Direct Aminophosphonylation of aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes

This work reports a novel method for the direct aminophosphonylation of aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes. The system HP(O)(OEt)₂/[CpRu(PPh₃)₂Cl] was very efficient for the aminophosphonylation of aldehydes with primary and secondary amines, producing the corresponding α-aminophosphonates in good to excellent yields. This novel method has several advantages including the use of a small amount of catalyst (0.5?mol%), high chemoselectivity, solvent-free conditions and application of the catalyst [CpRu(PPh₃)₂Cl] for at least 12 cycles with excellent activity.     

Alkyne activation by half-sandwich ruthenium(II) complexes bearing the water-soluble phosphane 1,3,5-triaza-7-phosphaadamantane (PTA)

Complex [RuCl{κ³(N,N,N)-Tp}(PPh₃)(PTA)] (κ³(N,N,N)-Tp = hydridotris(pyrazolyl)borate) containing the water-soluble phosphane 1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]decane (PTA) reacts with terminal alkynes producing to the corresponding neutral alkynyl complexes [Ru(CCR){κ³(N,N,N)-Tp}(PPh₃)(PTA)] (R = Ph (1a), ⁿBu (1b), 1-cyclopentenyl (1c), p-methoxyphenyl (1d), 6-methoxynaft-2-yl (1e)). When halide is extracted from complex [RuCl{κ³(N,N,N)-Tp}(PPh₃)(PTA)] followed by treatment with propargyl alcohols, the corresponding allenylidene complexes [Ru{κ³(N,N,N)-Tp}(PPh₃)(PTA)(CCCPh₂)][X] (X = PF₆ (2a), CF₃SO₃ (2b)) and [Ru{κ³(N,N,N)-Tp}(PPh₃)(PTA)(CCCC₁₂H₈)][PF₆] (3) result. Electrophilic attack on the complexes thus obtained leads chemoselectively to the alkynyl complexes [Ru(CCR){κ³(N,N,N)-Tp}(PPh₃)(1-CH₃-PTA)][CF₃SO₃] (R = Ph (4a), ⁿBu (4b), and 1-cyclopentenyl (4c)) and to the dicationic allenylidene complexes [Ru{κ³(N,N,N)-Tp}(PPh₃)(1-H-PTA)(CCCC₁₂H₈)][PF₆]₂ (5) and [Ru{κ³(N,N,N)-Tp}(PPh₃)(1-CH₃-PTA)(CCCPh₂)][CF₃SO₃]₂ (6).     

Equilibrium constants and kinetics of carbon monoxide insertion in alkyl complexes of ruthenium(II)

The equilibrium constants of the reaction of cis, trans-[Ru(CO)₂(PMe₃)₂(CH₃)I] (Mc) with carbon monoxide to give cis, trans[Ru(CO)₂(PMe₃)₂ (COMe)i] (Ac) and trans, trans[Ru(CO)₂(PMe₃)₂(COMe)I] (At) were measured at various temperatures in toluene. The thermodynamic parameters are compared with those obtained for the isoelectronic complexes of iron, and the trend is discussed. The kinetics of the carbonylation reaction of Mc, as well as those of the inverse decarbonylation reaction of At were measured. The kinetics of the carbonylation of the new complex trans, trans-[Ru(CO)₂(PMe₃)₂(CH₃)I] (Mt) were also investigated. All the results afford further support to the previously proposed CO insertion mechanism occurring via methyl migration. The comparison of these kinetic results with those of isoelectronic complexes of iron indicates that ruthenium is more reactive than iron, which is reflected by its greater aptitude to act as catalyst in many processes.     

Binuclear ruthenium(II) pyridazine complex catalyzed transfer hydrogenation of ketones

A convenient and general method of synthesis of binuclear ruthenium(II) pyridazine complex was reported. The synthesized complex was characterized by analytical and spectral methods. The structure of the complex was confirmed by X-ray diffraction technique and was found to be an efficient catalyst for the transfer hydrogenation of ketones with excellent conversions in the presence of isopropanol/KOH at 82 °C. The effect of solvents, bases, and different catalyst/substrate ratio for the reaction was also investigated.     

