- Visible Light Induced Reduction and Pinacol Coupling of Aldehydes and Ketones Catalyzed by Core/Shell Quantum Dots
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We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 × 104 and 4 × 105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.
- Xi, Zi-Wei,Yang, Lei,Wang, Dan-Yan,Feng, Chuan-Wei,Qin, Yufeng,Shen, Yong-Miao,Pu, Chaodan,Peng, Xiaogang
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p. 2474 - 2488
(2021/02/05)
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- Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
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Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
- Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
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supporting information
p. 11815 - 11818
(2021/11/30)
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- Redox-active ligand based Mn(i)-catalyst for hydrosilylative ester reduction
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Herein a Mn(i) catalyst bearing a redox-active phenalenyl (PLY) based ligand is reported for the efficient hydrosilylation of esters to alcohols using the inexpensive silane source polymethylhydrosiloxane (PMHS) under mild conditions. Mechanistic investigations suggest a strong ligand-metal cooperation where a ligand-based single electron transfer (SET) process initiates the reaction through Si-H bond activation.
- Chakraborty, Soumi,Das, Arpan,Mandal, Swadhin K.
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supporting information
p. 12671 - 12674
(2021/12/04)
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- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
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Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
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supporting information
p. 16865 - 16873
(2021/10/20)
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- Pd/Cu-Free Cobalt-Catalyzed Suzuki and Heck Using Green Bio-Magnetic Hybrid and DFT-Based Theoretical Study
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Abstract: Several highly efficient and magnetically recyclable cobalt catalytic systems were prepared using magnetic chitosan and some safe and available organic compounds (Co-ligand@MNPs/Ch). The structure of these nanocomposites was confirmed by various physicochemical techniques such as FT-IR, XRD, TGA, VSM, TEM, SEM, CHNS and ICP-OES. These nano composites exhibit remarkable catalytic efficiency for Suzuki and Heck cross-coupling reactions in mild and green reaction conditions. The facile accessibility of starting materials, possible performance in air and eco-friendly conditions are merits of our catalysts. In addition, to describe and go insight to role and effect of ligands present in these catalysts, electrostatic interactions, density functional theory (DFT) model in molecular method were employed. Graphic Abstract: [Figure not available: see fulltext.]
- Hajipour, Abdol R.,Khorsandi, Zahra,Ahmadi, Mehnoosh,Jouypazadeh, Hamidreza,Mohammadi, Bahareh,Farrokhpour, Hossein
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p. 2842 - 2850
(2021/02/01)
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- Pd-catalyzed atom-efficient cross-coupling of triarylbismuth reagents with protecting group-free iodophenylmethanols: Synthesis of biarylmethanols
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An atom-efficient procedure for the synthesis of functionalized biarylmethanols via the Pd-catalyzed cross-coupling reactions of differently functionalized iodophenylmethanols and triarylbismuth reagents is described. This protecting group-free direct couplings of 2-, 3- or 4-iodophenylmethanols with triarylbismuth reagents afforded biarylmethanols in good to high yields.
- Meka, Suresh,Rao, Maddali L. N.
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supporting information
(2020/02/11)
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- Pyridine-based hypercrosslinked polymers as support materials for palladium photocatalysts and their application in Suzuki-Miyaura coupling reactions
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A series of hypercrosslinked polymers (P1 to P8) was synthesized from pyridine and conjugated monomers to support palladium for photocatalytic Suzuki-Miyaura coupling reactions. The results of SEM, TEM and XRD analyses reveal that the supports possess a loose porous amorphous lamellar structure, and the TGA test shows that they are thermally stable. Among the prepared photocatalysts, the one using P6 as a support performed the best, displaying excellent photocatalytic and recycling performance under the irradiation of blue light at 30 °C.
- Zhang, Yan,Zhang, Le,Zhang, Xiaoli,Yang, Didi,Du, Cheng,Wan, Liu,Au, Chaktong,Chen, Jian,Xie, Mingjiang
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p. 15202 - 15208
(2020/09/23)
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- Ir(I)-Catalyzed Synthesis of (E)-4-Benzylidenylacridines and (E)-2-Styrylquinoline-3-carboxamide through Sequential Suzuki–Miyaura Coupling, Dehydrogenative Friedl?nder Reaction, and sp3-C–H Activation
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An efficient one-pot strategy evolved in the synthesis of (E)-4-benzylidenylacridin-1(2H)-ones, (4 or 9) (E)-2-styryl quinoline-3-carboxamides (5 or 10) by sequential Suzuki–Miyaura coupling-dehydrogenative Friedl?nder-sp3 C–H activation. The 2-amino-5-chloro benzhydrol 1, aromatic alcohol 2 or 6 ketones 3 or 3', and phenylboronic acid 7 underwent a smooth reaction in a basic deep eutectic solvent consisting of K2CO3 and ethylene glycol (DES-1,1:1). DES-1 could enable the Pd-catalyzed Suzuki coupling reaction of 6, as well as the rapid oxidation of primary, secondary, and Suzuki coupled primary alcohols (2, 1, and 8) in the presence of an iridium catalyst and 1,10-phenanthroline. The acidic DES-2 (dimethyl urea/tartaric acid, 7:3) assists the Friedl?nder annulation and subsequent sp3-C–H functionalization resulting in (E)-4-benzylidenylacridin-1(2H)-ones (4 or 9) and (E)-2-styryl quinoline-3-carboxamides (5 or 10).
