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C–H Activation

The possibility of direct introduction of a new functionality (or a new C–C bond) via direct C–H bond transformation is a highly attractive strategy in covalent synthesis. The range of substrates is virtually unlimited, including hydrocarbons, complex organic compounds of small molecular weight, and synthetic and biological polymers. Below is a list of recent articles on this topic. For a review, see

  1. Xiao Chen, Keary M. Engle, Dong-Hui Wang, Jin-Quan Yu*
    Palladium(II)-Catalyzed C–H Activation/C–C Cross-Coupling Reactions: Versatility and Practicality
    Angew. Chem. 2009, 121, 5196–5217; Angew. Chem. Int. Ed. 2009, 48, 5094–5115

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Recent Articles

Wen Ai , Xueyan Yang, Yunxiang Wu, Xuan Wang, Yuanchao Li, Yaxi Yang, Bing Zhou
Rhodium(III)- and Iridium(III)-Catalyzed C7 Alkylation of Indolines with Diazo Compounds [Full Paper]

Rhodium(III)- and Iridium(III)-Catalyzed C7 Alkylation of Indolines with Diazo Compounds

A RhIII-catalyzed procedure for the C7-selective C-H alkylation of indolines with α-diazo compounds at room temperature is reported. An IrIII-catalyzed intermolecular insertion of arene C-H bonds into α-diazo compounds has also been successfully developed (see scheme; EWG=electron-withdrawing group).

Chem. Eur. J., October 30, 2014, DOI: 10.1002/chem.201405077

Photochemical Reactions of [(η5-C5R5)Re(CO)3] (R = Me or H) with Aryl Halides in Benzene: Stoichiometric Formation of Biphenyl

Photolysis of [Cp*Re(CO)3] with bromo- or chlorobenzene in benzene results in the formation of biphenyl and the corresponding rhenium hydride halide complex trans-[Cp*Re(CO)2H(X)]. Isotopic labeling experiments indicate that one phenyl ring in the resulting biphenyl comes from the aryl halide and the other one from the solvent benzene. Plausible mechanisms are proposed that involve intermolecular C–X and C–H activation.

Eur. J. Inorg. Chem., October 30, 2014, DOI: 10.1002/ejic.201402793

Jitan Zhang, Hongsheng Qian, Zhanxiang Liu, Chunhua Xiong, Yuhong Zhang
Rhodium(III)-Catalyzed One-Pot Access to Isoquinolines and Heterocycle-Fused Pyridines in Aqueous Medium through C–H Cleavage [Full Paper]

Rhodium(III)-Catalyzed One-Pot Access to Isoquinolines and Heterocycle-Fused Pyridines in Aqueous Medium through C–H Cleavage

An efficient RhIII-catalyzed ortho-C–H bond activation for the synthesis of substituted isoquinolines and heterocycle-fused pyridines in aqueous medium has been developed. This method involves the in situ generation of ketimines from ketones and ammonium acetate and subsequent oxidative C–H bond activation/annulation of the ketimines with alkynes to form the C–C/C–N bonds spontaneously.

Eur. J. Org. Chem., October 30, 2014, DOI: 10.1002/ejoc.201403085

Ruthenium-Catalyzed Alkenylation of Arenes with Alkynes or Alkenes by 1,2,3-Triazole-Directed C–H Activation

The ruthenium-catalyzed alkenylation of arenes with unsaturated alkanes has been achieved by triazole-directed C–H activation. Dialkenylated arenes were efficiently produced by this method from internal alkynes as the sole products with high regio- and stereoselectivity.

Eur. J. Org. Chem., October 29, 2014, DOI: 10.1002/ejoc.201402938

Tuning CuII Coordination Polymers Derived from a Bis(pyrazolecarboxylate) Ligand by Solvothermal C–H Bond Activation: Synthesis, Structures, Catalysis, and Magnetic Properties

A new bis(pyrazolecarboxylate) ligand undergoes C–H bond activation in the presence of Cu(ClO4)2 under mild basic conditions. The resulting coordination polymers exhibit interesting structural features with promising catalytic and magnetic properties.

Eur. J. Inorg. Chem., October 28, 2014, DOI: 10.1002/ejic.201402642

Shin Miyamura, Misaho Araki, Takayoshi Suzuki, Junichiro Yamaguchi, Kenichiro Itami
Stereodivergent Synthesis of Arylcyclopropylamines by Sequential C-H Borylation and Suzuki–Miyaura Coupling [Communication]

Stereodivergent Synthesis of Arylcyclopropylamines by Sequential C-H Borylation and Suzuki–Miyaura Coupling

All about atmosphere: A step-economical synthesis of 2-arylcyclopropylamines through the title sequence has been developed. The iridium-catalyzed C-H borylation proceeds with cis selectivity, and the subsequent Suzuki–Miyaura coupling proceeds with retention of configuration at the carbon center bearing the Bpin group, and epimerization at the nitrogen-bound carbon atoms. Either isomer (cis or trans) can be accessed by simply changing the atmosphere (N2 or O2).

Angew. Chem. Int. Ed., October 27, 2014, DOI: 10.1002/anie.201409186

Malek Nechab, Shovan Mondal, Michèle P. Bertrand
1,n-Hydrogen-Atom Transfer (HAT) Reactions in Which n≠5: An Updated Inventory [Review]

1,n-Hydrogen-Atom Transfer (HAT) Reactions in Which n≠5: An Updated Inventory

Intramolecular HAT scope: The investigation of the less commonly encountered 1,n-hydrogen-atom transfer (HAT) reactions in which n≠5 has led to high yielding original synthetic applications. The aim of this review is to make a critical updated inventory, highlighting the most elegant cascade reactions based on a 1,n-HAT elementary step (from A to B) in which n=4, 6, 7, 8, 9, and so forth.

Chem. Eur. J., October 24, 2014, DOI: 10.1002/chem.201403951

Construction of Axial Chirality by Rhodium-Catalyzed Asymmetric Dehydrogenative Heck Coupling of Biaryl Compounds with Alkenes

An axe to grind? Novel axially chiral biaryls were synthesized by the direct C-H bond olefination of biaryl compounds, using a chiral [Cp*RhIII] catalyst (1), in good to excellent yields and enantioselectivities. The biaryls were found as suitable ligands for rhodium-catalyzed asymmetric conjugate addition reactions.

Angew. Chem. Int. Ed., October 24, 2014, DOI: 10.1002/anie.201408805

Amide-Functionalized Naphthyridines on a RhII–RhII Platform: Effect of Steric Crowding, Hemilability, and Hydrogen-Bonding Interactions on the Structural Diversity and Catalytic Activity of Dirhodium(II) Complexes

The introduction of structural diversity into RhII–RhII complexes is achieved with amide-functionalized 1,8-naphthyridine ligands modulated by steric crowding, bridging carboxylate groups that are labile, and hydrogen-bonding interactions between the amide hydrogen and carboxylate oxygen atoms. The amide functionality shows hemilabile behavior at the axial sites, thus making the dirhodium complex effective for the catalytic C-H functionalization of indoles with appropriate diazo compounds (see scheme).

Chem. Eur. J., October 21, 2014, DOI: 10.1002/chem.201402936

Xin Wang, Kai Sun, Yunhe Lv, Fengji Ma, Gang Li, Donghui Li, Zhonghong Zhu, Yongqing Jiang, Feng Zhao
Regioselective C-H Imidation of Five-Membered Heterocyclic Compounds through a Metal Catalytic or Organocatalytic Approach [Communication]

Regioselective C-H Imidation of Five-Membered Heterocyclic Compounds through a Metal Catalytic or Organocatalytic Approach

Give me five: A regioselective C-H imidation of five-membered heterocyclic pyrrole, furan, and thiophene derivatives was realized. Through a metal catalytic or organocatalytic approach, a series of 2-amino- and β-amino-substituted heterocyclic compounds was obtained under atmospheric conditions.

