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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: 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]

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]

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]