- Rhodium-catalyzed oxidative coupling of benzoic acids with propargyl alcohols: An efficient access to isocoumarins
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An efficient protocol of Rh(III)-catalyzed oxidative cyclization of benzoic acids with propargyl alcohols to give substituted isocoumarins under mild conditions was reported. A variety of substrates were applied in this reaction in yields up to 89%.
- Luo, Feihua,He, Shuhua,Gou, Quan,Chen, Jinyang,Zhang, mingzhong
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supporting information
(2020/12/29)
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- Hydrazine Hydrate Accelerates Neocuproine–Copper Complex Generation and Utilization in Alkyne Reduction, a Significant Supplement Method for Catalytic Hydrogenation
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Diimine (HN═NH) is a strong reducing agent, but the efficiency of diimine oxidized from hydrazine hydrate or its derivatives is still not good enough. Herein, we report an in situ neocuproine–copper complex formation method. The redox potential of this complex enable it can serve as an ideal redox catalyst in the synthesis of diimine by oxidation of hydrazine hydrate, and we successfully applied this technique in the reduction of alkynes. This reduction method displays a broad functional group tolerance and substrate adaptability as well as the advantages of safety and high efficiency. Especially, nitro, benzyl, boc, and sulfur containing alkynes can be reduced to the corresponding alkanes directly, which provides a useful complementary method to traditional catalytic hydrogenation. Besides, we applied this method in the preparation of the Alzheimer’s disease drug CT-1812 and studied the mechanism.
- Chen, Guoliang,He, Xiaoyan,Huang, Gang,Lu, Xiuhong,Wang, Jincheng,Yang, Zhenjiao,Zhang, Yongsheng,Zhang, Zeng
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p. 17696 - 17709
(2021/12/09)
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- Rhodium-Catalyzed Annulation of Phenacyl Ammonium Salts with Propargylic Alcohols via a Sequential Dual C-H and a C-C Bond Activation: Modular Entry to Diverse Isochromenones
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Given their omnipresence in natural products and pharmaceuticals, isochromenone congeners are one of the most privileged scaffolds to synthetic chemists. Disclosed herein is a dual (ortho/meta) C-H and C-C activation of phenacyl ammonium salts (acylammonium as traceless directing group) toward annulation with propargylic alcohols to accomplish rapid access for novel isochromenones by means of rhodium catalysis from readily available starting materials. This operationally simple protocol features broad substrate scope and wide functional group tolerance. Importantly, the protocol circumvents the need of any stoichiometric metal oxidants and proceeds under aerobic conditions.
- Nanubolu, Jagadeesh Babu,Reddy Singam, Maneesh Kumar,Sridhar Reddy, Maddi,Suresh, Vavilapalli,Suri Babu, Undamatla
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supporting information
p. 7888 - 7893
(2021/10/25)
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- Nickel-Catalyzed Sonogashira C(sp)-C(sp2) Coupling through Visible-Light Sensitization
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An efficient method for visible-light-initiated, nickel-catalyzed Sonogashira C(sp)-C(sp2) coupling has been developed via an energy-transfer mode. Thioxanthen-9-one as a photosensitizer could significantly accelerate the arylation of alkynes with a wide
- Zhu, Da-Liang,Xu, Ruijie,Wu, Qi,Li, Hai-Yan,Lang, Jian-Ping,Li, Hong-Xi
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p. 9201 - 9212
(2020/08/14)
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- Palladium(II)/Lewis acid cocatalyzed oxidative annulation of 2-alkenylanilines and propargylic esters: An access to benzo[ b]azepines
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An attractive approach to valuable yet synthetically challenging benzo[b]azepines was established via palladium(II)/Lewis acid cocatalyzed oxidative [5 + 2] annulation of readily available 2-alkenylanilines and propargylic esters. The protocol features mild reaction conditions and good functional group tolerance, constituting an array of benzo[b]azepines in yields of 30-75%.
