- Use of Tricyclohexylphosphine to Control Regiochemistry in Palladium-catalyzed Allylic Alkylation
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(Matrix Presented) Tricyclohexylphosphine, Cy3P, in conjuction with [(C3H5)PdCl]2 catalyzes allylic alkylation of terminal allylic acetates with high regioselectivity toward branched products, which is in contra
- Blacker, A. John,Clarke, Matthew L.,Loft, Michael S.,Williams, Jonathan M. J.
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- Nickel-catalyzed hydroalkylation of 1,3-dienes with malonates using a homoallyl carbonate as the 1,3-diene and hydride source
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The use of a malonate nucleophile in the transition metal-catalyzed hydroalkylation of 1,3-dienes remains immature. Herein, we report the nickel-catalyzed hydroalkylation of 1,3-dienes with malonates using a homoallyl carbonate as the 1,3-diene and hydride source. A broad range of homoally carbonates and malonate derivatives were well tolerated under a Ni/DPEphos catalyst system, providing the corresponding 1,2-hydroalkylation products in 40–94% yields with excellent regioselectivity (32 examples). We also suggested the possible reaction mechanism for the nickel-catalyzed hydroalkylation of in situ generated 1,3-dienes with malonates.
- Tsuji, Hiroaki,Takahashi, Yoshiyuki,Kawatsura, Motoi
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supporting information
(2021/03/03)
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- Efficient stereochemical communication in phosphine-amine palladium-complexes: Exploration of N-substituent effects in coordination chemistry and catalysis
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Six-membered chelate complexes of type [Pd(1a-e)Cl2] (2a-e) and [Pd(1a-e)(η3-PhCHCHCHPh)]BF4 (3a-e) of a series of systematically varied chiral phosphine-amine ligands (S,S)-Ph2PCH(CH3)CH2C
- Farkas, Gergely,Császár, Zsófia,Stágel, Kristóf,Nemes, Evelin,Balogh, Szabolcs,Tóth, Imre,Bényei, Attila,Lendvay, Gy?rgy,Bakos, József
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p. 129 - 140
(2017/06/19)
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- Efficient novel 1,2-diphosphite ligands derived from D-mannitol in the Pd-catalyzed asymmetric allylic alkylation
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A novel Pd/1,2-diphosphite catalyzed asymmetric allylic alkylation of 1,3-diarylpropenyl acetate with malonates was developed. Catalyst optimization via a variation in the protecting groups at the 1,2- and/or 5,6-positions of d-mannitol skeleton and in bi
- Xing, Ai-Ping,Pang, Zeng-Bo,Li, Hai-Feng,Wang, Lai-Lai
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p. 8822 - 8828
(2015/03/05)
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- Synthesis and Reactivity of Chiral, Wide-Bite-Angle, Hybrid Diphosphorus Ligands
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Effective and modular synthetic approaches toward phosphine-phosphite ligands and phosphine-phosphonite ligands featuring a diphenyl ether backbone have been developed. The phosphine-phosphite ligands are obtained by a two-step protocol from 2-bromo-2′-methoxydiphenyl ether. The phosphine-phosphonite ligands are prepared in a four-step synthetic protocol that involves a novel, unsymmetrical diphenyl ether derived phosphine-phosphorusdiamide as key building block. Structural studies on PtII complexes with either phosphine-phosphite or phosphine-phosphonite ligands indicate strict cis coordination for these ligand systems. High-pressure NMR spectroscopy studies of Rh complexes under syngas indicate the presence of two ea isomers for Rh(H)(CO)2(PP). The existence of this mixture is further supported by high-pressure IR spectroscopy studies. In order to benchmark the activity and selectivity of these novel, wide-bite-angle, mixed-donor ligands, they were screened in Pd-catalyzed asymmetric allylic alkylation as well as Rh-catalyzed hydrogenation and hydroformylation reactions. The ligands give 100-% conversion and low-to-moderate enantioselectivity in the allylic alkylation of 1,3-diphenyl-2-propenyl acetate and cyclohexyl-2-enyl acetate with dimethyl malonate. In the hydroformylation of styrene, good conversion and regioselectivities are achieved but only moderate enantioselectivity. The ligands give good conversions in asymmetric hydrogenation of typical substrates, with good-to-excellent enantioselectivities of up to 97-% depending on the substrate. Copyright
- Czauderna, Christine Fee,Cordes, David B.,Slawin, Alexandra M. Z.,Müller, Christian,Van Der Vlugt, Jarl Ivar,Vogt, Dieter,Kamer, Paul C. J.
