- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
-
We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
-
p. 13337 - 13347
(2021/11/20)
-
- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
-
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
-
supporting information
p. 9029 - 9039
(2021/06/28)
-
- Sustainable System for Hydrogenation Exploiting Energy Derived from Solar Light
-
Herein described is a sustainable system for hydrogenation that uses solar light as the ultimate source of energy. The system consists of two steps. Solar energy is captured and chemically stored in the first step; exposure of a solution of azaxanthone in ethanol to solar light causes an energy storing dimerization of the ketone to produce a sterically strained 1,2-diol. In the second step, the chemical energy stored in the vicinal diol is released and used for hydrogenation; the diol offers hydrogen onto alkenes and splits back to azaxanthone, which is easily recovered and reused repeatedly for capturing solar energy.
- Ishida, Naoki,Kamae, Yoshiki,Ishizu, Keigo,Kamino, Yuka,Naruse, Hiroshi,Murakami, Masahiro
-
supporting information
p. 2217 - 2220
(2021/02/16)
-
- Towards the Circular Economy: Converting Aromatic Plastic Waste Back to Arenes over a Ru/Nb2O5 Catalyst
-
The upgrading of plastic waste is one of the grand challenges for the 21st century owing to its disruptive impact on the environment. Here, we show the first example of the upgrading of various aromatic plastic wastes with C?O and/or C?C linkages to arenes (75–85 % yield) via catalytic hydrogenolysis over a Ru/Nb2O5 catalyst. This catalyst not only allows the selective conversion of single-component aromatic plastic, and more importantly, enables the simultaneous conversion of a mixture of aromatic plastic to arenes. The excellent performance is attributed to unique features including: (1) the small sized Ru clusters on Nb2O5, which prevent the adsorption of aromatic ring and its hydrogenation; (2) the strong oxygen affinity of NbOx species for C?O bond activation and Br?nsted acid sites for C?C bond activation. This study offers a catalytic path to integrate aromatic plastic waste back into the supply chain of plastic production under the context of circular economy.
- Jing, Yaxuan,Wang, Yanqin,Furukawa, Shinya,Xia, Jie,Sun, Chengyang,Hülsey, Max J.,Wang, Haifeng,Guo, Yong,Liu, Xiaohui,Yan, Ning
-
supporting information
p. 5527 - 5535
(2021/02/05)
-
- Raney nickel-catalyzed hydrodeoxygenation and dearomatization under transfer hydrogenation conditions—Reaction pathways of non-phenolic compounds
-
Catalytic reduction of oxygen-containing aromatic compounds has been studied under transfer hydrogenation (TH) conditions at 150 °C in 2-PrOH as a hydrogen donor. Raney nickel is used as a heterogeneous catalyst. The reaction of aromatic non-phenolic carbonyl compounds is most likely to proceed through the pathway “aromatic ketone (aldehyde)→aromatic alcohol→alkylaromatics→saturated alkylcyclohexane”. One of the main reactions under the TH conditions is a hydrodeoxygenation (HDO) process. Unexpectedly, the hydrodeoxygenation of aromatic ketones to alkylaromatics (C[dbnd]O → CH2) occurs faster than of corresponding aromatic alcohols (HC–OH → CH2) that means either additional reaction pathway of its hydrodeoxygenation missing for the corresponding aromatic alcohols or specific interaction of OH functionality with Raney nickel surface obstructing (hindering) the further reduction. Benzaldehyde is shown to be less reactive than the aromatic ketones under the same reaction conditions. The main reason is proposed to be carbon monoxide release resulted from the decarbonylation of the aldehyde. Carbon monoxide demonstrates a poisoning effect on Raney nickel surface that is evidenced in the catalyzed TH reaction of acetophenone. The HDO reaction of anisole under the same reaction conditions was a little slowly than of oxygen-containing non-phenolic aromatics.
- Philippov,Chibiryaev,Martyanov
-
-
- Cross-Coupling Reactions of Alkyl Halides with Aryl Grignard Reagents Using a Tetrachloroferrate with an Innocent Countercation
-
Bis(triphenylphosphoranylidene)ammonium tetrachloroferrate, (PPN)[FeCl4] (1), was evaluated as a catalyst for cross-coupling reactions. 1 exhibits high stability toward air and moisture and is an effective catalyst for the reaction of secondary alkyl halides with aryl Grignard reagents. The PPN cation is considered as an innocent counterpart to the iron center. We have developed an easy-to-handle iron catalyst for “ligand-free” cross-coupling reactions. (Figure presented.).
- Hashimoto, Toru,Maruyama, Tsubasa,Yamaguchi, Takamichi,Matsubara, Yutaka,Yamaguchi, Yoshitaka
-
supporting information
p. 4232 - 4236
(2019/08/16)
-
- Carbonyl and olefin hydrosilylation mediated by an air-stable phosphorus(iii) dication under mild conditions
-
The readily-accessible, air-stable Lewis acid [(terpy)PPh][B(C6F5)4]21 is shown to mediate the hydrosilylation of aldehydes, ketones, and olefins. The utility and mechanism of these hydrosilylations are considered.
- Andrews, Ryan J.,Chitnis, Saurabh S.,Stephan, Douglas W.
-
supporting information
p. 5599 - 5602
(2019/05/21)
-
- Mild and efficient rhodium-catalyzed deoxygenation of ketones to alkanes
-
A new and simple method for the deoxygenation of ketones to alkanes is presented. Most substrates are reduced under mild conditions by triethylsilane in the presence of catalytic amounts of [Rh(μ-Cl)(CO)2]2. This system selectively provides the methylene hydrocarbons in good to excellent yields starting from acetophenones and diaryl ketones. A rapid examination of the reaction pathway suggests that the ketone is first converted into an alcohol, which then undergoes hydrogenolysis to give the alkane.