- Prameela, Soda,Nawaz Khan, Fazlur-Rahman
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p. 5394 - 5410
(2020/08/27)
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- Borinic Acid Mediated Hydrosilylations: Reductions of Carbonyl Derivatives
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4-Fluoro-2-chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for the facile reduction of ketones, aldehydes and imines. Notably, synergistic mediation of a tertiary amine was found essential to trigger silicon to boron hydride transfer to generate a key amine–diarylhydroborane Lewis complex.
- Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 995 - 998
(2018/12/13)
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- 6-Arylphenanthridines from Aryl o-Biaryl Ketones with 1,1,1,3,3,3-Hexamethyldisilazane and Molecular Iodine
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Warming treatment of aryl o-biaryl ketones with 1,1,1,3,3,3-hexamethyldisilazane in the presence of Sc(OTf)3 in toluene, followed by the reaction with molecular iodine and K2CO3 in a mixture of THF and methanol at 60 °C gave the corresponding 6-arylphenanthridines in good to moderate yields. The present reaction is a one-pot method for the preparation of 6-arylphenanthridines from aryl o-biaryl ketones through the cyclization of imino-nitrogen-centered radicals that were generated from N-iodo aryl o-biaryl ketimines formed from the reaction of aryl biaryl ketimines with molecular iodine.
- Kobayashi, Eiji,Kishi, Atsushi,Togo, Hideo
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p. 7335 - 7347
(2019/11/22)
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- Lewis Base-Promoted Ring-Opening 1,3-Dioxygenation of Unactivated Cyclopropanes Using a Hypervalent Iodine Reagent
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A facile and effective system has been developed for the regio- and chemoselective ring-opening/electrophilic functionalization of cyclopropanes through C?C bond activation by [bis(trifluoroacetoxy)iodo]benzene with the aid of the Lewis basic promoter p-toluenesulfonamide. The p-toluenesulfonamide-promoted system works well for a wide range of cyclopropanes, resulting in the formation of 1,3-diol products in good yields and regioselectivity.
- Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 3782 - 3786
(2018/03/13)
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- Synthesis and use of phenylpropionic acid derivatives
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The invention discloses a series of phenylpropionic acid derivatives, a preparation method thereof, and a use of the derivatives in pharmacy. The derivatives are compounds represented by formula I. Pharmacodynamic experiments show that the compounds of formula I have good agonist activity to GPR120; an in-vivo metabolism research result shows that the compounds of the formula I have good metabolism stability; and unexpectedly, the compounds have substantially higher agonist activity to the GPR120 after a difluoro substitute group is introduced to a phenyl ring at the carboxyl terminal of the compounds of the formula I. The compounds of the formula I can be used for drugs for preventing diabetes, obesity and other metabolic diseases.
- -
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Paragraph 0038; 0052; 0053; 0074; 0075; 0076
(2017/03/17)
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- Synthesis and Characterization of Pd Schiff Base Complex Immobilized onto Functionalized Nanoporous MCM-41 and its Catalytic Efficacy in the Suzuki, Heck and Stille Coupling Reactions
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Abstract: The present work describes the use of palladium-vanillin-Schiff-base complex immobilized on MCM-41 nanostructure as efficient catalyst for the Suzuki–Miyaura, Stille and Mizoroki–Heck reactions of several aryl halides under aerobic conditions. All the reactions were carried out in green solvents (H2O and PEG-400). The developed procedure results bring several benefits such as uses of inexpensive and non-toxic ligand (vanillin), easy catalyst/product separation and catalyst recycling. The catalyst can be reused at least for five consecutive cycles without a significant loss of its catalytic activity or metal leaching. Graphical Abstract: [Figure not available: see fulltext.].
