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Abstract: Palladium nanoparticles supported on 5 %‐nitrogen‐doped, herringbone‐type carbon nanofibers (Pd/N‐CNF‐H), which are prepared by thermally decomposing [Pd2(dba)3⋅CHCl3] (dba=dibenzylideneacetone) in toluene in the presence of N‐CNF‐H, were found to be an efficient catalyst for the chemoselective hydrogenation of alkenyl and nitro moieties in benzyl‐protected alcohols and carboxylic acid derivatives with high turnover frequencies: the hydrogenation reactions of these functional groups proceeded smoothly even at ambient temperature under atmospheric H2 pressure, and the benzyl protecting groups in the molecules remained intact. Moreover, the recovered Pd/N‐CNF‐H catalyst could be reused without loss of its catalytic activity or chemoselectivity. The Pd/N‐CNF‐H catalyst also acted as an effective hydrogenation catalyst for the reduction of aromatic ketones to the corresponding benzyl alcohol derivatives with good to high product selectivity. [ABSTRACT FROM AUTHOR]

The reaction of three types of carbon nanofibers (CNFs; platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) with Ir4(CO)12 in mesitylene at 165 °C provided the corresponding CNF-supported iridium nanoparticles, Ir/CNFs (Ir content=2.3-2.6 wt. %). Transmission electron microscopy (TEM) studies of these Ir/CNF samples revealed that size-controlled Ir nanoparticles (average particle size of 1.1-1.5 nm) existed on the CNFs. Among the three Ir/CNF samples, Ir/CNF-T showed an excellent catalytic activity and chemoselectivity towards hydrogenation of functionalized nitroarenes and imines; the corresponding aniline derivatives were obtained with high turnover numbers at ambient temperature under 10 atm of H2, and the catalyst is reusable. Ir/CNF-T was also effective for the reductive N-alkylation of anilines with carbonyl compounds. [ABSTRACT FROM AUTHOR]

The article discusses a study which synthesized palladium nanoparticles supported on nitrogen-doped carbon nanofiber (N-CNF-H) by thermally decomposing Pd2(dba)3CHCl3 in the presence of N-CNF-H. The study found that the Pd/N-CNF-H compounds act as efficient catalysts in the partial hydrogenation of internal alkynes to the corresponding (Z)-alkenes. It also suggested the significance of N-CNF-H in the preparation of heterogenous poisoning catalysts.

The article focuses on research to immobilize platinum nanoparticles on the surface of nitrogen-doped, herringbone-type carbon nanofibers (N-CNF-H) with the formed Pt/N-CNF-H compounds becoming efficient poisoning catalysts for the nitro-selective hydrogenation of nitroarenes. Carbon-supported metal nanoparticles are used as sensors and electrocatalysts for lithium (Li) ion batteries. It involves synthesizing N-CNF-H using vapor deposition over an MgO supported Ni-Fe catalyst using hydrogen.

Bis(oxazolinyl)phenylrhodium(III) aqua complexes, (Phebox)RhX2(H2O) [X = Cl, Br], were found to be efficient Lewis acid catalysts for the enantioselective addition of allyl- and methallyltributyltin reagents to amino aldehydes. The reactions proceed smoothly in the presence of 5-10 mol % of (Phebox)RhX2(H2O) complex at ambient temperature to give the corresponding amino alcohols with modest to good enantioselectivity (up to 94% ee). [ABSTRACT FROM AUTHOR]

Abstract: Combination of commercially available platinum catalysts with siloxanes containing more than two Si–H groups is found to be an efficient catalyst system for the reduction of carboxamides to amines. In particular, facile removal of silicon and platinum residues from the product can be achieved by the use of polymethylhydrosiloxanes as reducing reagents. [Copyright &y& Elsevier]

