Tetsuya Satoh

Oxidative Coupling of Aromatic Substrates with Alkynes and Alkenes under Rhodium Catalysis

Aromatic substrates with oxygen- and nitrogen-containing substituents undergo oxidative coupling with alkynes and alkenes under rhodium catalysis through regioselective C-H bond cleavage. Coordination of the substituents to the rhodium center is the key to activate the C-H bonds effectively. Various fused-ring systems can be constructed through these reactions.

A New Entry of Amination Reagents for Heteroaromatic C−H Bonds: Copper-Catalyzed Direct Amination of Azoles with Chloroamines at Room Temperature

Chloroamine serves as an efficient amination reagent to the heteroaromatic C-H bond of azole under copper catalysis even at room temperature. This catalysis enables a rapid and concise construction of aminoazoles of great interest in biological and medicinal chemistry.

Ruthenium-Catalyzed Oxidative Vinylation of Heteroarene Carboxylic Acids with Alkenes via Regioselective C−H Bond Cleavage

The ruthenium-catalyzed oxidative vinylation of thiophene-2-carboxylic acids with alkenes efficiently proceeds through directed C-H bond cleavage to give the corresponding 3-vinylated products. Similarly, benzothiophene-, benzofuran-, pyrrole-, and indolecarboxylic acids also undergo regioselective vinylation.

Regioselective C−H Functionalization Directed by a Removable Carboxyl Group: Palladium-Catalyzed Vinylation at the Unusual Position of Indole and Related Heteroaromatic Rings

The palladium-catalyzed oxidative vinylation of indole-3-carboxylic acids with alkenes effectively proceeds via directed C-H functionalization and decarboxylation to produce the corresponding 2-vinylated indoles. Similarly, pyrrole-, furan-, and thiophenecarboxylic acids also undergo decarboxylative vinylation.

Copper-Mediated Intermolecular Direct Biaryl Coupling

Copper-mediated intermolecular direct biaryl coupling of arylazines and azoles via dual C-H bond cleavage proceeds even without palladium catalysts. The reaction system shows the high potential of copper salts in direct C-H arylation chemistry and provides a new approach to biaryl motifs, which are ubiquitous in pharmaceuticals and functional materials.

Nickel-Catalyzed Direct CH Arylation and Alkenylation of Heteroarenes with Organosilicon Reagents†

Organosilicon compounds are useful and ubiquitous synthetic reagents in modern organic chemistry. Among the versatile transformations involving them, transition metal catalyzed cross-coupling reactions of organic halides or pseudohalides, that is Hiyama cross-coupling, ranks as one of the most powerful and reliable C C bond-forming reactions in organic synthesis. Recent efforts by Nakao, Hiyama, and co-workers, and Denmark et al. introduce new types of stable and easy-to-handle silicon-based coupling reagents to enhance the generality of the reaction. In contrast, the development of new catalyst systems by Fu and co-workers and Wu and coworkers has expanded the scope of organic electrophiles into unactivated alkyl halides and arenesulfonates, respectively. In addition, the Hiyama coupling has significant benefits involving tractability, low toxicity, and environmentally benignity associated with organosilicon compounds, as well as organoboron reagents in the Suzuki–Miyaura coupling. Meanwhile, metal-mediated C C bond formation through direct C H functionalization has received much attention as a potentially more efficient and complementary process to the conventional cross-coupling methodology. Although the direct arylation of a variety of arenes and heteroarenes with arylboronic acids derivatives has been achieved, 8] the corresponding direct coupling with organosilanes still remains elusive. To the best of our knowledge, only two successful examples have been reported to date. Moreover, these processes rely on the palladium catalysis, and substrates are limited to those containing an acetamide moiety as the chelation-assisted cyclopalladation step is crucial in the catalytic reaction. Herein we report a new nickel-based catalyst system for the direct C H arylation and alkenylation of various heteroarenes with organosilanes. As an initial experiment, treatment of benzoxazole (1a, 0.50 mmol) with trimethoxyphenylsilane (2a, 1.0 mmol) in the presence of 10 mol% of NiBr2·diglyme, 10 mol% of 1,10phenanthroline (phen), and CsF in 3.0 mL of N,N-dimethylacetamide (DMAc) at 150 8C under air (O2 as an oxidant) provided 2-phenylbenzoxazole (3aa) in 8% yield (GC) (Table 1, entry 1). Apparently, arylsilane 2a participated in the reaction, and the desired cross-coupling involving C H

Rhodium-catalyzed oxidative coupling/cyclization of 2-phenylindoles with alkynes via C-H and N-H bond cleavages with air as the oxidant.

The straightforward and efficient synthesis of indolo[2,1-a]isoquinoline derivatives has been achieved by the rhodium-catalyzed aerobic oxidative coupling/cyclization of 2-phenylindoles with alkynes. Some of the polycyclic products exhibit solid-state fluorescence.

Rhodium-Catalyzed Mono- and Divinylation of 1-Phenylpyrazoles and Related Compounds via Regioselective C−H Bond Cleavage

The selective 2-mono- and 2,6-divinylations of (N-containing heteroaryl)benzenes can be achieved effectively through rhodium-catalyzed oxidative coupling reactions with alkenes. The installation of two different vinyl groups is also possible by a simple one-pot manner. Thus, a series of 1,3-divinylbenzene derivatives, some of which exhibit solid-state fluorescence, is readily prepared.

Copper-catalyzed direct amination of electron-deficient arenes with hydroxylamines.

The C-H amination of electron-deficient arenes such as polyfluoroarenes and azole compounds with O-acylated hydroxylamines effectively proceeds in the presence of a copper catalyst even at room temperature to provide the corresponding anilines and aminoazoles in good yields.

Rhodium-Catalyzed Regioselective Olefination Directed by a Carboxylic Group

The ortho-olefination of benzoic acids can be achieved effectively through rhodium-catalyzed oxidative coupling with alkenes. The carboxylic group is readily removable to allow ortho-olefination/decarboxylation in one pot. α,β-Unsaturated carboxylic acids such as methacrylic acid also undergo the olefination at the β-position. Under the rhodium catalysis, the cine-olefination of heteroarene carboxylic acids such as thiophene-2-carboxylic acid proceeds smoothly accompanied by decarboxylation to selectively produce the corresponding vinylheteroarene derivatives.