- Khanmoradi, Maryam,Nikoorazm, Mohsen,Ghorbani-Choghamarani, Arash
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p. 1114 - 1126
(2017/05/12)
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- Intramolecular Acylation of Unactivated Pyridines or Arenes via Multiple C-H Functionalizations: Synthesis of All Four Azafluorenones and Fluorenones
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An unprecedented intramolecular acylation of unactivated pyridines via multiple C(sp3/sp2)-H functionalizations of a methyl, hydroxymethyl, or aldehyde group has been developed providing a general access to all four azafluorenones. The application of this protocol is further demonstrated to the synthesis of azafluorenone related fused nitrogen heterocycles and fluorenones. In addition, design and synthesis of a novel fluorene based organic emitter for potential use in organic light emitting devices (OLEDs) is also reported.
- Laha, Joydev K.,Jethava, Krupal P.,Patel, Sagarkumar,Patel, Ketul V.
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- The selective oxidation of substituted aromatic hydrocarbons and the observation of uncoupling via redox cycling during naphthalene oxidation by the CYP101B1 system
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The cytochrome P450 monooxygenase enzyme CYP101B1, from Novosphingobium aromaticivorans DSM12444, efficiently and selectively oxidised a range of naphthalene and biphenyl derivatives. Methyl substituted naphthalenes were better substrates than ethylnaphthalenes and naphthalene itself. The highest product formation activity for a singly substituted alkylnaphthalene was obtained with 2-methylnaphthalene. The oxidation of alkylnaphthalenes was regioselective for the benzylic methyl or methine C-H bonds. The products from 1- and 2-ethylnaphthalene oxidation were highly enantioselective with a single stereoisomer being generated in significant excess. The disubstituted substrate, 2,7-dimethylnaphthalene, had a higher product formation activity than either 1- and 2-methylnaphthalene. Methyl substituted biphenyls were also better substrates than biphenyl and had similar biocatalytic parameters to 1-methylnaphthalene. CYP101B1 catalysed oxidation of 2- and 3-methylbiphenyl was selective for attack at the methyl C-H bonds. The exception was the turnover of 4-methylbiphenyl which generated 4′-(4-methylphenyl)phenol as the major product (70%) with 4-biphenylmethanol making up the remainder. The drug molecule diclofenac was also regioselectively oxidised to 4′-hydroxydiclofenac by CYP101B1. The activity of the CYP101B1 system with naphthalene was more complex and the rate of NADH oxidation increased over time but very little product, 1-naphthol, was generated. Addition of samples of 1-naphthol and 2-naphthol and low concentrations of 1,4-naphthoquinone induced rapid NADH oxidation activity in the in vitro turnovers in both the presence and absence of the cytochrome P450 enzyme. Hydrogen peroxide was generated in these reactions in absence of the P450 enzymes demonstrating that the ferredoxin and ferredoxin reductase in combination with quinones from naphthol oxidation and oxygen can undergo redox cycling giving rise to a form of uncoupling of the reducing equivalents.
- Hall, Emma A.,Sarkar, Md Raihan,Bell, Stephen G.
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p. 1537 - 1548
(2017/06/05)
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- Selective acetylation of primary alcohols by ethyl acetate
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A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
- Singha, Raju,Ray, Jayanta K.
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supporting information
p. 5395 - 5398
(2016/11/11)
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- Application of Pd-2A3HP-MCM-41 to the Suzuki, Heck and Stille coupling reactions and synthesis of 5-substituted 1H-tetrazoles
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An ecofriendly heterogeneous catalyst has been synthesized by anchoring palladium onto the surface of organically modified mesoporous silica. The prepared catalyst was characterized using X-ray diffraction, Fourier transform infrared and energy-dispersive X-ray spectroscopies, transmission and scanning electron microscopies, inductively coupled plasma and thermogravimetric techniques. The catalyst shows high activity in the Suzuki, Heck and Stille cross-coupling reactions and the synthesis of 5-substituted 1H-tetrazoles from sodium azide (NaN3). These methods have the advantages of high yields, green reaction conditions, simple methodology and easy separation and workup.
- Nikoorazm, Mohsen,Ghorbani-Choghamarani, Arash,Khanmoradi, Maryam
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p. 705 - 712
(2016/07/19)
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- Synthesis of Fluorenes Starting from 2-Iodobiphenyls and CH2Br2 through Palladium-Catalyzed Dual C-C Bond Formation
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A facile and efficient approach is developed for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C-C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C-H activation.