Abstract: Chiral palladium and platinum complexes bearing non-symmetrical, PCN pincer ligand, 6-methoxy-3-(4′-isopropyl-2′-oxazolin-2′-yl)phenyl diphenylphosphinite [i-Pr-Phemox-OPPh2], are first synthesized via oxidative addition of (i-Pr-Phemox-OPPh2)Br 6 to Pd2(dba)3 ·(CHCl3) or Pt(dba)2 and subsequent treatment with silver salts. [Copyright &y& Elsevier]

Abstract: Atom-transfer radical cyclization (ATRC) catalyzed by coordinatively unsaturated ruthenium alkoxides 4 , [(η5-C5Me5)Ru(OR)]2, is investigated, and ruthenium methoxide 4a (R=Me) is found to exhibit excellent catalytic activity for the cyclization of N-allyl-α,α-dichloroacetamides at ambient temperature. Addition of some amounts of two-electron donor ligands such as pyridine and triphenylphosphine improves the catalyst efficiency to afford the corresponding γ-lactams in high yields. The high catalytic activity of this catalyst system enables to control the diastereoselectivity of this 5-exo cyclization kinetically. The present 4a /pyridine system is also effective for the 4-exo cyclization of N-vinylacetamides to afford the corresponding β-lactams in quantitative yields. The 4a /pyridine system is also active towards the ATRP of methyl methacrylate (MMA) at room temperature to afford the poly(MMA) with narrow molecular weight distributions (M w/M n=1.2) at the initial stage. [Copyright &y& Elsevier]

Abstract: Atom-transfer radical cyclization (ATRC) and addition (ATRA) catalyzed by a coordinatively unsaturated diruthenium amidinate complex 4 , [(η5-C5Me5)Ru(μ2-i-PrN:italic>i-Pr)Ru(η5-C5Me5)]+, are investigated, and their features are compared with those of atom-transfer radical polymerization (ATRP). As an example of ATRC, a cationic diruthenium amidinate 4 is found to exhibit excellent catalytic reactivity for the cyclization of N-allyl α-halogenated acetamides including an alkaloid skeleton at ambient temperature. A catalytic species generated in situ from a halide complex, (η5-C5Me5)Ru(μ2-i-PrN:italic>i-Pr)Ru(η5-C5Me5)(X) [X=Cl, Br] and sodium salts of weakly coordinating anions such as NaPF6 and NaBPh4 also shows high catalytic activity; this actually provides a solution for a problematic instability of 4 as the practical catalyst. The in situ-generated catalyst species 4 is also active towards the intermolecular ATRA of α,α,γ-trichlorinated γ-lactam with alkenes at rt to afford the corresponding α-alkylated γ-lactams in moderate yields. Examination of ATRP of methyl methacrylate (MMA) showed that both the isolated 4 [Y=PF6] and in situ-generated 4 [Y=PF6] are effective for the polymerization of MMA in the presence of 2-bromoisobutylate as the initiator. Use of the isolated catalyst results in controlled polymerization at initial stage of the reaction; in contrast, the polymerization with in situ-generated catalyst produces poly(MMA) with wide molecular weight distribution. The isolated catalyst 4 is powerful for the activation of a C–Br bond of macromolecule initiators; BrCMe2CO2[O(CH2)4] n -n-Bu (M n=3800; M w/M n=1.2) initiated ATRP of MMA even at 25°C to afford the poly(THF)–poly(MMA) block copolymer of M n=26,000 and M w/M n=1.2 with the aid of 4 . The roles of the coordinatively unsaturated ruthenium species for these reactions are discussed. [Copyright &y& Elsevier]

Studies the asymmetric catalysis of diels-alder cycloadditions by a molecular sieve (MS)-free binaphthol-titanium complex. Diels-alder reaction with juglone; Reactions with glyoxylate; Comparison of linearity and positive nonlinearity.

