- Asymmetric synthesis of piperidines using the nitro-Mannich reaction☆
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A method for the synthesis of functionalized piperidines containing 3 contiguous stereocentres in the 2-,3- and 4- positions uses a diastereoselective nitro-Mannich to control stereochemistry. The nitro-Mannich reaction between a β-aryl/heteroaryl substituted nitroalkanes and glyoxylate imine provides β-nitro-amines with good selectivity (70:30 to >95:5) for the syn, anti-diastereoisomers. Reductive cyclisation with BF3.OEt2 and Et3SiH gave, after purification, stereochemically pure piperidines in 19–57% yield for ten examples with different 4-aryl/heteroaryl substituents.
- Anderson, James C.,Bouvier-Israel, Eva,Rundell, Christopher D.,Zhang, Xiangyu
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- Intramolecular Sakurai Allylation of Geminal Bis(silyl) Enamide with Indolenine. A Diastereoselective Cyclization to Form Functionalized Hexahydropyrido[3,4- b]Indole
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A fluoride-promoted intramolecular Sakurai allylation of geminal bis(silyl) enamide with indolenine has been developed. The reaction facilitates an efficient cyclization to give hexahydropyrido[3,4-b]indoles in good yields with high diastereoselectivity. The resulted cis, trans-stereochemistry further enables the ring-closing metathesis (RCM) reaction of two alkene moieties, giving a tetracyclic N-hetereocycle widely found as the core structure in akuammiline alkaloids.
- Chen, Yi,Gao, Lu,Song, Xuanyi,Song, Zhenlei
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supporting information
p. 124 - 128
(2021/01/13)
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- The Mizoroki-Heck reaction in mesoionic 1-butyl-3-methyltetrazolium-5-olate
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1-Butyl-3-methyltetrazolium-5-olate (1), a mesoionic compound, exists as a liquid at room temperature and can be used as a polar solvent for the Mizoroki-Heck reaction, wherein it has been proven to be a superior solvent to other solvents. The reaction of iodobenzene with ethyl acrylate in the presence of palladium acetate in mesoionic liquid 1 at 40 °C for 24 h gave ethyl cinnamate in 78% yield in the absence of ligands, while the use of other solvents, such as [bmim][BF4], [bmim][PF6], and DMF gave lower yields (43%, 37%, and 17%, respectively) under the same conditions. Heck-type coupling reactions of electron-deficient or electron-rich aryl iodides and bromobenzenes with olefins (15 examples, 7%–97%) were performed in 1. When a phosphine ligand was added to the reaction mixture, aryl bromides could be used, and the mesoionic liquid containing the catalysts could be reused at least five times.
- Araki, Shuki,Hirashita, Tsunehisa,Kurabayashi, Hideaki
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- Pd/Cu-Free Cobalt-Catalyzed Suzuki and Heck Using Green Bio-Magnetic Hybrid and DFT-Based Theoretical Study
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Abstract: Several highly efficient and magnetically recyclable cobalt catalytic systems were prepared using magnetic chitosan and some safe and available organic compounds (Co-ligand@MNPs/Ch). The structure of these nanocomposites was confirmed by various physicochemical techniques such as FT-IR, XRD, TGA, VSM, TEM, SEM, CHNS and ICP-OES. These nano composites exhibit remarkable catalytic efficiency for Suzuki and Heck cross-coupling reactions in mild and green reaction conditions. The facile accessibility of starting materials, possible performance in air and eco-friendly conditions are merits of our catalysts. In addition, to describe and go insight to role and effect of ligands present in these catalysts, electrostatic interactions, density functional theory (DFT) model in molecular method were employed. Graphic Abstract: [Figure not available: see fulltext.]
- Hajipour, Abdol R.,Khorsandi, Zahra,Ahmadi, Mehnoosh,Jouypazadeh, Hamidreza,Mohammadi, Bahareh,Farrokhpour, Hossein
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p. 2842 - 2850
(2021/02/01)
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- Magnetically recoverable nanostructured Pd complex of dendrimeric type ligand on the MCM-41: Preparation, characterization and catalytic activity in the Heck reaction
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A palladium complex of a dendrimer type ligand of aminoethylacrylamide immobilized onto the mesoporous channels of MCM-41 with magnetic core was prepared and characterized using various techniques such as XRD, TEM, BET, FT-IR, TGA, and VSM. The prepared nanostructured material was found as a magnetically recoverable catalyst for Heck reaction of aryl halides and vinylic C-H. The catalyst is easily recoverable with an external magnet and is reusable with different leaching amounts depending to loading of Pd. A hot filtration test was also performed and gave evidence that Palladium in heterogeneous samples can dissolve and then redeposit on the surface of the support material.
