- Photoredox-Catalyzed α-Aminomethyl Carboxylation of Styrenes with Sodium Glycinates: Synthesis of γ-Amino Acids and γ-Lactams
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A visible-light photoredox-catalyzed reductive α-aminomethyl carboxylation of styrenes with sodium glycinates and CO2 has been developed to synthesize a series of α,α-disubstituted γ-amino acids and γ-lactams with high efficiency and regioselectivity. Notably, CO2 released from the decarboxylation step can be reused for the subsequent carboxylation. Distinct from the previous reactions with the same type of substrates leading to simple decarboxylation and olefin hydroalkylation, this process involves additional CO2 sequestration, thus leading to olefin α-aminomethyl carboxylation. These findings not only provide new access to α,α-disubstituted γ-amino acids and γ-lactams but also serve as a proof of concept for CO2 reutilization in decarboxylation reactions.
- Zhou, Cong,Li, Miao,Sun, Jianwei,Cheng, Jiang,Sun, Song
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supporting information
p. 2895 - 2899
(2021/05/05)
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- Photoinduced Hydroarylation and Cyclization of Alkenes with Luminescent Platinum(II) Complexes
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Photoinduced hydroarylation of alkenes is an appealing synthetic strategy for arene functionalization. Herein, we demonstrated that aryl radicals generated from electron-deficient aryl chlorides/bromides could be trapped by an array of terminal/internal aryl alkenes in the presence of [Pt(O^N^C^N)] under visible-light (410 nm) irradiation, affording anti-Markovnikov hydroarylated compounds in up to 95 % yield. Besides, a protocol for [Pt(O^N^C^N)]-catalyzed intramolecular photocyclization of acrylanilides to give structurally diverse 3,4-dihydroquinolinones has been developed.
- Cheng, Hanchao,Lam, Tsz-Lung,Liu, Yungen,Tang, Zhou,Che, Chi-Ming
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supporting information
p. 1383 - 1389
(2020/11/30)
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- Direct 1,2-Dicarbonylation of Alkenes towards 1,4-Diketones via Photocatalysis
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1,4-Dicarbonyl compounds are intriguing motifs and versatile precursors in numerous pharmaceutical molecules and bioactive natural compounds. Direct incorporation of two carbonyl groups into a double bond at both ends is straightforward, but also challenging. Represented herein is the first example of 1,2-dicarbonylation of alkenes by photocatalysis. Key to success is that N(n-Bu)4+ not only associates with the alkyl anion to avoid protonation, but also activates the α-keto acid to undergo electrophilic addition. The α-keto acid is employed both for acyl generation and electrophilic addition. By tuning the reductive and electrophilic ability of the acyl precursor, unsymmetric 1,4-dicarbonylation is achieved for the first time. This metal-free, redox-neutral and regioselective 1,2-dicarbonylation of alkenes is executed by a photocatalyst for versatile substrates under extremely mild conditions and shows great potential in biomolecular and drug molecular derivatization.
- Chen, Bin,Cheng, Yuan-Yuan,Hou, Hong-Yu,Lei, Tao,Tung, Chen-Ho,Wu, Li-Zhu,Yu, Ji-Xin
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supporting information
p. 26822 - 26828
(2021/11/17)
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- Synthesis and characterization of Pd(II) and Ru(II) complexes of tetradentate N,N,N,N-(Diphosphinomethyl)amine ligands: Catalytic properties in transfer hydrogenation and heck coupling reactions
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– Tetradentate N,N,N,N-(diphosphinomethyl)amine ligands and their Pd(II) and Ru(II) complexes were synthesized under a nitrogen atmosphere using Schlenk technique. The synthesized ligands and the complexes were characterized with 1H- and 31P-NMR, FT-IR, TG/DTA, and elemental analysis techniques. Pd(II) Complexes were used as catalysts in Heck coupling reactions and Ru(II) complexes were tried in transfer hydrogenation reactions of acetophenone derivatives. According to the results, L4-Pd(II) complex showed the best catalytic activity in the Heck coupling reaction of p-methylbromobenzene with o-chlorostyrene. It was confirmed that the reduction of bromo and chloroacetophenones in all catalysts the conversions were higher. The results showed that Ru(II) complexes as efficient catalysts and up to 99percent conversions was occurred with bromo and chloro acetophenones in K2CO3/isopropyl alcohol media at 80 °C.