The combination of IrCl(CO)(PPh3)2 with 1,1,3,3-tetramethyldisiloxane or poly(methylhydrosiloxane) (PMHS) is found to be an efficient catalyst system for the preparation of aldenamines from carboxamides; in particular, facile removal of silicone and iridium residues from the product can be achieved by the use of PMHS. [ABSTRACT FROM AUTHOR]

Use of Ru/CNF-P, nanoruthenium particles dispersed on a nanocarbon fiber support, realizes highly efficient catalytic partial hydrogenation of 1,1′-bi-2-naphthol and -naphthyl- amine derivatives. The reactions proceed in high turnover numbers without racemization of the axial chirality, offering a practical procedure for the production of optically pure 5,5′,6,6′,7,7′,8,8′-octahydro- 1,1′-binaphthyls in good to high yields. [ABSTRACT FROM AUTHOR]

Combination of PdCl2 with 1,1,3,3‐tetramethyldisiloxane in the presence of activated carbon was found to be an effective catalyst system for the cleavage reaction of C−O bond of O−t‐Bu moieties. The present catalytic reaction offers a practical method for the deprotection of tert‐butyl esters, tert‐butyl ethers, O‐Boc, and N‐Boc derivatives under mild conditions. The addition of activated carbon in the reaction mixture was proved to be crucial for not only sustaining the catalytic activity but also trapping the palladium species after the reaction. [ABSTRACT FROM AUTHOR]

The article focuses on the self-encapsulation of homogeneous catalyst species into polymer gel leading to a facile and efficient separation system of amine products in the Ru-catalyzed reduction of carboxamides with Polymethylhydrosiloxane (PMHS). Reduction of carboxamides is a crucially important method in organic synthesis for the production of amines. Alkali metal hydrides have long been the reagents of choice for the reaction, and its utility has been demonstrated innumerable times. The siloxane waste can be removed from the amines by a workup process using strong acids and bases through the corresponding ammonium salts of the products formed. The present reduction of amides with PMHS offers a solution as an environmentally benign production of amines, namely, an efficient catalytic process involving facile separation of catalyst species and silicone byproducts from the product.

The easy synthesis of transition metal nanoparticles supported on three types of carbon nanofibers (platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) and nitrogen-doped CNF-H (N-CNF-H) is accomplished by pyrolysis of metal carbonyl clusters such as Ru 3 (CO) 12 , Rh 4 (CO) 12 , and Ir 4 (CO) 12 , and alkene complexes such as Pd 2 (dba) 3 ·CHCl 3 and Pt(dba) 2 [dba: dibenzylideneacetone]. Transmission electron microscopy of these CNFs with immobilized metal nanoparticles (M/CNFs and M/ N -CNF-H) showed that metal nanoparticles whose size could be controlled, existed on the CNFs, and that their location was dependent on the surface nanostructure of the CNFs: on the edge of the graphite layers (CNF-P), in the tubes and on the surface (CNF-T), and between the layers and on the edge (CNF-H). Among these M/CNFs, Ru/CNF-P and Rh/CNF-T showed excellent catalytic activity towards arene hydrogenation with high reusability and functional group tolerance, while the Pt/CNF-P behaves as an efficient catalyst for the hydrogenation of substituted nitroarenes to the corresponding aniline derivatives with the other functional groups remaining intact. Pt and Pd nanoparticles supported on N -CNF-H act as poisoning catalysts for the transformation of internal alkynes to ( Z )-alkenes over Pd/ N -CNF-H, and for the transformation of nitroarenes to the corresponding anilines and N -hydroxylamines over Pt/ N -CNF-H. [TANSO 2015 (No. 266) 35–40.] [ABSTRACT FROM AUTHOR]

The catalyst consisting of carbon nanofibers with tubular graphite layers is reused five times without loss of activity. [ABSTRACT FROM AUTHOR]

The bifunctional hydrosilane as well as the Ru catalyst are stable towards air and moisture. [ABSTRACT FROM AUTHOR]

