block.
- Funicello, Maria,Chiummiento, Lucia,Lupattelli, Paolo,Tramutola, Francesco
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p. 1799 - 1806
(2015/08/06)
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- Trifluoromethylchlorosulfonylation of alkenes: Evidence for an inner-sphere mechanism by a copper phenanthroline photoredox catalyst
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Abstract A visible-light-mediated procedure for the unprecedented trifluoromethylchlorosulfonylation of unactivated alkenes is presented. It uses [Cu(dap)2]Cl as catalyst, and contrasts with [Ru(bpy)3]Cl2, [Ir(ppy)2(dtbbpy)]PF6, or eosin Y that exclusively give rise to trifluoromethylchlorination of the same alkenes. It is assumed that [Cu(dap)2]Cl plays a dual role, that is, acting both as an electron transfer reagent as well as coordinating the reactants in the bond forming processes. Double role: The trifluoromethylchlorosulfonylation of unactivated alkenes was developed using [Cu(dap)2]Cl as catalyst (dap=2,9-bis(para-anisyl)-1,10-phenanthroline). [Cu(dap)2]Cl plays a dual role; acting as an electron transfer reagent as well as coordinating the reactants in the bond forming processes.
- Bagal, Dattatraya B.,Kachkovskyi, Georgiy,Knorn, Matthias,Rawner, Thomas,Bhanage, Bhalchandra M.,Reiser, Oliver
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supporting information
p. 6999 - 7002
(2015/06/08)
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- Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides
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The direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2)-C(sp3) cross-coupling showed excellent functional-group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2)-C(sp3) bonds. Zinc and you'll miss it. Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with alkyl halides proceeded rapidly at ambient temperature without a coordinating ethereal solvent or an added catalyst (see scheme). This versatile, operationally simple approach to C(sp2)-C(sp3) bond formation enables the expedient construction of a diverse array of carbon-based structural motifs.
- Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
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supporting information
p. 5688 - 5692
(2015/05/19)
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- Organoselenium-catalyzed, hydroxy-controlled regio- and stereoselective amination of terminal alkenes: Efficient synthesis of 3-amino allylic alcohols
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An efficient route to prepare 3-amino allylic alcohols in excellent regio- and stereoselectivity in the presence of bases by orangoselenium catalysis has been developed. In the absence of bases α,β-unsaturated aldehydes were formed in up to 97% yield. Control experiments reveal that the hydroxy group is crucial for the direct amination.
- Deng, Zhimin,Wei, Jialiang,Liao, Lihao,Huang, Haiyan,Zhao, Xiaodan
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supporting information
p. 1834 - 1837
(2015/04/27)
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- Catalyst-controlled reverse selectivity in C-C bond formation: NHC-Cu-catalyzed α-selective allylic alkylation with organolithium reagents
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An efficient and highly α-selective copper-catalyzed allylic alkylation of allylic halides with organolithium reagents is presented. The use of N-heterocyclic carbenes as ligands is key to reverse the common γ-selectivity of this transformation and gives rise to the corresponding linear products with high levels of regioselectivity.
- Pizzolato, Stefano F.,Giannerini, Massimo,Bos, Pieter H.,Fa?anás-Mastral, Martín,Feringa, Ben L.
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supporting information
p. 8142 - 8145
(2015/05/20)
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- Triarylphosphine ligands with hemilabile alkoxy groups: Ligands for nickel(II)-catalyzed olefin dimerization reactions. hydrovinylation of vinylarenes, 1,3-dienes, and cycloisomerization of 1,6-dienes
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Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl- and 2-benzyloxymethylphenyldiphenylphosphine (L5 and L6, respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at -55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, affording up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II) complexes of 2- benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl- (L6) and 2-benzyloxyethyldiphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II) complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II) complexes of N-heterocyclic carbene ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions.
