Methylation of C(sp²)−H bonds was achieved through the Ni^II-catalyzed reaction of benzamides with phenyltrimethylammonium bromide or iodide as the source of the methyl group. The reaction has a broad scope and shows high functional-group compatibility. The reaction is also applicable to the methylation of C(sp³)−H bonds in aliphatic amides.

Methylation of C(sp²)−H bonds was achieved through the Ni^II-catalyzed reaction of benzamides with phenyltrimethylammonium bromide or iodide as the source of the methyl group. The reaction has a broad scope and shows high functional-group compatibility. The reaction is also applicable to the methylation of C(sp³)−H bonds in aliphatic amides.

A nickel/NHC system for regioselective oxidative annulation by double C−H bond activation and concomitant alkyne insertion is described. The catalytic reaction requires a bidentate directing group, such as an 8-aminoquinoline, embedded in the substrate. Various 5,6,7,8-tetrasubstituted-N-(quinolin-8-yl)-1-naphthamides can be prepared as well as phenanthrene and benzo[h]quinoline amide derivatives. Diarylalkynes, dialkylalkynes, and arylalkylalkynes can be used in the system. A Ni⁰/Ni^II catalytic cycle is proposed as the main catalytic cycle. The alkyne plays a double role as a two-component coupling partner and as a hydrogen acceptor.

Chelation-assisted arylation of the ortho CH bonds in 2-arylpyridine derivatives was achieved by using [Ru(OAc)₂(p-cymene)] as the catalyst and diaryliodonium salts as the arylation reagent. The reaction can tolerate a broad range of functional groups and, in contrast to other Ru-catalyzed CH arylation reactions with diaryliodonium salts, appears to proceed by a mechanism similar to Pd-catalyzed CH arylation.

The palladium-catalyzed arylation/alkylation of ortho-CH bonds in N-benzoyl α-amino ester derivatives is described. In such a system both the NH-amido and the CO₂R groups in the α-amino ester moieties play a role in successful CH activation/CC bond formation using iodoaryl coupling partners. A wide variety of functional groups and electron-rich/deficient iodoarenes are tolerated. The yields obtained range from 20 to 95 %.

CH bonds are ubiquitous in organic compounds. It would, therefore, appear that direct functionalization of substrates by activation of CH bonds would eliminate the multiple steps and limitations associated with the preparation of functionalized starting materials. Regioselectivity is an important issue because organic molecules can contain a wide variety of CH bonds. The use of a directing group can largely overcome the issue of regiocontrol by allowing the catalyst to come into proximity with the targeted CH bonds. A wide variety of functional groups have been evaluated for use as directing groups in the transformation of CH bonds. In 2005, Daugulis reported the arylation of unactivated C(sp³)H bonds by using 8-aminoquinoline and picolinamide as bidentate directing groups, with Pd(OAc)₂ as the catalyst. Encouraged by these promising results, a number of transformations of CH bonds have since been developed by using systems based on bidentate directing groups. In this Review, recent advances in this area are discussed.

C-H-Bindungen sind in organischen Verbindungen allgegenwärtig. Daher erscheint die direkte Funktionalisierung von Substraten durch Aktivierung von C-H-Bindungen als eine gute Strategie, weil so die Herstellung funktionalisierter Ausgangsstoffe vermieden werden kann. Wichtig ist hierbei der Aspekt der Regioselektivität, da organische Moleküle viele C-H-Bindungen enthalten können. Erzielt werden kann eine solche Regiokontrolle durch die Verwendung einer dirigierenden Gruppe, die den Katalysator in unmittelbare Nähe zur umzusetzenden C-H-Bindung bringt. Viele funktionelle Gruppen wurden hinsichtlich der Verwendung als dirigierende Gruppen bei der Umwandlung von C-H-Bindungen getestet. 2005 berichteten Daugulis et al. über die Arylierung von nicht-aktivierten C(sp³)-H-Bindungen mit 8-Aminochinolin und Picolinamid als zweizähnigen dirigierenden Gruppen in Gegenwart von Pd(OAc)₂ als Katalysator. Basierend auf diesem Befund wurde seitdem eine Reihe von C-H-Funktionalisierungen unter Verwendung von Systemen zweizähniger dirigierender Gruppen entwickelt. In diesem Aufsatz werden die jüngsten Fortschritte auf diesem Gebiet erörtert.

Despite significant advances in the catalytic direct arylation of heteroarenes, the application of this reaction to pyridines has been met with limited success. An oxidative nucleophilic arylation strategy has been developed to overcome this problem. Pyridine, pyrazine, quinolone, and related electron-deficient N-heteroarenes can be arylated at the most electrophilic site using the developed nickel-catalyzed reaction. This protocol serves as a complementary method to catalytic direct arylation reactions.

This paper describes carbonylative cycloaddition reactions catalyzed by Ru₃(CO)₁₂. Ru₃(CO)₁₂ was found to catalyze an intramolecular Pauson–Khand-type reaction. Carbonylative cycloaddition reactions involving a carbonyl group in aldehydes, ketones, and esters as a two-atom assembling unit were also achieved in the presence of Ru₃(CO)₁₂ as the catalyst. The reaction of 5-hexyn-1-al and 6-heptyn-1-al derivatives with CO in the presence of Ru₃(CO)₁₂ resulted in cyclocarbonylation from which bicyclic α, β-unsaturated lactones were obtained. Intermolecular [2 + 2 + 1] carbonylative cycloaddition of alkenes, ketones, and CO was also catalyzed by Ru₃(CO)₁₂ as the catalyst to give saturated γ-lactone derivatives. Simple ketones were not applicable, but ketones having a CO or CN group at the α-position served as a good substrate. These reactions could be extended to carbonylative cycloaddition of the corresponding imines leading to γ-butyrolactam derivatives. The [4 + 1] carbonylative addition of α,β-unsaturated imines leading to unsaturated γ-lactams was achieved with Ru₃(CO)₁₂. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 201–212; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20149