Carbon‐nitrogen bond formation is an important method on both laboratory and industrial scales because it realizes the production of valuable pharmaceuticals, agrochemicals, and fine chemicals. Direct reductive N‐alkylation of amines with carbonyl compounds via intermediary imine compounds, especially under catalytic hydrogenation conditions, is one of the most convenient, economical, and environmentally friendly methods for this process. Here we report a novel palladium species on zirconia having specific activity towards hydrogenation of imines but other carbonyl groups remaining intact. The present catalytic property offers a practical synthetic method of functionalized secondary amines by reductive N‐alkylation under mild conditions with high atom‐efficiency. Mechanistic studies revealed that the catalytically active species is the palladium cluster, which is generated in situ from molecular palladium complexes on the support by exposure to atmospheric hydrogen. These fundamental findings are expected to progress in developing novel cluster catalysts for chemical processes directed towards a sustainable society. [ABSTRACT FROM AUTHOR]

The synergetic effect of two Si-H groups leads to efficient reduction of carboxamides to amines by platinum catalysts under mild conditions. The rate of the reaction is dependent on the distance of two Si-H groups; 1,1,3,3-tetramethyldisiloxane (TMDS) and 1,2-bis(dimethylsilyl)benzene are found to be an effective reducing reagent. The reduction of amides having other reducible functional groups such as NO2, CO2R, CN, CC, Cl, and Br moieties proceeds with these groups remaining intact, providing a reliable method for the access to functionalized amine derivatives. The platinum-catalyzed reduction of amides with polymethylhydrosiloxane (PMHS) also proceeds under mild conditions. The reaction is accompanied by automatic removal of both platinum and silicon wastes as insoluble silicone resin, and the product is obtained by simple extraction. A mechanism involving double oxidative addition of TMDS to a platinum center is discussed. [ABSTRACT FROM AUTHOR]

A triruthenium cluster, (μ3,η²,η³,η5-acenaphthylene)Ru3(CO)7 (1) catalyzes the reaction of secondary amides with hydrosilanes, yielding a mixture of secondary amines, tertiary amines, and silyl enamines. Production of secondary amines with complete selectivity is achieved by the use of higher concentration of the catalyst (3 mol %) and the use of bifunctional hydrosilanes such as 1,1,3,3-tetramethyldisiloxane. Acidic workup of the reaction mixture affords the corresponding ammonium salts, which can be treated with a base, providing a facile method for isolation of secondary amines with high purity. In contrast, tertiary amines are formed with high selectivity by using lower concentration of the catalyst (1 mol %) and polymeric hydrosiloxanes (PMHS) as reducing agent. Reduction with PMHS encapsulates the ruthenium catalyst and organic byproducts to the insoluble silicone resin. The two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired secondary or tertiary amine as a single product. The product contaminated with only minimal amounts of ruthenium and silicon residues. On the basis of the products and observed side products as well as NMR studies a mechanistic scenario for the reaction is also described. [ABSTRACT FROM AUTHOR]

Abstract: A triruthenium cluster, (μ3, η2, η3, η5-acenaphthylene)Ru3(CO)7 effectively catalyzes primary-alkylation reaction of electron-rich aromatic rings using a combination of hydrosilane and ester as a source of the primary-alkyl group. The reaction involves electrophilic substitution of arenes by carbocationic species stabilized by a neighboring alkoxy or siloxy group generated during the reduction of esters giving alkylated arenes after reductive removal of the alkoxy or siloxy group at the benzylic position. [Copyright &y& Elsevier]

Abstract: Bis(oxazolinyl)phenyl–palladium(II)(Phebox–Pd) complexes were found to be efficient catalysts for Suzuki–Miyaura coupling reactions of aryl boronic acids and their derivatives with aryl halides to give the corresponding biaryl products in high yield along with moderate enantioslectivities in the case of axially chiral induction. The catalytic activity was attained more than 900,000 of TON and 45,000 of TOF. The catalyst can be recovered quantitatively and could be reused for Suzuki–Miyaura reactions. [Copyright &y& Elsevier]