- Qiao, Hong,Zhang, Shengjun,Li, Kangkang,Cao, Zhengqiang,Zeng, Fanlong
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p. 10843 - 10851
(2019/09/12)
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- α-Hydroxy Ketones as Masked Ester Donors in Br?nsted Base Catalyzed Conjugate Additions to Nitroalkenes
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The catalyst-controlled enantioselective direct addition reaction of enolizable esters and related carboxylic acid derivatives to π electrophiles remains a difficult synthetic transformation. In this study, the suitability of α-hydroxy ketones as ester equivalents capable of being activated by bifunctional Br?nsted base catalysts in the context of conjugate addition reactions to nitroolefins is demonstrated. The scope of the reaction, which affords the corresponding Michael adducts with very high stereoselectivity (diastereomeric ratio (d.r.) ≥95:5, up to 99 % enantiomeric excess (ee)), and its limitations are explored, as is the aftermath elaboration of adducts into densely functionalized enantioenriched products.
- Olaizola, Iurre,Campano, Teresa E.,Iriarte, Igor,Vera, Silvia,Mielgo, Antonia,García, Jesús M.,Odriozola, José M.,Oiarbide, Mikel,Palomo, Claudio
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supporting information
p. 3893 - 3901
(2018/03/21)
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- Base-Catalyzed Borylation/B-O Elimination of Propynols and B2pin2 Delivering Tetrasubstituted Alkenylboronates
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An efficient approach to tetrasubstituted alkenylboronates via a cascade borylation/B-O elimination of propynols and B2pin2 was disclosed. A series of tetrasubstituted alkenylboronates were readily furnished with this strategy in good yields, with further transformations leading to tetrasubstituted alkenes and β-diketones demonstrating the synthetic potential of the alkenylboronates constructed by this strategy as versatile intermediates in organic synthesis.
- Kuang, Zhijie,Chen, Haohua,Yan, Jianxiang,Yang, Kai,Lan, Yu,Song, Qiuling
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supporting information
p. 5153 - 5157
(2018/09/12)
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- Synthesis and Simple Immobilization of Palladium(II) Acyclic Diaminocarbene Complexes on Polystyrene Support as Efficient Catalysts for Sonogashira and Suzuki-Miyaura Cross-Coupling
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Immobilization of palladium(II) acyclic diaminocarbene (Pd(II)-ADC) complexes on a resin support surface has been easily performed by metal-mediated addition of amino groups of benzhydrylamine-polystyrene to the coordinated isocyanide ligand of cis-PdCl2(CNR)2 (R = t-Bu, Cy). The investigation of the benzhydrylamine reaction with palladium-coordinated isocyanides in solution has revealed that, depending on the reaction conditions, two carbene-type complexes can be obtained as a result of the addition to the CN triple bond, as well as a third complex which is formed via substitution of the isocyanide ligand by benzhydrylamine. Nucleophilic addition of an amino group to the isocyanide ligand has led to a cis-acyclic diaminocarbene complex or a cationic diaminocarbene complex with trans configuration and an intramolecular hydrogen-bonded chloride anion (the nature of this noncovalent interaction was analyzed by DFT calculations, including AIM analysis). The unsupported and resin-supported palladium catalysts have demonstrated high catalytic activity in both Sonogashira and Suzuki-Miyaura cross-coupling. The supported catalyst can be recovered and repeatedly reused without a significant loss in efficiency. The degree of the palladium binding with polystyrene, the oxidation state, and the palladium leaching level were investigated by XPS and XRF analyses.
- Mikhaylov, Vladimir N.,Sorokoumov, Viktor N.,Korvinson, Kirill A.,Novikov, Alexander S.,Balova, Irina A.