Chem. Asian J., October 21, 2014, DOI: 10.1002/asia.201403052

Ke Yang, Peng Wang, Cheng Zhang, Adnan A. Kadi, Hoong-Kun Fun, Yan Zhang, Hongjian Lu
Nickel-Catalyzed Decarboxylative Arylation of Heteroarenes through sp2 C–H Functionalization [Short Communication]

Nickel-Catalyzed Decarboxylative Arylation of Heteroarenes through sp2 C–H Functionalization

The nickel-catalyzed direct decarboxylative arylation of hetereoarenes with benzoic acids through an sp2 C–H functionalization process is reported. This transformation provides the first examples of decarboxylative cross-coupling reactions with aromatic acids through nickel catalysis. IPr = 1,3-Bis(2,6-diisopropylphenyl)-imidazol-2-ylidene, BQ = 1,4-benzoquinone.

Eur. J. Org. Chem., October 21, 2014, DOI: 10.1002/ejoc.201403234

Lu Li, Xiaoyue Mu, Wenbo Liu, Xianghua Kong, Shizhao Fan, Zetian Mi, Chao-Jun Li
Thermal Non-Oxidative Aromatization of Light Alkanes Catalyzed by Gallium Nitride [Communication]

Thermal Non-Oxidative Aromatization of Light Alkanes Catalyzed by Gallium Nitride

Light weights: The readily available nondoped GaN material possesses superior thermal stability and catalytic activity towards the non-oxidative aromatization of light alkanes (from C1 to C6) at elevated temperature. Theoretical calculations propose an energetically favorable adsorption interaction between methane and the m-plane of GaN.

Angew. Chem. Int. Ed., October 21, 2014, DOI: 10.1002/anie.201408754

Wanrong Dong, Kanniyappan Parthasarathy, Ying Cheng, Fangfang Pan, Carsten Bolm
Hydroarylations of Heterobicyclic Alkenes through Rhodium-Catalyzed Directed C-H Functionalizations of S-Aryl Sulfoximines [Communication]

Hydroarylations of Heterobicyclic Alkenes through Rhodium-Catalyzed Directed C-H Functionalizations of S-Aryl Sulfoximines

Rhodium-catalyzed hydroarylations of heterobicyclic alkenes with NH-sulfoximines lead to products that can then be converted to aryl-fused thiazines. The initial process involves a C-H-functionalization directed by the sulfoximidoyl group. Aryl addition to the alkene is then followed by dehydration and palladium-catalyzed oxidative C-N coupling (see scheme).

Chem. Eur. J., October 19, 2014, DOI: 10.1002/chem.201404859

Highly Linear Selective Cobalt-Catalyzed Addition of Aryl Imines to Styrenes: Reversing Intrinsic Regioselectivity by Ligand Elaboration

Paired off: The title reaction has been achieved with cobalt-based catalytic systems featuring bis(2,4-dimethoxyphenyl)(phenyl)phosphine (L) and either 2-methoxypyridine or DBU (LB), thus affording a variety of 1,2-diarylethanes in good yields. Ligand screening and deuterium-labeling studies show the ligand and Lewis base to be important in the crucial C-C reductive elimination step. Cy=cyclohexyl, PMP=para-methoxyphenyl.

Angew. Chem. Int. Ed., October 19, 2014, DOI: 10.1002/anie.201408028

Zaini Jamal, Yong-Chua Teo, Ling-Keong Wong
Functionalization of the Benzylic C–H Bonds in Azaarenes by Cobalt-Catalyzed 1,4-Addition to Enones [Short Communication]

Functionalization of the Benzylic C–H Bonds in Azaarenes by Cobalt-Catalyzed 1,4-Addition to Enones

Functionalization of the C(sp3)–H bonds in azaarenes catalyzed by CoCl2 as an inexpensive Lewis acid catalyst is reported. Enones are demonstrated to be good C=C electrophilic acceptors for the construction of various azaarene-containing 1,4-addition products in yields up to 95 %.

Eur. J. Org. Chem., October 15, 2014, DOI: 10.1002/ejoc.201403203

Chinmoy Kumar Hazra, Quentin Dherbassy, Joanna Wencel-Delord, Françoise Colobert
Synthesis of Axially Chiral Biaryls through Sulfoxide-Directed Asymmetric Mild C-H Activation and Dynamic Kinetic Resolution [Communication]

Synthesis of Axially Chiral Biaryls through Sulfoxide-Directed Asymmetric Mild C-H Activation and Dynamic Kinetic Resolution

Pd makes it rotate: A C-H activation/dynamic kinetic resolution protocol is developed to access axially chiral biaryls. The isomerization step is believed to occur via a palladacyclic intermediate. Chiral induction is achieved using the sulfoxide motif as both “traceless” directing group and chiral source.

Angew. Chem. Int. Ed., October 10, 2014, DOI: 10.1002/anie.201407865

Iridium Complexes Containing Mesoionic C Donors: Selective C(sp3)-H versus C(sp2)-H Bond Activation, Reactivity Towards Acids and Bases, and Catalytic Oxidation of Silanes and Water

Selective C(sp2)-H activation of pyridylimidazolium or pyridyltriazolium salts affords isostructural iridium(III) complexes containing a mesoionic C-donor ligand. Despite the similar mesoionic character, the behavior of the ligands (e.g., in H/D isotope-exchange reactions) and of the complexes (in oxidation catalysis) is distinctly different (see scheme).

Chem. Eur. J., October 10, 2014, DOI: 10.1002/chem.201404776

Tobias Gylling Frihed, Christian Marcus Pedersen, Mikael Bols
Synthesis of All Eight L-Glycopyranosyl Donors Using C-H Activation [Communication]

Synthesis of All Eight L-Glycopyranosyl Donors Using C-H Activation

A one-pot four-step procedure was developed for the synthesis of all eight L-glycopyranosyl donors from the corresponding 6-deoxy thioglycosides. Ir-catalyzed silylation (a) and C-H activation (b), followed by a Fleming–Tamao oxidation (c) and acetylation (d) led to highly functionalized thioglycosides.

Angew. Chem. Int. Ed., October 10, 2014, DOI: 10.1002/anie.201408209

Yu Xue, Zhoulong Fan, Xiaolong Jiang, Kui Wu, Meining Wang, Chunyong Ding, Qizheng Yao, Ao Zhang
RhIII-Catalysed Hydrazine-Directed C(sp2)–H Amination of Phenidones with N-Alkyl-O-benzoyl-hydroxylamines [Full Paper]

RhIII-Catalysed Hydrazine-Directed C(sp2)–H Amination of Phenidones with N-Alkyl-O-benzoyl-hydroxylamines

A RhIII-catalysed ortho C–H amination of phenidones under mild conditions at room temperature was developed using N-alkyl-O-benzoyl-hydroxylamines as aminating agents, and with a cyclic hydrazine moiety as a directing group, yields of up to 97 % and a high functional group tolerance were observed.

Eur. J. Org. Chem., October 9, 2014, DOI: 10.1002/ejoc.201402999

Kevin Rousée, Cédric Schneider, Samuel Couve-Bonnaire, Xavier Pannecoucke, Vincent Levacher, Christophe Hoarau
Pd- and Cu-Catalyzed Stereo- and Regiocontrolled Decarboxylative/C-H Fluoroalkenylation of Heteroarenes [Communication]

Pd- and Cu-Catalyzed Stereo- and Regiocontrolled Decarboxylative/C-H Fluoroalkenylation of Heteroarenes

Two metals are better than one: Pd/Cu-catalyzed decarboxylative/direct C-H alkenylation of heteroarenes with α-fluoroacrylic acids is reported. This method offers step-economical and stereocontrolled access to valuable heteroarylated monofluoroalkenes as both Z and E isomers,.