- Shi, Guangfa,Chen, Dushen,Jiang, Hang,Zhang, Yu,Zhang, Yanghui
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supporting information
p. 2958 - 2961
(2016/07/06)
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- Water-soluble palladacycles containing hydroxymethyl groups: Synthesis, crystal structures and use as catalysts for amination and Suzuki coupling of reactions
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Two water-soluble monophosphine [PPh3 and 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(Sphos)]-palladacycles containing hydroxymethyl groups 2-3 were prepared by cyclopalladation and chloride bridge-splitting reactions. The complexes were characterized by elemental analysis, ESI-MS and NMR. In addition, single-crystal X-ray analysis reveals that they have one-dimensional lamellar structures involving intermolecular hydrogen bonds and π-π interactions. The use of these palladacycles as catalysts for amination and Suzuki coupling of aryl chlorides in water was investigated. Complex 3 was found to be very efficient for these coupling reactions. Additionally, it was also successfully used in Suzuki coupling of (hydroxymethyl)phenylboronic acid for the synthesis of substituted 2-N-heterocyclic biarylmethanols.
- Han, Xin,Li, Hong-Mei,Xu, Chen,Xiao, Zhi-Qiang,Wang, Zhi-Qiang,Fu, Wei-Jun,Hao, Xin-Qi,Song, Mao-Ping
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p. 403 - 411
(2016/04/19)
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- One-Pot Synthesis of Polysubstituted Spirofluorene-Indene via Ru(II)-Catalyzed [3 + 2] Annulation and Intramolecular Friedel-Crafts Cyclization
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Ru(II)-catalyzed one-pot synthesis of polysubstituted spirofluorene-indenes via [3 + 2] annulation and then intramolecular Friedel-Crafts alkylation has been achieved. The simple method provides a broad scope of aryl ketones and internal alkynes, achieving PAHs skeletons in moderate to good yields.
- Zhu, Yu-Qin,Dong, Lin
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p. 9973 - 9979
(2015/11/03)
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- Highly Active Bimetallic Nickel-Palladium Alloy Nanoparticle Catalyzed Suzuki-Miyaura Reactions
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A bimetallic Ni-Pd alloy nanoparticle catalyst with a low palladium content (Ni0.90Pd0.10 nanocatalyst) was prepared and its catalytic performance in Suzuki-Miyaura reactions was evaluated along with that of other Ni-Pd nanocatalysts (with varying Ni/Pd molar ratios in the range of ≈0.25-0.75) and the corresponding monometallic, Ni and Pd, analogues. Notably, the bimetallic Ni0.90Pd0.10 alloy nanocatalyst performed exceptionally well for the synthesis of biaryls by employing a wide range of substituted aryl halides and arylboronic acids having electron-donating and electron-withdrawing groups, and they exhibited high recyclability in water/ethanol solution at moderate reaction temperatures. Catalyst poisoning tests and leaching experiments inferred the heterogeneous nature of the Ni0.90Pd0.10 nanocatalysts. The significant synergistic interactions between Ni and Pd account for the observed high catalytic efficacy of the Ni0.90Pd0.10 nanocatalyst. Up, up, and alloy! Highly active bimetallic Ni-Pd alloy nanocatalysts with high Ni/Pd molar ratios facilitate the Suzuki-Miyaura reactions of a wide range of aryl iodides/bromides and arylboronic acids to biaryls in high yields at moderate temperatures in water/ethanol solution. High synergistic interaction between Ni and Pd accounts for the observed high activity and recyclability of the bimetallic Ni-Pd nanocatalysts. FG=functional group.
- Rai, Rohit Kumar,Gupta, Kavita,Behrens, Silke,Li, Jun,Xu, Qiang,Singh, Sanjay Kumar
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p. 1806 - 1812
(2015/06/23)
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- Gold-catalyzed 6-exo-dig cycloisomerization: A versatile approach to functionalized phenanthrenes
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A novel gold-catalyzed 6-exo-dig cycloisomerization of o-propargylbiaryls has been developed that provides ready access to functionalized phenanthrenes in largely good to excellent yields. Notable features of this method are readily available starting materials, mild reaction conditions, and broad substrate scope. Golden cat: A novel gold-catalyzed 6-exo-dig cycloisomerization of o-propargylbiaryls has been developed that provides ready access to functionalized phenanthrenes in largely good to excellent yields. Notable features of this method are readily available starting materials, mild reaction conditions, and broad substrate scope.
- Shu, Chao,Li, Long,Chen, Cheng-Bin,Shen, Hong-Cheng,Ye, Long-Wu
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supporting information
p. 1525 - 1529
(2014/06/09)
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- A new synthetic approach to 6-unsubstituted phenanthridine and phenanthridine-like compounds under mild and metal-free conditions
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A new and mild synthetic approach for the synthesis of 6-unsubstituted phenanthridine and phenanthridine-like compounds under metal-free conditions at room temperature has been developed. The strategy involved a tandem azide rearrangement/intramolecular annulation and oxidation reactions of biarylmethyl azide precursors to obtain the desired products in up to 99% yields with high regioselectivity.
