C-H Bond Activation and Catalytic Functionalization I

Table of Contents

1. Frontmatter

2. Rh(III)- and Ir(III)-Catalyzed C–C Bond Cross Couplings from C–H Bonds

   Joanna Wencel-Delord, Frederic W. Patureau, Frank Glorius

   Abstract

   Over the recent years, dicationic [Cp*Ir(III)] and more particularly [Cp*Rh(III)] complexes have established themselves as extremely powerful catalysts enabling direct C–H activation of various aromatic and vinylic compounds. During such transformations, a common metallacyclic intermediate [Cp*M(C^X)] (M=Ir, Rh) is formed and undergoes further transformations, according to the nature of the coupling partner, to finally afford a myriad of valuable, often complex, and otherwise difficult to access scaffolds like heterocycles and polyunsaturated skeletons. The major advances achieved in this field clearly showcase the potential of these catalysts to functionalize latent C–H bonds under surprisingly mild reaction conditions. The aim of this chapter is to present the latest and most representative contributions in the field of Rh(III)- and Ir(III)-catalyzed C–H activation by focusing on the reactivity of the corresponding metallacyclic intermediates.

3. Rh(III)- and Ir(III)-Catalyzed Direct C–H Bond Transformations to Carbon–Heteroatom Bonds

   Jeung Gon Kim, Kwangmin Shin, Sukbok Chang

   Abstract

   The direct manipulation of C–H bonds is now a powerful tool in chemical synthesis. In achieving the current high standard of research progresses, Rh(III) and Ir(III) complexes played an important role to understand the nature of C–H bond activation. While numerous stoichiometric reactions of hydrocarbons with Rh(III) or Ir(III) complexes were scrutinized, their use in catalytic transformations has been relatively undeveloped until recently. Given their outstanding reactivity in C–H activation, they are highly promising candidates for inducing mild C–H functionalizations. In spite of a short development history, numerous contributions from leading research groups made big strides in highly efficient and selective C–H bond transformations for the C–C and C–heteroatom bond formation. In this report, we specifically focus on the Rh(III)- or Ir(III)-mediated direct C–H functionalizations for the C–heteroatom bond formation that is now a rapidly growing area. This report presents the current status of such catalytic systems including scope of substrates and coupling partners as well as brief mechanistic descriptions.

4. Computational Studies on Heteroatom-Assisted C–H Activation and Functionalisation at Group 8 and 9 Metal Centres

   Kevin J. T. Carr, Stuart A. Macgregor, Claire L. McMullin

   Abstract

   This chapter surveys computational studies on heteroatom-assisted C–H activation at group 8 and 9 metal centres and will cover the literature since 2009. The chapter first considers work where the mechanism of the C–H activation step is the primary concern and categorizes these into intramolecular (with directing groups) and intermolecular processes. Studies on C–H activation and functionalization will be presented, classified in terms of the nature of the functionalization process (oxidative coupling to form heterocycles, alkenylation and amination).

5. Recent Developments in Pd-Catalyzed Direct Arylations of Heteroarenes with Aryl Halides

   Fabio Bellina

   Abstract

   The direct arylation of heteroaromatic compounds with aryl halides using palladium catalysts has significantly been developed as an effective method for making (hetero)aryl-heteroaryl bonds, which are frequently found in biologically active compounds and functional materials. However, issues regarding costly reagents, regioselectivity, and harsh reaction conditions have to be solved to really compete with the classical transition metal-mediated cross-coupling procedures involving stoichiometric organometallic reagents. In this review, the most relevant developments aimed at solving these issues are summarized.

6. New Arylating Agents in Pd-Catalyzed C–H Bond Functionalization of 5-Membered Ring Heteroarenes

   Jean-François Soulé, Henri Doucet

   Abstract

   In recent years, the palladium-catalyzed direct arylation of heteroaromatics via C–H bond activation has become a popular method for generating carbon–carbon bonds. In most cases, aryl halides were employed as the coupling partners. However, since a few years, several new coupling partners have emerged as useful alternatives for such couplings. This chapter focuses on the recent advances on the discovery of new arylating agents in the palladium-catalyzed arylation of 5-membered ring heteroaromatics.