Heterogeneous Suzuki and copper-free Sonogashira cross-coupling reactions catalyzed by a reusable palladium(II) complex in water medium

A new polystyrene anchored Pd(II) azo complex has been synthesized and characterized. The present Pd(II) azo complex behaves as a very efficient heterogeneous catalyst in the Suzuki coupling and Sonogashira coupling reaction in water medium. Aryl halides, coupled with phenylboronic acids (Suzuki-Miyaura reaction) or terminal alkyne (Sonogashira reaction), smoothly afford the corresponding cross-coupling products in excellent yields (83-100% yield for Suzuki reaction and 68-96% yield for Sonogashira reaction of aryl halides) under phosphine-free reaction conditions in the presence of polystyrene anchored Pd(II) azo complex catalyst in water medium. Furthermore, the catalyst has shown good thermal stability and recyclability. This polymer-supported Pd(II) catalyst could be easily recovered by simple filtration of the reaction mixture and reused for more than six consecutive trials without a significant loss of its catalytic activity.     

Direct reductive amination of carbonyl compounds with primary/secondary amines using recyclable water-soluble Fe/EDTA complex as catalyst

Direct reductive amination of aliphatic, aromatic and heterocyclic carbonyl compounds with primary/secondary amines is reported with water-soluble Fe^II/EDTA complex as a catalyst using low-pressure molecular hydrogen in a biphasic media. The catalyst is highly selective, recyclable and is an excellent replacement for expensive noble metal catalysts or stoichiometric reducing agents.     

Hiyama reaction of aryl bromides with arylsiloxanes catalyzed by a reusable palladium(II)/cationic bipyridyl system in water

A Pd(NH₃)₂Cl₂/cationic bipyridyl catalytic system catalyzed the cross-coupling reaction of aryl bromides with arylsiloxanes in water under aerobic conditions in the presence of NaOH to afford biaryls in good to high yields. The reaction was performed at 120 °C and the loading amount of catalyst can be as low as 0.001 mol %. After extraction, the residual aqueous phase can be reused several times with only a slight decrease in activity.     

Branch selective allylation of acetylacetone catalyzed by Water-soluble rhodium complex catalyst

[RhCl(1,5-cod)]₂/PTA is highly active branch-selective catalyst for C-allylation of acetylacetone by allylic carbonates in water/ethyl acetate biphasic system, where either crotyl or 1-methylallyl carbonates gives sterically congested branched allylation product, suggesting formation of a common allylrhodium intermediate.     

Aqueous Suzuki coupling reaction catalyzed by water-soluble diimine/Pd(II) systems

A series of water-soluble diimine ligands were applied for the Suzuki reaction of arylbromide in different media. Low loading of catalyst (0.01 mol%) were necessary for the coupling reaction to proceed in water or water/ethanol. The catalytic system was found to tolerate a broad range of functional groups.     

Vacuum-driven anionic ligand exchange in Buchmeiser-Hoveyda-Grubbs ruthenium(II) benzylidenes

Vacuum-driven anionic ligand exchange of a perfluorocarboxylic acid with ruthenate-bound perfluorocarboxylates is demonstrated and allows for a novel entry to solid-supported ruthenium benzylidenes.     

Application of ruthenium catalyzed oxidation of [tris(2-aminoethyl)amine] in trace determination of ruthenium in environmental water samples

The ruthenium catalyzed oxidation of tris(2-aminoethyl)amine (TREN) by hexacyanoferrate(III) has been utilized for the development of a new and sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III). The reaction was followed spectrophotometrically by the decrease in absorbance at 420nm (lambda(max) of [Fe(CN)(6)](3-)). The CKM developed utilizes fixed time procedure under optimum reaction conditions where the change in absorbance (DeltaA(t)) versus ruthenium(III) concentrations is plotted. The calibration curve recommended for the method is linear in the concentration range 10.11-252.67ngml(-1) with very good accuracy and reproducibility and a maximum error 2.20%. The detection limits of the method for ruthenium(III) corresponding to 10, 15 and 20min are 8.02, 5.03 and 3.15ngml(-1), respectively. The ruthenium(III) has also been determined in the presence of several other interfering and non-interfering cations and anions and no foreign ions interfered in the determination of ruthenium(III) up to five-fold higher concentration of the foreign ions tested. The method is highly sensitive, selective and stable. It has successfully been applied for the determination of trace ruthenium(III) in some synthetic and environmental water samples. A review of most of the published catalytic kinetic and some other important methods for the determination of ruthenium has also been presented.     