- Argouarch, Gilles
-
supporting information
p. 11041 - 11044
(2019/07/31)
-
- Bioinspired Metal-Free Formal Decarbonylation of α-Branched Aliphatic Aldehydes at Ambient Temperature
-
A sequence of a Baeyer–Villiger oxidation and a Lewis acid-promoted reduction of the resulting formate with Et3SiH enabled the metal-free formal decarbonylation of tertiary and secondary aliphatic aldehydes. The new methodology mimics the biosynthetic decarbonylation pathway through oxidative C?C bond cleavage rather than the C(O)?H bond activation known from conventional Tsuji–Wilkinson-type reactions. The substrate scope is complementary to existing transition-metal-catalyzed protocols.
- Richter, Sven C.,Oestreich, Martin
-
p. 8508 - 8512
(2019/06/04)
-
- Nickel-Catalyzed Cross-Coupling of Umpolung Carbonyls and Alkyl Halides
-
An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
-
p. 6312 - 6322
(2019/05/24)
-
- Nickel-catalyzed cross-coupling of umpolung carbonyls and alkyl halides
-
An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
-
-
- Breaking the Limit of Lignin Monomer Production via Cleavage of Interunit Carbon–Carbon Linkages
-
Conversion of lignin into monocyclic hydrocarbons as commodity chemicals and drop-in fuels is a highly desirable target for biorefineries. However, this is severely hindered by the presence of stable interunit carbon–carbon linkages in native lignin and those formed during lignin extraction. Herein, we report a new multifunctional catalyst, Ru/NbOPO4, that achieves the first example of catalytic cleavage of both interunit C–C and C–O bonds in one-pot lignin conversions to yield 124%–153% of monocyclic hydrocarbons, which is 1.2–1.5 times the yields obtained from the established nitrobenzene oxidation method. This catalyst also exhibits high stability and selectivity (up to 68%) to monocyclic arenes over repeated cycles. The mechanism of the activation and cleavage of 5–5 C–C bonds in biphenyl, as a lignin model adopting the most robust C–C linkages, has been revealed via in situ inelastic neutron scattering coupled with modeling. This study breaks the conventional theoretical limit on lignin monomer production. The conversion of lignin into monocyclic hydrocarbons as commodity chemicals and drop-in fuels is essential for the future of biorefineries. State-of-the-art lignin depolymerization is primarily achieved via cleavage of interunit C–O bonds to form low-molecular-weight feedstocks. However, these processes can hardly cleave interunit C–C bonds in lignin, and thus, the yields of lignin monomers are heavily restricted. Here, we report a multifunctional catalyst, Ru/NbOPO4, that achieves the first example of catalytic cleavage of both interunit C–C and C–O bonds in lignin in one-pot reactions to yield 153% of monocyclic C6–C9 hydrocarbons from Kraft lignin, which is 1.5 times the theoretical yield obtained from the established nitrobenzene oxidation (NBO) method. Thus, significantly, this study successfully breaks the conventional limit on lignin monomer production. Lignin, containing a large volume of aromatic functionalities, is the most energy-dense fraction of renewable biomass. Particularly, conversion of lignin into monocyclic hydrocarbons as commodity chemicals is a highly desirable target. However, this is severally hindered by the presence of stable interunit carbon–carbon linkages in native lignin and those formed during lignin extraction. Here, we report a multifunctional Ru/NbOPO4 catalyst that achieves the first example of catalytic cleavage of both interunit C–C and C–O bonds in lignin in one-pot reactions.
- Dong, Lin,Lin, Longfei,Han, Xue,Si, Xiaoqin,Liu, Xiaohui,Guo, Yong,Lu, Fang,Rudi?, Svemir,Parker, Stewart F.,Yang, Sihai,Wang, Yanqin
-
p. 1521 - 1536
(2019/06/14)
-
- Cobalt-Nanoparticles Catalyzed Efficient and Selective Hydrogenation of Aromatic Hydrocarbons
-
The development of inexpensive and practical catalysts for arene hydrogenations is key for future valorizations of this general feedstock. Here, we report the development of cobalt nanoparticles supported on silica as selective and general catalysts for such reactions. The specific nanoparticles were prepared by assembling cobalt-pyromellitic acid-piperazine coordination polymer on commercial silica and subsequent pyrolysis. Applying the optimal nanocatalyst, industrial bulk, substituted, and functionalized arenes as well as polycyclic aromatic hydrocarbons are selectively hydrogenated to obtain cyclohexane-based compounds under industrially viable and scalable conditions. The applicability of this hydrogenation methodology is presented for the storage of H2 in liquid organic hydrogen carriers.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Alshammari, Ahmad S.,Altamimi, Rashid M.,Kreyenschulte, Carsten,Pohl, Marga-Martina,Lund, Henrik,Jagadeesh, Rajenahally V.,Beller, Matthias
-
p. 8581 - 8591
(2019/09/12)
-
- Bimetallic Nanoparticles in Supported Ionic Liquid Phases as Multifunctional Catalysts for the Selective Hydrodeoxygenation of Aromatic Substrates
-
Bimetallic iron–ruthenium nanoparticles embedded in an acidic supported ionic liquid phase (FeRu@SILP+IL-SO3H) act as multifunctional catalysts for the selective hydrodeoxygenation of carbonyl groups in aromatic substrates. The catalyst material is assembled systematically from molecular components to combine the acid and metal sites that allow hydrogenolysis of the C=O bonds without hydrogenation of the aromatic ring. The resulting materials possess high activity and stability for the catalytic hydrodeoxygenation of C=O groups to CH2 units in a variety of substituted aromatic ketones and, hence, provide an effective and benign alternative to traditional Clemmensen and Wolff–Kishner reductions, which require stoichiometric reagents. The molecular design of the FeRu@SILP+IL-SO3H materials opens a general approach to multifunctional catalytic systems (MM′@SILP+IL-func).