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p. 1797 - 1810
(2014/04/17)
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- Synthesis and reactivity of chiral, wide-bite-angle, hybrid diphosphorus ligands
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Effective and modular synthetic approaches toward phosphine-phosphite ligands and phosphine-phosphonite ligands featuring a diphenyl ether backbone have been developed. The phosphine-phosphite ligands are obtained by a two-step protocol from 2-bromo-2′-methoxydiphenyl ether. The phosphine-phosphonite ligands are prepared in a four-step synthetic protocol that involves a novel, unsymmetrical diphenyl ether derived phosphine-phosphorusdiamide as key building block. Structural studies on PtII complexes with either phosphine-phosphite or phosphine-phosphonite ligands indicate strict cis coordination for these ligand systems. High-pressure NMR spectroscopy studies of Rh complexes under syngas indicate the presence of two ea isomers for Rh(H)(CO)2(PP). The existence of this mixture is further supported by high-pressure IR spectroscopy studies. In order to benchmark the activity and selectivity of these novel, wide-bite-angle, mixed-donor ligands, they were screened in Pd-catalyzed asymmetric allylic alkylation as well as Rh-catalyzed hydrogenation and hydroformylation reactions. The ligands give 100-% conversion and low-to-moderate enantioselectivity in the allylic alkylation of 1,3-diphenyl-2-propenyl acetate and cyclohexyl-2-enyl acetate with dimethyl malonate. In the hydroformylation of styrene, good conversion and regioselectivities are achieved but only moderate enantioselectivity. The ligands give good conversions in asymmetric hydrogenation of typical substrates, with good-to-excellent enantioselectivities of up to 97-% depending on the substrate. The design of two subclasses of chiral, mixed-donor diphosphorus ligands with a diphenylether backbone is described. Both phosphine-phosphonite and phosphine-phosphite derivatives are accessible. Coordination to PtII and RhI is described, and high-pressure spectroscopy under syngas provides information on coordination geometry. The chiral ligand systems are benchmarked in Pd-catalyzed allylic alkylation and Rh-catalyzed hydrogenation and hydroformylation.
- Czauderna, Christine Fee,Cordes, David B.,Slawin, Alexandra M. Z.,Müller, Christian,Van Der Vlugt, Jarl Ivar,Vogt, Dieter,Kamer, Paul C. J.
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p. 1797 - 1810
(2015/04/27)
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- Highly enantioselective alkylation of allyl acetates using tartrate-derived bioxazoline ligands
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Tartrate-derived bioxazoline ligands, which form a five-membered chelate ring with metals, were evaluated for use in the asymmetric allylic alkylation (AAA) reactions of various symmetrical and unsymmetrical allyl acetates. Excellent enantioselectivities
- Jayakumar, Samydurai,Prakash, Muthuraj,Balaraman, Kaluvu,Kesavan, Venkitasamy
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p. 606 - 615
(2014/02/14)
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- Palladium-catalyzed insertion of α,β-unsaturated N-tosylhydrazones and trapping with carbon nucleophiles
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Palladium-catalyzed carbene migratory insertion-cyclization reactions were reported, delivering dihydronaphthalene and indene derivatives in moderate to good yields. A three-component cross-coupling was also developed. The reactions are easy to handle, under mild conditions and various functional groups are tolerated. The Royal Society of Chemistry 2013.
