- Organoborane-catalyzed selective 1,2-reduction of alkynones with hydride transfer: Synthesis of benzyl alkynes
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Benzyl alkynes are important organic building blocks in organic synthesis. We report herein a B(C6F5)3-catalyzed site-selective 1,2-reduction of readily available alkynones to access benzyl alkyne derivatives. Under the de
- Zhai, Lele,Yang, Zhigang,Man, Qinghong,Yang, Mingyu,Ren, Yangqing,Wang, Lei,Li, Huilin,She, Xuegong
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- Compound containing carbon-silicon bond and application thereof
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The invention discloses a compound containing a carbon-silicon bond and application of the compound in construction of the carbon-carbon bond. The invention provides an application of a compound containing the carbon-silicon bond as shown in a formula I or a formula I' in a chemical reaction for constructing the carbon-carbon bond, wherein one carbon in the carbon-carbon bond is from carbon connected with silicon in the compound containing the carbon-silicon bond. According to the preparation method, the compound containing the carbon-silicon bond is used for providing a carbon free radical, and the carbon free radical can directly react with carbon provided in another molecule under a mild condition to construct the carbon-carbon bond; the preparation method is wider in substrate application range, is suitable for functional group activated C and carbon free radical substrates, and is also suitable for unactivated C-H bond substrates.
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Paragraph 0418-0421
(2020/09/08)
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- Regioselective Iron-Catalysed Cross-Coupling Reaction of Aryl Propargylic Bromides and Aryl Grignard Reagents
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An iron-catalysed Kumada-type cross-coupling reaction between aryl substituted propargylic bromides and arylmagnesium reagents has been developed. Propargylic coupling products were the main or only outcome, and propargyl/allene regioselectivity was shown to depend on the electronic nature of the substituents on the triple bond of the substrate and on the arylmagnesium halide. Best selectivities were observed when electron donating substituents were present in either reagent. The process is stereoespecific, occurs with configuration inversion and no carbon-based radicals seem to be involved in the mechanism. (Figure presented.).
- Manjón-Mata, Inés,Quirós, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
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supporting information
p. 146 - 151
(2019/12/11)
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- Fast heck-cassar-sonogashira (hcs) reactions in green solvents
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The replacement of toxic solvents with greener alternatives in Heck-Cassar-Sonogashira (HCS) cross-couplings was investigated. The fine-tuning of the HCS protocol allowed to achieve complete conversions and high speed under mild conditions. N-Hydroxyethylpyrrolidone (HEP) gave the best results. Moreover, the methodology was successfully applied to the synthesis of an intermediate of the anticancer drug Erlotinib, demonstrating the versatility of the new green protocol.
- Cabri, W.,Corbisiero, D.,Daka, A.,Fantoni, T.,Ferrazzano, L.,Martelli, G.,Ricci, A.,Tolomelli, A.,Viola, A.
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supporting information
p. 3969 - 3973
(2020/06/08)
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- Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
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Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.
- Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
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supporting information
p. 18251 - 18265
(2020/11/02)
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- A Copper-Catalyzed Sonogashira Coupling Reaction of Diverse Activated Alkyl Halides with Terminal Alkynes Under Ambient Conditions
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We describe a copper-catalyzed Sonogashira coupling reaction of alkyl halides with terminal alkynes under ambient conditions, efficiently providing a versatile tool for the construction of substituted alkynes. A new proline-based N,N,P-ligand is utilized to promote the transformation under a mild reaction condition. Diverse alkyl halides, such as primary and secondary (hetero)benzyl chlorides and bromides, secondary and tertiary α-bromo amides and propargylic bromide, are applicable to provide a wide array of alkynes. (Figure presented.).
- Cao, Yu-Xi,Dong, Xiao-Yang,Yang, Jun,Jiang, Sheng-Peng,Zhou, Shuangliu,Li, Zhong-Liang,Chen, Guo-Qiang,Liu, Xin-Yuan
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supporting information
p. 2280 - 2284
(2020/05/08)
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- Visible Light-Catalyzed Decarboxylative Alkynylation of Arenediazonium Salts with Alkynyl Carboxylic Acids: Direct Access to Aryl Alkynes by Organic Photoredox Catalysis
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A convenient method mediated by photoredox catalysis is developed for the direct construction of aryl alkynes. Readily available aromatic diazonium salts have been utilized as the aryl radical source to couple alkynyl carboxylic acids to feature the decarboxylative arylation. A wide range of substrates are amenable to this protocol with broad functional group tolerance, and diversely-functionalized aryl alkynes could be synthesized under mild, neutral and transition metal-free reaction conditions using visible light irradiation. Alongside synthetic sustainability associated with the photocatalytic and transition metal-free operation, another key point of this method is that the organic dye catalyst acts as an excited-state reductant, thus establishing the quenching cycle for radical addition and decarboxylative elimination. (Figure presented.).