- Akkaya, Seda K??ker,Kele?, Mustafa,Uru?, Serhan
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- Deaminative carbonylative coupling of alkylamines with styrenes under transition-metal-free conditions
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A transition-metal-free deaminative carbonylation of alkylamines with styrenes has been developed. The reaction shows good functional group compatibility and various α,β-unsaturated ketones were obtained in moderate to good yields. The alkyl radical generated from Katritzky salts via base-promoted C-N bond cleavage is one of the key intermediates in this reaction. This journal is
- Zhao, Fengqian,Li, Chong-Liang,Wu, Xiao-Feng
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supporting information
p. 9182 - 9185
(2020/08/26)
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- Photocatalytic Palladium-Catalyzed Fluoroalkylation of Styrene Derivatives
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A visible light induced palladium-catalyzed fluoroalkylation method was developed. The Heck-type alkyl coupling reaction enables the introduction of trifluoroethyl, difluoroethyl and other fluoroalkyl fragment into styrenes under mild reaction conditions without the use of additional photosensitizers and ensures access to fluoroalkylated olefins on a broad scale.
- Adamik, Réka,F?ldesi, Tamás,Novák, Zoltán
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supporting information
p. 8091 - 8095
(2020/11/02)
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- Iron-Catalyzed Direct Julia-Type Olefination of Alcohols
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Herein, we report an iron-catalyzed, convenient, and expedient strategy for the synthesis of styrene and naphthalene derivatives with the liberation of dihydrogen. The use of a catalyst derived from an earth-abundant metal provides a sustainable strategy to olefins. This method exhibits wide substrate scope (primary and secondary alcohols) functional group tolerance (amino, nitro, halo, alkoxy, thiomethoxy, and S- A nd N-heterocyclic compounds) that can be scaled up. The unprecedented synthesis of 1-methyl naphthalenes proceeds via tandem methenylation/double dehydrogenation. Mechanistic study shows that the cleavage of the C-H bond of alcohol is the rate-determining step.
- Landge, Vinod G.,Babu, Reshma,Yadav, Vinita,Subaramanian, Murugan,Gupta, Virendrakumar,Balaraman, Ekambaram
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p. 9876 - 9886
(2020/09/03)
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- Cu/Ni-Catalyzed Cyanomethylation of Alkenes with Acetonitrile for the Synthesis of β,γ-Unsaturated Nitriles
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We have developed a protocol for the Cu/Ni-catalyzed cyanomethylation of alkenes with acetonitrile for the synthesis of β,γ-unsaturated nitriles. This is the first example of a direct coupling of the alkene sp2 C - H bond and the acetonitrile sp3 C - H bond for the preparation of β,γ-unsaturated nitriles. Acetonitrile, an inexpensive and stable solvent, is demonstrated to be a useful cyanomethyl source. The combination of copper and nickel catalysts resulted in a high reaction efficiency.
- Jian, Hong,Shen, Zengming,Zhang, Saisai
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p. 6143 - 6150
(2020/05/22)
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- Pd-Catalyzed Oxidative Heck Reaction of Grignard Reagents with Diaziridinone as Oxidant
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A novel Pd-catalyzed oxidative Heck reaction with readily available Grignard reagents using di-t-butyldiaziridinone as an oxidant has been developed. Various substituted olefins were obtained in 46-91% yields with high regioselectivity under mild reaction conditions.
- Dai, Qipu,Zhao, Baoguo,Yang, Yihui,Shi, Yian
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supporting information
p. 5157 - 5161
(2019/07/04)
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- Halogenation of 1,1-diarylethylenes by N-halosuccinimides
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An efficient method for the preparation of 2,2-diarylvinyl halides from the corresponding 1,1-diarylethylenes has been developed. N-Halosuccinimides (N-bromosuccinimide or N-chlorosuccinimide) were used as the halogenation reagents. The practicability of this method is highlighted by its simple operation, broad substrate scope and capability for large-scale reaction.
- Zhang, Ge,Bai, Rui-Xue,Li, Chu-Han,Feng, Chen-Guo,Lin, Guo-Qiang
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supporting information
p. 1658 - 1662
(2018/12/11)
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- Photocatalytic, Phosphoranyl Radical-Mediated N-O Cleavage of Strained Cycloketone Oximes
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A photoinduced, phosphoranyl radical-mediated protocol for the direct N-O cleavage of strained cycloketone oximes via a polar/SET crossover process was developed for the first time. This visible-light-driven direct N-O activation mode for oxime offers beneficial features such as streamlined synthetic process and versatile photochemical reactivities. Consequently, the alkenes and α-trifluoromethyl alkenes with varied electronic and structural features acted as competent radical receptors in this protocol, enabling facile accesses to a range of elongated cyano and/or gem-difluoroalkene-bearing compounds.