- Ye, Yu-Ying,Zhou, Ping-Xin,Luo, Jian-Yi,Zhong, Mei-Jin,Liang, Yong-Min
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supporting information
p. 10190 - 10192
(2013/10/22)
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- Achieving chemo-, regio-, and stereoselectivity in palladium-catalyzed reaction of γ-borylated allylic acetates
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Three-carbon highly functionalized γ-borylated allylic acetates underwent a regio- and stereocontrolled Tsuji-Trost reaction in the presence of palladium complexes. An ipso substitution of the acetate with complete stereoretention of the chiral center was achieved, leading to vinylic boronates with enantiomeric excesses above 99%.
- Kukkadapu, Krishna Kishore,Ouach, Aziz,Lozano, Pedro,Vaultier, Michel,Pucheault, Mathieu
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p. 4132 - 4135
(2011/10/02)
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- Gold(I)-catalyzed [2 + 2]-cycloaddition of allenenes
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A cationic phosphinegold(I)-catalyzed intramolecular [2 + 2]-cycloaddition between an allene and an alkene to form alkylidene?cyclobutanes is described. Additionally, the reported cycloisomerization reaction provides access to enantioenriched bicyclo-[3.2.0] structures using chiral biarylphosphinegold(I) complexes as catalysts. Copyright
- Luzung, Michael R.,Mauleon, Pablo,Toste, F. Dean
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p. 12402 - 12403
(2008/09/17)
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- Iron-catalyzed allylic alkylation
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A method for performing an iron-catalyzed allylic alkylation includes the preparation of a reaction mixture obtainable from (i) an allylic substrate with the structural element C═C—C—X, wherein X comprises a leaving group that represents a carbonate, (ii) an active Fe(-II) catalyst complex, (iii) at least one ligand, (iv) at least one solvent, and (v) a nucleophile or pronucleophile.
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Page/Page column 3; Sheet 4
(2008/06/13)
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- Highly diastereoselective synthesis of 2,6-di[1-(2-alkylaziridin-1-yl) alkyl]pyridines, useful ligands in palladium-catalyzed asymmetric allylic alkylation
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C2-Symmetrical, enantiopure 2,6-di[1-(1-aziridinyl)alkyl] pyridines (DIAZAPs) were prepared by a high-yielding, three-step sequence starting from 2,6-pyridinedicarbaldehyde and (S)-valinol or (S)-phenylglycinol. The new compounds were tested as
- Savoia, Diego,Alvaro, Giuseppe,Di Fabio, Romano,Fiorelli, Claudio,Gualandi, Andrea,Monari, Magda,Piccinelli, Fabio
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p. 1883 - 1893
(2007/10/03)
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- Asymmetric allylic substitution catalyzed by palladium-Yliphos complex
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Allylic substitution reactions catalyzed by Pd- or Pt-Yliphos complexes are examined. The reaction of 1,3-diphenyl-2-propenyl acetate with benzylamine proceeded in the presence of Pd(dba)2-Yliphos to give N-benzyl-1,3-diphenyl-2-propenylamine i
- Ohta, Tetsuo,Sasayama, Hiroyuki,Nakajima, Osakazu,Kurahashi, Nobukazu,Fujii, Takeshi,Furukawa, Isao
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p. 537 - 542
(2007/10/03)
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- Molybdenum(0) and tungsten(0) catalysts with enhanced reactivity for allylic substitution: Regioselectivity and solvent effects
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The binuclear Mo(II) and W(II) complexes 28a,b and 29a,b have been developed as pre-catalysts for allylic substitution with β-dicarbonyl nucleophiles. These complexes are reduced in situ to Mo(0) and W(0) catalytic species 30a,b and 31a,b by excess of NaH, employed to generate sodiomalonate nucleophiles, or by DIBAL-H. 1,3-Dioxolane and 1,4-dioxane, when used as solvents, substantially accelerate the reaction. These new catalysts exhibit "traditional" Mo regiochemistry, i.e., the nucleophilic attack occurring preferentially at the more substituted carbon (5 → 9; 37 → 38), unless an additional factor, such as further coordination to another moiety of the allylic electrophile takes part (41), as in the case of the geranyl-type substrates (32 or 33 → 36).