Chem. Eur. J., October 9, 2014, DOI: 10.1002/chem.201405119

Xiaojin Wu, Jessica Wei Ting See, Kai Xu, Hajime Hirao, Julien Roger, Jean-Cyrille Hierso, Jianrong (Steve) Zhou
A General Palladium-Catalyzed Method for Alkylation of Heteroarenes Using Secondary and Tertiary Alkyl Halides [Communication]

A General Palladium-Catalyzed Method for Alkylation of Heteroarenes Using Secondary and Tertiary Alkyl Halides

A radical way: The title reaction has been realized for many unactivated alkyl halides and a variety of heteroarenes (see picture; red dots denote the point of alkylation with secondary and tertiary alkyl halides). Preliminary mechanistic studies indicate that the palladium catalyst initiates an alkyl radical addition to heterocycles.

Angew. Chem. Int. Ed., October 6, 2014, DOI: 10.1002/anie.201408355

János Daru, Zsuzsanna Benda, Adám Póti, Zoltán Novák, András Stirling
Mechanistic Study of Silver-Mediated Furan Formation by Oxidative Coupling [Full Paper]

Mechanistic Study of Silver-Mediated Furan Formation by Oxidative Coupling

Radical or ionic mechanism? Both. The detailed mechanism of a silver-mediated furan formation by oxidative C-H/C-H activation has been revealed by DFT calculations and additional experiments. The reaction path starts with a radical C-C coupling process. Then, an aromatic cyclization occurs featuring an ionic mechanism, which completes the furan formation. Silver plays crucial roles in the reaction: it is an oxidant and a catalyst simultaneously.

Chem. Eur. J., October 5, 2014, DOI: 10.1002/chem.201404302

Pietro Cotugno, Antonio Monopoli, Francesco Ciminale, Antonella Milella, Angelo Nacci
Palladium-Catalyzed Cross-Coupling of Styrenes with Aryl Methyl Ketones in Ionic Liquids: Direct Access to Cyclopropanes [Communication]

Palladium-Catalyzed Cross-Coupling of Styrenes with Aryl Methyl Ketones in Ionic Liquids: Direct Access to Cyclopropanes

Double activation: The combined use of Pd(OAc)2, Cu(OAc)2, and dioxygen in molten tetrabutylammonium acetate (TBAA) promotes an unusual cyclopropanation reaction between aryl methyl ketones and styrenes. The process is a dehydrogenative cyclizing coupling that involves a twofold C-H activation at the α-position of the ketone.

Angew. Chem. Int. Ed., October 5, 2014, DOI: 10.1002/anie.201408245

Ruthenium(II)-Catalyzed Oxidative C-H Alkenylations of Sulfonic Acids, Sulfonyl Chlorides and Sulfonamides

Versatile oxidative alkenylations of sulfonic acids, sulfonyl chlorides or sulfonamides were achieved by a robust ruthenium(II) catalyst with excellent substrate scope. Mechanistic studies suggested a reversible, acetate-assisted C-H ruthenation, along with a subsequent olefin insertion.

Chem. Eur. J., October 3, 2014, DOI: 10.1002/chem.201404604

Hang Zhang, Kang Wang, Bo Wang, Heng Yi, Fangdong Hu, Changkun Li, Yan Zhang, Jianbo Wang
Rhodium(III)-Catalyzed Transannulation of Cyclopropenes with N-Phenoxyacetamides through C-H Activation [Communication]

Rhodium(III)-Catalyzed Transannulation of Cyclopropenes with N-Phenoxyacetamides through C-H Activation

The three C's: An efficient rhodium(III)-catalyzed synthesis of 2H-chromenes from N-phenoxyacetamides and cyclopropenes has been developed. The reaction represents the first example of using cyclopropenes as a three-carbon unit in rhodium(III)-catalyzed C(sp2)-H activations. Preliminary mechanistic investigations are discussed.

Angew. Chem. Int. Ed., September 29, 2014, DOI: 10.1002/anie.201408555

Demyan E. Prokopchuk, Brian T. H. Tsui, Alan J. Lough, Robert H. Morris
Intramolecular C-H/O-H Bond Cleavage with Water and Alcohol Using a Phosphine-Free Ruthenium Carbene NCN Pincer Complex [Full Paper]

Intramolecular C-H/O-H Bond Cleavage with Water and Alcohol Using a Phosphine-Free Ruthenium Carbene NCN Pincer Complex

Proton pincer ping-pong: New phosphine-free Ru–NCN pincer complexes have been synthesized. The complexes’ dearomatized alkoxide/hydroxide analogues undergo unprecedented regioselective, intramolecular C-H/O-H bond activation with tert-butanol or water at 25 °C, as shown by NMR spectroscopy and DFT calculations.

Chem. Eur. J., September 29, 2014, DOI: 10.1002/chem.201404819

Copper-Catalyzed Asymmetric Addition to Isatins to give 3-Hydroxy-2-oxindoles by C–H Activation

A copper-catalyzed asymmetric addition to isatins to give 3-hydroxy-2-oxindoles by C–H activation with a fluorous bis(oxazoline) as ligand is presented. The fluorous ligand can be easily recovered and reused at least three times without significant loss in its activity.

Eur. J. Org. Chem., September 29, 2014, DOI: 10.1002/ejoc.201402852

First Principles (DFT) Characterization of RhI/dppp-Catalyzed C-H Activation by Tandem 1,2-Addition/1,4-Rh Shift Reactions of Norbornene to Phenylboronic Acid

Calculated barriers to C-H activation: The key 1,4-Rh shift step in the multiple, “merry-go-round” addition of norbornene to phenylboronic acid is shown to proceed by C-H oxidation addition (OA)/C-H reductive elimination (RE) to/from RhIII-hydride by DFT calculations (PCM/PBE0/DGDZVP level of theory). The calculated barriers are in excellent agreement with the experimental selectivity.

Chem. Eur. J., September 26, 2014, DOI: 10.1002/chem.201402988

Moritz Schubert, Simon Trosien, Lara Schulz, Carolin Brandscheid, Dieter Schollmeyer, Siegfried R. Waldvogel
Oxidative (Cross-)Coupling Reactions Mediated by C–H Activation of Thiophene Derivatives by Using Molybdenum(V) Reagents [Short Communication]

Oxidative (Cross-)Coupling Reactions Mediated by C–H Activation of Thiophene Derivatives by Using Molybdenum(V) Reagents

The unique performance of MoCl5 gives rise to a variety of complex structures involving the thiophene motif. The oxidative coupling is performed in the 2,3-positions of the thiophene moiety. In this approach, the first cross-coupling reactions by using MoCl5 are established.

Eur. J. Org. Chem., September 26, 2014, DOI: 10.1002/ejoc.201403188

Dmitry Katayev, Evgeny Larionov, Masafumi Nakanishi, Céline Besnard, E. Peter Kündig
Palladium–N-Heterocyclic Carbene (NHC)-Catalyzed Asymmetric Synthesis of Indolines through Regiodivergent C(sp3)-H Activation: Scope and DFT Study [Full Paper]

Palladium–N-Heterocyclic Carbene (NHC)-Catalyzed Asymmetric Synthesis of Indolines through Regiodivergent C(sp3)-H Activation: Scope and DFT Study

Overcoming inactivity: Bulky, chiral, monodentate N-heterocyclic carbene (NHC) ligands were successfully applied to the palladium-catalyzed, highly enantioselective CAr-Calkyl coupling of an unactivated C(sp3)-H bond (see scheme). Readily synthesized carbamates, containing a stereogenic center, were investigated and afforded different trans-2,3-substituted indolines. Furthermore, a DFT study was carried out to rationalize experimentally observed regio- and enantioselectivities.

