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ABSTRACT: Chlorocyclopropanes, e.g. I, and bicyclic chlorocyclopropanes, e.g. II, are prepd. in non basic conditions by electroreductive or Mg-promoted Barbier activation of PhCCl3 or Cl3CCO2Me in the presence of acyclic or cyclic α,β-unsatd. carbonyl compds., e.g. H2C:CHCO2Me and 2-cyclohexen-1-one. [on SciFinder(R)]
Tetrahedron 02/2013; 62(7):1583-1589. · 3.03 Impact Factor
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Hicham Bakkali,
Cécile Marie,
Akarim Ly,
Christine Thobie-Gautier,
Jérôme Graton,
Muriel Pipelier,
Stéphane Sengmany,
Eric Léonel, Jean-Yves Nédélec,
Michel Evain,
Didier Dubreuil
Annalen der Chemie und Pharmacie 03/2008; 2008(12):2156 - 2166. · 3.10 Impact Factor
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ABSTRACT: A general efficient electrochemical method for the preparation of aryl- and heteroarylpyridazines in a nickel-catalyzed cross-coupling reaction of 3-chloro-6-methoxypyridazine and 3-chloro-6-methylpyridazine with a range of functionalized aryl or heteroaryl halides is reported.
The Journal of Organic Chemistry 08/2007; 72(15):5631-6. · 4.45 Impact Factor
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ABSTRACT: It is about 20 years since the combination of transition-metal catalysis and electroreduction was shown to be applicable to the coupling of organic molecules. This was followed by a number of fundamental investigations and basic syntheses using various nickel, cobalt, or palladium compounds which can easily be reduced in situ electrochemically to low-valent reactive intermediates. The last decade has been less characterized by reports on new catalytic systems than by the development of new synthetic applications. The aim of this review is to show that the electrochemical processes described here offer valuable advantages in organic synthesis.
04/2006: pages 141-173;
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ABSTRACT: A two-steps procedure allowing the formation of alkyldiphenylphosphines and aryldiphenylphosphines in good yield is described. It relies on the electrochemical preparation of magnesium chloride diphenylphosphanide and its subsequent coupling with either alkyl halides or aryl fluorides. Phosphines are of high interest in homogeneous catalysis due to their broad activity as ligands. Since the pioneering work of Stille [1] concerning the palladium-catalyzed forma-tion of triarylphosphines, several studies have been devoted to transition metal-catalyzed cross-coupling reactions leading to arylated phosphines. For example, aryl triflates react with diphenylphosphine in the presence of palladium-[2] or nickel-based catalysts [3]. Aryldiphenylphosphine can be obtained through palladium-catalyzed couplings of tri-phenylphosphine with either aryltriflates [4] or aromatic bromides [5]. Some years ago, it was reported that nickel complexes NiCl 2 (dppe) [6] or NiCl 2 (PPh 3) 2 [7] are efficient catalysts for the synthesis of triarylphosphines through reductive coupling of aryl triflates with chlorodiphenylphos-phine. In related approaches, it was shown in this laboratory that a the NiBr 2 (bpy) catalyzed cross-coupling can be achieved by an electrochemical way [8] or using a zinc-med-iated reductive coupling between aryl halides and chlorodi-phenylphosphine in heated NMP (N-methylpyrrolidin-2-one) [9]. Another synthetic pathway based on the formation of carbon nucleophiles and the subsequent coupling with chlorophosphines has also been widely employed [10]. Thus, starting from aryl halides, lithium–halogen exchange [11,12] or Grignard reagents synthesis [12a] allows the for-mation of strong nucleophiles which easily displace chloro-diphenylphosphine giving rise to the formation of aryldiphenylphosphines in generally good yield. In a paper, Knochel et al. have reported that aliphatic or some aro-matic organozinc compounds can also be coupled with chlorophosphines [13]. Two-steps procedures relying on the use of potassium diphenylphosphanide were also employed [14,15]. Thus, it was shown that this nucleophile reacts efficiently with ortho-substituted aryl fluorides to yield aryldiphenylphos-phines in high yield [15]. Among the numerous topics developed in this labora-tory, the electrochemical activation of halogenated species is of constant interest. Indeed, reactions proceed generally smoothly and do not require the use of drastic conditions. Thus, several years ago, it was shown by Folest et al. that chlorodiphenylphosphine can be electrochemically coupled with some alkyl halides in a one-step reaction leading to alkyldiphenylphosphines [16]. As a part of our program
Journal of Organometallic Chemistry 03/2006; · 2.38 Impact Factor
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ABSTRACT: [reactions: see text] Nickel-catalyzed electroreductive homocoupling of 2-bromomethylpyridines and 2-bromopyridine has been investigated in an undivided cell in the presence of a zinc sacrificial anode. A series of reactions were performed with various types and concentrations of supporting electrolyte. It was observed that a key step in this process is the formation of an arylzinc through a nickel-zinc transmetalation. This intermediate can be transformed back to the reactive arylnickel species to afford the homocoupling as the final product. The back process from the arylzinc intermediate is, however, suppressed in the presence of high concentration (0.2 M) of tetraalkylammonium salts. On the contrary, with NaI, the formation of the dimer is not prevented, whatever the NaI concentration.