- Offner-Marko, Lisa,Bordet, Alexis,Moos, Gilles,Tricard, Simon,Rengshausen, Simon,Chaudret, Bruno,Luska, Kylie L.,Leitner, Walter
-
supporting information
p. 12721 - 12726
(2018/09/12)
-
- Intermolecular Pummerer Coupling with Carbon Nucleophiles in Non-Electrophilic Media
-
A new Pummerer-type C?C coupling protocol is introduced based on turbo-organomagnesium amides, which unlike traditional Pummerer reactions, does not require strong electrophilic activators, engages a broad range of C(sp3)-, C(sp2)-, and C(sp)-nucleophiles, and seamlessly integrates with C?H and C?X magnesiation. Given the central character of sulfur compounds in organic chemistry, this protocol allows access to unrelated carbonyls, olefins, organometallics, halides, and boronic esters through a single strategy.
- Colas, Kilian,Martín-Montero, Raúl,Mendoza, Abraham
-
supporting information
p. 16042 - 16046
(2017/11/21)
-
- Catalytic Hydrogenation of Arenes in Water Over In Situ Generated Ruthenium Nanoparticles Immobilized on Carbon
-
We describe a tandem process to generate active Ru nanoparticles (≈7 nm) immobilised in situ on carbon from an organometallic precursor and formic acid to afford the hydrogenation of a wide range of arenes and heteroarenes in yields up to 72 % with high conversions and selectivities for the desired products. The hydrogenation of several substrates analogous to lignin-derived fragments to the corresponding alicyclic products was also achieved. Our experimental investigations evidenced that the observed enhanced activity for arene hydrogenation was driven by the unique structural advantages of the organometallic precursor to activate formic acid, in which the presence of a nitrogen ligand is crucial to achieve a high catalytic activity. TEM analysis revealed the formation of Ru0 nanoparticles, and Hg0 poisoning experiments support the heterogeneous nature of the active catalyst.
- Dwivedi, Ambikesh Dhar,Rai, Rohit Kumar,Gupta, Kavita,Singh, Sanjay Kumar
-
p. 1930 - 1938
(2017/06/13)
-
- Highly selective catalytic hydroconversion of benzyloxybenzene to bicyclic cyclanes over bifunctional nickel catalysts
-
An active bifunctional nickel catalyst was prepared by decomposing Ni(CO)4 to highly dispersed metallic Ni onto Hβ zeolite and first applied in hydroconverting benzyloxybenzene (BOB), which was used as a lignin-related model compound. Ni/Hβ proved to be effective for converting BOB to bicyclic cyclanes (BCCs) via Calk–O bond cleavage induced by H+ addition, benzylium addition to 2- and 4-positions in phenol, hydrogenation of benzene ring, dehydration, and H? abstraction. Compared to one-step conversion, the total BCC selectivity (TBCCS) significantly increases from catalytic hydroconversion of catalytically converted BOB by pretreatment under pressurized N2.
- Zhou, Xiao,Wei, Xian-Yong,Liu, Zhong-Qiu,Lv, Jing-Hui,Wang, Yue-Lun,Li, Zhan-Ku,Zong, Zhi-Min
-
-
- Ferrocenyl-derived electrophilic phosphonium cations (EPCs) as Lewis acid catalysts
-
Oxidation of diphenylphosphinoferrocene and 1,1′-bis(diphenylphosphino)ferrocene with XeF2, resulted in the formation of CpFe(η5-C5H4PF2Ph2) 1 and Fe(η5-C5H4PF2Ph2)22 respectively. Subsequent reactions with [SiEt3][B(C6F5)4] yielded [CpFe(η5-C5H4PFPh2)][B(C6F5)4] 3 and [Fe(η5-C5H4PFPh2)2] [B(C6F5)4]24. PhP(η5-C5H4)2Fe 5 was prepared, converted to [PhMeP(η5-C5H4)2Fe][O3SCF3] 6 and then to [PhMeP(η5-C5H4)2Fe][B(C6F5)4] 7. The ability of the salts 3, 4 and 7 to catalyze Friedel-Crafts dimerization of 1,1-diphenylethylene, dehydrocoupling of phenol and triethylsilane, deoxygenation of acetophenone and hydrodefluorination of 1-fluoropentane were probed. While compound 7 proved to be ineffective, compounds 3 and 4 were useful Lewis acid catalysts. Compounds 3 and 4 were shown to catalyze the deoxygenation of a series of ketones.
- Mallov, Ian,Stephan, Douglas W.
-
supporting information
p. 5568 - 5574
(2016/04/09)
-
- Use of steric encumbrance to develop conjugated nanoporous polymers for metal-free catalytic hydrogenation
-
The design and synthesis of metal-free heterogeneous catalysts for efficient hydrogenation remains a great challenge. Here we report a novel approach to create conjugated nanoporous polymers with efficient hydrogenation activities toward unsaturated ketones by leveraging the innate steric encumbrance. The steric bulk of the framework as well as the local sterics of the Lewis basic sites within the polymeric skeleton result in the generation of the putative catalyst. This approach opens up new possibilities for the development of innovative metal-free heterogeneous catalysts.
