- Some Observations on the Mechanism of Diorganocuprate 1,4-Addition Reactions with α,β-Unsaturated Ketones: Effects of Diethyl Ether in Reactions of Butylcoppers in Toluene
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Mixtures of butyllithium and copper iodide prepared in toluene react with α,β-unsaturated ketones predominantly in a 1,2-fashion. Addition of 2 equiv of diethyl ether to the system results in a dramatic preference for the 1,4-product, as found normally with diorganocuprates in ethereal solvents. These results are in accordance with the theoretical predictions that a suitable ligand is required to facilitate the stabilization of a formally copper(III) reaction intermediate on the 1,4-addition mechanistic pathway.
- Kingsbury, Celia L.,Smith, Robin A.J.
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Read Online
- Palladium-catalyzed site-selective arylation of aliphatic ketones enabled by a transient ligand
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Transition metal-catalyzed direct C-H bond functionalization enabled by transient ligands has become an attractive topic. Here we report a palladium-catalyzed site-selective arylation of β-C(sp3)-H bonds in aliphatic ketones with β-alanine as the transient ligand.
- Pan, Lei,Yang, Ke,Li, Guigen,Ge, Haibo
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supporting information
p. 2759 - 2762
(2018/03/21)
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- CuCl/bipyridine-catalyzed addition reactions of arylboroxines with aldehydes, α,β-unsaturated ketones, and N-tosyl aldimines
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CuCl/bipyridine-catalyzed addition reactions of arylboroxines with aldehydes and α,β-unsaturated ketones at elevated temperatures were described. By using the microwave energy, CuCl/bipyridine-catalyzed addition reactions of arylboroxines with aldimines were also realized.
- Liao, Yuan-Xi,Hu, Qiao-Sheng
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experimental part
p. 7602 - 7607
(2011/11/12)
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- Enders SAMP-hydrazone as traceless auxiliary in the asymmetric 1,4-addition of cuprates to enones
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Conjugate additions of Gilman cyanocuprates to (5)-N-amino-2- (methoxymethyl)pyrrolidine (SAMP)-hydrazones 4, 5 derived from cyclic and acyclic α,β-unsaturated ketones were investigated. A protocol utilizing copper(II) sulfate/ammonium chloride was evolved, which allowed cleavage of SAMP (S)-1 under the hydrolysis and work-up conditions, followed by recovery of the auxiliary with ethylenediaminetetraacetic acid (EDTA). The enantioselectivity of cuprate additions was dominated for cyclic SAMP-hydrazones 4 by the cuprate alkyl substituent and the ring size, in the case of acyclic arylidene SAMP-hydrazones 5, however, by the nature of the aryl substituent. Electron-donating substituents gave poor enantiomeric excesses, whereas electron-withdrawing groups provided excellent ee values of 98-99%. The configuration of the new stereocenter was determined to be (R). Moreover, a reaction sequence was developed which integrates a tandem 1,4-addition/ methylation and traceless hydrolytic cleavage of the auxiliary (S)-1 in a one-pot reaction, resulting in enantiomerically pure methyl ketones 11-13, each of them with > 99% ee.
- Sammet, Karsten,Gastl, Christoph,Baro, Angelika,Laschat, Sabine,Fischer, Peter,Fettig, Ina
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supporting information; experimental part
p. 2281 - 2290
(2010/12/29)
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- Orthoplatinated triarylphosphite as a highly efficient catalyst for addition reactions of arylboronic acids with aldehydes: Low catalyst loading catalysis and a new tandem reaction sequence
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(Chemical Equation Presented) Readily available, air/moisture-stable orthoplatinated triarylphosphite catalyzes the addition reactions of arylboronic acids with aldehydes with the catalyst loading as low as 0.01%. It also cataylzes a new tandem reaction of arylboronic acids with α,β- unsaturated aldehydes to form 1,3-diaryl-1-propanols. Our study provides a new paradigm for the application of orthoplatinated triarylphosphites, and may pave the road to develop other Pt(II) catalysts for such addition reactions and other tandem reactions with such addition reactions as part of the reaction sequence.
- Liao, Yuan-Xi,Xing, Chun-Hui,He, Ping,Hu, Qiao-Sheng
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supporting information; experimental part
p. 2509 - 2512
(2009/05/26)
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- Synthesis of β-aryl ketones by tetraphosphine/palladium catalysed Heck reactions of 2- or 3-substituted allylic alcohols with aryl bromides
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Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides undergoes Heck reaction using 2- or 3-subtituted allylic alcohols. With these sterically congested alkenes, the selective formation of β-aryl ketones was observed when appropriate reaction conditions were used. The influence of the functional group on the aryl bromide and of the base on the selectivity is remarkable. With several substrates, much higher selectivities were obtained using NaHCO3 instead of K2CO3 as base. Furthermore, this catalyst can be used at low loading with several substrates.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 4372 - 4383
(2007/10/03)
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- Palladium-catalyzed enantioselective conjugate addition of arylboronic acids
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(Chemical Equation Presented) The first asymmetric palladium-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated aldehydes, ketones, and esters is described. For cyclic substrates, excellent chemo-, regio-, and enantioselectivities are achieved when a Pd(O2CCF 3)2/DuPHOS catalyst is applied.