The Journal of Organic Chemistry 01/2006; 70(26):10778-81. · 4.45 Impact Factor
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ABSTRACT: Direct or Ni-catalysed electroreductive homocouplings of organic halides and couplings of organic halides with activated olefins are efficiently conducted by constant current electrolyses in an undivided cell in room-temperature ionic liquids as the solvent-electrolyte media.
Chemical Communications 07/2003; · 6.17 Impact Factor
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ABSTRACT: The study of the electrochemical behavior of cobalt bromide, CoBr2, in the presence of zinc bromide, ZnBr2, and aryl halides, ArX, in a dimethylformamide (DMF)/pyridine (9:1, v/v) mixture allowed us to complete the study of the mechanism of the electrochemical conversion of aryl halides into arylzinc compounds by using cobalt catalysis. The last step of the catalytic process has been shown to be a transmetalation reaction between the arylcobalt(II) species and zinc ions that regenerates the cobalt(II) catalyst. The effect of zinc bromide on each step of the catalytic cycle has been studied. It is especially shown that the presence of ZnBr2 stabilizes the electrogenerated Co1 but has no effect on the rate constant of the oxidative addition of aryl halides, ArX, to Co1. Rate constants for the disproportionation reaction of Co1 and the oxidative addition have been determined in the presence of ZnBr2 and compared with the values obtained in its absence.
Chemistry 07/2002; 8(11):2534-8. · 5.93 Impact Factor
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ABSTRACT: 2,2'-Bipyridine (bpy) and a series of dimethyl-2,2'-bipyridines were synthesized from 2-bromopyridine and 2-bromomethylpyridines, respectively, using an electrochemical process catalyzed by nickel complexes. The method is simple and efficient, with isolated yields between 58 and 98% according to the structure. We first studied the influence of the presence and the position of the methyl group on the yield, using N,N-dimethylformamide (DMF) or acetonitrile (AN) as the solvent, NiBr(2)bpy as the catalyst, and Zn as the sacrificial anode, in an undivided cell and at ambient temperature. On the basis of a better understanding of the reaction mechanism based on electroanalytical studies, we could improve the dimerization both by substituting the catalyst ligand (bpy) by the reagent itself, i.e., 2-bromomethylpyridine or 2-bromopyridine, and by using Fe instead of Zn as the sacrificial anode.
The Journal of Organic Chemistry 04/2002; 67(6):1838-42. · 4.45 Impact Factor
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ABSTRACT: Electroreduction of aryl-chlorides or -bromides in an electrochemical cell fitted with a sacrificial zinc anode and in the presence of cobalt halide associated with pyridine as ligand in DMF or acetonitrile as solvent affords the corresponding organozinc species in good yields.
08/2000;
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Synthetic Communications 11/1999; 29(22):4015-4024. · 1.06 Impact Factor
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Tetrahedron Letters 01/1999; 40:9009. · 2.68 Impact Factor
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Novel Trends in Electro-organic Synthesis; 01/1998
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The Journal of Organic Chemistry 12/1997; 62(23):7914-7915. · 4.45 Impact Factor
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Ref. No: FR.N° 97 07908 PCT/FR98/01336, Year: 06/1997
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Tetrahedron Letters 01/1997; 38:8683. · 2.68 Impact Factor
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ABSTRACT: The electrochemical reduction of a mixture of aryl halides and activated alkyl halides in DMF in the presence of catalytic amount of NiBr(2)bipy leads to cross-coupling products in good to high yields. The method applies to the synthesis of alpha-aryl ketones, alpha-aryl esters, and allylated compounds from readily available organic halides. Optimization of the process has been obtained by slowly adding the most reactive organic halide (usually the activated alkyl halide) during the electrolysis which is best conducted at 70 degrees C when aryl bromides are involved.
The Journal of Organic Chemistry 04/1996; 61(5):1748-1755. · 4.45 Impact Factor
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Journal of Electroanalytical Chemistry 01/1996; 412:85. · 2.58 Impact Factor
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Novel Trends in Electro-organic Synthesis; 01/1995
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Synthetic Communications 01/1994; 24(2):145-151. · 1.06 Impact Factor
