application-elemental-lanthanides-selective-c-f-activation

Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

The selective activation of one carbon-fluorine bond in polyfluorinated aromatic molecules or in trifluoromethyl-containing substrates offers the ...

Ecole Nationale Supérieure de Chimie de Montpellier

[reaction: see text] An efficient method for the synthesis of diaryl ethers under particularly mild conditions is described. Inexpensive ligands were found to greatly accelerate the Ullmann-type coupling of aryl bromides or iodides with phenols. A series of diaryl ethers were obtained with excellent yields in acetonitrile in the presence of Cs(2)CO(3) and catalytic copper(I) oxide. The reaction tolerates substrates with unfavorable substitution patterns, such as sterically hindered coupling partners or electron-rich aryl halides.

A general and mild Ullmann-type synthesis of diaryl ethers.

An efficient copper-catalyzed cyanation of aryl iodides and bromides is reported. Our system combines catalytic amounts of both copper salts and chelating ligands. The latter, which have potential nitrogen- and/or oxygen-binding sites, have never previously been used in this type of reaction. A protocol has been developed that enables the cyanation of aryl bromides through the copper-catalyzed in situ production of the corresponding aryl iodides using catalytic amounts of potassium iodide. Aryl nitriles are obtained in good yields and excellent selectivities in relatively mild conditions (110 degrees C) compared with the Rosenmund-von Braun cyanation reaction. Furthermore, the reaction is compatible with a wide range of functional groups including nitro and amino substituents. The protocol reported herein involves two main innovations: the use of catalytic amounts of ligands and the use of acetone cyanohydrin as the cyanating agent in copper-mediated cyanation reactions.

Mild and efficient copper-catalyzed cyanation of aryl iodides and bromides.

An efficient and straightforward copper-catalyzed method allowing vinylation of N- or O-nucleophiles with di- or trisubstituted vinyl bromides is reported. The procedure is applicable to a broad range of substrates since N-vinylation of mono-, di-, and triazoles as well as O-vinylation of phenol derivatives can be performed with catalytic amounts of copper iodide and inexpensive nitrogen ligands 3 or 8. In the case of more hindered vinyl bromides, the use of the original bidentate chelator 8 was shown to be more efficient to promote the coupling reactions than our key tetradentate ligand 3. The corresponding N-(1-alkenyl)azoles and alkenyl aryl ethers are obtained in high yields and selectivities under very mild temperature conditions (35-110 degrees C for N-vinylation reactions and 50-80 degrees C for O-vinylation reactions). Moreover, to our knowledge, this method is the first example of a copper-catalyzed vinylation of various azoles. Finally, this protocol, practical on a laboratory scale and easily adaptable to an industrial scale, is very competitive compared to the existing methods that allow the synthesis of such compounds.

Mild copper-catalyzed vinylation reactions of azoles and phenols with vinyl bromides.

Various strong non-ionic phosphazene bases were obtained by a new, efficient and very simple method involving the lithium phosphonium azayldiide Ph3P=NLi as a precursor.

A new and convenient method for the synthesis of strong non-ionic bases.

Efficient iron/copper co-catalyzed arylation of nitrogen nucleophiles.

Copper- or iron-catalyzed arylation of phenols from respectively aryl chlorides and aryl iodides.

We have developed an inexpensive catalytic system using a readily available copper/ligand combination for the Sonogashira-type cross-coupling of aryl iodides and phenyl- and hexyl-acetylene which affords disubstituted alkynes in good to excellent yields.

Copper-catalyzed sonogashira-type reactions under mild palladium-free conditions.

The N-arylation of aromatic and aliphatic secondary acyclic amides, known to be poor nucleophiles, has been accomplished using a simple and cheap copper catalytic system. The corresponding tertiary acyclic amides, which can be found in numerous biologically active compounds, have been obtained in good to excellent yields.

A simple copper-catalyzed synthesis of tertiary acyclic amides.

The one-pot synthesis of symmetrical or unsymmetrical di- or triarylamines using aryl iodides or bromides and LiNH(2) as ammonia source is reported. This highly selective method is based, for the first time, on a copper-catalyzed system, which does not require the presence of any additional ligand.