- Abdollahi-Alibeik, Mohammad,Gharibpour, Najmeh,Ramazani, Zahra
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p. 184 - 199
(2020/11/19)
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- Synthesis and characterization of a new bis-NHC palladium complex and its catalytic activity in the Mizoroki–Heck reaction
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A new bis-N-heterocyclic carbene palladium complex, (C13H9N2F2)2PdCl2, is synthesized by a three-step reaction and characterized by 1H NMR and 13C NMR spectroscopy as well as by X-ray crystallography. This new bis-N-heterocyclic carbene palladium complex has excellent stability and is capable of efficiently catalyzing the Mizoroki–Heck coupling reaction of aryl halides with acrylates.
- Cui, Jin,Feng, Can,Liu, Cheng-Xin,Wang, Yu-Fang,Zhang, Ming-Jie
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p. 684 - 688
(2020/05/22)
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- Synthesis and in vitro evaluation of antimycobacterial and cytotoxic activity of new α,β-unsaturated amide, oxazoline and oxazole derivatives from L-serine
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The synthesis of 19 compounds derived from L-serine and analogs of p-substituted cinnamic acid is reported. Oxazolines 9 and oxazoles 10 have high antitubercular activity with Minimum Inhibitory Concentration (MIC) of 0.7812–25.0 μg/mL (3.21–100.3 μM), against two strains of Mycobacterium tuberculosis sensitive to first-line drugs Isoniazid (INH), Rifampicin (RIF), Ethambutol (EMB), Pyrazinamide (PZE) (H37Rv) and a clinical isolate resistant to INH, RIF and EMB (G122). The cytotoxic evaluation shows that oxazoles have low activity, finding viability>96% against the VERO cell line. The results show these compounds could be considered as future alternatives for antitubercular treatment.
- Aguirre-Rentería, Saúl A.,Arredondo-Espinoza, Eder,Avalos-Alanís, Francisco G.,Carrizales-Castillo, Juan J. J.,Garza-González, Elvira,Hernández-Fernández, Eugenio,Rivas-Galindo, Verónica M.,del Rayo Camacho Corona, María
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supporting information
(2020/03/13)
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- Palladium Immobilized on 2,2′-Dipyridyl-Based Hypercrosslinked Polymers as a Heterogeneous Catalyst for Suzuki–Miyaura Reaction and Heck Reaction
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Abstract: 2,2′-Bipyridine was successfully integrated into the skeleton of hypercrosslinked polymers networks (HCPs-bipy) via Friedel–Crafts reaction and Scholl coupling reaction, and PdCl2 was locked in this network polymers by coordination with pyridine motif. The preparation of HCPs-bipy has the advantages of low cost, mild conditions, easy separation and high yield. FT-IR, TGA, N2 sorption, ICP, XPS, SEM, EDX and TEM was employed to characterize the structure and composition of the heterogeneous catalysts. The result indicates that HCPs-bipy-Pd possess high specific surface areas, large microporous volume, thermal stability, and highly dispersion of palladium species. HCPs-bipy-Pd can be applied in Suzuki–Miyaura reactions and Heck reactions as robust heterogeneous catalyst to afford high yield. The reusability test demonstrates that HCPs-bipy-Pd could be recovered and reused for at least five times without losing catalytic activity. Graphic Abstract: [Figure not available: see fulltext.].