Chem. Eur. J., September 26, 2014, DOI: 10.1002/chem.201403985

Yasutomo Segawa, Takehisa Maekawa, Kenichiro Itami
Synthesis of Extended π-Systems through C–H Activation [Review]

Synthesis of Extended π-Systems through C–H Activation

By no means π in the sky! The activation of aromatic C-H bonds by a transition metal catalyst has received significant attention in the synthetic chemistry community. In recent years, rapid and site-selective extension of π-electron systems by C–H activation has emerged as an ideal methodology for preparing conjugated organic materials. This Review focuses on recently developments in this area directed toward new optoelectronic materials.

Angew. Chem. Int. Ed., September 26, 2014, DOI: 10.1002/anie.201403729

Catalytic Asymmetric Functionalization of Aromatic C-H Bonds by Electrophilic Trapping of Metal-Carbene-Induced Zwitterionic Intermediates

Caught in a trap: The title reaction of N,N-disubstituted anilines with diazo compounds and imines is reported for the efficient construction of α,α-diaryl benzylic quaternary stereocenters in good yields with high diastereoselectivities and excellent enantioselectivities. Efficient electrophilic trapping of the metal-carbene-induced zwitterionic intermediate is crucial for the enantiocontrol under RhII/chiral phosphoric acid (PPA) co-catalysis.

Angew. Chem. Int. Ed., September 4, 2014, DOI: 10.1002/anie.201406492

Katharina Neufeld, Birgit Henßen, Jörg Pietruszka
Enantioselective Allylic Hydroxylation of ω-Alkenoic Acids and Esters by P450 BM3 Monooxygenase [Communication]

Enantioselective Allylic Hydroxylation of ω-Alkenoic Acids and Esters by P450 BM3 Monooxygenase

Modern biocatalysts on the rise: The P450 BM3 monooxygenase mutant A74G/L188Q catalyzes the enantioselective allylic hydroxylation of ω-alkenoic acids and esters under mild conditions using O2 as an oxidant. This reaction offers access to important chiral building blocks for the synthesis of biologically active compounds and demonstrates the highest chemo- and enantioselectivity observed to date for the C-H oxidation of acyclic terminal olefins.

Angew. Chem. Int. Ed., August 27, 2014, DOI: 10.1002/anie.201403537

On the Mechanism of the Palladium Bis(NHC) Complex Catalyzed CH Functionalization of Propane: Experiment and DFT Calculations

No propane, no gain: The mechanism for the functionalization of propane with palladium(NHC) catalysts was investigated in detail. The combined experimental and computational (DFT) results favor a mechanism with CH activation by palladium(II) and oxidation by bromine to palladium(IV). It is proposed that the oxidation of palladium(II) to palladium(IV) alkyl species proceeds faster for iso-alkyl than for n-alkyl complexes.

Chem. Eur. J. 2014, 20, No. 45, 14872-14879

Chiral Counteranion Strategy for Asymmetric Oxidative C(sp3)-H/C(sp3)-H Coupling: Enantioselective α-Allylation of Aldehydes with Terminal Alkenes

Go with the combo: The title reaction is realized by combining asymmetric counteranion catalysis and palladium-catalyzed allylic C-H activation. This method tolerates a wide scope of α-branched aromatic aldehydes and terminal alkenes, thus affording allylation products in high yields and with good to excellent levels of enantioselectivity.

Angew. Chem. Int. Ed. 2014, 53, No. 45, 12218-12221

Quentin Michaudel, Guillaume Journot, Alicia Regueiro-Ren, Animesh Goswami, Zhiwei Guo, Thomas P. Tully, Lufeng Zou, Raghunath O. Ramabhadran, Kendall N. Houk, Phil S. Baran
Improving Physical Properties via C-H Oxidation: Chemical and Enzymatic Approaches [Communication]

Improving Physical Properties via C-H Oxidation: Chemical and Enzymatic Approaches

A handle on [O]: A variety of C-H oxidation methods were explored on the betulin skeleton to improve the solubility of this bioactive, yet poorly water-soluble, natural product. The innate reactivity of the molecule, as well as the molecular handles present on the core, allowed oxidations at different positions. Solubility enhancement was observed for many of the synthesized compounds.

Angew. Chem. Int. Ed. 2014, 53, No. 45, 12091-12096

William J. Kerr, Richard J. Mudd, Laura C. Paterson, Jack A. Brown
Iridium(I)-Catalyzed Regioselective C-H Activation and Hydrogen-Isotope Exchange of Non-aromatic Unsaturated Functionality [Communication]

Iridium(I)-Catalyzed Regioselective C-H Activation and Hydrogen-Isotope Exchange of Non-aromatic Unsaturated Functionality

Selective iridium: The first β-selective Ir-catalyzed C-H activation and hydrogen-isotope-exchange process by using active IrI catalyst was established. Under practically accessible reaction conditions and by employing low levels of catalyst loading, very good levels of deuterium incorporation have been obtained with appreciable selectivity over the potentially competing reduction process across a series of α,β-unsaturated substrates (see scheme).

Chem. Eur. J. 2014, 20, No. 45, 14604-14607

Polymer- and Silica-Supported Iron BPMEN-Inspired Catalysts for C-H Bond Functionalization Reactions

Minor adjustments: Two approaches are presented to functionalize the popular N1,N2-dimethyl-N1,N2-bis(pyridin-2-ylmethyl)ethane-1,2-diamine (BPMEN) ligand, so that it can be supported on porous silica or polymer resin supports. Iron that complexes with this ligand can be used in an array of catalytic C-H functionalization reactions (see picture).

Chem. Asian J. 2014, 9, No. 11, 3142-3152

Laura Rubio-Pérez, Manuel Iglesias, Ricardo Castarlenas, Victor Polo, Jesús J. Pérez-Torrente, Luis A. Oro
Selective C-H Bond Functionalization of 2-(2-Thienyl)pyridine by a Rhodium N-Heterocyclic Carbene Catalyst [Full Paper]

Selective C-H Bond Functionalization of 2-(2-Thienyl)pyridine by a Rhodium N-Heterocyclic Carbene Catalyst

For your C-H bond only: [Rh(μ-Cl)(H)2(IPr)]2 (IPr=1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) catalyzes the selective functionalization of 2-(2-thienyl)pyridine efficiently with a range of alkenes and internal alkynes. A catalytic cycle is proposed on the basis of the identification of key reaction intermediates and the study of their reactivity by NMR spectroscopy.

ChemCatChem 2014, 6, No. 11, 3192-3199

Peng Yu, Jin-Shun Lin, Lei Li, Sheng-Cai Zheng, Ya-Ping Xiong, Li-Jiao Zhao, Bin Tan, Xin-Yuan Liu
Enantioselective C-H Bond Functionalization Triggered by Radical Trifluoromethylation of Unactivated Alkene [Communication]

Enantioselective C-H Bond Functionalization Triggered by Radical Trifluoromethylation of Unactivated Alkene

En route: The title redox-neutral reaction provides a convenient route to valuable enantioenriched trifluoromethylated N,O-aminals in good to excellent yields and with excellent regio-, chemo-, and enantioselectivity. The reaction features a CuI/Brønsted acid system and broad substrate scope.

Angew. Chem. Int. Ed. 2014, 53, No. 44, 11890-11894

Upendra Sharma, Rajesh Kancherla, Togati Naveen, Soumitra Agasti, Debabrata Maiti
Palladium-Catalyzed Annulation of Diarylamines with Olefins through C-H Activation: Direct Access to N-Arylindoles [Communication]

Palladium-Catalyzed Annulation of Diarylamines with Olefins through C-H Activation: Direct Access to N-Arylindoles

No group help needed: A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins and obviates the need for any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of an olefinated intermediate.