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p. 1684 - 1697
(2016/07/06)
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- Hydroxyl-Assisted Carbonylation of Alkenyltin Derivatives: Development and Application to a Formal Synthesis of Tubelactomicin A
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Alkenyltin derivatives flanked by a hydroxyl group are subject to methoxycarbonylation when treated with catalytic amounts of Pd(OAc)2 and Ph3As in MeOH under a CO atmosphere; key to success is the use of 1,4-benzoquinone as a stoich
- Sommer, Heiko,Fürstner, Alois
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supporting information
p. 3210 - 3213
(2016/07/13)
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- Palladium-Catalyzed Nitration of Meyer-Schuster Intermediates with tBuONO as Nitrogen Source at Ambient Temperature
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A novel domino palladium-catalyzed nitration of Meyer-Schuster intermediates which were generated in situ from propargylic alcohols was developed, by the use of t-BuONO, leading to α-nitro enones in good to excellent yields at room temperature with a broa
- Lin, Yuanguang,Kong, Weiguang,Song, Qiuling
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supporting information
p. 3702 - 3705
(2016/08/16)
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- Palladium-catalyzed oxidative deacetonative coupling of 4-aryl-2-methyl-3-butyn-2-ols with H-phosphonates
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An efficient and generally applicable protocol for palladium-catalyzed oxidative deacetonative coupling of 4-aryl-2-methyl-3-butyn-2-ols with dialkyl H-phosphonates has been developed. This methodology provides a new and practical route to alkynylphosphonates using the inexpensive 4-aryl-2-methyl-3-butyn-2-ols as the alkyne sources. This reaction could also be performed with aryl bromides, 2-methyl-3-butyne-2-ol and dialkyl H-phosphonates using the cheap 2-methyl-3-butyne-2-ol as an alkyne source. This journal is
- Li, Xiang,Sun, Suyan,Yang, Fan,Kang, Jianxun,Wu, Yusheng,Wu, Yangjie
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p. 2432 - 2436
(2015/03/04)
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- Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions
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Two efficient protocols for the palladium-catalyzed synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides in the absence of copper were developed. A simple catalytic system consisting of Pd(OAc)2 and P(p-tol)3 using DBU as the base and THF as the solvent was found to be highly effective for the coupling reaction of 2-methyl-3-butyn-2-ol (4) with a wide range of aryl bromides in good to excellent yields. Analogously, the synthesis of aryl-2-methyl-3-butyn-2-ols was performed also through the decarboxylative coupling reaction of 4-hydroxy-4-methyl-2-pentynoic acid with aryl bromides, using a catalyst containing Pd(OAc)2 in combination with SPhos or XPhos in the presence of tetra-n-butylammonium fluoride (TBAF) as the base and THF as the solvent. Therefore, new efficient approaches to the synthesis of terminal acetylenes from widely available aryl bromides rather than expensive iodides and using 4 or propiolic acid rather than TMS-acetylene as inexpensive alkyne sources are described.
- Caporale, Andrea,Tartaggia, Stefano,Castellin, Andrea,De Lucchi, Ottorino
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supporting information
p. 384 - 393
(2014/03/21)
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- Antiprotozoal activity of dicationic 3,5-diphenylisoxazoles, their prodrugs and aza-analogues
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Fifty novel prodrugs and aza-analogues of 3,5-bis(4-amidinophenyl)isoxazole and its derivatives were prepared. Eighteen of the 24 aza-analogues exhibited IC50 values below 25 nM against Trypanosoma brucei rhodesiense or Plasmodium falciparum. S
- Patrick, Donald A.,Bakunov, Stanislav A.,Bakunova, Svetlana M.,Wenzler, Tanja,Brun, Reto,Tidwell, Richard R.
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p. 559 - 576
(2014/01/17)
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- Sonogashira reaction of aryl and heteroaryl halides with terminal alkynes catalyzed by a highly efficient and recyclable nanosized MCM-41 anchored palladium bipyridyl complex
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A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence of CuI and triphenylphosphine. The coupling products were obtained in high yields using low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by centrifugation of the reaction solution and re-used in further runs without significant loss of reactivity.