7. Functionalization of [60]Fullerene via Palladium-Catalyzed C–H Bond Activation

   Guan-Wu Wang

   Abstract

   The palladium-catalyzed C–H bond activation strategy has been successfully applied to fullerene chemistry, and several types of [60]fullerene-fused heterocycles and carbocycles have been obtained. The synthesis of [60]fullerene-fused indolines, isoquinolinones, azepines, tetrahydroisoquinolines, tetrahydrobenzazepines, sultones, tetrahydrobenzooxepines/isochromans, and dihydrophenanthrenes has been achieved by the palladium-catalyzed reactions of [60]fullerene with anilides, benzamides, N-sulfonyl-2-aminobiaryls, N-benzyl sulfonamides, N-(2-arylethyl) sulfonamides, arylsulfonic acids, 2-phenylethyl/benzyl alcohols, and 2-arylbenzoic acids, respectively.

8. Ruthenium(II)-Catalysed Functionalisation of C–H Bonds with Alkenes: Alkenylation versus Alkylation

   Christian Bruneau, Pierre H. Dixneuf

   Abstract

   This chapter describes the recent achievements since 2011 of ruthenium(II)-catalysed transformations of sp²C–H bonds of a variety of functional arenes, heterocycles, alkenes and ferrocene derivatives on their reaction with alkenes, either via oxidative dehydrogenation to produce functional alkenes or via formal insertion of alkene into C–H bonds to afford alkylated products. The regioselectivity of ortho C–H bond alkenylation or alkylation is shown to be directed by both strongly and weakly coordinating functional groups from N-heterocycles and bidentate groups to carbonyl-containing groups such as ketone, ester, amide, carbamate and sulfonic acid derivatives. The ruthenium(II) catalysts often based on [RuCl₂(p-cymene)]₂ or RuCl₂(PPh₃)₃ derivatives sometimes require the presence of a halide abstractor and an oxidant. The alkenylation of heterocycles will be shown to occur in the presence of base and their alkylation in the presence of proton source to give branched or linear alkylated isomers. Discussion of catalytic mechanism will involve the initial formation of a cyclometallate via C–H bond deprotonation and that of an intermediate resulting from alkene insertion into the Ru–C bond before its evolution to alkenylation or alkylation.

9. Ruthenium-Catalyzed C−N and C−O Bond-Forming Processes from C−H Bond Functionalization

   Suman Dana, M. Ramu Yadav, Akhila K. Sahoo

   Abstract

   This chapter highlights the robust, cost-effective Ru catalyst-mediated direct functionalization of C−H bonds. The development of Ru-catalyzed novel synthetic methods for the construction of C−N and C−O bonds through the activation of inert sp² and sp³ C−H bonds is enumerated. The effect of a directing group (DG) for the chemo- and regioselective introduction of heteroatoms in the molecule replacing the unactivated C−H bonds is discussed.

10. meta- and para-Selective C–H Functionalization by C–H Activation

    Jie Li, Suman De Sarkar, Lutz Ackermann

    Abstract

    Transition metal-catalyzed C–H bond functionalization has recently emerged as an indispensable tool for transforming otherwise unreactive C–H bonds. In addition to various strategies for ortho-selective functionalization via chelation assistance, organometallic C–H activation has recently enabled novel functionalizations of (hetero)arenes at remote meta- or para-positions. The meta- and para-selectivity was governed either by the inherent substrate structure or by the transition metal catalyst. Herein we summarize the rapid recent progress in meta- and para-selective aromatic C–H functionalization until May 2015.

11. Erratum to: Ruthenium(II)-Catalysed Functionalisation of C–H Bonds with Alkenes: Alkenylation versus Alkylation

    Christian Bruneau, Pierre H. Dixneuf

12. Backmatter