Angew. Chem. Int. Ed. 2014, 53, No. 44, 11895-11899

Alexander G. O'Brien, Akinobu Maruyama, Yasuhide Inokuma, Makoto Fujita, Phil S. Baran, Donna G. Blackmond
Radical C-H Functionalization of Heteroarenes under Electrochemical Control [Communication]

Radical C-H Functionalization of Heteroarenes under Electrochemical Control

Electrochemical reactions are shown to be effective for the C-H functionalization of a number of heterocyclic substrates that are recalcitrant to conventional peroxide radical initiation conditions and of interest in medicinal chemistry. Monitoring reaction progress under electrochemical conditions provides mechanistic insight into the C-H functionalization process.

Angew. Chem. Int. Ed. 2014, 53, No. 44, 11868-11871

Chunxiang Wang, Dongping Wang, Hao Yan, Haolong Wang, Bin Pan, Xiaoyi Xin, Xincheng Li, Fan Wu, Boshun Wan
Rhodium-Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight-Membered Heterocycles [Communication]

Rhodium-Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight-Membered Heterocycles

Five-atom building unit: N-aryl-substituted nitrones were employed as five-atom coupling partners in the rhodium-catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C-H activation of the N-aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight-membered heterocycles with broad substrate scope.

Angew. Chem. Int. Ed. 2014, 53, No. 44, 11940-11943

Sulfonamide-Promoted Palladium(II)-Catalyzed Alkylation of Unactivated Methylene C(sp3)-H Bonds with Alkyl Iodides

Branching off: The title reaction of unactivated β-methylene C(sp3)-H bonds of α-amino acid substrates with alkyl iodides is described. The C(alkyl)–C(alkyl) bond-forming reaction proceeds in good yields, and β-branched amino acids can be obtained by using sequential reactions.

Angew. Chem. Int. Ed. 2014, 53, No. 44, 11950-11954

Jianbin Chen, Kishore Natte, Anke Spannenberg, Helfried Neumann, Matthias Beller, Xiao-Feng Wu
Palladium-Catalyzed Carbonylative [3+2+1] Annulation of N-Aryl-Pyridine-2-Amines with Internal Alkynes by C-H Activation: Facile Synthesis of 2-Quinolinones [Communication]

Palladium-Catalyzed Carbonylative [3+2+1] Annulation of N-Aryl-Pyridine-2-Amines with Internal Alkynes by C-H Activation: Facile Synthesis of 2-Quinolinones

Carbonylative C-H activation: A procedure for the synthesis of highly substituted 2-quinolinones has been developed. By this newly developed approach, 2-quinolinone derivatives were prepared in moderate to good yields by carbonylative [3+2+1] annulation of N-aryl-pyridine-2-amines and internal alkynes by C-H activation (see scheme).

Chem. Eur. J. 2014, 20, No. 44, 14189-14193

Ruthenium(II)-Catalyzed C-H Activation with Isocyanates: A Versatile Route to Phthalimides

A convenient route to phthalimide: A convergent method for the ruthenium(II)-catalyzed imidation of easily accessible benzamides by C-H functionalization was developed (see scheme). The methodology was successfully applied to the preparation of synthetically challenging unsymmetrical heteroaromatic diamides and proved amenable to a step-economic synthesis of a potent COX-2 enzyme inhibitor.

Chem. Eur. J. 2014, 20, No. 43, 13932-13936

Yoshihiro Oonishi, Adrián Gómez-Suárez, Anthony R. Martin, Yusuke Makida, Alexandra M. Z. Slawin, Steven P. Nolan
[Au]/[Pd] Multicatalytic Processes: Direct One-Pot Access to Benzo[c]chromenes and Benzo[b]furans [Communication]

[Au]/[Pd] Multicatalytic Processes: Direct One-Pot Access to Benzo[c]chromenes and Benzo[b]furans

Very neat reactions! A new strategy for the synthesis of benzo[c]chromenes and benzo[b]furans from commercially available starting materials is reported. This two-step, one-pot strategy consists in a gold-catalyzed hydrophenoxylation reaction followed by Pd-catalyzed C-H activation or Mizoroki–Heck reactions.

Chem. Eur. J. 2014, 20, No. 42, 13507-13510

Palladium(0)-Catalyzed Heck Reaction/C-H Activation/Amination Sequence with Diaziridinone: A Facile Approach to Indolines

Good form: Indolines are important moieties present in various biologically significant molecules. Described is the title sequence for forming indolines with di-tert-butyldiaziridinone. The reaction process likely proceeds via a pallada(II)cycle, which is converted into an indoline by oxidative addition to the diaziridinone and two subsequent C-N bond formations.

Angew. Chem. Int. Ed. 2014, 53, No. 42, 11280-11284

Fanzhi Yang, Karsten Rauch, Katharina Kettelhoit, Lutz Ackermann
Aldehyde-Assisted Ruthenium(II)-Catalyzed C-H Oxygenations [Communication]

Aldehyde-Assisted Ruthenium(II)-Catalyzed C-H Oxygenations

The weakest link: Challenging aryl C-H oxygenations with very weakly coordinating aldehydes proceed chemoselectively in the presence of versatile ruthenium(II) catalysts under mild reaction conditions. This transformation features an ample substrate scope and excellent positional selectivity.

Angew. Chem. Int. Ed. 2014, 53, No. 42, 11285-11288

Jianbin Chen, Lin He, Kishore Natte, Helfried Neumann, Matthias Beller, Xiao-Feng Wu
Palladium@Cerium(IV) Oxide-Catalyzed Oxidative Synthesis of N-(2-Pyridyl)indoles via C-H Activation Reaction [Communication]

Matthijs Ruitenbeek, Bert M. Weckhuysen
A Radical Twist to the Versatile Behavior of Iron in Selective Methane Activation [Highlight]

A Radical Twist to the Versatile Behavior of Iron in Selective Methane Activation

Things go better without coke! The selective activation of methane and its direct conversion into light olefins and aromatic compounds remains a formidable challenge. Recent work shows that a catalyst material consisting of lattice-confined single iron atoms is very active and selective in the direct, nonoxidative conversion of methane into ethylene, benzene, and naphthalene without the formation of coke deposits.

Angew. Chem. Int. Ed. 2014, 53, No. 42, 11137-11139

Anna M. Rydzik, Ivanhoe K. H. Leung, Grazyna T. Kochan, Michael A. McDonough, Timothy D. W. Claridge, Christopher J. Schofield
Oxygenase-Catalyzed Desymmetrization of N,N-Dialkyl-piperidine-4-carboxylic Acids [Communication]

Oxygenase-Catalyzed Desymmetrization of N,N-Dialkyl-piperidine-4-carboxylic Acids

Thinking outside the BBOX: γ-Butyrobetaine hydroxylase (BBOX) is a 2-oxoglutarate (2OG) dependent oxygenase that catalyzes the final hydroxylation step in the biosynthesis of carnitine. BBOX was shown to catalyze the oxidative desymmetrization of achiral N,N-dialkyl-piperidine-4-carboxylates to give products with two or three stereogenic centers.

Angew. Chem. Int. Ed. 2014, 53, No. 41, 10925-10927

Brendan M. Monks, Erin R. Fruchey, Silas P. Cook
Iron-Catalyzed C(sp2)-H Alkylation of Carboxamides with Primary Electrophiles [Communication]

Iron-Catalyzed C(sp2)-H Alkylation of Carboxamides with Primary Electrophiles

The direct ortho alkylation of 8-aminoquinoline-based aryl amides was achieved with primary alkyl bromides in high yields in the presence of an iron catalyst, 1,2-bis(diphenylphosphino)ethane (dppe), and PhMgBr in 2-MeTHF.

