Fumitoshi Kakiuchi 교수

The cleavage and addition of ortho C-H bonds in various aromatic compounds such as ketones, esters, imines, imidates, nitrile, and aldehydes to olefins and acetlylenes can be achieved catalytically with the aid of ruthenium catalysts. The reaction is generally highly efficient and useful in synthetic methods. The coordination to the metal center by a heteroatom in directing groups such as carbonyl and imino groups is the key. The reductive elimination to form a C-C bond is the rate-determining s

Abstract The development of catalytic reactions involving carbon‐hydrogen bond cleavage is currently one of the most attractive research subjects in organic and organometallic chemistry. About 40 years have past since the pioneering report of the cleavage of CH bonds with transition metal complexes. Since that time, a vast number of studies of the cleavage of CH bonds, using stoichiometric amounts of transition metal complexes has appeared. In the last decade, a variety of catalytic reactions

Catalytic functionalization of unreactive C-H bond has become one of the most attractive research subjects in modern organic chemistry. To date, a variety of catalytic reactions involving C-H bond cleavage have been reported. In this review, we briefly survey the reported research with respect to efficient and selective transition-metal-catalyzed C-C bond formation via C-H bond cleavage.

The ruthenium-catalyzed reaction of aromatic ketones with arylboronic acid esters (arylboronates) gave the ortho arylation product. For this coupling reaction, a RuH2(CO)(PPh3)3 complex exhibited the highest catalytic activity among the complexes screened. Several aromatic ketones, for example, acetophenones, acetonaphthone, alpha-tetralone, and benzosuberone, can be used in this coupling reaction. A variety of arylboronates containing electron-donating (OMe and NMe2) and -withdrawing (F and CF3

A new strategy for catalytic functionalization of C-H bonds by means of electrochemical oxidation is described. Combination of palladium-catalyzed aromatic C-H bond cleavage and halogenation with electrochemically generated halonium ions enables highly efficient, selective halogenations of aromatic compounds in a green-sustainable manner. The required reagents for this reaction are an arene and an aqueous hydrogen halide as substrates, a palladium salt as a catalyst, and an organic solvent. No f

Abstract Ruthenium complexes, e.g., Ru(H)2(CO)(PPh3)3, have been found to catalyze the addition of ortho C–H bonds of aromatic ketones to olefins with a high degree of efficiency and selectivity. 2′-Methylacetophenone reacts with various types of terminal olefins to give 1 : 1 coupling products in good to excellent yields. The C–C bond formation takes place exclusively at the terminal carbon atom of olefins except for styrene which affords a mixture of two regioisomers. Acetylnaphthalenes, cycli

When the reaction of aromatic ketones with arylboronates (arylboronic acid esters) using RuH(2)(CO)(PPh(3))(3) (3) as a catalyst was conducted in toluene, the corresponding arylation product was obtained in moderate yields. In this case, a nearly equivalent amount of a benzyl alcohol derived from a reduction of an aromatic ketone was also formed. The use of aliphatic ketones, such as pinacolone and acetone, as an additive or a solvent dramatically suppressed the reduction of the aromatic ketones

The ruthenium-catalyzed reaction of aryl ethers having a carbonyl group at the ortho position to the ether group with organoboronates (R-B(OCH2CMe2CH2O), R = aryl, alkenyl, and alkyl) resulted in site-selective C-C bond formation. Among the transition metal complexes screened, the RuH2(CO)(PPh3)3 complex showed the highest activity. Several aromatic ketones having methoxy or phenoxy groups at the ortho position can also be used in this coupling reaction. A variety of arylboronates containing ele

Abstract The reaction of α-tetralone with various internal acetylenes can be catalyzed by Ru(H)2(CO)(PPh3)3 and gives 1:1 addition products. Symmetrically substituted dialkyl- and diarylacetylenes gave an E/Z mixture of 1:1 coupling products in good yields. 1-Phenyl-1-butyne afforded all four possible regio- and stereoisomers. 1-Trimethylsilyl-1-propyne gave only E-isomer with C–C bond formation exclusively at the carbon atom substituted with the silyl group. Other internal acetylenes having a t

Ruthenium-catalyzed silylation of sp3 C-H bonds at a benzylic position with hydrosilanes gave benzylsilanes. For this silylation reaction, Ru3(CO)12 complex showed high catalytic activity. This silylation proceeded at the methyl C-H bond selectively. For this silylation reaction, pyridyl and pyrazolyl groups, and the imino group in hydrazones, can function as a directing group. Several hydrosilanes involving triethyl-, dimethylphenyl-, tert-butyldimethyl-, and triphenylsilanes can be used as a s

Abstract Addition of C–H bonds in α,β-enones to olefins were attained by Ru(H)2(CO)(PPh3)3 catalyst. The reactions of acylated heterocyclic olefins with triethoxyvinylsilane in the presence of the ruthenium catalyst afforded the coupling product in good to excellent yields. The reactions of 3,4-dihydro-6-pivaloyl-2H-pyran with several olefins were also catalyzed by the ruthenium complex to give the corresponding coupling products.

Abstract Ruthenium-catalyzed reactions of aromatic compounds having an amino group or a heteroaromatic ring as a directing group with triethylsilane gave the corresponding ortho silylated products in good to excellent yields. In contrast to our previous results, in which the reactive substrates with π-conjugation between the hetero atom in the directing group and the carbon atom possessing the C-H bond to be cleaved were used, the present reaction proceeds in cases of substrates having no such π