- Tian, Chengcheng,Zhu, Xiang,Abney, Carter W.,Tian, Ziqi,Jiang, De-En,Han, Kee Sung,Mahurin, Shannon M.,Washton, Nancy M.,Dai, Sheng
-
supporting information
p. 11919 - 11922
(2016/10/11)
-
- Use of Trifluoromethyl Groups for Catalytic Benzylation and Alkylation with Subsequent Hydrodefluorination
-
The electrophilic organofluorophosphonium catalyst [(C6F5)3PF][B(C6F5)4] is shown to effect benzylation or alkylation by aryl and alkyl CF3 groups with subsequent hydrodefluorination, thus resulting in a net transformation of CF3 into CH2-aryl fragments. In the case of alkyl CF3 groups, Friedel-Crafts alkylation by the difluorocarbocation proceeded without cation rearrangement, in contrast to the corresponding reactions of alkyl monofluorides.
- Zhu, Jiangtao,Prez, Manuel,Caputo, Christopher B.,Stephan, Douglas W.
-
supporting information
p. 1417 - 1421
(2016/02/14)
-
- Mechanistic Studies of Catalytic Carbon-Carbon Cross-Coupling by Well-Defined Iron NHC Complexes
-
The mechanism of iron-catalyzed carbon-carbon cross-coupling reactions between Grignard reagents and alkyl halides has been investigated using well-defined N-heterocyclic carbene (NHC) compounds. The iron(II) precatalyst, [Fe2Cl2(μ-Cl)2(IPr)2], was employed in several C-C cross coupling reactions exhibiting the ability to efficiently couple primary and secondary alkyl halides with several aryl and alkyl Grignard reagents. For selected substrates, a 2 mol % catalyst loading (4 mol % Fe) afforded conversions of >99% and were achieved with 8% homocoupling of the electrophile. The mechanism of the coupling reaction was studied by means of radical clock, radical trap, and single-turnover experiments, which support a radical-based cycle involving an Fe(II/III) redox couple. The implications of this mechanism on the efficacy of iron-NHC-catalyzed cross-coupling reactions are discussed.
- Przyojski, Jacob A.,Veggeberg, Kevin P.,Arman, Hadi D.,Tonzetich, Zachary J.
-
p. 5938 - 5946
(2015/10/12)
-
- Mild Deoxygenation of Aromatic Ketones and Aldehydes over Pd/C Using Polymethylhydrosiloxane as the Reducing Agent
-
Herein, a practical and mild method for the deoxygenation of a wide range of benzylic aldehydes and ketones is described, which utilizes heterogeneous Pd/C as the catalyst together with the green hydride source, polymethylhydrosiloxane. The developed catalytic protocol is scalable and robust, as exemplified by the deoxygenation of ethyl vanillin, which was performed on a 30 mmol scale in an open-to-air setup using only 0.085 mol% Pd/C catalyst to furnish the corresponding deoxygenated product in 93% yield within 3 hours at room temperature. Furthermore, the Pd/C catalyst was shown to be recyclable up to 6 times without any observable decrease in efficiency and it exhibited low metal leaching under the reaction conditions.
- Volkov, Alexey,Gustafson, Karl P. J.,Tai, Cheuk-Wai,Verho, Oscar,B?ckvall, Jan-E.,Adolfsson, Hans
-
supporting information
p. 5122 - 5126
(2015/04/27)
-
- Solvothermal synthesis of MoS2 nanospheres in DMF-water mixed solvents and their catalytic activity in hydrocracking of diphenylmethane
-
MoS2 nanospheres were successfully prepared via a solvothermal process using 1-ethyl-3-methylimidazolium bromide ([EMIM]Br) in a mixed solvent of DMF-water. A probable [EMIM]Br aggregation in different mixed solvents and the formation mechanism of the MoS2 nanospheres are presented. The MoS2 nanospheres delivered high catalytic activity in hydrocracking of diphenylmethane.
- Du, Hui,Liu, Dong,Li, Min,Al Otaibi, Raja L.,Lv, Renqing,Zhang, Yadong
-
p. 79724 - 79728
(2015/10/05)
-
- Scope and Mechanistic Analysis for Chemoselective Hydrogenolysis of Carbonyl Compounds Catalyzed by a Cationic Ruthenium Hydride Complex with a Tunable Phenol Ligand
-
A cationic ruthenium hydride complex, [(C6H6)(PCy3)(CO)RuH]+BF4- (1), with a phenol ligand was found to exhibit high catalytic activity for the hydrogenolysis of carbonyl compounds to yield the corresponding aliphatic products. The catalytic method showed exceptionally high chemoselectivity toward the carbonyl reduction over alkene hydrogenation. Kinetic and spectroscopic studies revealed a strong electronic influence of the phenol ligand on the catalyst activity. The Hammett plot of the hydrogenolysis of 4-methoxyacetophenone displayed two opposite linear slopes for the catalytic system 1/p-X-C6H4OH (ρ = -3.3 for X = OMe, t-Bu, Et, and Me; ρ = +1.5 for X = F, Cl, and CF3). A normal deuterium isotope effect was observed for the hydrogenolysis reaction catalyzed by 1/p-X-C6H4OH with an electron-releasing group (kH/kD = 1.7-2.5; X = OMe, Et), whereas an inverse isotope effect was measured for 1/p-X-C6H4OH with an electron-withdrawing group (kH/kD = 0.6-0.7; X = Cl, CF3). The empirical rate law was determined from the hydrogenolysis of 4-methoxyacetophenone: rate = kobsd[Ru][ketone][H2]-1 for the reaction catalyzed by 1/p-OMe-C6H4OH, and rate = kobsd[Ru][ketone][H2]0 for the reaction catalyzed by 1/p-CF3-C6H4OH. Catalytically relevant dinuclear ruthenium hydride and hydroxo complexes were synthesized, and their structures were established by X-ray crystallography. Two distinct mechanistic pathways are presented for the hydrogenolysis reaction on the basis of these kinetic and spectroscopic data. (Chemical Equation Presented).