Angew. Chem. Int. Ed. 2014, 53, No. 41, 11065-11069

C(sp3)-H Activation without a Directing Group: Regioselective Synthesis of N-Ylide or N-Heterocyclic Carbene Complexes Controlled by the Choice of Metal and Ligand

Which C-H bond reacts? N-Ylide complexes of Ir were generated by α-C(sp3)-H activation with [Cp*IrCl2]2 and NaOAc. The reaction of an α-imidazolium ester is a rare example of a C-H activation where the site selectivity can be controlled by the choice of metal and ligand; DFT calculations revealed that the N-ylide complex is the kinetic product of an ambiphilic C-H activation, in which the acetate ligand plays the dominant role (see scheme; Cp*=pentamethylcyclopentadiene).

Chem. Eur. J. 2014, 20, No. 41, 13203-13209

Yingjun Zhu, Michaela Bauer, Jasper Ploog, Lutz Ackermann
Late-Stage Diversification of Peptides by Metal-Free C-H Arylation [Communication]

Late-Stage Diversification of Peptides by Metal-Free C-H Arylation

Metal-free direct arylations of engineered indole-3-acetamides set the stage for the late-stage diversifications of highly functionalized peptides under mild reaction conditions.

Chem. Eur. J. 2014, 20, No. 41, 13099-13102

Ryo Murakami, Kiyoshi Tsunoda, Tomohiro Iwai, Masaya Sawamura
Stereoselective C-H Borylations of Cyclopropanes and Cyclobutanes with Silica-Supported Monophosphane–Ir Catalysts [Communication]

Stereoselective C-H Borylations of Cyclopropanes and Cyclobutanes with Silica-Supported Monophosphane–Ir Catalysts

Heteroatom-directed C-H borylations of small-ring carbocycles, such as cyclopropanes and cyclobutanes, were achieved with silica-supported monophosphane–Ir catalysts (see scheme). Borylation occurred at the C-H bonds located γ to the directing N or O atoms with exceptional cis stereoselectivity relative to the directing groups (cod=1,5-cyclooctadiene, pin=pinacolato).

Chem. Eur. J. 2014, 20, No. 41, 13127-13131

Spiroacetal Formation through Telescoped Cycloaddition and Carbon–Hydrogen Bond Functionalization: Total Synthesis of Bistramide A

Actin' out: Spiroacetals can be prepared from aldehydes and functionalized dienes through a convergent, telescoped sequence of cycloaddition, oxidative C-H bond cleavage, and acid treatment. The functional-group tolerance and facile accessibility of the components render this procedure suitable for the synthesis of structurally complex natural products such as the actin-binding cytotoxin bistramide A.

Angew. Chem. Int. Ed. 2014, 53, No. 41, 11075-11078

Synthesis of Urchin-Like FeF2 Nanoarchitectures and Their Conversion into Three-Dimensional Urchin-Like Mesoporous α-Fe2O3 Nanoarchitectures for Methane Activation

Novel urchin-like FeF2 nanoarchitectures have been fabricated by an unconventional nonhomogeneous ionic liquid/diphenyl ether solvothermal method and converted into 3D urchin-like mesoporous α-Fe2O3 nanoarchitectures by solid-state thermal annealing. The α-Fe2O3 nanoarchitectures exhibit good catalytic properties in methane activation reactions.

Eur. J. Inorg. Chem. 2014, No. 28, 4779-4787

A Common Synthetic Protocol for the Cyclic and Acyclic Core of Migrastatin, Isomigrastatin, and Dorrigocin via a Chiral β-Hydroxy-γ-butyrolactone Intermediate

The synthesis of a key intermediate chiral β-hydroxy-γ-butyrolactone (A) by PdII-catalysed stereoselective allylic C–H oxidation is reported. A common synthetic route to transform this intermediate into key building blocks for the synthesis of migrastatin family members has been developed.

Eur. J. Org. Chem. 2014, No. 29, 6558-6564

Nikolay S. Sitnikov, Antonina S. Kokisheva, Georgy K. Fukin, Jörg-Martin Neudörfl, Hannah Sutorius, Aram Prokop, Valery V. Fokin, Hans-Günther Schmalz, Alexey Yu. Fedorov
Synthesis of Indole-Derived Allocolchicine Congeners through Pd-Catalyzed Intramolecular C-H Arylation Reaction [Full Paper]

Synthesis of Indole-Derived Allocolchicine Congeners through Pd-Catalyzed Intramolecular C-H Arylation Reaction

The synthesis of indole-derived structural analogs of natural antimitotic agent allocolchicine is reported. In a key step, an intramolecular Pd-catalyzed C–H arylation reaction serves to construct the polycyclic ring system, by connecting the two electron-rich arene fragments.

Eur. J. Org. Chem. 2014, No. 29, 6481-6492

Niles J. Gunsalus, Michael M. Konnick, Brian G. Hashiguchi, Roy A. Periana
Discrete Molecular Catalysts for Methane Functionalization [Review]

Woo-Jin Yoo, Arata Tanoue, Shū Kobayashi
Zinc(II) Hexachloroantimonate-Catalyzed Oxidative Allylation of Glycine Derivatives [Communication]

Zinc(II) Hexachloroantimonate-Catalyzed Oxidative Allylation of Glycine Derivatives

Proof-of-concept for the use of metal antimonates as bifunctional catalysts for oxidative coupling reactions is described. A well-defined zinc(II) antimonate salt enables the α-functionalization of glycine derivatives through a sequential aerobic oxidation-allylation reaction, in which the antimonate anion is responsible for the aerobic oxidation and the zinc cation acts as a Lewis acid for the allylation reaction. EWG=electron-withdrawing group; PMP=p-methoxyphenyl.

Asian J. Org. Chem. 2014, 3, No. 10, 1066-1069

Nicholas Phillips, Lucinda Treasure, Nicholas H. Rees, Rémi Tirfoin, John E. McGrady, Simon Aldridge
Rationalizing and Disrupting Fluxional Processes in Agostically Stabilized 14-Electron Alkyliridium Hydride Complexes [Full Paper]

Rationalizing and Disrupting Fluxional Processes in Agostically Stabilized 14-Electron Alkyliridium Hydride Complexes

By NMR spectroscopy and DFT methods, the mechanism of fluxional exchange in cationic bis(NHC) IrIII systems with an agostic C–H bond and cis-alkyl/hydride ligands is shown to feature an oxidative pathway. Related nonfluxional systems can be “trapped” by the addition of two-electron donors (L), and their stability to C–H reductive elimination can be tuned through the π-acceptor properties of L.

Eur. J. Inorg. Chem. 2014, No. 28, 4877-4885

Konstantin Junold, Johannes A. Baus, Christian Burschka, Maik Finze, Reinhold Tacke
Selective C–H Bond Activation of 1,2-Dicarba-closo-dodecaborane by the Donor-Stabilized Silylene Bis[N,N'-diisopropylbenzamidinato(–)]silicon(II) [Short Communication]

Selective C–H Bond Activation of 1,2-Dicarba-closo-dodecaborane by the Donor-Stabilized Silylene Bis[N,N'-diisopropylbenzamidinato(–)]silicon(II)

Reaction of donor-stabilized silylene 1 with 1,2-dicarba-closo-dodecaborane leads to the formation of neutral six-coordinate silicon(IV) complex 2 (selective C–H bond activation). Compound 2 reacts with acetonitrile to form neutral six-coordinate silicon(IV) complex 3 and 1,2-dicarba-closo-dodecaborane.

Eur. J. Inorg. Chem. 2014, No. 30, 5099-5102

C-H Functionalization/Asymmetric Michael Addition Cascade Enabled by Relay Catalysis: Metal Carbenoid Used for C-C Bond Formation

Square deal: A combination of either ruthenium(II) or rhodium(II) complexes and quinine-derived squaramide enables 3-diazooxindoles, indole, and nitroalkenes to undergo a highly efficient asymmetric three-component reaction. Based on this metal/organo relay catalysis, a total synthesis of (−)-folicanthine was accomplished in seven steps with 14.5 % overall yield.

