Hayato Tsurugi

We found that <i>in situ</i> generated cerium(IV) carboxylate generated by mixing the precursor Ce(O<i>^t</i>Bu)₄ with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control ex

Recent advances in the catalytic application of cerium complexes were achieved through controlling the Ce(IV/III) redox couple. Although Ce(IV) complexes have been extensively investigated as stoichiometric oxidants in organic synthesis on the basis of their highly positive redox potentials, these complexes can be used as catalysts, not only by introducing supporting ligands around the coordination sphere of cerium, but also by taking advantage of the photoresponsive properties of Ce(IV) and Ce(

The combination of VCl₃(THF)₃ and N, N-bis(trimethylsilyl)aniline (1a) is an efficient catalyst for the [2+2+1] coupling reaction of alkynes and azobenzenes, giving multisubstituted pyrroles. A plausible reaction mechanism involves the generation of a mono(imido)vanadium(III) species as an initiation step, where 1a served as an imido source with concomitant release of 2 equiv of ClSiMe₃, followed by a reaction with azobenzene to form a catalytically active bis(im

Abstract Stoichiometric organomagnesium chemistry has continually progressed since its initiation by Victor Grignard over one century ago. Other than acting as a Lewis acid, however, homogeneous magnesium catalysis is a rare topic in the literature. Magnesium catalysts that govern reactions within the coordination sphere of magnesium have only recently begun to appear. This Concept covers recent progress in this young but potentially powerful new chapter of magnesium chemistry.

High-valent tantalum complexes having redox-active α-diimine ligands, (α-diimine)TaCl(n) (n = 3, 4), are prepared by the reaction of TaCl(5), α-diimine ligands, and an organosilicon-based reductant, 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene. Reductive cleavage of the C-Cl bond of polyhaloalkanes is accomplished by trichlorotantalum complexes having dianionic α-diimine ligands via electron transfer from the dianionic ligands, whereas oxidative decomposition of tetraphenylborate is obser

This perspective summarizes direct C-H bond functionalization reactions catalyzed by group 3-5 metal alkyl complexes. Metal-carbon bonds of group 3-5 metals have potentially high reactivity toward both C-H bond activation reactions through the intrinsic σ-bond metathesis pathway and insertion of unsaturated organic molecules. Upon the combination of these two elemental steps, direct C-H bond functionalization reactions of (hetero)aromatic compounds, methane, alkylamines, and terminal alkynes, pr

Amido-pyrrolyl complexes of zirconium (3a−d) and hafnium (4a−f) were prepared by the reaction of tetrabenzyl-zirconium and -hafnium with 2,5-bis(N-aryliminomethyl)pyrrole ligands (2a−e), respectively. During the course of the reaction, one of two imino moieties of the ligand was selectively benzylated to give unique dianionic tridentate ligands, which stabilized dibenzyl complexes of zirconium and hafnium. The coordinative unsaturation around the metal center was compensated by not only the dona

4,4'-Bipyridyl worked as an organocatalyst for the reduction of nitroarenes by bis(neopentylglycolato)diboron (B₂nep₂), followed by hydrolysis to give the corresponding anilines. This reduction proceeded under aerobic conditions without any prepurification of substrates and reagents. We found broad functional group tolerance and compatibility for O- and N-protecting groups under the reaction conditions. The key in this catalytic system was the addition of B₂nep<s

Cyclotrimerization of alkynes catalyzed by transition metal complexes is a straightforward synthetic method for constructing a benzene skeleton in organic synthesis. Not only mononuclear complexes, but also multinuclear complexes act as catalysts for alkyne cyclotrimerization, and their reaction mechanisms have been intensively investigated toward developing highly efficient and regio- and chemo-selective catalysts. In this review, we summarize stoichiometric and catalytic alkyne coupling reacti

A mixed ligated amidoyttrium complex, Y(NBn₂)(L1)(THF)₂ (8, L1 = N, N'-bis(2,6-diisopropylphenyl)ethylenediamine), served as a catalyst for addition of the ortho-pyridyl C(sp²)-H bond of 2-substituted pyridines to nonactivated imines; complex 8 showed superior catalytic performance compared with Y[N(SiMe₃)₂]₃ (1) and Y[N(SiMe₃)₂]₂(NBn₂)(THF) (2). Concerning the reaction mechanism, we con

We developed a non-toxic cyanation reaction of various aryl halides and triflates in acetonitrile using a catalyst system of [Ni(MeCN)₆](BF₄)₂, 1,10-phenanthroline, and 1,4-bis(trimethylsilyl)-2,3,5,6-tetramethyl-1,4-dihydropyrazine (<i>Si</i>-Me₄-DHP). <i>Si</i>-Me₄-DHP was found to function as a reductant for generating nickel(0) species and a silylation reagent to achieve the catalytic cyanation <i>via</i> C-CN bond cleavage.

We have developed a novel oxidant-free direct cross-coupling reaction of 2,6-lutidine and internal alkynes leading to five-membered carbocyclic compounds mediated by nonmetallocene cationic hafnium alkyl complexes. Mechanistic studies of the coupling reaction showed that the reaction begins with C(sp(3))-H bond activation via σ-bond metathesis, after which the coordinatively unsaturated hafnium center mediates further insertion, migration, and β-H elimination reactions to give five-membered carb

Chemical reduction of transition metals provides the corresponding low-valent transition metal species as a key step for generating catalytically active species in metal-assisted organic transformations and is a fundamental unit reaction for preparing organometallic complexes. A variety of metal-based reductants, such as metal powders and organometallic reagents of alkali and alkaline-earth metals, have been developed to date to access low-valent metal species. During the reduction, however, red

We developed a salt-free reduction of WCl6 using 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (MBTCD) in toluene to give a low-valent trinulcear tungsten complex involving W(II) and W(III) centers, while in the presence of redox active ligands such as α-diketone and α-diimine the same reduction produced W(IV) complexes with the corresponding redox-active ligands, (α-diketone)WCl4 and (α-diimine)WCl4. A W(VI) complex with two α-diketone ligands, (α-diketone)2WCl2, was found to be synthetic