- Kalutharage, Nishantha,Yi, Chae S.
-
supporting information
p. 11105 - 11114
(2015/09/15)
-
- Imidazolidinium ferrate complexes: Synthesis and catalytic properties
-
The new well-defined and air stable anionic iron complexes bearing an imidazolidinium ligand (2a-d) have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction studies. Starting from FeBr2, [imidazolidinium][FeBr4] complexes 2a and 2b were prepared. The reaction of imidazolidinium chlorides with Fe(OAc)2, followed by a recrystallization in the air led to bis(imidazolidinium) μ-oxido-bis[trichloroferrate(III)] complexes 2c and 2d. The catalytic activity of these novel complexes has been evaluated in the cross-coupling reactions of alkyl halides with Grignard reagents.
- Demir, Serpil,G?k?e, Yasemin,Roisnel, Thierry,Sortais, Jean-Baptiste,Darcel, Christophe,?zdemir, Ismail
-
p. 541 - 548
(2014/06/09)
-
- A NiPdB-PEG(800) amorphous alloy catalyst for the chemoselective hydrogenation of electron-deficient aromatic substrates
-
A new Pd and polyethylene glycol 800 [PEG(800)]-modified NiB [NiPdB-PEG(800)] amorphous alloy catalyst was prepared, which demonstrated excellent activities, similar to those of noble metal catalysts, in the chemoselective hydrogenation of a series of electron-deficient aromatic substrates in water. The addition of small amounts of Pd to NiB markedly improved its activity. The Pd not only benefits the dispersion of active species but also contributes to the activity of the catalyst. The accompanying agglomeration can be inhibited with the further addition of PEG(800), which results in the largest surface area, the smallest particle size, and the greatest number of active species, resulting in optimum H2- chemisorption and accounting for its highest activity. The key factors determining the main reaction products depend not only on the structures of the substrates but also on the character of the solvents. Water is found to be the most effective solvent for most of the substrates. Disperse and be active! A Pd and polyethylene glycol 800 [PEG(800)]-modified NiB [NiPdB-PEG(800)] amorphous alloy catalyst demonstrates excellent activities, similar to those of noble metal catalysts, in the chemoselective hydrogenation of a series of electron-deficient aromatic substrates in water. The addition of Pd benefits the dispersion of active species and contributes to the activity of the catalyst. Copyright
- Bai, Guoyi,Zhao, Zhen,Dong, Huixian,Niu, Libo,Wang, Yalong,Chen, Qingzhi
-
p. 655 - 662
(2014/03/21)
-
- Reduction of aromatic compounds with Al powder using noble metal catalysts in water under mild reaction conditions
-
In water, Al powder becomes a powerful reducing agent, transforming in cyclohexyl either one or both benzene rings of aromatic compounds such as biphenyl, fluorene and 9,10-dihydroanthracene under mild reaction conditions in the presence of noble metal catalysts, such as Pd/C, Rh/C, Pt/C, or Ru/C. The reaction is carried out in a sealed tube, without the use of any organic solvent, at low temperature. Partial aromatic ring reduction was observed when using Pd/C, the reaction conditions being 24 h and 60 °C. The complete reduction process of both aromatic rings required 12 h and 80 °C with Al powder in the presence of Pt/C.
- Rayhan, Ummey,Kwon, Hyeokmi,Yamato, Takehiko
-
p. 952 - 957
(2014/08/18)
-
- Dispersion and hydrogenation activity of surfactant-stabilized Rh(0) nanoparticles prepared on different mesoporous supports
-
Supported Rh(0) colloidal particles were prepared by the reduction of Rh(III) ions by sodium borohydride in the presence of N-N-dimethyl-N-cetyl-N-(2- hydroxyethyl) ammonium chloride (HEA16Cl), usually used as a stabilizing agent in solution. Tested supports were Na-Al-SBA-15, SBA-15 and CMK-3. In each case, the influence of HEA16Cl was studied by comparison with blank samples. Surfactant and rhodium uptake were evaluated by means of elemental analysis and eventually thermogravimetry. Obtained materials were also characterized by XRD, N2 sorption and TEM. Given the results, it appears that HEA16Cl promotes rhodium uptake in all cases. Most significant effects on the size and dispersion of particles were observed for the system combining HEA16Cl and Na-Al-SBA-15. All the solids prepared in this study were tested in the room temperature hydrogenation of styrene as well as that of a more demanding substrate, diphenylmethane, at 0.1 MPa of H2. All of them were generally more active than their commercial analogue (5 wt.% Rh0/C). Best catalysts, i.e., those prepared from Na-Al-SBA-15 in the presence of HEA16Cl as well as CMK-3 without HEA16Cl, allowed almost 100% yield of dicyclohexylmethane within 6 h (molar substrate/Rh = 100).
- Boutros, Maya,Shirley, Guillaume,Onfroy, Thomas,Launay, Franck
-
scheme or table
p. 158 - 165
(2012/01/02)
-
- Iron-catalyzed cross-coupling of alkyl sulfonates with arylzinc reagents
-
Iron-catalyzed cross-coupling reactions of primary and secondary alkyl sulfonates with arylzinc reagents proceed smoothly In the presence of excess TMEDA and a concomitant magnesium salt. The arylzinc reagents are prepared from the corresponding aryllithium or magnesium reagents with ZnI2. The In situ formation of alkyl Iodides and consecutive rapid cross-coupling avoids discrete preparation of the unstable secondary alkyl halides and also achieves high product selectivity.