- Malkov,Baxendale,Mansfield,Kocovsky
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p. 1234 - 1240
(2007/10/03)
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- Platinum-catalysed allylic alkylation: Reactivity, enantioselectivity, and regioselectivity
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The use of platinum complexes as catalysts for allylic substitution has been studied. A variety of different complexes catalyse the reaction, and several substrates have been tested. In the alkylation of mono(alkyl)-substituted allylic acetates, regioselectivity is highly dependent on ligand choice. By using tricyclohexylphosphine as the ligand, almost complete formation of branched products is observed. The development of a highly enantioselective (ca. 80-90% ee) reaction that makes use of chiral diphenylphosphinooxazoline ligands (abbreviated as (S)-P∧N) is also described. The enantioselectivity is highly dependent on the ratio of ligand to platinum (when the ratio ligand/Pt is greater than 1:1, the ee drops off dramatically). This is in contrast to palladium and is interpreted in terms of differing coordination chemistry for the two metals ((S)-P∧N is hemilabile when complexed to platinum) and should be of significance to future systems that utilise heterobidentate ligands. The crystal structures of two isoelectronic platinum and palladium complexes [{(S)-P∧N}MCl2] are also described.
- Blacker, A. John,Clarke, Matthew L.,Loft, Michael S.,Mahon, Mary F.,Humphries, Mark E.,Williams, Jonathan M. J.
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p. 353 - 360
(2007/10/03)
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- Molybdenum(II)- and tungsten(II)-catalyzed allylic substitution
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The molybdenum(II) complexes Mo(CO)5(OTf)2 (7a), [Mo(CO)4Br2]2 (8a), their tungsten(II) congeners 7b and 8b, and bimetallic complex Mo(CO)3(MeCN)2(SnCl3)Cl (9a) have been found to catalyze the C-C bond-forming allylic substitution with silyl enol ethers derived from β-dicarbonyls (e.g., 16 + 30 → 46) or from simple ketones (e.g., 16 + 32 → 50), aldehydes, and esters as nucleophiles under mild conditions (room temperature, 1-2 h). Methanol, as a prototype oxygen nucleophile, reacts in a similar fashion (e.g., 16 + MeOH → 43). Mechanistic and stereochemical experiments are indicative of Lewis-acid catalysis rather than a metal template-controlled process.
- Malkov, Andrei V.,Baxendale, Ian R.,Dvorak, Dalimil,Mansfield, Darren J.,Kocovsky, Pavel
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p. 2737 - 2750
(2007/10/03)
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- Studies on a Chiral (N,P) Ligand Containing a C2-Symmetric Aziridine Unit
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As part of a program on the use of chiral aziridines in asymmetric synthesis and catalysis, the enantiopure (N,P) ligand 1, consisting of a C2-symmetric chiral aziridine and a triarylphosphine unit, was prepared. The synthesis was convergent and efficient, proceeding in five steps and 37% overall yield from 2-bromotoluene. The ligand was designed (a) for a study of the asymmetric Pd-catalyzed allylic substitution reaction, (b) in an attempt to obtain a measure of the trans effect of phosphorus relative to an aziridine nitrogen, and (c) to compare its performance with the corresponding chiral phosphinooxazoline species (computational studies having indicated certain similarities between the two ligand types). However, the new aziridine species did not provide levels of enantioselectivity comparable to those obtained with the phosphinooxazoline analogs, and our results serve to underline once more the difficulties associated with the rational design of ligands for asymmetric catalysis.
- Tanner, David,Wyatt, Paul,Johansson, Fredrik,Bertilsson, Sophie K.,Andersson, Pher G.
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p. 263 - 268
(2007/10/03)
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- Palladium catalysed allylic substitution via in situ activation of allylic alcohols
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In-situ activation of a variety of allylic alcohols by hexachlorophosphazene (or oxalyl chloride) followed by Pd(0) catalysed reactions with lithio dimethyl malonate leads to the regio and steroselective alkylations in god yields.
- Kumareswaran,Vankar, Yashwant D.