- Xia, Peng-Ju,Ye, Zhi-Peng,Hu, Yuan-Zhuo,Song, Dan,Xiang, Hao-Yue,Chen, Xiao-Qing,Yang, Hua
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supporting information
p. 2658 - 2662
(2019/04/25)
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- Oxidative [4+2] Cycloaddition of α-(N-Arylamino) Carbonyls with Aryl Alkenes by Multiple C-H Functionalizations and [1,2]-Aryl Shifts
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A new, general copper-catalyzed oxidative tandem [4+2] cycloaddition of α-(N-arylamino) carbonyl compounds with aryl alkenes to produce highly substituted quinolines has been developed, which allows the formation of three new C-C bonds through a sequence of multiple C-H functionalizations, annulation, and [1,2]-aryl shifts.
- Wei, Wen-Ting,Teng, Fan,Li, Yang,Song, Ren-Jie,Li, Jin-Heng
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supporting information
p. 6285 - 6288
(2019/09/06)
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- Dehydrative Cross-Coupling of 1-Phenylethanol Catalysed by Palladium Nanoparticles Formed in situ under Acidic Conditions
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A dehydrative cross-coupling of 1-phenylethanol catalysed by sugar derived, in situ formed palladium(0) nanoparticles under acidic conditions is realised. The acidic conditions allow for use of alcohols as a feedstock in metal-mediated coupling reactions via their in situ dehydration and subsequent cross-coupling. Extensive analysis of the size and morphology of the palladium nanoparticles formed in situ showed that the zero-valent metal was surrounded by hydrophilic hydroxyl groups. EDX-TEM imaging studies using a prototype silicon drift detector provided insight into the problematic role of molecular oxygen in the system. This increased understanding of the catalyst deactivation allowed for the development of the cross-coupling methodology. A 250-12,000 fold increase in molar efficiency was observed when compared to related two-step protocols that use alternative feedstocks for the palladium-mediated synthesis of stilbenes. This work opens up a new research area in which the active catalyst is formed, stabilised and regenerated by a renewable sugar.
- Camp, Jason E.,Bousfield, Thomas W.,Dunsford, Jay J.,Adams, James,Britton, Joshua,Fay, Michael W.,Angelis-Dimakis, Athanasios
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supporting information
p. 3862 - 3874
(2018/09/29)
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- Nickel-Catalyzed Direct Synthesis of Aryl Olefins from Ketones and Organoboron Reagents under Neutral Conditions
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Nickel-catalyzed addition of arylboron reagents to ketones results in aryl olefins directly. The neutral condition allows acidic protons of alcohols, phenols, and malonates to be present, and fragile structures are also tolerated.
- Lei, Chuanhu,Yip, Yong Jie,Zhou, Jianrong Steve
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supporting information
p. 6086 - 6089
(2017/05/08)
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- High-enantioselectivity 1,1-diarylboroalkanes and preparation method thereof
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The invention provides high-enantioselectivity 1,1-diarylboroalkanes and a preparation method thereof, belonging to the technical field of organic synthetic chemistry. The structural general formula of the compounds is disclosed as Formula I. The invention also provides a preparation method of the high-enantioselectivity 1,1-diarylboroalkanes. The method comprises the following steps: carrying out reaction on a copper salt and an alkali under the catalytic action of an alkali to generate a tert-butyl oxy copper intermediate, and reacting with pinacol biborate to generate a copper-boron material, inserting C-C double bonds, and obtaining the hydrogen bononization products under the action of alcohol. The 1,1-diarylboroalkanes have high enantioselectivity; and the high performance liquid chromatography experiment proves that the ee value can reach 90% or above.
- -
-
Paragraph 0056; 0057; 0058; 0059
(2017/07/21)
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- Branched Arylalkenes from Cinnamates: Selectivity Inversion in Heck Reactions by Carboxylates as Deciduous Directing Groups
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A decarboxylative Mizoroki–Heck coupling of aryl halides with cinnamic acids has been developed in which the carboxylate group directs the arylation into its β-position before being tracelessly removed through protodecarboxylation. In the presence of a copper/palladium catalyst, both electron-rich and electron-deficient aryl bromides and chlorides bearing numerous functionalities were successfully coupled with broadly available cinnamates, with selective formation of 1,1-disubstituted alkenes. This reaction concept, in which the carboxylate acts as a deciduous directing group, ideally complements traditional 1,2-selective Heck reactions of styrenes.