- Ito, Shingo,Fujiwara, Yu-Ichi,Nakamura, Eiichi,Nakamura, Masaharu
-
supporting information; experimental part
p. 4306 - 4309
(2009/12/26)
-
- Nickel complexes of a pincer amidobis(amine) ligand: Synthesis, structure, and activity in stoichiometric and catalytic C-C bond-forming reactions of alkyl halides
-
The synthesis, properties, and reactivity of nickel(II) complexes of a newly developed pincer amidobis(amine) ligand (McNN2) are described. Neutral or cationic complexes [(MeNN2)NiX] (X = OTf (6), OC(O)CH3 (7), CH3CN (8), OMe (9)) were prepared by salt metathesis or chloride abstraction from the previously reported [( MeNN2)NiCl] (1). The Lewis acidity of the {( McNN2)Ni) fragment was measured by the 1H NMR chemical shift of the coordinated CH3CN molecule in 8. Electrochemical measurements on 1 and 8 indicate that the electron-donating properties of NN2 are similar to those of the analogous amidobis(phosphine) (pnp) ligands. The solid-state structures of 6-8 were determined and compared to those of 1 and [(MeNN2)NiEt] (3). In all complexes, the MeNN2 ligand coordinates to the NiII ion in a mer fashion, and the square-planar coordination sphere of the metal is completed by an additional donor. The coordination chemistry of MeNN 2 thus resembles that of other three-dentate pincer ligands, for example, pnp and arylbis(amine) (ncn). Reactions of 2 with alkyl monohalides, dichlorides, and trichlorides were investigated. Selective C-C bond formation was observed in many cases. Based on these reactions, efficient Kumada-Corriu-Tamao coupling of unactivated alkyl halides and alkyl Grignard reagents with 1 as the precatalyst was developed. Good yields were obtained for the coupling of primary and secondary iodides and bromides. Double C-C coupling of CH2Cl2 with alkyl Grignard reagents by 1 was also realized. The scope and limitations of these transformations were studied. Evidence was found for a radical pathway in Ni-catalyzed C-C cross-coupling reactions, which involves NiIl alkyl intermediates.
- Vechorkin, Oleg,Csok, Zsolt,Scopelliti, Rosario,Hu, Xile
-
experimental part
p. 3889 - 3899
(2009/12/26)
-
- Rhodium/graphite-catalyzed hydrogenation of carbocyclic and heterocyclic aromatic compounds
-
Rhodium on graphite (Rh/Gr, C24Rh) was prepared by reaction of anhydrous rhodium trichloride with potassium graphite (C8K, 3 equivalents) and used as a heterogeneous catalyst for the hydrogenation of carbocyclic and heterocyclic aromatic compounds at room temperature and 1 atm of hydrogen pressure. The effect of substitution on the benzene ring was examined in a variety of derivatives, including those with alkyl, hydroxy, alkoxy, aryloxy, carboxy, amino, nitro, acyl, chloro, or functionalized alkyl groups. Reduction of carbonyl functions of aromatic aldehydes and ketones occurred with complete or partial cleavage of the benzylic C-O bond; this cleavage also occurred in the hydrogenation of benzylic alcohols and esters. Georg Thieme Verlag Stuttgart.
- Falini, Giuseppe,Gualandi, Andrea,Savoia, Diego
-
experimental part
p. 2440 - 2446
(2010/02/27)
-
- Efficient and Practical Arene Hydrogenation by Heterogeneous Catalysts under Mild Conditions
-
An efficient and practical arene hydrogenation procedure based on the use of heterogeneous platinum group catalysts has been developed. Rh/C is the most effective catalyst for the hydrogenation of the aromatic ring, which can be conducted in iPrOH under neutral conditions and at ordinary to medium H 2 pressures (10 atm). A variety of arenes such as alkylbenzenes, benzoic acids, pyridines, furans, are hydrogenated to the corresponding cyclohexyl and heterocyclic compounds in good to excellet yields. The use of Ru/C, less expensive than Rh/C, affords an effective and practical method for the hydrogenation of arenes including phenols. Both catalysts can be reused several times after simple filtration without any significant loss of catalytic activity.
- Maegawa, Tomohiro,Akashi, Akira,Yaguchi, Kiichiro,Iwasaki, Yohei,Shigetsura, Masahiro,Monguchi, Yasunari,Sajiki, Hironao
-
experimental part
p. 6953 - 6963
(2010/02/28)
-
- Silver-catalyzed benzylation and allylation reactions of tertiary and secondary alkyl halides with grignard reagents
-
Treatment of alkyl halides, including tertiary alkyl bromides, with benzylic or allylic Grignard reagent in the presence of a catalytic amount of silver nitrate in ether yielded the corresponding cross-coupling products in high yields. The coupling reactions of tertiary alkyl halides provide efficient access to quaternary carbon centers.
- Someya, Hidenori,Ohmiya, Hirohisa,Yorimitsu, Hideki,Oshima, Koichiro
-
scheme or table
p. 969 - 971
(2009/04/10)
-
- New method for the reduction of benzophenones with Raney Ni-Al alloy in water
-
Raney Ni-Al alloy in a dilute alkaline aqueous solution has been shown to be a powerful reducing agent, which is highly effective in the reduction of benzophenones to the corresponding hydrocarbon derivatives, in the absence of any organic solvents. Copyright Taylor & Francis Group, LLC.
