Kohei Takahashi

The catalyst system for tandem hydroformylation/hydrogenation of terminal alkenes to the corresponding homologated normal alcohol was developed. The reaction mechanism for the Rh/Ru dual catalyst was investigated by real-time IR monitoring experiments and (31)P NMR spectroscopy, which proved the mutual orthogonality of Rh-catalyzed hydroformylation and Ru-catalyzed hydrogenation. Detailed investigation about Ru-catalyzed hydrogenation of undecanal under H(2)/CO pressure clarified different kinet

A dual catalyst system has been developed for tandem hydroformylation/hydrogenation to produce n-undecanol from 1-decene in one pot. A combination of xantphos/[Rh(acac)(CO)2] and Shvo's catalyst (1) afforded the best results (see scheme; acac=acetylacetonate, DMA=N,N-dimethylacetamide). Polar solvents effectively suppressed the formation of undecyl formate. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy

Beim Test dualer Katalysatorsysteme für die Tandemsequenz aus Hydroformylierung und Hydrierung zur einstufigen Herstellung von n-Undecanol aus 1-Decen ergab die Kombination von Xantphos/[Rh(acac)(CO)2] mit dem Shvo-Katalysator 1 das beste Resultat (siehe Schema; acac=Acetylacetonat, DMA=N,N-Dimethylacetamid). Der Einsatz polarer Lösungsmittel verhindert die Bildung von Undecylformiat. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are

A way into normality: By using [Cp*Ru] complexes with bisphosphite or bisphosphine ligands, selective hydroformylation of propene and 1-decene to homologated normal aldehydes was accomplished with the highest levels of activity and selectivity ever reported for ruthenium catalyst systems (see scheme). The reaction mechanism was investigated using stoichiometric amounts of [Cp*Ru(Xantphos)H] and [D2]-1-decene.

By using a nickel complex with an N-phosphinomethyl-N-heterocyclic carbene ligand (NHC-P), the reducing ability and thermal stability of the complex were improved considerably compared to the previously reported bipyridine and bisphosphine complexes, and acrylate salt was prepared from ethylene and CO₂ with the highest TON ever reported for nickel systems even without using metallic zinc. Oxidative cyclization of ethylene and CO₂ on the NHC-P nickel complex was found to pro

In this work, we developed a nickel-catalyzed transfer hydrogenolysis of 1-aryloxy-3-amino-2-propanols, which is a model compound of an amine-cured bisphenol A (BPA)-based epoxy resin. Mechanistic investigation revealed that the hydroxy group acts as the hydrogen donor to generate α-aryloxy ketone, which undergoes an unprecedented remote-concerted oxidative addition of the C(sp³)-O bond as suggested by DFT calculation. Successful application of this method was demonstrated by the degr

Der Weg zur Normalität: In Gegenwart von [Cp*Ru]-Komplexen mit Bisphosphit- oder Bisphosphan-Liganden gelang die selektive Hydrofomylierung von Propen und 1-Decen zum verlängerten normal-Aldehyd mit den höchsten Aktivitäten und Selektivitäten, die für Rutheniumkatalysatoren beschrieben wurden (siehe Schema). Der Reaktionsmechanismus wurde durch Experimente mit stöchiometrischen Mengen an [Cp*Ru(Xantphos)H] und [D2]-1-Decen untersucht.

Catalytic 1,1-dicarboxylation of ethylene with CO2 to form a methylmalonate salt was achieved by a Ni/Ir dual-catalyst system under photoirradiation conditions. In this reaction, photoenergy was utilized not only for the reduction of the methylmalonate Ni(II) complex but also for the transformation of the nickelalactone to the methylmalonate complex. By careful mechanistic investigations, it was revealed that photoirradiation promotes not only isomerization of five-membered to four-membered nick

Here we describe detailed mechanistic analyses of the ruthenium-catalyzed synthesis of acrylate salt from ethylene and CO2. All of the primary steps of the catalytic cycle, that is (i) oxidative cyclization of ethylene and CO2 to give ruthenalactones, (ii) thermal β-H elimination of ruthenalactones to hydrido acrylato complexes, and (iii) base-mediated generation of ethylene-coordinated, zerovalent ruthenium complexes from hydrido acrylato complexes, are found to proceed more rapidly on the more

Guest-controlled diastereoselective self-assembly of a diboryltellurophene and a chiral tetrol bearing an indacene backbone was achieved to give either hetero- or homochiral macrocyclic boronic esters, selectively. The heterochiral isomer (hetero-[2+2]^Te ) exhibited a higher inclusion ability for electron-deficient aromatic guests, leading to effective quenching of phosphorescence from the diboryltellurophene moieties. The reported macrocycles collectively represent a promising arene

The hydrogenation of aldehyde utilizing synthesis gas as a dihydrogen source was examined with various ruthenium catalysts, among which Ru-cyclopentadienone complexes (Shvo-type catalysts) exhibited higher activity than others. DFT calculations proved that the exchange of coordinated carbon monoxide by dihydrogen is relatively preferable in Shvo-type catalysts compared to others, which is a pre-equilibrium for the generation of the hydrogenation-active species.

Crystalline polyethylenes bearing carboxylic acid groups in the main chain were successfully degraded with a Ce catalyst and visible light. The reaction proceeds in a crystalline solid state without swelling in acetonitrile or water at a reaction temperature as low as 60 or 80 °C, employing dioxygen in air as the only stoichiometric reactant with nearly quantitative recovery of carbon atoms. Heterogeneous features of the reaction allowed us to reveal a dynamic morphological change of polymer cry

Although the use of biodegradable plastics is suitable for unrecoverable, single-use plastic, their high production cost and much lower variety compared to commodity plastics limit their application. In this study, we developed a new polymer with potential biodegradability, poly(ketone/ester), synthesized from propylene and carbon monoxide. Propylene and carbon monoxide are easily available at low costs from fossil resources, and they can also be derived from biomass. Using an atom insertion rea

Long-chain polyamides (polyethyleneamides) were prepared from polyethylenes bearing in-chain carbonyl groups (polyethyleneketones) by the oxime formation and successive Beckmann rearrangement. (Diethylamino)sulfur trifluoride (DAST) was utilized as a promoter, which allowed mild conversion of the oxime group in spite of low solubility of the polymers. The polyethyleneamide exhibited different tensile property compared to a commercial HDPE.

In this study, a new synthetic method for structurally controlled polyethyleneketones, a photodegradable polyethylene-like polymer, has been developed. Telechelic Zn-polyethylene was prepared from α,ω-diene, diethylzinc, and ethylene, which was allowed to react with diacid chlorides to give polyethyleneketones with defined spacing between the neighboring ketone functionalities. The photodegradation of these polymers under UV light demonstrated a degradation rate dependency on the spacer units be