- Lin, Bo-Nan,Huang, Shao-Hsien,Wu, Wei-Yi,Mou, Chung-Yuan,Tsai, Fu-Yu
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experimental part
p. 9157 - 9173
(2011/02/27)
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- Perfluoro-tagged, phosphine-free palladium nanoparticles supported on silica gel: Application to alkynylation of aryl halides, Suzuki-Miyaura cross-coupling, and Heck reactions under aerobic conditions
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The utilization of perfluoro-tagged palladium nanoparticles immobilized on fluorous silica gel through fluorous-fluorous interactions (Pd np-A/FSG) or through covalent bonding to silica gel (Pd np-B) in the alkynylation of aryl halides, in the Suzuki-Miyaura cross-coupling, as well as in the Heck reaction between methyl acrylate and aryl iodides is described. The reactions are carried out under aerobic and phosphine-free conditions with excellent to quantitative product yields in each case. The catalysts are easily recovered and reused several times without significant loss of activity. The alkynylation of aryl halides (under copper-free conditions) and the Suzuki-Miyaura cross-coupling are carried out in water. The Heck reaction of methyl acrylate with aryl iodides is best performed in MeCN. The utilization of Pdnp-B in the synthesis of 2,3-disubstituted indoles from 2-(alkynyl)trifluoroacetanilides and aryl halides is also reported.
- Bernini, Roberta,Cacchi, Sandro,Fabrizi, Giancarlo,Forte, Giovanni,Petrucci, Francesco,Prastaro, Alessandro,Niembro, Sandra,Shafir, Alexandr,Vallribera, Adelina
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supporting information; experimental part
p. 150 - 158
(2010/05/18)
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- 2,2 (Diarlyl) Vinylphosphine compound, palladium catalyst thereof, and process for producing arylamine, diaryl, or arylalkyne with the catalyst
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A novel 2,2-(diaryl)vinylphosphine compound represented by the following general formula (1): (wherein R1 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 5 to 7 carbon atoms, etc.; R2, R3, R4, R5, R6, and R7 may be the same or different and each is an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 5 to 7 carbon atoms, etc., provided that R4 and R5 taken together and/or R6 and R7 taken together may represent a fused benzene ring, a substituted fused benzene ring, a trimethylene group, etc.; and p, q, r, and s each is 0 to 5, provided that p+q and r+s each is in the range of from 0 to 5); a palladium-phosphine catalyst obtained by causing a palladium compound to act on the novel 2,2-(diaryl)vinylphosphine compound; and a process for obtaining an arylamine, a diaryl and an arylalkyne in the presence of the palladium-phosphine catalyst.
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- 2,2-(Diaryl)vinylphosphine compound, palladium catalyst thereof, and process for producing arylamine, diaryl, or arylalkyne with the catalyst
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A novel 2,2-(diaryl)vinylphosphine compound represented by the following general formula (1): (wherein R1 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 5 to 7 carbon atoms, etc.; R2, R3, R4, R5, R6, and R7 may be the same or different and each is an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 5 to 7 carbon atoms, etc., provided that R4 and R5 taken together and/or R6 and R7 taken together may represent a fused benzene ring, a substituted fused benzene ring, a trimethylene group, etc.; and p, q, r, and s each is 0 to 5, provided that p+q and r+s each is in the range of from 0 to 5); a palladium-phosphine catalyst obtained by causing a palladium compound to act on the novel 2,2-(diaryl)vinylphosphine compound; and a process for obtaining an arylamine, a diaryl and an arylalkyne in the presence of the palladium-phosphine catalyst.
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- Tolan derivative, liquid crystal composition containing the derivative, and liquid crystal display device having the composition
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A tolan derivative of a formula: STR1 where R represents a linear alkyl group having from 1 to 10 carbon atoms; X1, X2 and X3 independently represent a fluorine atom or a hydrogen atom, provided that one of them is necessarily a fluorine atom and the others are hydrogen atoms; and Y represents a nitrile group or a linear alkyl group having from 1 to 10 carbon atoms; and a liquid crystal composition containing the derivatives; and a liquid crystal display device having the composition are produced. The compound is compatible with other liquid crystal compounds, and by blending the compound with ordinary liquid crystal compounds, a liquid crystal composition having a broadened practical temperature range and an enlarged double refraction anisotropy is obtained.
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- Tolane derivatives, liquid crystal compositions containing the derivatives and liquid crystal display devices using the compositions
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A tolane derivative, a liquid crystal composition containing the derivative, and a liquid crystal display device including the composition, in which the tolane derivative is represented by the following general formula: STR1 wherein R represents a straigh
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