- Biswas, Souvagya,Zhang, Aibin,Raya, Balaram,Rajanbabu
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p. 2281 - 2292
(2014/07/21)
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- Asymmetric construction of quaternary stereogenic centers via auxiliary-based SN2′ reactions: A case of 1,7-relative stereogenesis
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The stereoselective construction of quaternary stereogenic centers is described that employs an allylic substitution through the intermediacy of a chiral carbamate leaving group. Five carbamates with two substituents at the allylic terminus combined with
- Denmark, Scott E.,Marble, Lyndon K.
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p. 559 - 590
(2016/11/15)
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- Reactivity of mixed organozinc and mixed organocopper reagents: 11. Nickel-catalyzed atom-economic aryl-allyl coupling of mixed (n-alkyl)(aryl)zincs
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Group selectivity in the allylation of mixed (n-butyl)(phenyl)zinc reagent can be controlled by changing reaction parameters. CuCN-catalyzed allylation in tetrahydrofuran (THF)-hexamethylphosphoric triamide is n-butyl selective and also γ-selective in the presence of MgCl2, whereas CuI-catalyzed allylation in THF in the presence of n-Bu3P takes place with a n-butyl transfer:phenyl transfer ratio of 23:77 and an α:γ transfer ratio of phenyl of 76:24. NiCl2(Ph3P) 2-catalyzed allylation in the presence of LiCl is phenyl selective with an α:γ ratio of 65:35. The reaction of methyl- or n-butyl(aryl)zinc reagents with an allylic electrophile in THF at room temperature in the presence of NiCl2(Ph3P)2 catalyst and LiCl as an additive provides an atom-economic alternative to aryl-allyl coupling using diarylzincs. Copyright
- Kalkan, Melike
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p. 725 - 732
(2014/11/08)
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- Exploring palladium nanoparticles protected with alkanethiolates functionalized with organometallic units as potential catalysts for sequential reactions
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Palladium nanoparticles peripherally functionalized with "RuCl 2(p-cymene)" (NP2), "RhCl(cod)" (NP3) and "PdCl(η3-2-MeC3H4)" (NP4) units show catalytic activity in CC coupling reactions, hydrogenation and hydrovinylation processes. We report for the first time an example of a catalytic precursor for the hydrovinylation/CC coupling sequential process by using the two catalytic centres displayed by NP4, the Pd core and the PdCl(η3-2-MeC3H4) moieties.
- Friederici, Mario,Angurell, Inmaculada,Rossell, Oriol,Seco, Miquel,Muller, Guillermo
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- NOBIN-based phosphoramidite and phosphorodiamidite ligands and their use in asymmetric nickel-catalysed hydrovinylation
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Phosphoramidite and P-stereogenic phosphorodiamidite ligands derived from (Sa)-2-phenylamino-2′-hydroxy-1,1′-binaphthyl (N-Ph-NOBIN) and bis(1-phenyl-ethyl)amine were synthesised, fully characterised, and the absolute configuration of the stereogenic phosphorus atoms was assigned. The phosphoramidite ligand L2 features three non-bridged substituents at phosphorus comprising the bis(1-phenylethyl)amine and two NOBIN moieties. The NOBIN units are bound to the phosphorus through the oxygen atoms with two pendant nitrogen atoms. In the Ni-catalysed hydrovinylation of styrene no conversion was observed with the phosphorodiamidites, while the phosphoramidite ligands led to active catalysts with a marked co-operative effect on selectivities. Whereas the racemic product was obtained with the (S a,Sa,SC,SC) diastereomer, the (Sa,Sa,RC,RC) diastereomer proved to be one of the best ligands for this reaction, leading to almost perfect selectivity and ees of up to 91%.
