Ahmed Battace

Bio: Ahmed Battace is an academic researcher from Université Paul Cézanne Aix-Marseille III. The author has contributed to research in topics: Palladium & Aryl. The author has an hindex of 8, co-authored 15 publications receiving 237 citations. Previous affiliations of Ahmed Battace include University of Rennes & Centre national de la recherche scientifique.

Direct arylation of thiophenes via palladium-catalysed C-H functionalisation at low catalyst loadings

Abstract: Palladium associated with cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) was found to promote the direct 2-arylation of a variety of thiophene derivatives via CH functionalisation in good yields using very low catalyst loadings. Electron-deficient, electron-excessive or sterically-congested aryl bromides are tolerated. Moreover, several substituents on the aryl bromide or thiophene derivatives such as acetyl, formyl, nitrile, nitro, ester, methoxy, fluoro or trifluoromethyl are tolerated. The most reactive aryl bromides were coupled with thiophenes derivatives using as little as 0.1–0.01 mol % catalyst.

Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage.

Abstract: The area of transition-metal-catalyzed direct arylation through cleavage of CH bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners—including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations

Recent advances in aryl–aryl bond formation by direct arylation

Abstract: The abundance of the biaryl structural motif in natural products, in biologically active molecules and in materials chemistry has positioned aryl–aryl (Ar–Ar) bond formation high on the agenda of synthetic chemists. For decades well-known reactions such as the Mizoroki–Heck and Suzuki–Miyaura have been the methods of choice to furnish biaryls. More recently, however, alternative methods, most notably direct arylation via C–H activation, have become the focus of many research groups. Compared to traditional methods, direct arylation affords Ar–Ar compounds in fewer steps by removing the need for prefunctionalisation. Furthermore, given that either one or two hydrogens are targeted, less waste and good atom economy are features of this methodology. This critical review covers, in the main part, reports from January 1, 2006, to October 22, 2008 (117 references).

Transition metal-catalyzed direct arylation of substrates with activated sp3-hybridized C-H bonds and some of their synthetic equivalents with aryl halides and pseudohalides.

Abstract: Transition metal-catalyzed cross-coupling reactions of alkyl metals and aryl halides or pseudohalides have emerged as a powerful methodology for the formation of Csp3-Csp2 bonds over the past decades.1 However, significant attention has also been focused on Pdand Ni-catalyzed Csp3-Csp2 bond-forming reactions that involve aryl metals and haloalkyl compounds lacking -hydrogen atoms as cross-coupling partners.2 In contrast, until a few years ago, few examples were reported in the literature concerning transition metalcatalyzed reactions of aryl metals with functionalized alkyl halides including R-halocarbonyl compounds and R-bromosulfones bearing -hydrogen atoms,3 and a single example of Pd-catalyzed cross-coupling reaction of aryl metals and unfunctionalized alkyl halides bearing -hydrogen atoms had been described.4 Only in recent years, successful procedures for the Pd-,5 Ni-,6 Rh-,7 Fe-,8 V-,9 Co-,10 and Cu-catalyzed11 cross-coupling reactions of aryl metals and unfunctionalized alkyl halides bearing -hydrogen atoms have been developed.12 Nevertheless, new, effective, and more environmentallybenignmethodologiesfortheformationof(cyclo)alkyl-aryl bonds, which require a reduced number of synthetic operations, have emerged as valuable alternatives to the conventional cross-coupling reactions. These methodologies (Scheme 1) are based on transition metal-catalyzed simple or 2-fold C-H bond functionalization according to the following approaches: (a) highly regioselective Pd-catalyzed direct arylation reactions of unactivated sp3-hybridized C-H bonds with aryl halides (eq a, Scheme 1);13 (b) Pd-catalyzed direct alkylation reactions of aryl C-H bonds with alkyl metals (eq b, Scheme 1);14 Au-15 or Pdcatalyzed16 direct alkylation reactions of aryl C-H bonds with alkyl halides or pseudohalides (eq c, Scheme 1); (d) Pd-catalyzed arylations of unactivated sp3-hybridized C-H bonds with aryl metals (eq d, Scheme 1);14c (e) Pd-, Ru-, or Cu-catalyzed cross-coupling reactions of sp3-hybridized C-H bonds with arylboronic acids using air as oxidant (eq d, Scheme 1);17 and (f) cross-dehydrogenative coupling of alkyl and aryl C-H bonds (eq e, Scheme 1).18 Finally, great attention, particularly in the past decade, has also been focused on the design, development, and application of transition metal-catalyzed coupling reactions of aryl halides and pseudohalides with a wide variety of substrates containing activated sp3-hybridized C-H bonds (eq f, Scheme 1). A mini-review on this topic was published by Scolastico and Poli in 1999,19 and three excellent reviews that concern the results obtained in this rapidly growing area of extensive research by the groups of Miura, Natsume, Hartwig, and Buchwald up to the end of 2002 were published by Miura,20 Hartwig,21 and Lloyd-Jones22 a few years later. However, the reviews by Miura20 and Hartwig21 were limited in that they fundamentally emphasized the author’s own work and * To whom correspondence should be addressed. E-mail: rossi@dcci.unipi.it. Chem. Rev. 2010, 110, 1082–1146 1082

Analysis of the palladium-catalyzed (aromatic)C-H bond metalation-deprotonation mechanism spanning the entire spectrum of arenes.

Abstract: A comprehensive understanding of the C–H bond cleavage step by the concerted metalation–deprotonation (CMD) pathway is important in further development of cross-coupling reactions using different catalysts. Distortion–interaction analysis of the C–H bond cleavage over a wide range of (hetero)aromatics has been performed in an attempt to quantify the various contributions to the CMD transition state (TS). The (hetero)aromatics evaluated were divided in different categories to allow an easier understanding of their reactivity and to quantify activation characteristics of different arene substituents. The CMD pathway to the C–H bond cleavage for different classes of arenes is also presented, including the formation of pre-CMD intermediates and the analysis of bonding interactions in TS structures. The effects of remote C2 substituents on the reactivity of thiophenes were evaluated computationally and were corroborated experimentally with competition studies. We show that nucleophilicity of thiophenes, evalua...