- Tang, Jie,Hackenberger, Dagmar,Goossen, Lukas J.
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supporting information
p. 11296 - 11299
(2016/10/13)
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- Traceless directing group mediated branched selective alkenylation of unbiased arenes
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Owing to the synthetic importance of branched olefinated products, we report palladium catalyzed formation of branched olefins facilitated by a C-H activation based protocol. This involves selective insertion of olefins and subsequent decarboxylation using a completely unbiased benzene ring as the starting precursor. The significance of the protocol has been further highlighted by exhibition of functionality tolerance along with a late-stage modification of the branched olefinated products leading to the formation of other functionalized molecules.
- Agasti, Soumitra,Dey, Aniruddha,Maiti, Debabrata
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supporting information
p. 12191 - 12194
(2016/10/21)
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- Metal-free oxidative cross-coupling of diazirines with arylboronic acids
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We report herein a metal-free cross-coupling of diazirines with arylboronic acids under oxidative conditions. The reaction affords a series of substituted olefins. It is proposed that the interaction between the nitrogen on diazirine with arylboronic acid plays a key role in this transformation.
- Wu, Guojiao,Zhao, Xia,Ji, Wenzhi,Zhang, Yan,Wang, Jianbo
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p. 1961 - 1963
(2016/02/05)
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- Immobilized palladium nanoparticles on potassium zirconium phosphate as an efficient recoverable heterogeneous catalyst for a clean Heck reaction in flow
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Palladium nanoparticles on layered potassium α-zirconium phosphate (PdNP/α-ZrPK) with high palladium loading (10.6 wt%) have been prepared and used as catalyst in low amount (0.1 mol% of Pd) in the Heck reaction of methyl acrylate and styrene with a series of aryl iodides in CH3CN/H2O azeotrope as a green medium. The procedure has been optimized under flow conditions obtaining an extremely low waste production (E-factor) and allowing to isolate the final product with very low residual palladium content without any purification step.
- Petrucci, Chiara,Cappelletti, Matteo,Piermatti, Oriana,Nocchetti, Morena,Pica, Monica,Pizzo, Ferdinando,Vaccaro, Luigi
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- Electrophilic Fluorophosphonium Cations in Frustrated Lewis Pair Hydrogen Activation and Catalytic Hydrogenation of Olefins
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The combination of phosphorus(V)-based Lewis acids with diaryl amines and diaryl silylamines promotes reversible activation of dihydrogen and can be further exploited in metal-free catalytic olefin hydrogenation. Combined experimental and density functional theory (DFT) studies suggest a frustrated Lewis pair type activation mechanism. FLP hydrogenation: The combination of a phosphorus(V)-based Lewis acid with diaryl amines or diaryl silylamines promotes reversible activation of dihydrogen and can be further exploited in metal-free catalytic olefin hydrogenation. Combined experimental and density functional theory (DFT) studies suggest a frustrated Lewis pair (FLP)-type activation mechanism.
- Vom Stein, Thorsten,Perz, Manuel,Dobrovetsky, Roman,Winkelhaus, Daniel,Caputo, Christopher B.,Stephan, Douglas W.
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supporting information
p. 10178 - 10182
(2015/09/01)
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- Efficient synthesis of polysubstituted olefins using stable palladium nanocatalyst: Applications in synthesis of tamoxifen and isocombretastatin A4
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A phosphine-free stable palladium nanocatalyst was used for an efficient synthesis of polysubstituted olefins from N-tosylhydrazones and aryl iodides. This methodology was successfully utilized in the synthesis of biologically important tamoxifen and isocombretastatin A4. The nanocatalyst was easily recovered and reused without any apparent loss in size and catalytic activity.
- Ganapathy, Dhandapani,Sekar, Govindasamy
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supporting information
p. 3856 - 3859
(2014/08/18)
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- Synthesis of [N,P] ligands based on pyrrole. Application to the total synthesis of arnottin i
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This paper describes the synthesis of a new class of [N,P] ligands based on pyrrole with a dimethylamino group as hard donor and a phosphine moiety as soft base. We have also modified the phosphine fragment to change the electronic and steric properties of these ligands. Palladium complex 3a proved to be very efficient in Heck cross-coupling reactions and in intramolecular aryl-aryl couplings of esters and amides. We have demonstrated the applicability and efficiency of this novel catalyst in the total synthesis of the natural product arnottin I.
