There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The chemistry of heterocyclic carbenes has experienced a rapid development over the last years. In addition to the imidazolin-2-ylidenes, a large number of cyclic diaminocarbenes with different ring sizes have been described. Aside from diaminocarbenes, P-heterocyclic carbenes, and derivatives with only one, or even no heteroatom within the carbene ring are known. New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclization of β-functionalized isocyanides have been developed recently. This review summarizes the new developments regarding the synthesis of N-heterocyclic carbenes and their metal complexes.

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

Palladium-catalyzed amination reactions of aryl halides have undergone rapid development in the last 12 years, largely driven by the implementation of new classes of ligands. Biaryl phosphanes have proven to provide especially active catalysts in this context. This Review discusses the application of these catalysts in C-N cross-coupling reactions in the synthesis of heterocycles and pharmaceuticals, in materials science, and in natural product synthesis.

/pdf/biaryl-phosphane-ligands-in-palladium-catalyzed-amination-5180ia9hmu.pdf

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

Ru-, Rh-, and Pd-Catalyzed C-C Bond Formation Involving C-H Activation and Addition on Unsaturated Substrates: Reactions and Mechanistic Aspects

https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/180280/1/c2cc33848c.pdf

Carbon dioxide as a carbon source in organic transformation: carbon–carbon bond forming reactions by transition-metal catalysts

The ruthenium catalyzed N-alkylation and N-heterocyclization of aniline using alcohols and aldehydes

to the corresponding methyl ester 2aMe.Byemploying [IPrCuCl] + tBuONa (Table 1, entry 1) or[IMesCuCl] + tBuONa (Table 1, entry 2) as a catalyst,2aMe was obtained in only trace amounts and 49% yield,respectively. In the latter case, a considerable amount (19%yield)ofcis-stilbene(3a)wasobservedasaby-product.When[IPrCuF]

Copper-catalyzed hydrocarboxylation of alkynes using carbon dioxide and hydrosilanes.

In homogeneous catalyst systems, there is the persistent problem that metal aggregation and precipitation cause catalyst decomposition and considerable loss of catalytic activity. Pd black formation is a typical example. Pd catalysts are known to easily aggregate and form Pd black, although they realize a wide variety of useful reactions in organic synthesis. In order to overcome this intrinsic problem of homogeneous Pd catalysis, we explored a new class of Pd catalyst by adopting aerobic oxidation of alcohols as a probe reaction. Herein we report a new catalyst system that suppresses the Pd black formation even under air and with a high substrate to catalyst molar ratio (S/C:  more than 1000) in oxidation of alcohols. The novel pyridine derivatives having a 2,3,4,5-tetraphenylphenyl substituent and its higher dendritic unit at the 3-position of the pyridine ring were found to be excellent ligands with Pd(OAc)2 in the palladium-catalyzed air (balloon) oxidation of alcohols in toluene at 80 °C. Comparison ...

Homogeneous Palladium Catalyst Suppressing Pd Black Formation in Air Oxidation of Alcohols

Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide has been developed. The reactions proceeded under a CO2 pressure of 1 atm at room temperature in the presence of nickel catalysts and Mn powder as a reducing agent. Various aryl chlorides could be converted to the corresponding carboxylic acid in good to high yields. Furthermore, vinyl chlorides were successfully carboxylated with CO2. Mechanistic study suggests that Ni(I) species is involved in the catalytic cycle.

Yasushi Tsuji

Papers

Carbon dioxide as a carbon source in organic transformation: carbon–carbon bond forming reactions by transition-metal catalysts

The ruthenium catalyzed N-alkylation and N-heterocyclization of aniline using alcohols and aldehydes

Copper-catalyzed hydrocarboxylation of alkynes using carbon dioxide and hydrosilanes.

Homogeneous Palladium Catalyst Suppressing Pd Black Formation in Air Oxidation of Alcohols

Nickel-Catalyzed Carboxylation of Aryl and Vinyl Chlorides Employing Carbon Dioxide