- Gini, Francesca,Hessen, Bart,Minnaard, Adriaan J.
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p. 5309 - 5312
(2007/10/03)
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- Enantioselective conjugate addition of diethylzinc to enones with chiral copper-QUIPHOS catalyst influence of the addition of water on the enantioselectivity
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The use of a new chiral copper catalyst involving QUIPHOS as ligand in the 1,4-addition of Et2Zn to enones is reported. The dramatic beneficial effect of addition of water or Zn(OH)2 to this system has been investigated, and led to a
- Delapierre, Guillaume,Constantieux, Thierry,Brunel, Jean Michel,Buono, Gerard
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p. 2507 - 2511
(2007/10/03)
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- Novel tridentate diamino organomanganese(II) complexes as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon-carbon bond forming reactions
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The new, paramagnetic arylmanganese(II) complex Li[MnCl2(NCN)] (2, NCN [C6H3(CH2NMe2)2-2,6] -) has been obtained in high yield from the reaction of MnCl2 and [Li(NCN)]2 in a 2:1 molar ratio. In THF solution, 2 is likely an ionic species [Li(THF)n] [MnCl2(NCN)] (molecular weight determination and conductivity measurements), while magnetic measurements indicate that a high spin d5 manganese(II) center is present. Subsequent reaction of 2 with RLi afforded [MnR(NCN)] (R=Me (3a), n-Bu (3b)). Complex 2, using CuCl as a co-catalyst, is an effective catalyst system for cross-coupling of Grignard reagents with alkyl bromides and the 1,4-addition of organomagnesium halides to α,β-unsaturated ketones. No further additives or co-solvents are necessary. For both reactions a dramatic decrease in reaction times is observed when compared to standard manganese/copper systems. Alkyl bromides with unsaturated or heteroatom functionalities can be cross-coupled. Also, excellent reactivity towards normally unreactive β,β-disubstituted ketones has been observed in the 1,4-addition reaction.
- Donkervoort, Johannes G.,Vicario, Jose L.,Jastrzebski, Johann T.B.H.,Gossage, Robert A.,Cahiez, Gerard,Van Koten, Gerard
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- Chiral copper amine complexes
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Disclosed herein is a class of chiral copper-amine complexes of the formula R(L*) CuLi in which L* is selected from: STR1 In this formula, R is a transferable ligand, which can be alkyl, aryl or aralkyl. M is a metal ion such as Li, Na, K, Cs, Rb, Be, Mg
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- Application of Indium Ate Complexes to Synthetic Chemistry. Selective Conjugate Addition to Enones and Coupling with Allylic Halides
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Tetraorganoindium ate complexes, prepared by the addition of organolithium reagents to trialkylindium, reacted with α,β-unsaturated ketones in a 1,4-addition fashion; allylic indates derived from allylic indium sesquihalides coupled with allylic halides regio- and stereo-specifically to give high yields of hed-to-tail 1,5-dienes.
- Araki, Shuki,Shimizu, Toshio,Jin, Shun-Ji,Butsugan, Yasuo
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p. 824 - 825
(2007/10/02)
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- Mechanism of the Grignard Adddition Reaction. XVI. Homolytic and Concerted Mechanisms in the Reaction of α,β-Unsatureted Carbonyl Compounds with Grignard Reagents
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Kinetic measurements have shown that the addition of Grignard reagents to α,β-unsaturated carbonyl compounds takes place either by a concerted mechanism or by a homolytic mechanism.Phenylmagnesium bromide, which is incapable of homolysis, reacts rapidly in a 1,4-fashion if an s-cis conformation exists between the C=C and the C=O bonds, but only 1,2-addition takes place if the conformation is s-trans.tert-Butylmagnesium bromide is unsuited to the concerted reaction, but 1,4-addition takes place via homolysis.Primary and secondary Grignard reagents, like phenyl, react rapidly in a concerted manner with s-cis substrates, but unlike phenyl, these Grignard reagents may, with s-trans substrates, produce some 1,4-adduct via the homolytic mechanism.
- Holm, Torkil
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p. 925 - 929
(2007/10/02)
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- Direct Michael-Type Addition of Si-Groups to α,β-unsaturated β-Aryl-Substituted Enones with R3SiCl/Bu2Cu(CN)Li2
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(E)-5-Benzylidene-2-tert-butyl-6-methyl-1,3-dioxan-4-one (1) undergoes conjugative silylation (Me3Si, Et3Si, tBuMe2Si, Me2PhSi, products 2-5) with the reagent specified in the title.The reaction is highly diastereoselective, with formal anti addition of R
- Amberg, Willi,Seebach, Dieter
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p. 2439 - 2444
(2007/10/02)
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- ORGANOCOPPER-IODOSILANE COMBINATIONS IN CONJUGATE ADDITIONS
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This paper concerns new possibilities opened by the addition of (mono)organocopper compounds and iodotrimethylsilane (TMSI) to α,β-unsaturated ketones and esters giving the silyl enol ethers and ketene acetals, respectively.We demonstrate the homogeneous addition of methylcopper-tributyl-phosphine-iodotrimethylsilane to methyl cinnamate, the use of organocopper-bromotrimethylsilane combinations, the dominating formation of Z-silyl enol ethers on conjugate addition of methyl- and butylcopper/TMSI to benzalacetone, and the formation of silyl enol ethers in other additions of organocopper compounds and TMSX to conjugated ketones.The Z-selectivity for addition to benzalacetone corresponds to s-cis conformations in ?-complexes between copper(I) chloride and 1-penten-3-one or 3-buten-2-one.The stereoselectivity could support a reaction path via ?-complexes between organocopper-iodotrimethylsilane complexes and s-cis conformers of the substrates.