- Yang, Liangfeng,Li, Haifeng,Du, Yijun,Cheng, Kai,Qi, Chenze
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p. 5030 - 5041
(2019/11/03)
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- Palladium-Catalyzed Coupling of Terminal Alkynes with Benzyl Ammonium Salts
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A highly efficient palladium-catalyzed Sonogashira coupling of benzylic ammonium salts with terminal alkynes is developed. This strategy provides a facile access to a series of internal alkyne derivatives in moderate to excellent yields via C-N bond cleavage and C(sp3)-C(sp) bond formation. The broad substrate scope and high functional group tolerance make this reaction attractive for organic synthesis.
- Xu, Silin,Zhang, Zhenming,Han, Chunyu,Hu, Wenkai,Xiao, Tiwen,Yuan, Yanan,Zhao, Junfeng
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p. 12192 - 12197
(2019/10/11)
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- The Direct Conversion of α-Hydroxyketones to Alkynes
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Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the direct conversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C-C bond, it enables a highly versatile fragment coupling approach toward alkynes. A broad scope for this novel transformation is shown alongside mechanistic insights. Furthermore, the utility of our protocol is demonstrated through its application in concert with varied α-hydroxyketone syntheses, giving access to a broad spectrum of alkynes.
- Ghiringhelli, Francesca,Nattmann, Lukas,Bognar, Sabine,Van Gemmeren, Manuel
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p. 983 - 993
(2019/01/24)
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- Conjugated mesoporous polyazobenzene–Pd(II) composite: A potential catalyst for visible-light-induced Sonogashira coupling
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We herein report the direct harnessing of visible light energy by a novel semiconducting azobenzene-based colloidal porous organic polymer, B3-Azo4 amenable to post-synthetic Pd(II)-complexation for photo-induced Sonogashira coupling using polymer → metal energy transfer process. Completely mesoporous nano-sized particles of the obtained organic network manifested excellent Pd(II) coordinating ability and afforded desired catalytic products at room temperature under aerobic condition in aqueous medium. The protocol remained valid for different aromatic and aliphatic substrates as well. A possible reaction mechanism for photo-mediated Sonogashira coupling catalyzed by Pd-B3-Azo4 is also proposed.
- Nath, Ipsita,Chakraborty, Jeet,Khan, Anish,Arshad, Muhammad N.,Azum, Naved,Rab, Malik A.,Asiri, Abdullah M.,Alamry, Khalid A.,Verpoort, Francis
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p. 183 - 189
(2019/08/07)
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- Visible light-driven cross-coupling reactions of alkyl halides with phenylacetylene derivatives for C(sp3)-C(sp) bond formation catalyzed by a B12 complex
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Visible light-driven cross-coupling reactions of alkyl halides with phenylacetylene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ir(dtbbpy)(ppy)2]PF6 photocatalyst at room temperature are reported. The robust B12 catalyst and Ir photocatalyst provided high turnover numbers of over 33?000 for the reactions.
- Chen, Li,Kametani, Yohei,Imamura, Kenji,Abe, Tsukasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Hisaeda, Yoshio,Shimakoshi, Hisashi
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supporting information
p. 13070 - 13073
(2019/11/11)
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- Application of Hantzsch Ester and Meyer Nitrile in Radical Alkynylation Reactions
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The first example of constructing a Csp3-Csp bond with substituted Hantzsch ester and Meyer nitrile is reported. When benziodoxole-activated alkyne was applied as the alkynyl donor, products containing Csp3-Csp bonds involving primary, secondary, and tertiary carbon centers were achieved in up to 97% yields. K2S2O8 was the optimum radical initiator in this reaction.