Selective one-pot synthesis of symmetrical and unsymmetrical di- and triarylamines with a ligandless copper catalytic system.

Copper-catalyzed hydroamination of aromatic or heteroaromatic alkynes with cyclic secondary aliphatic amines undergoes generation of an enamine-type intermediate. The latter is transformed in situ via a coupling reaction with a second molecule of alkyne to afford regioselectively (1E,3E)-1,4-disubstituted-1,3-dienes with the formation of C-N, C-C, and C-H bonds. 

Copper-catalyzed hydroamination of alkynes with aliphatic amines: regioselective access to (1E,3E)-1,4-disubstituted-1,3-dienes.

A simple and convenient copper-catalyzed hydroamination of arylacetylenes with secondary amines has been performed giving a simple access to aliphatic amines after reduction of the hydroaminated products (E-enamines). Here we described a mild catalytic system utilizing CuCN precatalyst without any additive ligands in a solvent-free system. 

Hydroamination of terminal alkynes with secondary amines catalyzed by copper: regioselective access to amines.

The direct, nucleophilic imidation of acetanilide derivatives has been performed under mild, iodine(III)-mediated or -catalyzed conditions, employing lithium triflimide as the nitrogen source. The reaction exhibits exclusive regioselectivity for the para position and shows a good tolerance for varied functional groups at both the ortho or meta positions. Preliminary mechanistic data suggest that the LiNTf2 reagent plays a key role in the reactivity. 

Iodine(III)-Mediated para-Selective Direct Imidation of Anilides.

The α-arylation of enolizable aryl ketones can be carried out with aryl halides under transition-metal-free conditions using KOtBu in DMF. The α-aryl ketones thus obtained can be used for step- and cost-economic syntheses of fused heterocycles and Tamoxifen. Mechanistic studies demonstrate the synergetic role of base and solvent for the initiation of the radical process. 

Transition-Metal-Free α-Arylation of Enolizable Aryl Ketones and Mechanistic Evidence for a Radical Process.

Well-defined ruthenium complexes and simple copper-ligand systems proved to be powerful catalysts for the construction of complex molecules from simple and abundant organic sources. In this account, chosen examples of reactions involving C-C bond formation catalyzed by [Ru(η(5)-C(5)H(5))-(CH(3)CN)(3)][PF(6)] will be presented. A practical synthesis of the versatile catalyst [Ru(η(5)-C(5)H(5))-(CH(3)CN)(3)][PF(6)] is also described via a simple and easy-handled procedure discovered in Geneva ten years ago. The second part of this review is focused on methodologies catalyzed by an association of a copper salt and a simple ligand for the formation of C-N, C-O and C-C bonds developed in our group in Montpellier. A brief overview of applications in life sciences and materials will conclude this article.

From Ruthenium to Copper: A la carte Tools for the Synthesis of Molecules of Interest.

The ligand-free copper-catalyzed hydroamination of allenes has been accomplished in the presence of cyclic secondary amines or anilines derivatives. This novel methodology undergoes the selective generation of (E)-allylamines under smooth conditions with total regio- and stereoselectivity. 

Copper-Catalyzed Hydroamination of Terminal Allenes.

Simple ligand-free copper systems were found as efficient catalysts for the addition of 1,3-dicarbonyl compounds to N-allenyl derivatives. This highly regio- and stereoselective reaction has been accomplished in the presence of malonates, 1,3-ketoesters, and 1,3-diketones with good to excellent yields under mild conditions. This methodology represents the first allylation of 1,3-dicarbonyl compounds with allenes catalyzed by copper.

Marc Taillefer

Institut Charles Gerhardt Montpellier UMR 5253

Ecole Nationale Supérieure de Chimie de Montpellier

Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

Marc Taillefer

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Institut Charles Gerhardt Montpellier UMR 5253

Ecole Nationale Supérieure de Chimie de Montpellier

Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

Institut Charles Gerhardt Montpellier UMR 5253