- Bergdahl, Mikael,Lindstedt, Eva-Lotte,Nilsson, Martin,Olsson, Thomas
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p. 535 - 544
(2007/10/02)
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- Reactions of Carbonyl Compounds with Grignard Reagents in the Presence of Cerium Chloride
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The addition of Grignard reagents to ketones is significantly enhanced by cerium chloride with remarkable supression of side reactions, particularly enolization.Some esters, which are prone to side reactions, also react readily with Grignard reagents in the presence of cerium chloride to give normal reaction products in reasonable to high yields.
- Imamoto, Tsuneo,Takiyama, Noboyuki,Nakamura, Kimikazu,Hatajima, Toshihiko,Kamiya, Yasuo
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p. 4392 - 4398
(2007/10/02)
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- CHLORO- AND IODOTRIMETHYLSILANE-ACTIVATED ADDITIONS OF ORGANOCOPPER COMPOUNDS TO ENONES AND ENOATES
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Organocopper compounds add to enones and enoates in the presence of chloromethylsilane in ether giving the conjugate adducts in preparatively usefu yields via the silyl enol ethers.Presence of lithium iodide is important and excess of chlorotrimethylsilane accelerates the reactions.The combination of organocopper compound, iodotrimethylsilane and dimethyl sulfide gave faster reactions and very high yields, particularly in dichloromethane, where the reaction mixtures gradually became homogeneous.
- Bergdahl, Mikael,Lindstedt, Eva-Lotte,Nilsson, Martin,Olsson, Thomas
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p. 2055 - 2062
(2007/10/02)
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- 2-Thienyl as Auxiliary Group in Mixed Lithium Diorganocuprate
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2-Thienylcopper (ThCu) gives mixed lithium organothienylcuprate reagents (LiRThCu) with organolithium compounds (R = methyl, butyl, phenyl and 2-pyridyl) in ether.These cuprates react with enones or enoates adding the group R, 1,4 to the substrates, 2-thienylcopper being regenerated.The isolated yields of conjugate addition are substantial (40-89percent) and comparable to those obtained with LiR2Cu in corresponding addition.Since a mixed organothienylcuprates are rather stable at 0 deg C, and sometimes even at room temperature, the 2-thienyl group is an useful auxiliary in mixed lithium organocuprates for conjugate addition.Lithium bis(2-thienyl)cuprate, on the other hand, gives 1,2- as well as 1,4-addition of the 2-thienyl group to enones and to methyl crotonate.
- Lindstedt, Eva-Lotte,Nilsson, Martin
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p. 466 - 469
(2007/10/02)
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- CERIUM CHLORIDE-PROMOTED NUCLEOPHILIC ADDITION OF GRIGNARD REAGENTS TO KETONES AN EFFICIENT METHOD FOR THE SYNTHESIS OF TERTIARY ALCOHOLS
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In the presence of anhydrous cerium(III) chloride, Grignard reagents react with ketones to afford addition products in high yields, even though the substrates are susceptible to abnormal reactions with Grignard reagents alone.
- Imamoto, Tsuneo,Takiyama, Nobuyuki,Nakamura, Kamikazu
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p. 4763 - 4766
(2007/10/02)
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- Lewis Acid Mediated Reactions of Organocopper Reagents. Entrainment in the Conjugate Addition to α,β-Unsaturated Ketones, Esters, and Acids via the RCu*BF3 System
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Lewis acid mediated reactions of organocopper reagents with various kinds of α,β-unsaturated carbonyl derivatives are described.RCu*BF3, as well as RCu-other Lewis acid systems, is useful for the conjugate addition to the α,β-unsaturated ketones and esters, whose double bonds are sterically crowded.Certain α,β-unsaturated carboxylic acids also undergo a 1,4-addition through this reagent.Methyl sorbate undergos a 1,4-addition via BuCu*BF3, while undergoing a 1,6-α,δ-addition via Bu2CuLi.BuCu*BF3 reacts more readily with an aldehyde than with a ketone; the degree of chemoselectivity is greater than that of Bu2CuLi, BuLi, or BuMgBr.The R2CuLi-BF3 system is useful for the double alkylation of α,β-unsaturated esters at the β-position and the carbonyl center.Stereochemical aspects of these new copper reagents are also reported.
- Yamamoto, Yoshinori,Yamamoto, Sinichi,Yatagai, Hidetaka,Ishihara, Yuji,Maruyama, Kazuhiro
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p. 119 - 126
(2007/10/02)
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