- Liu, Xu,Liu, Ruoyu,Dai, Jie,Cheng, Xu,Li, Guigen
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supporting information
p. 6906 - 6909
(2018/10/25)
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- Cleavage of C–C and C–O Bonds to Form C–C Bonds: Direct Cross-Coupling between Acetylenic Alcohols and Benzylic Carbonates
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A palladium-catalyzed cross-coupling reaction between C(sp) and C(sp3) centers was achieved in excellent yields via C–C bond cleavage and C–O bond cleavage. This procedure uses relatively stable acetylenic alcohols as reactants instead of unsta
- Mi, Zhiyuan,Tang, Jiahao,Guan, Zhipeng,Shi, Wei,Chen, Hao
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p. 4479 - 4482
(2018/09/10)
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- Palladium-Catalyzed Decarboxylative Benzylation of Acetylides and Enolates
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Benzylic alkylation of enolates and acetylides has been achieved through the use of a decarboxylative benzylation strategy. Previous research in this area is often limited by the need for extended conjugation in the electrophiles that are coupled. Herein, we report that the use of 1,1'-bis(diphenylphosphino)ferrocene (dppf) ligand allows the coupling of simple benzyl electrophiles with enolates, while the use of XPhos ligand promotes the decarboxylative couplings of propiolates.
- Torregrosa, Robert R. P.,Mendis, Shehani N.,Davies, Alex,Tunge, Jon A.
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p. 3205 - 3216
(2018/08/17)
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- Matched Coupling of Propargylic Carbonates with Cyclopropanols
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The ring opening-coupling reaction of cyclopropanols with propargylic carbonates affording synthetically attractive allenyl ketones has been developed. The mechanism involves the ligand-exchange reaction of in situ formed allenyl palladium methoxide with cyclopropanols followed by carbon-carbon bond cleavage and reductive elimination. The reactions proceeded smoothly under mild reaction conditions with Pd(0)/XPhos catalysis in the absence of any external base and displayed a wide scope and application to a steroidal skeleton. The efficiency of chirality transfer and synthetic utility of the allene products have also been demonstrated.
- Wu, Penglin,Jia, Minqiang,Lin, Weilong,Ma, Shengming
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supporting information
p. 554 - 557
(2018/02/10)
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- Synthesis of Pd(II) large dinuclear macrocyclic complex tethered through two dipyridine-bridged aza-crowns as an efficient copper- and phosphine-free Sonogashira catalytic reaction
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For the first time the new 32-membered macrocyclic dinuclear palladium complex of two aza-crown macrocycles, bearing two pyridine arms, Pd2L2Cl4 was synthesized and characterized by elemental analysis, IR, NMR spectroscopy and single crystal X-ray diffraction methods. Pd2L2Cl4 was investigated as a moisture/air-stable catalyst for Sonogashira cross-coupling reaction in the absence of copper and phosphine ligand in DMSO. Thermal stability, possible occurrence of tandem reactions, promoted catalytic performance as well as synergistic effects are of advantageous features of Pd2L2Cl4. By employing Taguchi method, optimum conditions (110 °C, 6 h, KOAc, 2 mol% cat.) were determined. Moreover, the homogenous catalyst represented good reusability up to four cycles. Comparing the catalytic activity of several other previously reported Pd(II) dinuclear complexes, Pd2L2Cl4 enjoys the advantages of short time of reaction and thermal stability.
- Ghanbari, Bahram,Shahhoseini, Leila,Hosseini, Hadighehsadat,Bagherzadeh, Mojtaba,Owczarzak, Agata,Kubicki, Maciej
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- Redox-Activated Amines in C(sp3)-C(sp) and C(sp3)-C(sp2) Bond Formation Enabled by Metal-Free Photoredox Catalysis
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The amino group represents one of the most prevalent structural motifs in organic chemistry. Therefore, application of amines as alkylating agents in synthesis is highly compelling. Herein, we present a metal-free photoredox strategy for the formation of C(sp3)-C(sp) and C(sp3)-C(sp2) bonds from redox-activated primary amine derivatives. The developed reaction of 2,4,6-triphenylpyridinium salts with alkynyl p-tolylsulfones, leading to functionalized alkynes, is easily scalable and offers broad substrate scope, high chemoselectivity, and mild conditions. Its potential is also highlighted by diversification of complex molecular scaffolds. Additionally, the approach is also suitable for synthesis of (E)-alkenes from vinyl phenyl sulfones. Mechanistic studies contribute to the elucidation of unexpected differences in reactivity of primary and secondary alkyl substituted pyridinium salts.