- Schmitkamp, Mike,Leitner, Walter,Francio, Giancarlo
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p. 589 - 594
(2013/05/08)
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- Short synthesis of chiral 4-substituted (S)-imidazolinium salts bearing sulfonates and their use in γ-selective reactions of allylic halides with grignard reagents
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A one-pot reaction of Boc-protected amino alcohols and 2-sulfobenzoic anhydride followed by the addition of a wide variety of primary amines has allowed rapid access to diverse libraries of amidosulfonates 1,2-C 6H4(SO3su
- Latham, Christopher M.,Blake, Alexander J.,Lewis, William,Lawrence, Matthew,Woodward, Simon
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supporting information; experimental part
p. 699 - 707
(2012/03/11)
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- Enantioselective hydrovinylation via asymmetric counteranion-directed ruthenium catalysis
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The first Ru-catalyzed enantioselective hydrovinylation has been realized by using an asymmetric counteranion-directed catalysis strategy. Styrene derivatives react with ethylene in excellent yields and promising enantioselectivity using this approach. Th
- Jiang, Gaoxi,List, Benjamin
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supporting information; experimental part
p. 10022 - 10024
(2011/10/12)
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- Highly selective cobalt-catalyzed hydrovinylation of styrene
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Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3-phenyl-1-butene (3P1B). Double-bond isomerization, a common problem in codimerization reactions, only occurs after full conversion with these catalyst systems, even at elevated temperature. The most active catalysts are based on cobalt halide species combined with either C1- or C 2-bridged diphosphines, heterodonor P,N or P,O ligands, flexible bidentate phosphine ligands or monodentate phosphine ligands. Kinetic investigations show an order >1 in catalyst, which indicates either the involvement of dinuclear species in the catalytic cycle or partial catalyst decomposition via a bimolecular pathway.
- Grutters, Michiel M. P.,Van Der Vlugt, Jarl Ivar,Pei, Yuxin,Mills, Allison M.,Lutz, Martin,Spek, Anthony L.,Mueller, Christian,Moberg, Christina,Vogt, Dieter
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scheme or table
p. 2199 - 2208
(2009/12/27)
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- Palladium-catalyzed cross-coupling reaction of secondary benzylic bromides with grignard reagents
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"Chemical Equation Presented" A mild palladium-catalyzed Kumada-Corriu reaction of secondary benzylic bromides with aryl and alkenyl Grignard reagents has been developed. In the presence of the Xantphos ligand, the undesired β-elimination pathway Is minimized, affording the corresponding cross-coupling products In acceptable to good yields. The reaction proceeds with inversion of the configuration.
- Lopez-Perez, Ana,Adrio, Javier,Carretero, Juan C.
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supporting information; experimental part
p. 5514 - 5517
(2010/02/28)
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- Catalytic enantioselective synthesis of vicinal dialkyl arrays
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(Chemical Equation Presented) With a consecutive "asymmetric allylic alkylation (AAA)/cross-metathesis (CM)/conjugate addition (CA)" protocol it is possible to synthesize either stereoisomer of compounds containing a vicinal dialkyl array with excellent stereoselectivity. The versatility of this protocol in natural product synthesis is demonstrated in the preparation of the ant pheromones faranal and lasiol.
- Van Zijl, Anthoni W.,Szymanski, Wiktor,Lopez, Ferrnando,Minnaard, Adriaan J.,Feringa, Ben L.
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supporting information; body text
p. 6994 - 7002
(2009/05/09)
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- O-DPPB-directed copper-mediated and -Catalyzed allylic substitution with grignard reagents
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The ortho-diphenylphosphanylbenzoyl (o-DPPB) group was explored as a directing leaving group in copper-mediated and copper-catalyzed allylic substitution with Grignard reagents. Complete control of chemo-, regio- and stereoselectivity with complete syn-1,3-chirality transfer was observed as a result of the directed nature of the reaction. No excess of or ganometallic reagent is required and the directing group can be recovered quantitatively. Coordination studies in the solid state and in solution have shown that two substrates are bound via the phosphine function of the directing group at copper. Dynamic NMR experiments in solution are in agreement with a ligand-exchange process at copper, a prerequisite for the development of a substoichiometric process.