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p. 8421 - 8424
(2007/10/03)
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- Molecular mechanics predictions and experimental testing of asymmetric palladium-catalyzed allylation reactions using new chiral phenanthroline ligands
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Molecular mechanics calculations were used to probe the conformational properties of a number of substituted phenanthrolines and their η3- allylpalladium complexes. Special attention was focused on phenanthrolines bearing chiral, terpene-derived, alkyl and alkenyl groups at C(2). Based upon these calculations, predictions could then be made regarding the suitability of the several ligands for use in asymmetric palladium-catalyzed substitution reactions of allylic acetates. Each of the substituted phenanthrolines was prepared by straightforward means. Use of these ligands in catalytic allylations gave results which were in good agreement with the calculation- based predictions. The highest levels of asymmetric induction were predicted and were obtained with a readily available 2-(2-bornyl)phenanthroline ligand 13. The results were compared with previously reported data obtained using other ligands. Overall, this work provides further indication of the potential utility of a combined calculational/experimental approach for the design of chiral catalysts.
- Pe?a-Cabrera, Eduarde,Norrby, Per-Ola,Sj?gren, Magnus,Vitagliano, Aldo,De Felice, Vineenzo,Oslob, Johan,Ishii, Sbingo,O'Neill, David,?kermark, Bj?rn,Helquist, Paul
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p. 4299 - 4313
(2007/10/03)
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- Allylic alcohols as substrates for the palladium(0)-catalyzed allylic substitution
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A new method has been developed which allows palladium(0)-catalyzed allylic substitution to occur between allylic alcohols and anionic C-nucleophiles: on reaction with Ph3B, the allylic alkoxide 7 is first converted in situ into the more reactive species 8 which then undergoes a Pd(0)-catalyzed reaction with lithiodiethyl malonate via the η3-complex 9.
- Stary,Stara,Kocovsky
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p. 179 - 182
(2007/10/02)
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- Stereo- and Regiochemistry in Palladium-Catalyzed Nucleophilic Substitution of Optically Active (E)- and (Z)-Allyl Acetates
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Optically acive (E)- and (Z)-allyl acetates, 3-acetoxy-1-phenyl-1-butene (1) and its regioisomer, 1-acetoxy-1-phenyl-3-butene (2), were allowed to react with sodium dimethyl malonate, sodium acetylacetonate, and sodium methyl acetoacetate in the presence of a palladium catalyst.The reaction of (E)-acetates proceeded with retention of configuration and that of (Z)-acetates proceeded with inversion accompanied by geometrical isomerization from Z to E.The stereochemistry observed in the reaction with phenylzinc bromide was opposite to that with the soft nucleophiles.
- Hayashi, Tamio,Yamamoto, Akihiro,Hagihara, Toshiya
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p. 723 - 727
(2007/10/02)
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- Palladium-Catalyzed Propargylic vs. Allylic Alkylation
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The relative reactivities of allylic propargylic acetates toward palladium(0)-catalyzed substitution by various nucleophiles were studied bu using three types of model substrates: (a) monofunctional allylic and propargylic acetates with similar structural properties; (b) a bifunctional substrate containing both allyl and propargyl functionalities with no apparent interaction between them; (c) conjugated bifunctional systems, in which the two functionalities may interact with one another.Palladium(0)-catalyzed substitution of propargylic acetates by various carbon nucleophiles was found to be less general than the analogous substitution of allylic acetates.Three modes of reactivity were observed, corresponding to three groups of nucleophiles; (a) stabilized carboanions such as sodium dimethyl malonate, which do not react with propargylic acetates but react readily with allylic acetates; (b) nonstabilized organometallics such as phenylzinc chloride, which react with propargylic and allylic acetates at comparable rates (reaction with the former yielding the allenic product exlusively); and (c) allyl- and allenylstannanes, which react with allylic acetates but do not react with isolated propargylic acetates (except for special cases where the propargylic acetate is also an allylic one).Certain similarities between regioselectivity phenomena in organopalladium and organocopper chemistry are discussed.
- Keinan, Ehud,Bosch, Eric
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p. 4006 - 4016
(2007/10/02)
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