- Ociepa, Micha,Turkowska, Joanna,Gryko, Dorota
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p. 11362 - 11367
(2018/11/23)
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- Regio- and Stereospecific Copper-Catalyzed Substitution Reaction of Propargylic Ammonium Salts with Aryl Grignard Reagents
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We have developed a copper-catalyzed substitution reaction of propargylic ammonium salts with aryl Grignard reagents. The reaction is stereospecific and α-regioselective and proceeds with exceptional functional group tolerance. Conveniently, a stable, inexpensive, and commercially available copper salt is used and no added ligand is required.
- Guisán-Ceinos, Manuel,Martín-Heras, Victor,Tortosa, Mariola
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p. 8448 - 8451
(2017/07/06)
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- Decarboxylative/Sonogashira-type cross-coupling using PdCl2(Cy?Phine)2
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The PdCl2(Cy?Phine)2 precatalyst containing the meta-terarylphosphine ligand, Cy?Phine, can effectively mediate decarboxylative cross-coupling with a diverse range of (hetero-)aryl, aryl and alkyl chlorides including those with unprotected functionality. Using a facile and robust protocol, this process was extended to the first synthesis of symmetrical di(heteroaryl)alkynes via tandem Sonogashira/decarboxylative cross-coupling of heteroaryl chlorides and propiolic acid.
- Yang, Yong,Lim, Yee Hwee,Robins, Edward G.,Johannes, Charles W.
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p. 72810 - 72814
(2016/08/09)
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- Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation
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Pd-catalysed C-C bond formation is an essential tool within the pharmaceutical and agrochemical industries. Many of these reactions rely heavily on polar aprotic solvents; however, despite their utility, these solvents are incompatible with the drive towards more sustainable chemical synthesis. Herein, we describe the scope and limitations of an alternative to DMF derived from renewable sources (Cyrene) in Sonogashira cross-coupling and Cacchi-type annulations.
- Wilson, Kirsty L.,Kennedy, Alan R.,Murray, Jane,Greatrex, Ben,Jamieson, Craig,Watson, Allan J. B.
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supporting information
p. 2005 - 2011
(2016/10/05)
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- ONO pincer type binuclear Pd(II) complex: Synthesis, crystal structure and catalytic utilization of the resulting organopalladium complex in catalytic copper-free Sonogashira coupling reaction
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New binuclear palladium (II) complex featuring ONO pincer type hydrazone ligand was synthesized and characterized by spectroscopic and single-crystal XRD analysis. This complex showed excellent catalytic activity towards the copper-free Sonogashira cross coupling reaction. The main advantages over previous methodologies include low catalyst loading, less problematic reaction media (H2O–DMSO) and reusability in homogenous systems for optimal performance.
- Bagherzadeh, Mojtaba,Mousavi, Narges-alsadat,Zare, Maryam,Jamali, Sirous,Ellern, Arkady,Woo, L. Keith
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p. 227 - 232
(2016/08/05)
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- Copper-free Sonogashira cross-coupling reactions catalyzed by an efficient dimeric C,N-palladacycle in DMF/H2O
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Very small concentrations of a dimeric C,N-palladacycle were used as an efficient homogeneous catalyst for Sonogashira cross-coupling reactions between various aryl halides and phenylacetylene. The catalytic reactions were performed without the need for copper in DMF/H2O. This catalytic system shows excellent yields for aryl iodides and bromides and even in the case of aryl chlorides.
- Karami, Kazem,Haghighat Naeini, Nasrin
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p. 1199 - 1207
(2016/03/01)
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- A copper-free Sonogashira reaction using nickel ferrite as catalyst in water
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The Sonogashira reaction using nickel ferrite nanoparticles as catalyst and under copper-free conditions was investigated in water as a green solvent. Various types of aryl and alkyl halides were successfully coupled with phenyl acetylene under the optimized reaction conditions with very good to excellent yields at a short time. The catalyst is easily recoverable and can be reused for several runs with a good turnover number.