- Tummatorn, Jumreang,Krajangsri, Suppachai,Norseeda, Krissada,Thongsornkleeb, Charnsak,Ruchirawat, Somsak
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supporting information
p. 5077 - 5081
(2014/07/08)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Direct access to fluorene by successive C-O/C-H bond activations of 2-phenylbenzyl ester
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Catalytic formation of fluorene has been achieved from 2-phenylbenzyl trifluoroacetate via successive C-O and C-H bond cleavage reactions by Pd(OAc)2/PPh3 in 97% yield. This reaction involves the oxidative addition of ester to give (carboxylato)(2-phenylbenzyl)palladium(II) species and deprotonation from the 2-phenylbenzyl group by the cleaved carboxylato group via an internal electrophilic substitution mechanism.
- Hirano, Masafumi,Kawazu, Sosuke,Komine, Nobuyuki
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supporting information
p. 1921 - 1924
(2014/05/20)
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- Ni2O3-around-Pd hybrid on graphene oxide: An efficient catalyst for ligand-free Suzuki-Miyaura coupling reaction
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Ni2O3-around-Pd hybrid can be fabricated on graphene oxide (Pd-Ni/RGO) by a simple one-pot wet chemical route. These isolated Pd clusters showed significantly improved performance for Suzuki coupling reaction compared to that of pure Pd/RGO, Ni2O3/RGO, popularly reported Pd/AC, as well as homogeneous PdCl2 and PdCl 2(PPh3)2. Characterizations disclosed that Ni2O3 plays multiple roles in exfoliating graphene sheets, mediating the size as well as stability of Pd clusters. Pd-Ni/RGO dispersed homogeneously in the aqueous reaction mixture, exhibited high enrichment towards reactants as well as extremely high activity and stability for the Suzuki coupling reaction. The best turnover frequencies of all Pd atoms reached 38,750 h-1 at 80 C for bromobenzene coupling. It was concluded that the intimate interaction between Ni2O3 nanoparticles and Pd clusters appears to be beneficial for activating the Pd surface for the catalytic cycle.
- Nie, Renfeng,Shi, Juanjuan,Du, Weichen,Hou, Zhaoyin
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- An easily prepared palladium-hydrogel nanocomposite catalyst for C-C coupling reactions
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Supported metallic nanoparticles are important composite materials owing to their enormous potential for applications in various fields. In this work, palladium nanoparticles were prepared in situ in a calcium-cholate (Ca-Ch) hydrogel by reduction with sodium cyanoborohydride. The hydrogel matrix appeared to assist the controlled growth as well as stabilization of palladium nanoparticles. The palladium nanoparticle/Ca-Ch hydrogel hybrid was characterized by scanning and transmission electron microscopy, atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Furthermore, the PdNP/Ca-Ch hybrid xerogel was shown to act as an active catalyst for the Suzuki reaction under aqueous aerobic conditions. The PdNP/Ca-Ch xerogel retains its catalytic activities on storage for several months.
- Maity, Mitasree,Maitra, Uday
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supporting information
p. 18952 - 18958
(2014/12/10)
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- A novel 4-aminoantipyrine-Pd(II) complex catalyzes Suzuki-Miyaura cross-coupling reactions of aryl halides
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A simple and efficient catalytic system based on a Pd complex of 4-aminoantipyrine, 4-AAP-Pd(II), was found to be highly active for Suzuki-Miyaura cross-coupling of aryl iodides and bromides with phenylboronic acids under mild reaction conditions. Good to excellent product yields from the cross-coupling reaction can be achieved when the reaction is carried out in ethanol, in the open air, using low loading of 4-AAP-Pd(II) as a precatalyst, and in the presence of aqueous K2CO3 as the base. A variety of functional groups are tolerated.
- Contreras-Celedn, Claudia A.,Mendoza-Rayo, Daro,Rincn-Medina, Jos A.,Chacn-Garca, Luis
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supporting information
p. 2821 - 2826
(2015/02/19)
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- An efficient dehydroxymethylation reaction by a palladium catalyst
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A general method for selective dehydroxymethylation has been discovered by using widely available Pd(OAc)2. The present study offers a new synthetic strategy for the regioselective functionalization by employing the steric, electronic and coordinating nature of the hydroxymethyl (-CH 2OH) group temporarily.