Angew. Chem. Int. Ed. 2014, 53, No. 40, 10763-10767

Rhodium(III)-Catalyzed C-C and C-O Coupling of Quinoline N-Oxides with Alkynes: Combination of C-H Activation with O-Atom Transfer

A chance meeting: A rhodium(III)-catalyzed redox-neutral coupling of quinoline N-oxides with alkynes has been realized, thus leading to the synthesis of α-substituted acetophenones. This system integrates C-H activation with O-atom transfer.

Angew. Chem. Int. Ed. 2014, 53, No. 40, 10794-10798

Unexpected Cyclization of Tritylamines Promoted by Copper Salt through C-H and C-N Bond Cleavages to Produce Acridine Derivatives

Construction of 9-arylacridines was achieved through a new copper-mediated dehydrogenative cyclization of tritylamines involving two C-H and one C-N bond cleavages. Some of the obtained acridine derivatives exhibited intense fluorescence in the solid state (see scheme).

Chem. Eur. J. 2014, 20, No. 40, 12720-12724

Rhodium(III)-Catalyzed Intramolecular Redox-Neutral Annulation of Tethered Alkynes: Formal Total Synthesis of (±)-Goniomitine

C-H activation: A RhIII-catalyzed intramolecular redox-neutral atom-economic annulation of a tethered alkyne has been developed to efficiently construct 2-amidealkyl indoles with completely reversed regioselectivity by a C-H activation pathway (see scheme). A one-pot synthesis of pyrido[1,2-a]indoles has also been developed and applied to a highly efficient formal total synthesis of (±)-goniomitine.

Chem. Eur. J. 2014, 20, No. 40, 12768-12772

Rowan D. Young
Characterisation of Alkane σ-Complexes [Minireview]

Characterisation of Alkane σ-Complexes

The coordination of alkanes to metal centers is a complex matter! Advances in synthetic strategies to produce alkane σ-complexes, and ever more detailed analyses of such complexes, is leading to an understanding of how alkanes bind to specific metal centers. Such analysis is vital in understanding selectivity in C-H activation reactions.

Chem. Eur. J. 2014, 20, No. 40, 12704-12718

K. C. Nicolaou, Philipp Heretsch, Abdelatif ElMarrouni, Christopher R. H. Hale, Kiran K. Pulukuri, Avinash K. Kudva, Vivek Narayan, K. Sandeep Prabhu
Total Synthesis of Δ12-Prostaglandin J3, a Highly Potent and Selective Antileukemic Agent [Communication]

Total Synthesis of Δ12-Prostaglandin J3, a Highly Potent and Selective Antileukemic Agent

Leukemia ablator: The naturally occurring and highly potent and selective antileukemic agent Δ12-prostaglandin J312-PGJ3) has been assembled through a catalytic, asymmetric, and convergent strategy. The total synthesis renders this precious but rare substance readily available for thorough biological investigations and opens the way for analogue design, synthesis, and biological evaluation.

Angew. Chem. Int. Ed. 2014, 53, No. 39, 10443-10447

Michael M. Konnick, Brian G. Hashiguchi, Deepa Devarajan, Nicholas C. Boaz, T. Brent Gunnoe, John T. Groves, Niles Gunsalus, Daniel H. Ess, Roy A. Periana
Selective CH Functionalization of Methane, Ethane, and Propane by a Perfluoroarene Iodine(III) Complex [Communication]

Selective CH Functionalization of Methane, Ethane, and Propane by a Perfluoroarene Iodine(III) Complex

Gas up: Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate (TFA) esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic solvent (HTFA). The reaction is highly selective, and for ethane, greater than 0.5 M Et-TFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism.

Angew. Chem. Int. Ed. 2014, 53, No. 39, 10490-10494

Ming Shang, Shang-Zheng Sun, Hong-Li Wang, Brian N. Laforteza, Hui-Xiong Dai, Jin-Quan Yu
Exceedingly Fast Copper(II)-Promoted ortho C-H Trifluoromethylation of Arenes using TMSCF3 [Communication]

Exceedingly Fast Copper(II)-Promoted ortho C-H Trifluoromethylation of Arenes using TMSCF3

CF3 installation: The direct ortho-trifluoromethylation of arenes including heteroarenes with TMSCF3 has been accomplished by a copper(II)-promoted C-H activation reaction. Mechanistic investigations are consistent with the involvement of C-H activation rather than a simple electrophilic aromatic substitution as the key step. DG=directing group, TMS=trimethylsilyl.

Angew. Chem. Int. Ed. 2014, 53, No. 39, 10439-10442

Aniline Carbamates: A Versatile and Removable Motif for Palladium-Catalyzed Directed C-H Activation

G'day, (carba)mate! A new removable directing group for sp2 C-H activation, the aniline carbamate, is examined in detail. Its utility as a directing group is demonstrated by the ortho-arylation of aniline derivatives under PdII catalysis, with iodonium salts as aryl donors and oxidants. Excellent regio- and chemoselectivity were observed. The directing group can also be easily removed to yield 2-aminobiaryl products (see scheme).

Chem. Eur. J. 2014, 20, No. 38, 12066-12070

Combining Rhodium and Photoredox Catalysis for C-H Functionalizations of Arenes: Oxidative Heck Reactions with Visible Light

Much milder and environmentally friendly reaction conditions can be used for oxidative Heck reactions through the combined use of rhodium and redox catalysis. This allows the rhodium complex to be catalytically regenerated. A broad range of substrates was tolerated in the reaction and afforded different amides in good to very good yields.

Angew. Chem. Int. Ed. 2014, 53, No. 38, 10228-10231

Johannes Schranck, Anis Tlili, Matthias Beller
Functionalization of Remote C-H Bonds: Expanding the Frontier [Highlight]

Functionalization of Remote C-H Bonds: Expanding the Frontier

Novel tool set: New methodologies for the functionalization of remote C-H bonds have been developed recently. In diverse approaches high selectivities are achieved for the functionalization of less reactive C(sp2)-H as well as C(sp3)-H bonds distal to any substituents.

Angew. Chem. Int. Ed. 2014, 53, No. 36, 9426-9428

Grzegorz Filipczyk, Alexander Hildebrandt, Ulrike Pfaff, Marcus Korb, Tobias Rüffer, Heinrich Lang
Combining Cobalt-Assisted Alkyne Cyclotrimerization and Ring Formation through C–H Bond Activation: A “One-Pot” Approach to Complex Multimetallic Structures [Short Communication]

Combining Cobalt-Assisted Alkyne Cyclotrimerization and Ring Formation through C–H Bond Activation: A “One-Pot” Approach to Complex Multimetallic Structures

A straightforward one-pot synthetic method including cyclotrimerization, C–H activation, and ring formation to novel hexaferrocenylbenzene is discussed. The electrochemical and spectro-electrochemical behavior as well as a mechanism for the formation of the title compound is reported.

Eur. J. Inorg. Chem. 2014, No. 26, 4258-4262

A Unified Strategy Towards N-Aryl Heterocycles by a One-Pot Copper-Catalyzed Oxidative C–H Amination of Azoles

An efficient one-pot synthesis of N-aryl heterocycles by a Cu-catalysed double C–N bond formation is reported. This strategy involves a CuI-catalysed C–N bond-forming reaction between azoles and electron-deficient bromopyridines followed by an intramolecular sp2 C–H amination.

Eur. J. Org. Chem. 2014, No. 27, 5986-5997

Frédéric Liron, Julie Oble, Mélanie M. Lorion, Giovanni Poli
Direct Allylic Functionalization Through Pd-Catalyzed C–H Activation [Microreview]

Direct Allylic Functionalization Through Pd-Catalyzed C–H Activation

This review outlines some selected examples and present challenges relating to palladium-catalyzed direct allylic functionalization. This old reaction, ignored for many years, is enjoying a new age.