- Moghaddam, Firouz Matloubi,Tavakoli, Ghazal,Rezvani, Hamid Reza
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- Synthesis of Multinuclear Copper Complexes Bridged by Diquinolylamidinates and Their Application to Copper-Catalyzed Coupling of Terminal Alkynes and Aryl, Allyl, and Benzyl Halides
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A dinuclear copper complex containing N,N′-diquinolylformamidinate and a tetranuclear copper complex containing N,N′-diquinolylacetamidinate were synthesized. The structure of complexes was confirmed by X-ray analysis, showing that copper atoms were bridg
- Nakane, Takayuki,Tanioka, Yuta,Tsukada, Naofumi
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p. 1191 - 1196
(2015/04/27)
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- Synthesis of Ni(II) complexes with unsymmetric [O,N,O′]-pincer ligands and their use as precatalysts in carbon-carbon bond formations to access diarylmethanes
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1-Acetyl-[1a,3,5-CF3,1-C(=O)CH3] and 1-benzoyl-5-hydroxypyrazolines [1b, 3,5-CF3, 1-C(=O)C 6H5] have been synthesized and reacted with Ni(OAc) 2·4H2O in the presence of PPh3 to form square planar nickel complexes, which revealed a O,N,O′-coordination. An additional coordination site on the nickel center is occupied by one triphenylphosphane ligand. After having investigated the properties of the complexes, catalytic experiments have been carried out to synthesize diarylmethanes. Applying the complexes in the nickel-catalyzed carbon-carbon cross coupling of aryl halides with benzylzinc bromide excellent yields and selectivities of the corresponding diarylmethane have been obtained. Moreover, various experiments have been performed to shed light on the underlying reaction mechanism.
- Someya, Chika I.,Irran, Elisabeth,Enthaler, Stephan
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p. 136 - 144
(2014/07/08)
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- Copper-catalyzed aerobic oxidative transformation of ketone- Derived N-tosyl hydrazones: An entry to alkynes
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A novel strategy involving Cu-catalyzed oxidative transformation of ketone-derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross-coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu-carbene intermediate is proposed for the CC triple bond formation.
- Li, Xianwei,Liu, Xiaohang,Chen, Huoji,Wu, Wanqing,Qi, Chaorong,Jiang, Huanfeng
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p. 14485 - 14489
(2015/02/05)
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- Reactions of phenylethynyl cuprates of lanthanides with organyl halides and synthesis of the related polyfunctional compounds
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Phenylethynyl cuprate complexes of lanthanides react with organyl halides RX, Ph3CX, R3SiX, and RC(O)X (X = Cl, I; R = alkyl) in tetrahydrofuran to give polyfunctional organic and hetero-organic compounds with high yield. The reactio
- Zhil'tsov,Druzhkova,Dydykina,Makarov
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p. 2167 - 2173
(2015/02/05)
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- Nickel-catalyzed substitution reactions of propargyl halides with organotitanium reagents
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A simple and mild catalytic coupling reaction of propargyl halides with organotitanium reagents is reported. The reaction of propargyl bromide with organo-titanium reagents mediated by NiCl2(2 mol%) and PCy3(4 mol%) in CH2
- Li, Qing-Han,Liao, Jung-Wei,Huang, Yi-Ling,Chiang, Ruei-Tang,Gau, Han-Mou
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p. 7634 - 7642
(2014/12/11)
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- Transition-metal-free Suzuki-Miyaura coupling reaction of arylpropargylic bromides with aryl- and alkenylboronic acids
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In the absence of transition-metal catalyst, Suzuki-Miyaura coupling reaction between aryl- and alkenylboronic acids and arylpropargylic bromides proceeded to give the corresponding acetylenic products selectively. Georg Thieme Verlag Stuttgart New York.
- Ueda, Mitsuhiro,Nishimura, Kota,Ryu, Ilhyong
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p. 1683 - 1686
(2013/09/02)
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- Highly chemoselective calcium-catalyzed propargylic deoxygenation
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A calcium-catalyzed direct reduction of propargylic alcohols and ethers has been accomplished by using triethylsilane as a nucleophilic hydride source. At room temperature a variety of secondary propargylic alcohols was deoxygenated to the corresponding h
- Meyer, Vera J.,Niggemann, Meike
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supporting information; experimental part
p. 4687 - 4691
(2012/05/04)
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- Base-free palladium-catalyzed sonogashira coupling using organogold complexes
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Turn to gold: An effective protocol for base-free Sonogashira coupling reactions using organogold complexes as nucleophilic partners has been developed. The palladium-catalyzed methodology offers a general synthesis of aryl-alkynes under operationally simple conditions in good to excellent yields. Copyright
- Pankajakshan, Sreekumar,Loh, Teck-Peng
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experimental part
p. 2291 - 2295
(2012/06/30)
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- Simple and efficient nickel-catalyzed cross-coupling reaction of alkynylalanes with benzylic and aryl bromides
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Highly efficient and simple coupling reactions of benzylic and aryl bromides with aluminium acetylide catalyzed by NiCl2(PPh 3)2 are reported. The coupling reactions proceed at room temperature employing 4 mol% catalyst, affording coupling products in excellent yields of up to 95% in short reaction times. The system worked efficiently with aryl and heterocyclic bromides as well.