- Modak, Atanu,Naveen, Togati,Maiti, Debabrata
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supporting information
p. 252 - 254
(2013/02/22)
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- S-farnesyl-thiopropionic acid triazoles as potent inhibitors of isoprenylcysteine carboxyl methyltransferase
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We report the design and synthesis of novel FTPA-triazole compounds as potent inhibitors of isoprenylcysteine carboxyl methyltransferase (Icmt), through a focus on thioether and isoprenoid mimetics. These mimetics were coupled utilizing a copper-assisted cycloaddition to assemble the potential inhibitors. Using the resulting triazole from the coupling as an isoprenyl mimetic resulted in the biphenyl-substituted FTPA triazole 10n. This lipid-modified analogue is a potent inhibitor of Icmt (IC50 = 0.8 ± 0.1 μM; calculated Ki = 0.4 μM).
- Bergman, Joel A.,Hahne, Kalub,Song, Jiao,Hrycyna, Christine A.,Gibbs, Richard A.
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supporting information; experimental part
p. 15 - 19
(2012/03/27)
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- Water-soluble palladium nanoparticles: Click synthesis and applications as a recyclable catalyst in Suzuki cross-couplings in aqueous media
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A new PEG-tagged material, which was prepared by a threefold copper-catalyzed [3+2] cycloaddition (click chemistry), was found to act as an efficient stabilizer for palladium nanoparticles. The newly formed material proved to be active asa recyclable catalyst in Suzuki coupling the presence of polyether chains allowed for the catalytic runs to be conducted in aqueous media.
- Mejias, Nereida,Pleixats, Roser,Shafir, Alexandr,Medio-Simon, Mercedes,Asensio, Gregorio
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supporting information; experimental part
p. 5090 - 5099
(2010/10/21)
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- Silicon-Based Cross-Coupling Reagent and Production Method of Organic Compound Using the Same
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In one embodiment of the present invention, a silicon-based cross-coupling reagent is disclosed which is a highly stable tetraorganosilicon compound allowing for a cross-coupling reaction under mild reaction conditions without using fluoride ions, transition metal promoter, or strong bases, and the residue of the silicon reagent can be recovered and reused. The silicon-based cross-coupling reagent is a silicon compound in which an o-hydroxymethylphenyl group is connected to a silicon atom for intramolecular activation.
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Page/Page column 20
(2009/04/24)
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- MODULATORS OF C3A RECEPTOR AND METHODS OF USE THEREOF
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Provided are compounds that are modulators of C3a receptor activity, compositions containing the compounds and methods of use of the compounds and compositions. In certain embodiments, the compounds are pyridones. In certain embodiments, provided are methods for treatment or amelioration of diseases associated with modulation of C3a receptor activity.
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Page/Page column 82
(2008/12/07)
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- A convenient and general iron-catalyzed hydrosilylation of aldehydes
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A general and highly chemoselective hydrosilylation of aldehydes using iron catalysts is reported. Fe(OAc)2 in the presence of tricyclohexylphosphine as ligand and polymethylhydrosiloxane (PMHS) as an economical hydride source forms an efficient catalyst system for the hydrosilylation of a variety of aldehydes. Aryl, heteroaryl, alkyl and α,β-unsaturated aldehydes are successfully reduced to the corresponding primary alcohols. Broad substrate scope and high tolerance against several functional groups make the process synthetically useful.
- Shaikh, Nadim S.,Junge, Kathrin,Beller, Matthias
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p. 5429 - 5432
(2008/09/19)
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- Direct diazo-transfer reaction on β-lactam: Synthesis and preliminary biological activities of 6-triazolylpenicillanic acids
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In this study we report the first example of a direct diazo-transfer reaction on readily available 6-aminopenicillanates to give 6-azidopenicillanates in high yield. Subsequent Cu(I)-catalyzed Huisgen cycloaddition between these 6-azidopenicillanates and assorted terminal alkynes facilely furnished 6-triazolylpenicillanic acids. Preliminary biological screening indicates that these triazolylpenicillanic acids possess low to moderate antibacterial activities.
- Chen, Po C.,Wharton, Rebekah E.,Patel, Pratiq A.,Oyelere, Adegboyega K.