- Suárez-Meneses, Jesús V.,Bonilla-Reyes, Edgar,Blé-González, Ever A.,Ortega-Alfaro, M. Carmen,Toscano, Rubén Alfredo,Cordero-Vargas, Alejandro,López-Cortés, José G.
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supporting information
p. 1422 - 1430
(2014/02/14)
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- Selective arylation and vinylation at the α position of vinylarenes
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In intermolecular Heck reactions of styrene and vinylarenes, the aryl and vinyl groups routinely insert at the β position. However, selective insertion at the α position has been very rare. Herein, we provide a missing piece in the palette of Heck reaction, which gave >20:1 α selectivity. The key to our success is a new ferrocene 1,1′-bisphosphane (dnpf) that carries 1-naphthyl groups. Our mechanistic studies revealed that the high α selectivity is partly attributable to the steric effect of dnpf. The rigid and bulky 1-naphthyl groups of dnpf sterically disfavor β insertion. What the Heck! In intermolecular Heck reactions, insertion at the β position of aromatic olefins is very common, but reversal of the selectivity for selective α insertion has been a longstanding problem. A general method to couple aryl and vinyl triflates with aromatic olefins in >20:1 α selectivity is presented. The key to this successful approach is a new ferrocene bisphosphane with naphthyl groups on the phosphorus atom (see scheme; OTf=triflate). Copyright
- Zou, Yinjun,Qin, Liena,Ren, Xinfeng,Lu, Yunpeng,Li, Yongxin,Zhou, Jianrong
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p. 3504 - 3511
(2013/07/05)
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- Oxime palladacycle-catalyzed Suzuki-Miyaura alkenylation of aryl, heteroaryl, benzyl, and allyl chlorides under microwave irradiation conditions
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A simple new protocol for the palladium-catalyzed Suzuki-Miyaura cross-coupling of organic chlorides under microwave irradiation is presented. Deactivated aryl and heteroaryl chlorides are efficiently cross-coupled with alkenylboronic acids and potassium alkenyltrifluoroborates using the 4,4′-dichlorobenzophenone oxime-derived palladacycle 1b as precatalyst in 0.1 to 0.5 mol% palladium loading, tris(tert-butyl)phosphonium tetrafluoroborate {[HP(t-Bu)3]BF4} as ligand, tetra-n-butylammonium hydroxide as cocatalyst, and potassium carbonate as base in N,N- dimethylformamide at 130°C under microwave irradiation conditions. Under these conditions, styrenes, stilbenes, and alkenylarenes are obtained in good to high yields, and with high regio- and diastereoselectivities in only 20 min. The reported protocol is also very efficient for the regioselective alkenylation of benzyl and allyl chlorides to afford allylarenes and 1,4-dienes. Copyright
- Civicos, Jose F.,Alonso, Diego A.,Najera, Carmen
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supporting information; experimental part
p. 1683 - 1687
(2011/09/19)
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- Gas-phase ion-molecule reaction of alpha-phenylvinyl cation towards substituted benzenes in the environment of an ITMS
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Ion-molecule reactions between the α-phenylvinyl cation (α-PVC) and mono-substituted benzenes have been investigated using a quadrople ion-trap mass spectrometer. The α-PVC, generated by chemical ionization from phenylacetilene, was found to react selectively with mono-substituted benzenes bearing electron withdrawing groups to give the product ions [M + 103] + and the trans-vinylating product ions [M + 25]+. To characterize the reaction products, a combination of collision-induced dissociation, isotope-labeling experiments and model compounds were used. The results indicate, in addition to direct heteroatom alkylation, high extent of ortho attack. We attributed the positional selectivity of the α-PVC to the nature of the substituent on the neutral molecule. In particular, hydroxy and amino groups promoted the alkenylation at ortho position. Copyright
- Begala, Michela,Tocco, Graziella
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experimental part
p. 1115 - 1124
(2012/02/03)
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- Selective cine substitution of 1-arylethenyl acetates with arylboron reagents and a diene/rhodium catalyst
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When the crowd says Bo: A carbon-carbon bond is selectively formed at the β position of 1- arylethenyl acetate when the alkenyl substrate is reacted with arylboronic acids in the presence of a cycloocta-1,5-diene/rhodium catalyst. The choice of the ligand is crucial for the unusual cine substitution. Copyright
- Yu, Jung-Yi,Shimizu, Ryosuke,Kuwano, Ryoichi
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supporting information; experimental part
p. 6396 - 6399
(2010/11/17)
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- Construction of polysubstituted olefins through Ni-Catalyzed direct activation of Alkenyl C-O of substituted alkenyl acetates
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(Figure Presented) Reliable companion: For the first time cross-coupling between alkenyl acetates and arylboroxines/PhZnCl has been developed via Ni catalysis. Alkenyl acetates could be well-differ-entiated from aryl acetates (see scheme). This reliable method provides a convenient pathway to construct polysubstituted styrene derivatives.