- Biradar, Deepak B.,Gau, Han-Mou
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supporting information; experimental part
p. 10467 - 10469
(2011/10/19)
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- Palladium-catalyzed Sonogashira reactions of aryl amines with alkynes via in situ formation of arenediazonium salts
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A general and convenient palladium-catalyzed Sonogashira reaction of in situ generated arenediazonium salts has been developed and various internal arylalkynes are produced in good yields under mild conditions.
- Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 7959 - 7961
(2011/08/05)
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- Fritsch-Buttenberg-Wiechell rearrangement to alkynes from gem-dihaloalkenes with lanthanum metal
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The first example of the FBW rearrangement using of lanthanum metal and a catalytic amount of iodine was disclosed. When gem-diiodo- and gem-dibromoalkenes were treated with lanthanum metal in the presence of a catalytic amount of iodine, the reductive dehalogenation of these compounds smoothly proceeded to produce the corresponding alkynes in moderate to good yields.
- Umeda, Rui,Yuasa, Takumi,Anahara, Namika,Nishiyama, Yutaka
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supporting information; experimental part
p. 1916 - 1919
(2011/05/14)
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- Silver triflate-catalyzed cyclopropenation of internal alkynes with donor-/acceptor-substituted diazo compounds
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Silver triflate was found to be an efficient catalyst for the cyclopropenation of internal alkynes using donor-/acceptor-substituted diazo compounds as carbenoid precursors. Highly substituted cyclopropenes, which cannot be synthesized directly via rhodium(II)-catalyzed carbenoid chemistry, can now be readily accessed.
- Briones, John F.,Davies, Huw M. L.
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supporting information; experimental part
p. 3984 - 3987
(2011/09/16)
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- Palladium-catalyzed cross-coupling reactions of organogold(I) reagents with organic electrophiles
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The palladium-catalyzed cross-coupling reaction of organogold(I) reagents (alkyl, alkenyl, aryl, and alkynyl) with organic electrophiles, such as aryl and alkenyl halides, aryl triflates, benzyl bromide, and benzoyl chloride is reported. The reaction takes place, under palladium catalysis, at room temperature with short reaction times to give the corresponding cross-coupling products in high yields.
- Pena-Lopez, Miguel,Ayan-Varela, Miguel,Sarandeses, Luis A.,Perez Sestelo, Jose
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supporting information; experimental part
p. 9905 - 9909
(2010/10/19)
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- Palladium-catalyzed decarboxylative coupling of alkynyl carboxylic acids with benzyl halides or aryl halides
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(Figure presented) The synthesis of internal benzyl alkynes and 1,2-diarylalkynes has been developed via palladium-catalyzed decarboxylative coupling reactions of alkynyl carboxylic acids with benzyl chlorides or aryl halides. In the presence of Pd(OAc)2 and Xphos (L3), alkynyl carboxylic acids smoothly underwent the reaction with various benzyl halides, providing the corresponding benzyl alkynes in moderate to good yields. It is noteworthy that the optimal conditions are compatible with a wide range of aryl halides including less active aryl chlorides.
- Zhang, Wen-Wu,Zhang, Xing-Guo,Li, Jin-Heng
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experimental part
p. 5259 - 5264
(2010/10/04)
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- Selective synthesis of allenes and alkynes through ligand-controlled, palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates
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Ligand-controlled regioselective palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates is described. A wide range of allenes and alkynes were obtained by using either 1,2-diphenylphosphinoethane (DPPE) or 1,6-bisdiphenylphosphinohexane (DPPH) as a catalyst ligand.