水溶性Ru-TPPTS配合物催化对-氯硝基苯选择性加氢

研究了水／有机两相催化体系中,水溶性Ru-TPFrS配合物催化对-氯硝基苯中硝基的选择性加氢反应。考察了溶剂种类、水溶液的pH值、添加助剂三乙胺、水／有机两相体积、底物浓度等对对-氯硝基苯转化率和生成对-氯苯胺选择性的影响,并在90℃、4.0MPa、反应时间为6h的条件下,进行了催化剂的循环实验。     

Biphasic asymmetric hydroformylation and hydrogenation by water-soluble rhodium and ruthenium complexes of sulfonated (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl in ionic liquids

A biphasic catalytic system with water-soluble rhodium complexes of sulfonated (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (labeled as (R)-BINAPS) in ionic liquid BMI·BF₄ has been developed for the asymmetric hydroformylation of vinyl acetate under mild conditions. The corresponding ruthenium complexes have been investigated for the biphasic asymmetric hydrogenation of dimethyl itaconate. The biphasic asymmetric hydroformylation of vinyl acetate provided 28.2% conversion and 55.2% enantiomeric excess when BMI·BF₄–toluene was used as the reaction medium at 333 K and 1.0 MPa for 24 h. The biphasic asymmetric hydrogenation of dimethyl itaconate in BMI·BF₄–ⁱPrOH at 333 K and 2.0 MPa afforded 65% enantiomeric excess with an activity similar to the homogenous analogs. Both biphasic catalytic systems with (R)-BINAPS ligand could be reused several times without significantly decrease in the activity, enantio- and regio-selectivities. The effects of properties of ionic liquid, molar ratio of ligand to rhodium, temperature, pressure and reaction time have been discussed.     

Heterogeneous copper-free Sonogashira coupling reaction catalyzed by a reusable palladium Schiff base complex in water

Heterogeneous Sonogashira coupling of terminal alkynes with aryl halides was studied over a polymer-supported macrocyclic Schiff base palladium complex. The cross-coupling reaction proceeded smoothly by adding a piperidine in water medium. The catalyst exhibited effective catalytic activities to afford the corresponding products in good to excellent yields under copper-free conditions. Furthermore, the catalyst could be easily recovered and reused for several times without a significant loss of its activity.     

Aerobic oxidative dehydrogenation of benzylamines catalyzed by a cyclometalated ruthenium complex

The ruthenium(III) complex bearing phenylpyridine as a cyclometalated ligand serves as an efficient catalyst for the aerobic oxidative dehydrogenation of benzylamines to the corresponding benzonitriles under mild conditions.     

A hydroxyquinoline-appended ruthenium(II)-polypyridyl complex that induces and stabilizes G-quadruplex DNA

A polypyridyl ruthenium(II) complex with hydroxyquinoline-derived ligand has been synthesized and characterized. The ability to act as telomeric quadruplex inducer and stabilizer, and quadruplex-binding properties of the complex have been evaluated by absorption and emission analyses, fluorescent intercalator displacement (FID) titrations, circular dichroism (CD) spectroscopy, polymerase chain reaction (PCR) stop assay, color reaction studies, fluorescence resonance energy transfer (FRET) melting assay, Job plot, and molecular modeling. Observations revealed that the complex could well induce and stabilize the formation of antiparallel G-quadruplex of telomeric DNA in the presence or absence of metal cations, and showed superior G-quadruplex selectivity over duplex DNA with remarkable ΔT_m value of 18.0?°C even at 50-fold excessive supplies of calf thymus (ct) DNA. The complex exhibited high interaction affinity of 2.56?×?10⁶ M^?1 with G-quadruplex DNA and evident luminescence enhancements of 3.1 and 4.2 times for quadruplex binding in Na⁺ and K⁺ buffer, respectively. In addition, the 1:1 [quadruplex]/[complex] binding mode ratio was determined. The results suggest that the complex can be developed as potential anticancer reagent through binding and stabilization of G-quadruplex DNA.