- Liu, Guo-Bin,Zhao, Hong-Yun,Zhu, Jia-Da,He, Hong-Jie,Yang, Hong-Jie,Thiemann, Thies,Tashiro, Hideki,Tashiro, Masashi
-
p. 1651 - 1661
(2008/09/20)
-
- Preparation and application of odorless 1,3-propanedithiol reagents
-
2-Dodecyl-1,3-propanedithiol (2a) was prepared without a malodorous procedure as an odorless reagent that was usable in place of 1,3-propanedithiol (1) in organic reactions, e.g., in the reduction of azides and protection of carbonyl groups. The 1,3-dithioacetals obtained in the latter reaction were effectively reduced to methylene with Raney nickel and reconverted to the original carbonyl compounds by hydrolysis with N-bromosuccinimide in aqueous 2-butanone. In addition, the anion of 1,3-dithiane prepared from 2a and formaldehyde could be utilized as a synthetic equivalent of an anionic carbonyl carbon.
- Matoba, Manabu,Kajimoto, Tetsuya,Nishide, Kiyoharu,Node, Manabu
-
p. 141 - 146
(2007/10/03)
-
- A mild and facile method for complete hydrogenation of aromatic nuclei in water
-
A mild and complete hydrogenation of aromatic rings catalyzed by heterogeneous 10% Rh/C proceeds at 80 °C in water under 5 atm of H 2 pressure. This method is applicable to the hydrogenation of various carbon and heteroaromatic compounds such as alkylbenzenes, biphenyls, pyridines and furans. Georg Thieme Verlag Stuttgart.
- Maegawa, Tomohiro,Akashi, Akira,Sajiki, Hironao
-
p. 1440 - 1442
(2007/10/03)
-
- Biphasic Suzuki coupling reactions of aryl or benzyl bromides employing cobalt-containing phosphine ligand coordinated palladium complex
-
Biphasic Suzuki-coupling reactions of aryl and benzyl bromides employing a cobalt-containing phosphine ligand chelated palladium complex 2 were carried out in various reaction conditions. Comparisons of the catalytic efficiencies in the presence/absence of a phase-transfer agent, TBAB, were presented. In addition, the effects of altering solvents, temperatures, catalysts, and substrates on the reactions were monitored and reported. Better yields were commonly observed while a phase-transfer agent TBAB was participated in the reactions. The factor of reaction time is more crucial than that of temperature in short reaction hour experiments. Obviously, an induction period for the reduction of Pd(II) to Pd(0) active species is needed for this type of reaction.
- Chang, Chin-Pei,Huang, Yi-Luen,Hong, Fung-E
-
p. 3835 - 3839
(2007/10/03)
-
- QUINOLINE-DERIVED AMIDE MODULATORS OF VANILLOID VR1 RECEPTOR
-
This invention is directed to vanilloid receptor VR1 ligands. More particularly, this invention relates to quinoline-derived amides that are potent antagonists or agonists of VR1 which are useful for the treatment and prevention of inflammatory and other pain conditions in mammals.
- -
-
-
- Cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic and benzylic grignard reagents and their application to tandem radical cyclization/cross-coupling reactions
-
Details of cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic Grignard reagents are disclosed. A combination of cobalt(II) chloride and 1,2-bis(diphenylphosphino)ethane (DPPE) or 1,3-bis(diphenylphosphino)propane (DPPP) is suitable as a precatalyst and allows secondary and tertiary alkyl halides-as well as primary ones-to be employed as coupling partners for allyl Grignard reagents. The reaction offers a facile synthesis of quaternary carbon centers. which has practically never been possible with palladium, nickel, and copper catalysts. Benzyl, methallyl, and crotyl Grignard reagents can all couple with alkyl halides. The benzylation definitely requires DPPE or DPPP as a ligand. The reaction mechanism should include the generation of an alkyl radical from the parent alkyl halide. The mechanism can be interpreted in terms of a tandem radical cyclization/cross-coupling reaction. In addition, serendipitous tandem radical cyclization/cyclopropanation/carbonyl allylation of 5-alkoxy-6-halo-4-oxa-1-hexene derivatives is also described. The intermediacy of a carbon-centered radical results in the loss of the original stereochemistry of the parent alkyl halides, creating the potential for asymmetric cross-coupling of racemic alkyl halides.
- Ohmiya, Hirohisa,Tsuji, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
-
p. 5640 - 5648
(2007/10/03)
-
- Disproportionation of diarylmethanol derivatives by using supercritical water
-
Non-catalytic disproportionation of diarylmethanol derivatives was found to proceed efficiently in supercritical water. This method was also applied to various diarylmethylamine derivatives to give the disproportionation products in good yields.
- Hatano, Bunpei,Kadokawa, Jun-Ichi,Tagaya, Hideyuki
-
p. 5859 - 5861
(2007/10/03)
-
- Orbital Symmetry Control in the Photochemistry of trans-2,3-Diphenyloxirane
-
We report quantum yields following 266 nm photolysis of trans-2,3-diphenyloxirane (TDPO) for the formation of the trans-ylide (Scheme 1, φ = 0.099 ± 0,014), cis-2,3-diphenyloxirane (CDPO, φ = 0.10 ± 0.009), benzaldehyde (φ = 0.47 ± 0.04), and deoxybenzoin (φ = 0.077 ± 0.002). Photolysis of TDPO may lead to both orbital symmetry allowed and forbidden products, but the trans-ylide decays solely via an orbital symmetry predicted pathway to CDPO. Coupling our quantum yields to results of Das and co-workers,1 we report an extinction coefficient for the trans-ylide of 9.4 × 104 M-1 cm-1 at 470 nm. We also report pseudo-first-order rate constants for the reaction between maleic anhydride and the trans-ylide in acetonitrile (kQ = 3.32 ± 0.04 × 109 M-1 s-1) and in cyclohexane (kQ = 5.36 ± 0.07 × 109 M-1 s-1) and between fumaronitrile and the trans-ylide in acetonitrile (kQ = 1.57 ± 0.02 × 109 M-1 s-1) and cyclohexane (kQ = 3.69 ± 0.04 × 109 M-1 s-1). We report the crystal structure of rac-(2R,3R,4R,5R)-3,4-dicyano-2,5-diphenyltetrahydrofuran, the sole product of 1,3-dipolarophilic addition between the trans-ylide and fumaronitrile in cyclohexane. A brief discussion of solvent and steric effects in 1,3-dipolarophilic additions is included.