- Ohmiya, Hirohisa,Yang, Mingyu,Yamauchi, Yoshihiro,Ohtsuka, Yuhki,Sawamura, Masaya
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supporting information; experimental part
p. 1796 - 1799
(2010/09/07)
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- Gold(I)-catalyzed arylmethylation of terminal alkynes
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AuCl/AgOTf catalyzes the reaction of terminal alkynes with aryl trichloroacetimidate to afford arylmethylation products in moderate to good yields.
- Li, Changkun,Li, Weibin,Wang, Jianbo
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supporting information; experimental part
p. 2533 - 2535
(2009/07/26)
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- Palladium-catalyzed cross-coupling reaction of aryl trimethoxysilanes with terminal alkynes
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A palladium-catalyzed cross-coupling reaction of aryl trimethoxysilanes with terminal alkynes was described. Thus, di-substituted alkynes were prepared in moderate to good yields. The electron-deficient terminal alkynes also worked well in the procedure.
- Ye, Zhishi,Liu, Miaochang,Lin, Baoda,Wu, Huayue,Ding, Jinchang,Cheng, Jiang
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scheme or table
p. 530 - 532
(2009/04/14)
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- Preparation, structure, and reactivity of nonstabilized organoiron compounds. Implications for iron-catalyzed cross coupling reactions
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A series of unprecedented organoiron complexes of the formal oxidation states -2, 0, +1, +2, and +3 is presented, which are largely devoid of stabilizing ligands and, in part, also electronically unsaturated (14-, 16-, 17- and 18-electron counts). Specifically, it is shown that nucleophiles unable to undergo β-hydride elimination, such as MeLi, PhLi, or PhMgBr, rapidly reduce Fe(3+) to Fe(2+) and then exhaustively alkylate the metal center. The resulting homoleptic organoferrate complexes [(Me4Fe)(MeLi)] [Li(OEt2)]2 (3) and [Ph4Fe][Li(Et 2O)2][Li(1,4-dioxane)] (5) could be characterized by X-ray crystal structure analysis. However, these exceptionally sensitive compounds turned out to be only moderately nucleophilic, transferring their organic ligands to activated electrophiles only, while being unable to alkylate (hetero)aryl halides unless they are very electron deficient. In striking contrast, Grignard reagents bearing alkyl residues amenable to β-hydride elimination reduce FeXn (n = 2, 3) to clusters of the formal composition [Fe(MgX)2]n. The behavior of these intermetallic species can be emulated by structurally well-defined lithium ferrate complexes of the type [Fe(C2H4) 4][Li(tmeda)]2 (8), [Fe(cod)2][Li(dme)] 2 (9), [CpFe(C2H4)2][Li(tmeda)] (7), [CpFe(cod)][Li(dme)] (11), or [Cp*Fe(C2H4) 2][Li(tmeda)] (14). Such electron-rich complexes, which are distinguished by short intermetallic Fe-Li bonds, were shown to react with aryl chlorides and allyl halides; the structures and reactivity patterns of the resulting organoiron compounds provide first insights into the elementary steps of low valent iron-catalyzed cross coupling reactions of aryl, alkyl, allyl, benzyl, and propargyl halides with organomagnesium reagents. However, the acquired data suggest that such C-C bond formations can occur, a priori, along different catalytic cycles shuttling between metal centers of the formal oxidation states Fe(+1)/Fe(+3), Fe(0)/Fe(+2), and Fe(-2)/Fe(0). Since these different manifolds are likely interconnected, an unambiguous decision as to which redox cycle dominates in solution remains difficult, even though iron complexes of the lowest accessible formal oxidation states promote the reactions most effectively.
- Fuerstner, Alois,Martin, Ruben,Krause, Helga,Seidel, Guenter,Goddard, Richard,Lehmann, Christian W.
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p. 8773 - 8787
(2008/12/23)
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- Lewis acid catalyzed propargylation of arenes with O-propargyl trichloroacetimidates: Synthesis of 1,3-diarylpropynes
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(Chemical Equation Presented) The BF3·OEt 2-catalyzed Friedel-Crafts propargylation of aromatic compounds with O-propargyl trichloroacetimidates is highly efficient and affords 1,3-diarylpropyne derivatives in good yields.