Eur. J. Org. Chem. 2014, No. 27, 5863-5883

Chen-Hsun Hung, Parthasarathy Gandeepan, Chien-Hong Cheng
Ruthenium(II)-Catalyzed C-H Bond Activation: An Efficient Route toward Indenamines [Full Paper]

Ruthenium(II)-Catalyzed C-H Bond Activation: An Efficient Route toward Indenamines

Atomic bean counters succeed! An efficient and atom-economical method for the synthesis of substituted indenamines from N-tosylarylimines and alkynes via ruthenium(II)-catalyzed C-H bond activation and annulation is described.

ChemCatChem 2014, 6, No. 09, 2692-2697

Catalytic Borylation of SCF3-Functionalized Arenes by Rhodium(I) Boryl Complexes: Regioselective C-H Activation at the ortho-Position

SCF3 building blocks: A unique reaction route allows access to SCF3-functionalized arenes, which are borylated at the ortho-position. The functionalization proceeds by C-H borylation with [Rh(Bpin)(PEt3)3] (pin=pinacolato), and the SCF3 group likely serves as directing group. The generated borylated SCF3 compounds are versatile building blocks for further transformations.

Angew. Chem. Int. Ed. 2014, 53, No. 35, 9311-9315

Laurent Djakovitch, François-Xavier Felpin
Direct C sp2-H and C sp3-H Arylation Enabled by Heterogeneous Palladium Catalysts [Minireview]

Direct C sp2-H and C sp3-H Arylation Enabled by Heterogeneous Palladium Catalysts

When palladium meets a support: The functionalization of the C-H bond is the most straightforward approach to create new bonds. Although most studies involve homogeneous transition-metal catalysts, in this Minireview we aim to give a picture of recent advances of direct C-H arylations enabled by heterogeneous Pd catalysts.

ChemCatChem 2014, 6, No. 08, 2175-2187

Ligands Control Reactivity and Selectivity in Palladium-Catalyzed Functionalization of Unactivated C sp3-H Bonds

Ligands at the wheel: The pivotal role of ligands for the palladium-catalyzed functionalization of remote C sp3-H bonds has been demonstrated. The presence of the ligand enhances the reactivity of the inert C sp3-H bond and controls the selectivity of the process. DG=Directing group, FG=functional group.

ChemCatChem 2014, 6, No. 08, 2188-2190

Jamal Koubachi, Saïd El Kazzouli, Mosto Bousmina, Gérald Guillaumet
Functionalization of Imidazo[1,2-a]pyridines by Means of Metal-Catalyzed Cross-Coupling Reactions [Microreview]

Functionalization of Imidazo[1,2-a]pyridines by Means of Metal-Catalyzed Cross-Coupling Reactions

The latest developments in the field of imidazo[1,2-a]pyridine functionalization by means of cross-coupling reactions such as the Sonogashira, Heck, Negishi, Suzuki–Miyaura, and Stille reactions, as well as by C-arylation, C-alkenylation, carbonylation, and double functionalization, are reviewed and discussed.

Eur. J. Org. Chem. 2014, No. 24, 5119-5138

Direct Functionalization with Complete and Switchable Positional Control: Free Phenol as a Role Model

PhenAll: Recent breakthroughs in site-selective and direct functionalization of free phenols by transition-metal-catalyzed C-O or C-H bond activation are highlighted here as role models for the complete and switchable positional control of transformations of important core structures.

Angew. Chem. Int. Ed. 2014, 53, No. 30, 7710-7712

Christoph Kornhaaß, Christian Kuper, Lutz Ackermann
Ferrocenylalkynes for Ruthenium-Catalyzed Isohypsic C-H/N-O Bond Functionalizations [Update]

Yan Li, Yun Wu, Guang-Shui Li, Xi-Sheng Wang
Palladium-Catalyzed C-F Bond Formation via Directed C-H Activation [Review]

Suman De Sarkar, Weiping Liu, Sergei I. Kozhushkov, Lutz Ackermann
Weakly Coordinating Directing Groups for Ruthenium(II)- Catalyzed C-H Activation [Review]

Zhao-Lei Yan, Wen-Liang Chen, Ya-Ru Gao, Shuai Mao, Yan-Lei Zhang, Yong-Qiang Wang
Palladium-Catalyzed Intermolecular C-2 Alkenylation of Indoles Using Oxygen as the Oxidant [Update]

José Luis García Ruano, José Alemán, Alejandro Parra, Leyre Marzo
Sulfonyl Acetylenes as Alkynylating Reagents Under Radical or Anionic Conditions [Microreview]

Sulfonyl Acetylenes as Alkynylating Reagents Under Radical or Anionic Conditions

We summarize a powerful methodology for the alkynylation of C(sp3), C(sp2), and C(sp) carbon atoms, as well as some heteroatoms, with alkynylsulfones. It is based on the fact that β-substituted sulfonylacetylenes undergo unexpected anti-Michael addition of organolithiums and radical species, giving intermediates that evolve into alkynyl derivatives in situ by elimination of the anion or radical TolSO2.

Eur. J. Org. Chem. 2014, No. 08, 1577-1588

Philipp J. Gritsch, Christian Leitner, Magnus Pfaffenbach, Tanja Gaich
The Witkop Cyclization: A Photoinduced C-H Activation of the Indole System [Minireview]

The Witkop Cyclization: A Photoinduced C-H Activation of the Indole System

To wit: The title reaction resembles a photoinduced electron-transfer process, and allows the direct formation of medium-sized lactams by C-H activation of the indole nucleus. Therefore it is a versatile tool for the construction of polycyclic indole alkaloid scaffolds.

Angew. Chem. Int. Ed. 2014, 53, No. 05, 1208-1217

Towards Ideal Synthesis: Alkenylation of Aryl C-H Bonds by a Fujiwara–Moritani Reaction

Chemical power tools: The Fujiwara–Moritani reaction is the palladium-catalyzed coupling reaction of a simple aryl C-H bond with an alkenyl C-H bond to form a new C-C bond (see scheme). This Minireview focuses on the advances in the past five years related to the activation of various aryl C-H bonds in this coupling reaction.

Chem. Eur. J. 2014, 20, No. 03, 634-642

The Cross-Dehydrogenative Coupling of Csp3-H Bonds: A Versatile Strategy for C-C Bond Formations

Waste not, want not: The title CDC reactions have emerged as versatile tools for selective and waste-minimized C-C bond formations. They rely on the direct coupling of two different C-H bonds under oxidative conditions. This Review focuses on the recent progress in cross-dehydrogenative Csp3-C formation and provides a comprehensive overview on existing procedures and employed methodologies.

Angew. Chem. Int. Ed. 2014, 53, No. 01, 74-100

New Site-Selective Organoradical Based on Hypervalent Iodine Reagent for Controlled Alkane sp3 C-H Oxidations

Large Iodine: The site-selective oxidation of unactivated secondary sp3 C-H bonds was accomplished by using a newly defined reactive hypervalent iodine(III) radical in the presence of tert-butyl hydroperoxide (see scheme). Recent studies on hypervalent iodine radicals have significantly contributed to the further development and design of organic molecules in radical oxidation chemistry.

ChemCatChem 2014, 6, No. 01, 76-78

Yinuo Wu, Jun Wang, Fei Mao, Fuk Yee Kwong
Palladium-Catalyzed Cross-Dehydrogenative Functionalization of C(sp2)-H Bonds [Focus Review]

Palladium-Catalyzed Cross-Dehydrogenative Functionalization of C(sp2)-H Bonds

Caught in the cross-fire: This Review highlights the recent developments in catalytic cross-dehydrogenative coupling (CDC) reactions, which join together two aromatic C-H fragments through a palladium-catalyzed dehydrogenative pathway.

Chem. Asian J. 2014, 9, No. 01, 26-47

© Wiley-VCH 2013.