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p. 7288 - 7300
(2008/03/28)
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- The iminophosphorane-phosphane Ph2PC6H 4OC6H4PPh2=NP(O)(OPh)2: Synthesis, reactivity, and catalytic activity in Suzuki cross-coupling and the homogeneous hydrogenation of olefins
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The iminophosphorane-phosphane ligand Ph2PC6H 4OC6H4-PPh2=NP(O)(OPh)2 (1) has been synthesized by partial imination of bis[2-(diphenylphosphanyl) phenyl] ether (DPEphos) with phosphoryl azide (PhO)2P(O)N 3. A similar reaction in a 1:2 stoichiometry affords the bis(iminophosphorane) O-{C6H4PPh2=NP(O)(OPh) 2}2 (2). The chalcogen derivatives O{C6H 4P(E)Ph2}2 [E = S (3) and Se (4)] and Ph 2P(E)-C6H4OC6H4PPh 2=NP(O)(OPh)2 [E = S (5) and Se (6)] are also synthesized by treating DPEphos and 1 with elemental sulfur and selenium, respectively. The mononuclear complexes trans-[MCl2{κ1-P-Ph 2PC6H4OC6H4PPh 2=NP(O)(OPh)2}2] [M = Pt (7) Pd (8)] and trans-[Rh(CO)Cl{κ1-P-Ph2PC6-H 4OC6H4PPh2=NP(O)(OPh) 2}2] (12) are prepared by the reaction of 1 with [Pt(COD)Cl2], [Pd(COD)Cl2], and [{Rh(CO) 2-Cl}2], respectively. Treatment of 1 with [Pd 2(dba3)] (dba = dibenzylideneacetone) affords the mononuclear complex [Pd0{κ2-P,O-Ph 2PC6H4OC6H4PPh 2=NP(O)(OPh)2}2] (9) in which ligand 1 coordinates through its P and O centers in a κ2-P,O chelating fashion. The monocoordinated AuI complex [AuCl{κ1-P- Ph2PC6H4OC6H4PPh 2=NP(O)(OPh)2}] (10) has been prepared by the reaction of 1 and [AuCl(SMe2)] and its structure has been confirmed by X-ray crystallography. The reaction of 1 with [{Rh(COD)Cl}2] in the presence of AgOTf affords the cationic RhI complex cis-[Rh(COD){κ2-P,O-Ph2PC6H 4OC6H4PPh2=NP(O)(OPh) 2}][OTf] (11). The catalytic activity of the Pd0 complex 9 has been investigated in Suzuki cross-coupling reactions. Homogeneous catalytic hydrogenation of olefins has also been studied using the cationic Rh I complex 11. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Venkateswaran, Ramalingam,Balakrishna, Maravanji S.,Mobin, Shaikh M.
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p. 1930 - 1938
(2008/02/09)
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- Ligands for metals and improved metal-catalyzed processes based thereon
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One aspect of the present invention relates to ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
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- Ligands for metals and improved metal-catalyzed processes based thereon
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One aspect of the present invention relates to novel ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
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- Synthesis of biaryls by intramolecular radical transfer in phosphinates
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Phosphinates 20a-35a give biaryls 20b-35b on heating with stannanes in the presence of AIBN. The process involves a radical ipso substitution on the migrating aryl ring.
- Clive,Kang
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p. 6083 - 6091
(2007/10/03)
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- Palladium-Catalyzed Cross-Coupling Reaction of Organoindiums with Aryl Halides in Aqueous Media
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(matrix presented) Diaryl-, divinyl-, and dialkylindium proved to be stable in aqueous media and to undergo a palladium-catalyzed cross-coupling reaction with aryl halides in aqueous THF. Treatment of 3-iodophenol with diphenylindium compound, generated from indium trichloride and two equimolar amounts of a phenyl Grignard reagent, in aqueous media under palladium catalysis provided the corresponding coupling product in excellent yield. Divinyl- and diethlindium can be used for the coupling reaction in the presence of water. A wide range of functional groups, including a hydroxy group and a formyl group, are compatible with this reaction.
- Takami, Kazuaki,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
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p. 1997 - 1998
(2007/10/03)
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- A new vinyl ether type linker for solid-phase synthesis
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A new vinyl ether type of linker based on 4.-hydroxy phenethyl alcohol is developed for the solid-phase synthesis as demonstrated in the Suzuki type of aryl-aryl coupling reaction for the preparation of various biphenyl tetrazole derivatives. (C) 2000 Elsevier Science Ltd.
- Yoo,Gong,Choi,Seo,Kyu Yang Yi
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p. 6415 - 6418
(2007/10/03)
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- Synthesis of biaryls by intramolecular radical aryl migration from silicon to carbon
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(equation presented) A new method for the preparation of biaryls via intramolecular 1,5 aryl migration reaction from silicon in silyl ethers to aryl radicals is presented. Various readily available diphenylsilyl ethers can be used as substrates in this reaction. Functionalized aryl groups can also be transferred. The analogous 1,4 aryl migration reaction is less efficient.
- Studer, Armido,Bossart, Martin,Vasella, Tomaso
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p. 985 - 988
(2007/10/03)
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- Synthesis of biaryls by intramolecular radical transfer: Use of phosphinates
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Phosphinates 4a-13a give biaryls 4b-13b on heating with stannanes in the presence of a radical initiator. (C) 2000 Elsevier Science Ltd.