- Demel, Peter,Keller, Manfred,Breit, Bernhard
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p. 6669 - 6683
(2008/09/16)
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- A highly effective (Triphenyl phosphite)palladium catalyst for a cross-coupling reaction of allylic alcohols with organoboronic acids
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The cross coupling reaction of aryl and vinyl boronic acids and allylic alcohols proceeded smoothly in toluene or dioxane in the presence of a (triphenyl phosphite)palladium catalyst to give the corresponding allylbenzene derivatives and 1,4-dienes. Neither cocatalysts for promoting C-O bond cleavage of allylic alcohols nor bases for activation of organoboron reagents are required for promoting the coupling process. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Kayaki, Yoshihito,Koda, Takashi,Ikariya, Takao
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p. 4989 - 4993
(2007/10/03)
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- Reaction of indium ate complexes with allylic compounds. Controlling S N2/SN2′ selectivity by solvents
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Vinyl and methylindium ate complexes (indates) were prepared and both the tendency of immigration and regioselectivity toward cinnamyl bromide were investigated. The vinyl group was more preferably transferred than the Me group, giving a regioisomeric mixture of SN2 and SN2′ products. The ratio of SN2/SN2′ selectivity can be controlled by solvents; in the presence of polar solvents, such as N-butylpyrrolidone (NBP) and THF, the SN2′ product was mainly obtained, whereas the SN2 product was selectively prepared in solutions containing hexane. The vinylindium compound, generated by the reaction of allylic-type diindium reagents with imine, was also converted to the corresponding vinyl indate, which was allowed to react with allyl chloride to give a three-component coupling product.
- Hirashita, Tsunehisa,Hayashi, Yousuke,Mitsui, Kazuma,Araki, Shuki
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p. 3225 - 3228
(2007/10/03)
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- Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis
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Through a systematic examination of ligand and counterion effects, new protocols for a nearly quantitative and highly selective codimerization of ethylene and various functionalized vinylarenes have been discovered. In a typical reaction, 4-bromostyrene and ethylene undergo codimerization in the presence of 0.0035 equiv each of [(allyl)NiBr]2, triphenylphosphine, and AgOTf in CH2Cl2 at -56 °C to give 3-(4-bromophenyl) -1-butene in >98% yield and selectivity. Corresponding reactions with [(allyl)PdX]2 are much less efficient and less selective and may require further optimization before a viable system can be identified. Another useful protocol that gives comparable yield and selectivity involves the use of a single-component catalyst prepared from allyl 2-diphenylphosphinobenzoate, Ni(COD)2, and (C6F5)3B. Recognition of a synergistic relationship between a chiral hemilabile ligand (for example, (R)-2-methoxy-2′-diphenylphosphino-1,1′-binaphthyl, MOP) and a highly dissociated counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1,1-binaphthyl derivatives, prepared to probe the effect of hemilabile coordination on the efficiency and selectivity of the reaction, are also described.