     

水溶性配合物[RuCl2(TPPTS)2]2催化卤代硝基苯选择性加氢

以合成的水溶性钌配合物[RuC l2(TPPTS)2]2作为催化剂,用于水/有机两相体系中催化卤代硝基苯中硝基的选择性加氢反应.以对-氯硝基苯为底物,考察了反应温度、氢气压力、催化剂浓度、水溶液的pH值等对对-氯硝基苯转化率和生成对-氯苯胺选择性的影响.在100℃,氢气压力3.0 MPa时,反应6h,对-氯硝基苯转化率可达100%,生成对-氯苯胺的选择性可达95.2%.该催化剂对其他卤代硝基苯的加氢反应也表现出较高的催化活性.     

Inducement and stabilization of G-quadruplex DNA by a thiophene-containing dinuclear ruthenium(II) complex

G-quadruplex structures are attractive targets for the development of anticancer drugs, as their formation in human telomere could impair telomerase activity, thus inducing apoptosis in cancer cells. In this work, a thiophene-containing dinuclear ruthenium(II) complex, [Ru₂(bpy)₄(H₂bipt)]⁴⁺ {bpy = 2,2′-bipyridine, H₂bipt = 2,5-bis[1,10]phenanthrolin[4,5-f]-(imidazol-2-yl)thiophene}, was prepared and the interaction between the complex and human telomeric DNA oligomers 5′-G₃(T₂AG₃)₃-3′ (HTG21) has been investigated by UV-Vis, fluorescence and circular dichroism (CD) spectroscopy, fluorescence resonance energy transfer (FRET) melting assay, polymerase chain reaction (PCR) stop assay, fluorescent intercalator displacement (FID) titrations, Job plot and color reaction studies. The results indicate that the complex can well induce and stabilize the formation of antiparallel G-quadruplex of telomeric DNA in the presence or absence of metal cations, and the ΔT_m value of the G-quadruplex DNA treated with the complex was obtained to be 12.8 °C even at levels of 50-fold molar of duplex DNA (calf-thymus DNA), suggesting that the complex exhibits higher G-quadruplex DNA selectivity over duplex DNA. The complex shows high interaction ability with G-quadruplex DNA at (1.17 ± 0.12) × 10⁷ M^?1 binding affinity using a 2:1 [complex]/[quadruplex] binding mode ratio. A novel visual method has been developed here for making a distinction between G-quadruplex DNA and duplex DNA by our ruthenium complex binding hemin to form the hemin-G-quadruplex DNAzyme.     

The first ruthenium(II) complex with benzotriazole and pyridylcarboxylato ligands

The reaction of [RuCl₂(PPh₃)₃] with 1-(2-pyridylcarbonyl)benzotriazole has been examined. A new ruthenium(II) complex–[RuCl(PPh₃)₂(C₆H₅N₃)(C₅H₄NCO₂)] has been obtained and characterized by IR and UV–Vis measurements. The crystal structure of the complex has been determined. The electronic spectrum of the complex has been calculated by TDDFT method.     

Highly efficient oxidation of alcohols using Oxone(R) as oxidant catalyzed by ruthenium complex under mild reaction conditions

Aromatic and alkyl alcohols were oxidized to the corresponding aldehydes or ketones at room temperature with high conversion and selectivity using Oxone (2KHSO5·KHSO4·K2SO4) as oxidant catalyzed by ruthenium complex Quin-Ru-Quin (where Quin = 8-hydroxyquinoline). The reaction time is very short and the preparation of complex is simple. 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.