- Sun, Chang-Liang,Yang, Wang,Xiao, Zhou,Wu, Zhen-Hua,Li, Bi-Jie,Guan, Bing-Tao,Shi, Zhang-Jie
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supporting information; experimental part
p. 5844 - 5847
(2010/09/03)
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- A ligand free and room temperature protocol for Pd-catalyzed kumada-corriu couplings of unactivated alkenyl phosphates
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Kumada - Corriu cross-couplings of nonactivated cyclic and acyclic vinyl phosphates with aryl magnesium reagents afforded a series of 1,1-disubtituted alkenes in good yields for most cases when the reactions were performed at room temperature with the sim
- Gauthier, Delphine,Beckendorf, Stephan,Gogsig, Thomas M.,Lindhardt, Anders T.,Skrydstrup, Troels
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supporting information; experimental part
p. 3536 - 3539
(2009/09/30)
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- Synthesis of benzophenones from geminal biaryl ethenes using m-chloroperbenzoic acid
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The oxidation of geminal biaryl ethenes 3 and 1,3-enynes 5 using m-chloroperbenzoic acid in dichloromethane at room temperature presents a catalyst-free approach for the synthesis of functionalized benzophenones 4 and ynones 6, respectively.
- Singh, Fateh V.,Milagre, Humberto M.S.,Eberlin, Marcos N.,Stefani, Helio A.
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experimental part
p. 2312 - 2316
(2009/09/06)
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- Studies on the 1,2-migrations in Pd-catalyzed negishi couplings with JosiPhos ligands
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(Chemical Equation Presented) We report an initial investigation with the goal of determining the factors that control the 1,2-migration in the Negishi cross-coupling, which is promoted by palladium catalyst systems generated with JosiPhos ligands. Severa
- Lindhardt, Anders T.,G?gsig, Thomas M.,Skrydstrup, Troels
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supporting information; experimental part
p. 135 - 143
(2009/04/07)
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- Metal-free hydroarylation of alkynes: A very convenient, simple procedure for substituted arylalkenes
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Hydroarylation of aryl-substituted alkynes with simple and substituted arenes was conducted in the presence of trifluoroacetic acid in dichloromethane without any metal catalysts or additives. Electron-rich arenes coupled with aryl-substituted alkynes to give 1,1-diarylalkenes in good to high yields. Georg Thieme Verlag Stuttgart.
- Rahman, Md. Ataur,Ogawa, Osamu,Oyamada, Juzo,Kitamura, Tsugio
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experimental part
p. 3755 - 3760
(2009/06/06)
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- Rationally designed pincer-type heck catalysts bearing aminophosphine substituents: PdIV intermediates and palladium nanoparticles
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The aminophosphine-based pincer complexes [C6H 3-2,6-{XP(piperidinyl)2}2Pd(Cl)] (X = NH 1; X = O 2) are readily prepared from cheap starting materials by sequential addition of 1,1′,1″-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(Cl)2] (cod = cyclooctadiene) in toluene under N2 in "one pot". Compounds 1 and 2 proved to be excellent Heck catalysts and allow the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins as coupling partners at 140°C within very short reaction times and low catalyst loadings. Increased reaction temperatures also enable the efficient coupling of olefins with electronically deactivated and sterically hindered aryl chlorides in the presence of only 0.01 mol% of catalyst. The mechanistic studies performed rule out that homogeneous Pd0 complexes are the catalytically active forms of 1 and 2. On the other hand, the involvement of palladium nanoparticles in the catalytic cycle received strong experimental support. Even though pincer-type PdIV intermediates derived from 1 (and 2) are not involved in the catalytic cycle of the Heck reaction, their general existence as reactive intermediates (for example, in other reactions) cannot be excluded. On the contrary, they were shown to be thermally accessible. Compounds 1 and 2 show a smooth halide exchange with bromobenzene to yield their bromo derivatives in DMF at 100°C. Experimental observations revealed that the halide exchange most probably proceeded via pincer-type PdIV intermediates. DFT calculations support this hypothesis and indicated that aminophosphine-based pincer-type PdIV intermediates are generally to be considered as reactive intermediates in reactions with aryl halides performed at elevated temperatures.