- RajanBabu,Nomura, Nobuyoshi,Jin, Jian,Nandi, Malay,Park, Haengsoon,Sun, Xiufeng
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p. 8431 - 8446
(2007/10/03)
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- Nickel(II) compounds derived from tripod ligands: Efficient catalysts for the stereoselective heterodimerization of styrene and propene
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The tripod ligands RCH2C(CH2X)(CH2Y)(CH2Z) form tetracoordinate compounds with NiHal2. If two of the donor functions X, Y, Z are phosphanes, square-planar coordination is observed. In contrast, donor sets X,Y,Z = P,N,N or N,N,N form tetrahedral compounds, by P,N or N,N coordination, that are active in the catalysis of olefin oligomerization with MAO as a co-catalyst. These catalyst systems are also active in the stereoselective heterodimerization of olefins. The co-dimerization of styrene and propene by these systems leads to 4-phenyl-2-pentene almost exclusively, with regioselectivities up to 98% and (E)/(Z) ratios of up to 95:5, surpassing other reported catalysts for this process. The products of these catalytic transformations have been fully characterized by GC/MS techniques as well by isolation, NMR and MS characterization of the pure compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Faissner, Ralf,Huttner, Gottfried
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p. 2239 - 2244
(2007/10/03)
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- Regio- and enantiospecific rhodium-catalyzed arylation of unsymmetrical fluorinated acyclic allylic carbonates: Inversion of absolute configuration
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The transition metal-catalyzed allylic substitution with unstabilized carbon nucleophiles represents an important cross-coupling reaction for the construction of ternary carbon stereogenic centers. We have developed a new regio- and enantiospecific rhodium-catalyzed allylic alkylation of acyclic unsymmetrical chiral nonracemic allylic alcohol derivatives with aryl zinc bromides. This study demonstrates that the hydrotris(pyrazolyl)borate rhodium catalyst and zinc(II) halide salt are crucial for efficiency, while the addition of lithium bromide to the catalyst is necessary for obtaining optimal regiospecificity. The stereochemical course of this reaction was established through the synthesis of (S)-ibuprofen, which demonstrated that the alkylation proceeds with net inversion of absolute configuration consistent with direct addition of the nucleophile to the metal center followed by reductive elimination. Copyright
- Evans, P. Andrew,Uraguchi, Daisuke
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p. 7158 - 7159
(2007/10/03)
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- Copper-catalyzed regioselective allylic substitution reactions with indium organometallics
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The first nucleophilic allylic substitution reactions of triorganoindium compounds with allylic halides and phosphates are reported. The reactions of trialkyl- and triarylindium reagents with cinnamyl and geranyl halides and phosphates, with the aid of co
- Rodriguez, David,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 2518 - 2520
(2007/10/03)
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- Synthesis and characterization of novel aminophosphine ligands based on ferrocenodecaline backbones
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Novel aminophosphine ligands for enantioselective transition metal catalysts based on different ferroceno cis- and trans-decaline backbones were synthesized and structurally characterized. Their palladium dichloride complexes were tested in the asymmetric
- Weissenbacher, Max,Sturm, Thomas,Kalchhauser, Hermann,Kratky, Christoph,Weissensteiner, Walter
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p. 991 - 1009
(2007/10/03)
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- Enantioselective copper-catalyzed allylic alkylation with dialkylzincs using phosphoramidite ligands
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Matrix presented In the presence of a catalytic amount of copper salts, cinnamyl halides undergo a regio- and enantioselective SN2′ alkylation with dialkylzincs using chiral phosphoramidites as ligands. An SN2′:SN2 ratio o
- Malda, Hinke,Van Zijl, Anthoni W.,Arnold, Leggy A.,Feringa, Ben L.
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p. 1169 - 1171
(2007/10/03)
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- Heterodimerization of propylene and vinylarenes: Functional group compatibility in a highly efficient Ni-catalyzed carbon-carbon bond-forming reaction
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Unlike heterodimerization reactions of ethylene and vinylarenes, no such synthetically useful reactions using propylene are known. We find that propylene reacts with various vinylarenes in the presence of catalytic amounts of [(allyl)NiBr]2, tr
- Jin, Jian,Rajanbabu
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p. 2145 - 2151
(2007/10/03)
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- Nickel catalyzed hydrovinylation of arylethylenes: General method of synthesis of α-arylpropionic acids intermediates
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The hydrovinylation of arylethylenes catalyzed by [Ni(MeCN)6][BF4]2/AlEt2Cl/PPh3 was modulated to obtain 3-aryl-1-butenes in high yields and selectivities. A wide variety of arylethylenes containing electron-donating or electron-withdrawing groups and Lewis basic group, can be hydrovinylated at room temperature and under mild conditions by changing the relative ratios of the three-component catalyst. Similar activities and selectivities were observed for o-, m- and p-substituted styrenes. Also, the hydrovinylation of olefins with substituents in the vinyl fragment, such as α-methylstyrene and indene, can be accomplished. (C) 2000 Elsevier Science Ltd.