- Li, Changkun,Wang, Jianbo
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p. 7431 - 7434
(2008/02/11)
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- Synthesis of naphthalenes and 2-naphthols by the electrophilic cyclization of alkynes
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A wide variety of substituted naphthalenes are readily prepared regioselectively under mild reaction conditions by the 6-endo-dig electrophilic cyclization of appropriate arene-containing propargylic alcohols by IC1, I 2, Br2, NBS, and PhSeBr. 3-Iodo-2-naphthols have also been prepared in excellent yields by the cyclization of analogous 1-aryl-3-alkyn-2-ones. This methodology readily accommodates various functional groups and has been successfully extended to the synthesis of substituted carbazoles and dibenzothiophenes.
- Zhang, Xiaoxia,Sarkar, Sampa,Larock, Richard C.
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p. 236 - 243
(2007/10/03)
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- Palladium-catalyzed Heck alkynylation of benzyl chlorides
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An efficient and general protocol for the palladium-catalyzed Heck alkynylation of benzyl chlorides was developed. A catalyst system comprised of PdCl2(CH3CN)2 and 2-dicyclohexylphosphino- 2′,4′,6′-triisopropylbiphenyl (XPhos), with Cs 2CO3 as the base, efficiently couples a wide range of functionalized terminal alkynes and substituted benzyl chlorides at 65 °C. We have also demonstrated that the corresponding aryl allene product can be selected for using an excess amount of base and higher reaction temperatures (80 °C) in a one-pot procedure. Georg Thieme Verlag Stuttgart.
- Larsen, Catharine H.,Anderson, Kevin W.,Tundel, Rachel E.,Buchwald, Stephen L.
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p. 2941 - 2946
(2008/02/12)
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- Indium tribromide-catalyzed deacetoxylation of propargylic acetate with triethylsilane
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Indium(III) bromide catalyzed the deacetoxylation of propargylic acetates with Et3SiH to produce the corresponding internal alkynes containing a variety of functional groups in good yields.
- Sakai, Norio,Hirasawa, Maki,Konakahara, Takeo
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p. 6407 - 6409
(2007/10/03)
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- Palladium-catalyzed cross-coupling reaction of alkynylzincs with benzylic electrophiles
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The reaction of alkynylzinc bromides with benzyl bromides or chlorides in the presence of a catalytic amount of Pd(DPEphos)Cl2 in THF at 23°C cleanly produces the corresponding benzylated alkynes in 73-97% yields. With 10-3 mol % of Pd(DPEphos)Cl2, the maximum turnover number of 7.1 × 104 has been observed for the formation of PhCCCH2Ph.
- Qian, Mingxing,Negishi, Ei-Ichi
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p. 2927 - 2930
(2007/10/03)
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- Cross-coupling of alkyl halides with aryl Grignard reagents catalyzed by a low-valent iron complex
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A striking reversal of the usual reactivity pattern of aryl Grignard reagents is observed for reactions in the presence of catalytic amounts of the "bare" ferrate complex [Li(tmeda)]2[Fe(C2H 4)4] (1). Highly reduced iron-magnesium clusters may play a decisive role in the exceptionally facile and chemoselective cross-coupling reaction with alkyl halides (see scheme).
- Martin, Ruben,Fuerstner, Alois
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p. 3955 - 3957
(2007/10/03)
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- A copper- and amine-free Sonogashira reaction employing aminophosphines as ligands
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An efficient Pd-catalyzed Sonogashira coupling reaction was achieved in the absence of a copper salt or amine with an inorganic base and easily prepared, air-stable aminophosphine ligands in commonly used organic solvents; good to excellent yields were ob
- Cheng, Jiang,Sun, Yanhui,Wang, Feng,Guo, Minjie,Xu, Jian-Hua,Pan, Yi,Zhang, Zhaoguo
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p. 5428 - 5432
(2007/10/03)
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- Synthesis of allenes by double Horner-Wadsworth-Emmons reaction
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LDA treatment of aldehydes or ketone with alkenylphosphonates 2, prepared by Horner-Wadsworth-Emmons (HWE) reaction of methylenebisphosphonate 1 with aldehydes, afforded Baylis-Hillman reaction-type products 5 in high yields. HWE olefination of 5 with KH or KH-18-crown-6 as a base provided allenes in good yields. One-flask procedure was successfully developed starting from 1 to afford an allene in a reasonably good yield.
- Inoue, Hideki,Tsubouchi, Hiroshi,Nagaoka, Yasuo,Tomioka, Kiyoshi
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