- Bolliger, Jeanne L.,Blacque, Olivier,Frech, Christian M.
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experimental part
p. 7969 - 7977
(2009/09/08)
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- Carbocyclic carbene ligands derived from aromatic nitrones: Formation and catalytic activity of their Pd(II) complexes
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Nitrones derived from aromatic aldehydes were shown to be convenient precursors to a novel class of carbocyclic carbene ligands. Air- and moisture-stable palladium complexes derived from the carbocyclic carbene ligands exhibit unprecedented catalytic efficiency in the Heck reaction. Deactivated aryl bromides, such as 4-bromoanisole, undergo coupling with styrene in the presence of 8 × 10-5 mol % of the catalysts with TON exceeding 0.9 million. Copyright
- Yao, Qingwei,Zabawa, Mark,Woo, Joyce,Zheng, Chong
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p. 3088 - 3089
(2007/10/03)
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- Direct synthesis of 1,1-diarylalkenes from alkenyl phosphates via nickel(0)-catalysed Suzuki-Miyaura coupling
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A combination of Ni(COD)2 and PCy3 promotes effectively the Suzuki-Miyaura cross coupling of 1-arylalkenyl phosphates with aryl boronic acids with yields attaining 99%. The Royal Society of Chemistry 2006.
- Hansen, Anders L.,Ebran, Jean-Philippe,Gogsig, Thomas M.,Skrydstrup, Troels
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p. 4137 - 4139
(2007/10/03)
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- Gold(I)-catalyzed oxidative cleavage of a C-C double bond in water
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Oxidative cleavage of the C=C bond to afford ketone or aldehyde products with tert-butyl hydrogenperoxide (TBHP) as the oxidant can be catalyzed by AuCl with neocuproine (1) in water.
- Xing, Dong,Guan, Bingtao,Cai, Guixin,Fang, Zhao,Yang, Liping,Shi, Zhangjie
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p. 693 - 696
(2007/10/03)
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- Decarbonylative Heck olefination of enol esters: Salt-free and environmentally friendly access to vinyl arenes
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Thank you, no salt on the side. In this variant of the Heck olefination, enol esters serve as environmentally friendly synthetic equivalents of aryl halides. These reactants, in turn, are available from a waste-free synthesis from carboxylic acids and propyne. Thus, a salt-free overall process has been devised for preparing vinyl arenes from a variety of aromatic carboxylic acids.
- Goossen, Lukas J.,Paetzold, Jens
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p. 1095 - 1098
(2007/10/03)
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- Synthesis of polysubstituted alkenes by Heck vinylation or Suzuki cross-coupling reactions in the presence of a tetraphosphane-palladium catalyst
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Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3, 4-tetrakis[(diphenylphosphanyl)methyl]cyclopentane as a catalyst, a range of vinyl bromides undergo Suzuki cross-couplings with arylboronic acids in good yields. Furthermore, the catalyst can be used at low loadings, even for reactions of sterically hindered substrates. Mediated by this catalyst, stilbene and 1,1-diphenylethylene undergo Heck reactions with aryl halides to give triarylethylene derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 1091 - 1096
(2007/10/03)
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- Arylation of Olefins by N-Nitroso-N-arylacetamides under Palladium(0) Catalysis: A New Precursor of Arylpalladium Species
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Olefins (styrene, octene-1, cycloheptene, ethyl acrylate, and vinyl acetate) were easily arylated in good yields with N-nitroso-N-arylacetamides (ArN(NO)COCH3: Ar= Ph, 4-MeC6H4, 4-MeOC6H4, 4-ClC6H4, 4-BrC6H4, and 4-IC6H4) under palladium(0) catalysis at 40 deg C within 40 min.
- Kikukawa, Kiyoshi,Naritomi, Masaki,He, Gong-Xin,Wada, Fumio,Matsuda, Tsutomu
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p. 299 - 301
(2007/10/02)
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