- Fassina, Viviane,Ramminger, Carolina,Seferin, Marcus,Monteiro, Adriano L
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p. 7403 - 7409
(2007/10/03)
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- Phosphino carboxylic acid ester functionalized carbosilane dendrimers: Nanoscale ligands for the Pd-catalyzed hydrovinylation reaction in a membrane reactor
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Phosphino carboxylic acid ester terminated G0 compounds Si{(CH2)3SiMe2(C6H4 CH2OC(O)(CH2)nCH2PPh2} 4 (9a and 9b; n = 1, 2) and the carbosilane dendrimers Si{(CH2)3 Si((CH2)3SiMe2(C6H4 CH2OC(O)(CH2)nCH2PPh2) 3}4 (10a and 19b; n = 1, 2) have been prepared as hemilabile nanoscale ligands for the palladium-catalyzed codimerization of olefins. The hydrovinylation of styrene was carried out in a continuously operated nanofiltration membrane reactor. Under continuous conditions, the selectivity of the reaction is increased considerably. Monomeric model complexes and the dendritic catalysts were compared for their activity and selectivity in batch reactions. The Pd catalyst complexes were prepared in situ from the dendritic ligands and an (allyl)palladium(II) precursor.
- Eggeling,Hovestad,Jastrzebski,Vogt,Van Koten
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p. 8857 - 8865
(2007/10/03)
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- First Enantioselective Protonation of Prochiral Allyltrimethyltins Using Lewis Acid Assisted Chiral Br?nsted Acids
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The LBA which is prepared from tin tetrachloride and optically active binaphthol or its monomethyl ether is a highly effective reagent for the enantioselective protonation of prochiral allyltrimethyltins. The absolute stereochemical selectivity is quite different from that in the protonation of silyl enol ethers which we reported earlier.
- Ishihara, Kazuaki,Ishida, Yuji,Nakamura, Shingo,Yamamoto, Hisashi
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p. 758 - 760
(2007/10/03)
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- Synthesis of 3-aryl-1-butenes by the nickel catalyzed hydrovinylation of styrene derivatives
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The synthesis of 3-aryl-1-butenes is performed by hydrovinylation of styrene and alkyl-substituted styrenes catalyzed by [Ni(MeCN)6][BF4]2/Et2AlCl/PPh3 under mild conditions with very good activities
- Monteiro, Adriano Lisboa,Seferin, Marcus,Dupont, Jairton,De Souza, Roberto Fernando
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p. 1157 - 1160
(2007/10/03)
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- Addition of organocopper reagents to allylic acrylates - The preparation of γ, δ-unsaturated acids and subsequent functionalization to γ-lactones
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Conjugate addition of monoorganocopper compounds with iodotrimethylsilane (TMSI) or lithium diorganocuprates, with or without halosilanes, to allylic acrylates give allylic silyl ketene acetals/ester enolates. These can undergo Claisen rearrangement to give diastereomeric mixtures of γ, δ-unsaturated acids after aqueous work-up. For organocuprates, the diastereomeric ratio is strongly affected by the halosilane. Either diastereomer can be obtained as major product by proper choice of copper reagent. Cyclization of the acids followed by reduction gives γ-lactones in good yields. A copper iodide/dimethyl sulfide complex is introduced as an excellent precursor to organocopper reagents.