- Clive, Derrick L.J.,Kang, Shunzhen
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p. 1315 - 1319
(2007/10/03)
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- Chemically modified β-cyclodextrins as supramolecular carriers in the biphasic palladium-catalyzed cleavage of allylic carbonates: Activity enhancement and substrate-selective catalysis
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Catalytic amounts of chemically modified β-cyclodextrins allowed us to achieve, in high yields, the deprotection of various water-insoluble allylic carbonates in a genuine two-phase system without co-solvent. The catalytic activities were up to 300 times higher than those observed without modified cyclodextrins, The process of molecular recognition between the cyclodextrin and the substrate allowed us to perform substrate-selective catalytic reactions which cannot be achieved in homogeneous or biphasic media with conventional transition metal catalysts.
- Lacroix, Thibaut,Bricout, Herve,Tilloy, Sebastien,Monflier, Eric
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p. 3127 - 3129
(2007/10/03)
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- Highly active palladium catalysts for Suzuki coupling reactions
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Mixtures of palladium acetate and o-(di-tert-butylphosphino)biphenyl (4) catalyze the room-temperature Suzuki coupling of aryl bromides and aryl chlorides with 0.5-1.0 mol % Pd. Use of o-(dicyclohexylphosphino)biphenyl (2) allows Suzuki couplings to be carried out at low catalyst loadings (0.000001-0.02 mol % Pd). The process tolerates a broad range of functional groups and substrate combinations including the use of sterically hindered substrates. This is the most active catalyst system in terms of reaction temperature, turnover number, and steric tolerance which has been reported to date.
- Wolfe, John P.,Singer, Robert A.,Yang, Bryant H.,Buchwald, Stephen L.
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p. 9550 - 9561
(2007/10/03)
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- Carbon-13 chemical shift tensors in aromatic compounds. 3. Phenanthrene and triphenylene
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Measurements of the principal values of the 13C chemical shift tensor are presented for the three carbons in triphenylene and for three different α-carbons in phenanthrene. The measurements in triphenylene were made in natural abundance samples at room temperature, while the phenanthrene tensors were obtained from selectively labeled compounds (99% 13C) at low temperatures (~25 K). The principal values of the shift tensors were oriented in the molecular frame using ab initio LORG calculations. The steric compression at C4 in phenanthrene and in corresponding positions in triphenylene is manifested in a sizable upfield shift in the σ33 component relative to the corresponding σ33 values at C1 and C9 in phenanthrene. The upfield shift in σ33 is mainly responsible for the well-known upfield shift of the isotropic chemical shifts of such sterically perturbed carbons. In phenanthrene C9 exhibits a unique σ22 value reflecting the greater localization of π-electrons in the C9-C10 bond. This localization of the π-electrons at the C9-C10 bond in the central ring of phenanthrene also corresponds with the most likely ordering of electrons described by the various Kekule? structures in phenanthrene. The analysis of the 13C chemical shieldings of the bridgehead carbons in triphenylene provides significant experimental information on bonding between rings in polycyclic aromatic compounds. The results confirm that the electronic structure of triphenylene is best described by three fairly isolated benzene rings linked by C-C bonds of essentially single bond character. Similarly in phenanthrene, the bonding structure which correlates the shielding information may be characterized by the dominance of two benzene rings comprising the biphenyl moiety. A strong C9-C10 π-bond with only limited π-electron character in the C8a-C9 and C10-C10a bonds is indicated by both the experimental and theoretical results.
- Soderquist, Arien,Hughes, Craig D.,Horton, W. James,Facelli, Julio C.,Grant, David M.
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p. 2826 - 2832
(2007/10/02)
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- Solid-State Chemistry, Kinetics, and Electron Spin Resonance Spectroscopy of 2-Biphenylmethylene
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The chemistry and kinetics of 2-biphenylmethylene have been examined in low-temperature glasses and polycrystals.Photolysis of 2-biphenyldiazomethane at 77 K produces a single set of triplet carbene resonance peaks.They have been assigned to the unresolved superposition of syn and anti rotamers of the carbene.The carbene kinetics are fastest in diethyl ether glass.The decay rates of 4T in diethyl-d10 ether and in a perfluorinated alkane polycrystal are comparable.This indicated that the main carbene reaction in diethyl ether is hydrogen atom abstraction.The reaction of 4T in diethyl-d10 ether is a mixture of reaction with solvent and cyclization to fluorene.These interpretations are consistent with the observed product distributions.Matrix effects on the observed chemistry are discussed.
- Palik, Eric C.,Platz, Matthew S.
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p. 963 - 969
(2007/10/02)
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