- Lipson, Matthew,Noll, Bruce C.,Peters, Kevin S.
-
p. 2409 - 2413
(2007/10/03)
-
- A modified Clemmensen reduction procedure for conversion of aryl ketones into aryl alkenes
-
Aryl alkenes can be prepared from aryl ketones through reduction by refluxing with amalgamated zinc in a mixture of formic acid and ethanol.
- Hiegel, Gene A.,Carney, John R.
-
p. 2625 - 2631
(2007/10/03)
-
- Hydrogenation of Biphenyls over the Hydrogen Storage Alloy MmNi3.5Co0.7Al0.8H4
-
Hydrogenation of biphenyl with the activated hydrogen storage alloy, MmNi3.5Co0.7Al0.8H4 (Mm: La, 30; Ce, 52; Pr, 5; Nd, 13 wtpercent), as a stoichiometric reductant proceeded effectively at 160 deg C for 3 h under nitrogen to give either phenylcyclohexane or bicyclohexyl selectively, according to the ratio of the alloy to biphenyl.
- Nakagawa, Shin-ichi,Murata, Satoru,Sakai, Tetsuo,Nomura, Masakatsu
-
p. 431 - 432
(2007/10/02)
-
- Photolysis of Benzyl Chloride included in NaY Zeolite: Product Study Evidence for the Implication of Benzyl Cation
-
The photochemical behaviour of benzyl chloride is strongly altered by inclusion within the zeolite micropores; evidence is presented for the existence of an ionic pathway in zeolites which is not present when the photochemical reaction occurs in liquid media.
- Alvaro, Mercedes,Corma, Avelino,Garcia, Hermenegildo,Miranda, Miguel A.,Primo, Jaime
-
p. 1041 - 1042
(2007/10/02)
-
- Synthesis and evaluation of 4-alkylanilines as mammary tumor inhibiting aromatase inhibitors
-
The 4-alkylanilines 1-20 were synthesized to elucidate the importance of the glutarimide moiety for the aromatase inhibiting activity of aminoglutethimide [3-(4-aminophenyl)-3-ethylpiperidine-2,6-dione, AG], the only non-steroidal aromatase inhibitor which is commercially available at present. The most interesting compounds were the (4-aminophenyl)cycloalkanes 4-6 (4, c-pentyl; 5, c-hexyl; 6, c-heptyl) and the 1-alkyl-1-(4-aminophenyl)cyclohexanes 1-3 (1, CH3; 2, C2H5; 3, n-C3H7). Derivatives 1-6 are stronger inhibitors of human placental aromatase than AG exhibiting relative potencies from 1.5 to 2.7 (AG≡1). For selectivity of action, the inhibition of desmolase (cholesterol side chain cleavage enzyme) was determined. Compounds 1-3 showed an inhibition comparable to AG, whereas compounds 4-6 exhibited no effect on desmolase. Being more potent and selective aromatase inhibitors in vitro, compounds 4-6, however, were not superior to AG in vivo, when the reduction of plasma estradiol concentration and the tumor inhibiting activity (PMSG-primed SD rats and DMBA-induced mammary carcinoma of the SD rat, postmenopausal model) were concerned.
- Hartmann,Batzl
-
p. 537 - 544
(2007/10/02)
-
- A one-pot synthesis of ibuprofene involving three consecutive steps of superbase metalation
-
A one-pot reaction sequence consisting of three consecutive metalation and electrophilic substitution stages leads to 2-(4-isobutylphenyl)propanoic acid with 52% over-all yield. A crucial step is the alkylation of deprotonated p-ethyltoluene with isopropyl bromide. In general terms, sec-alkyl halides and benzyl or allyl type alkalimetal reagents undergo coupling reactions with surprising ease.
- Faigl,Schlosser
-
p. 3369 - 3370
(2007/10/02)
-
- The Effect of Hydrogen Sulfide on Acridine Hydrodenitrogenation on a Sulfided NiMo/Al2O3 Catalyst
-
The effect of hydrogen sulfide on acridine hydrodenitrogenation over a sulfided NiMo/Al2O3 catalyst at 280-380 deg C and 10.1 MPa total pressure was studied.The result showed that the presence of H2S depressed the total C-N hydrogenolysis at a low PH2S/PH2 ratio of 1.1-79x10-5, but that it rarely affected the C-N hydrogenolysis at a ratio above 0.003.
- Nagai, Masatoshi
-
p. 330 - 332
(2007/10/02)
-
- AZO ANIONS IN SYNTHESIS. USE OF TRITYL- AND DIPHENYL-4-PYRIDYLMETHYLHYDRAZONES FOR REDUCTIVE C-C BOND FORMATION.
-
The lithium salts of trityl- and diphenyl-4-pyridylmethyl-hydrazones of both aldehydes and ketones react with electrophiles (alkyl halides, aldehydes, ketones, crotonates) at low temperature to form C-trapped azo compounds; these intermediates decompose homolytically with loss of nitrogen below room temperature and can be diverted in a synthetically useful way to alkanes, alkenes, alcohols or saturated esters.
- Baldwin, Jack E.,Adlington, Robert M.,Bottaro, Jeffrey C.,Kolhe, Jayant N.,Newington, Ian M.,Perry, Matthew W. D.
-
p. 4235 - 4246
(2007/10/02)
-