- Eriksson, Magnus,Hjelmencrantz, Anders,Nilsson, Martin,Olsson, Thomas
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p. 12631 - 12644
(2007/10/02)
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- Nickel catalysed coupling of allylamines and boronic acid
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Allylamines function as substrates for cross-coupling with boronic acids in the presence of nickel(0) catalysts rather than palladium(0) catalysts.Aryl-, vinyl- and methyl-boronic acids function well.With vinyl derivatives, E-isomers couple more efficiently than Z-isomer and both fully retain the geometrical integrity.Methylations preferably employ the boronic esters like 2-methyl-1,3,2-benzodioxaborole or 2-methyl-1,3,2-dioxaborolane rather than methylboronic acid.The stereochemistry of the reaction involves a net inversion with respect to the allylamine.The regioselectivity is a function of ligand.Generally, sterically bulky donor phosphines promote new C-C bond formation at the less substituted position.Bidentate ligands, notably 1,1'-binaphthyl-2,2'-ylbis(diphenylphosphinite) (BINAPO), promote new C-C bond formation at the more substituted allyl terminus.The amines appear to be the preferred partner compared to allyl alcohols and esters with the boronic acids and give higher stereospecificity.
- Trost, Barry M.,Spagnol, Michel D.
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p. 2083 - 2096
(2007/10/02)
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- Diastereoselectivity of Additions to Chiral Carbonyl Oxides
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The influence of a resident stereocenter on the formation of hydroperoxy acetals from carbonyl oxides is investigated.Addition of either methanol or 2-propanol to 2-phenylpropanal O-oxide proceeds with modest stereoselectivity; addition of a tertiary alco
- Dussault, Patrick H.,Zope, Umesh R.
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p. 8218 - 8222
(2007/10/02)
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- Telluroxide Elimination by Oxidation of Alkyl Aryl Tellurides: Remarkable Effect of Added Triethylamine
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Treatment of various alkyl phenyl tellurides with 1-2 mol equiv. of m-chloroperbenzoic acid in diethyl ether in the presence of triethylamine at 25 deg C for 2 h affords the corresponding alkenes highly selectively in fair to good yields.From stereochemical studies using erythro- and threo-phenyl 3-phenylbutan-2-yl tellurides as substrates it was revealed that although Et3N partly faciliates E2 elimination of the telluroxide, the main reaction course is the telluroxide syn-elimination (Ei elimination).Without the addition of Et3N the elimination was quite slow in many cases, and in fact the compounds derived from the addition of m-chlorobenzoic acid to tetradecyl and cyclohexyl phenyl telluroxides were isolated, the pyrolysis (ca. 250 deg C) of which afforded tetradec-1-ene and cyclohexene, respectively.A 2-pyridyltelluro moiety was revealed for the first time to be a better leaving group than a phenyltelluro moiety in telluroxide elimination.
- Nishibayashi, Yoshiaki,Komatsu, Naoki,Ohe, Kouichi,Uemura, Sakae
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p. 1133 - 1138
(2007/10/02)
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- Copper-catalyzed reactions of organotitanium reagents. Highly selective SN2′-allylation and conjugate addition
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In the presence of a catalytic amount of CuI·ILiCl, alkyltitanium (RTi(O-I-Pr)3) and titanate reagents (RnTi(O-i-Pr)5-nLi) undergo highly selective SN2′-alkylation reactions with allylic chlorides and allylic diethylphosphates in high yields. The regioselectivity of the reaction is as high as 99.8%. The reaction proceeds with excellent anti-stereoselectivity with respect to the nucleophile and the leaving group, and exhibits high 1,2-anti-diastereoselectivity with a δ-chiral allylic chloride. The catalytic copper reagent is also a mild agent to transfer an alkyl group to an enone in the presence of Me3SiCl. The alkyltitanium-based catalytic reagent selectively reacts with an allylic phosphate rather than with an enone, while in the presence of a silicon activator, it reacts preferentially with the enone rather than with the phosphate. 1H NMR studies on a mixture of Me2CuLi and TiCl(O-i-Pr)3 provided information on reagent composition.
- Arai, Masayuki,Lipshutz, Bruce H.,Nakamura, Eiichi
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p. 5709 - 5718
(2007/10/02)
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