- Liu, Cijie,Xu, Wei,Xiang, Dexuan,Luo, Qionglin,Zeng, Shunqin,Zheng, Lijuan,Tan, Yujie,Ouyang, Yuejun,Lin, Hongwei
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p. 2558 - 2565
(2020/03/23)
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- Coumaric acid derivatives as tyrosinase inhibitors: Efficacy studies through in silico, in vitro and ex vivo approaches
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p-Coumaric acid is a known inhibitor of tyrosinase, an enzyme involved in the initial steps of the melanin synthesis in human and other species. However, its low lipophilicity impairs its penetration through skin and efficacy as antimelanogenic agent indeed. Accordingly, this paper reports the assessment of several coumaric acid derivatives as tyrosinase inhibitors and antimelanogenic agents in in vitro, in silico and ex vivo assays. The compounds were designed with modifications in the aromatic and acid moieties of p-coumaric acid, being the coumarate esters the most promising derivatives. The compounds showed higher tyrosinase inhibitory activity (pIC50 3.7–4.2) than the parent acid, being compounds 1d, 1e and 1f the most potent inhibitors. Docking analysis showed that these esters are competitive inhibitors per se, and act independently of a redox mechanism as suggested by DPPH assays. Moreover, the esters showed efficacy in reducing the melanin deposition in human skin fragments at 0.1% concentration, especially compound 1e. In summary, there is an important equilibria between tyrosinase affinity and lipophilicity that must be considered to get effective antimelanogenic agents with adequate permeability in the skin.
- Fernandes, Jo?o Paulo S.,Ferrarini, Márcio,Mercaldi, Vitória Gallo,Nazato, Lucas Idacir Sbrugnera,Padovani, Giovana,Sufi, Bianca da Silva,Varela, Marina Themoteo
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- Phosphorus-recycling wittig reaction: Design and facile synthesis of a fluorous phosphine and its reusable process in the wittig reaction
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This study shows that phosphorus sources can be recycled using the appropriate fluorous phosphine in the Wittig reaction. The designed fluorous phosphine, which has an ethylene spacer between its phosphorus atom and the perfluoroalkyl group, was synthesized from air-stable phosphine reagents. The synthesized phosphine can be used for the Wittig reaction process to obtain various alkenes in adequate yields and stereoselectivity. The concomitantly formed fluorous phosphine oxide was extracted from the reaction mixture using a fluorous biphasic system. The fluorous phosphine was regenerated by reducing the fluorous phosphine oxide with diisobutylaluminum hydride. Finally, a series of gram scale phosphorus recycling processes were performed, which included the Wittig reaction, separation, reduction, and reuse.
- Yamamoto, Yuki,Kawaguchi, Shin-Ichi,Nishimura, Misaki,Sato, Yuki,Shimada, Yoshihisa,Tabuchi, Akihiro,Nomoto, Akihiro,Ogawa, Akiya
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p. 14684 - 14696
(2020/11/30)
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- Gold-catalyzed partial hydrogenation of activated alkynes mediated by triphenylphosphine
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Gold(I) can exhibit a cooperative effect with triphenylphosphine, accelerating the triphenylphosphine-mediated partial hydrogenation of activated alkynes. In this protocol, 3-arylpropiolates are selectively reduced to the Z -isomer when the aryl ring bears an electron-donor substituent, whereas 3-arylpropynones are reduced to the E-isomers.
- Cocoletzi-Xochitiotzi, Ana Patricia,Hernández-Hernández, Miguel,Medina-Mercado, Ignacio,Jiménez-Martínez, Williams De Jesús,Mastranzo, Virginia Maricela,Porcel, Susana
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p. 2379 - 2386
(2020/08/19)
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- 1,3-Diphenyldisiloxane Enables Additive-Free Redox Recycling Reactions and Catalysis with Triphenylphosphine
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The recently reported chemoselective reduction of phosphine oxides with 1,3-diphenyldisiloxane (DPDS) has opened up the possibility of additive-free phosphine oxide reductions in catalytic systems. Herein we disclose the use of this new reducing agent as an enabler of phosphorus redox recycling in Wittig, Staudinger, and alcohol substitution reactions. DPDS was successfully utilized in ambient-temperature additive-free redox recycling variants of the Wittig olefination, Appel halogenation, and Staudinger reduction. Triphenylphosphine-promoted catalytic recycling reactions were also facilitated by DPDS. Additive-free triphenylphosphine-promoted catalytic Staudinger reductions could even be performed at ambient temperature due to the rapid nature of phosphinimine reduction, for which we characterized kinetic and thermodynamic parameters. These results demonstrate the utility of DPDS as an excellent reducing agent for the development of phosphorus redox recycling reactions.
- Buonomo, Joseph A.,Cole, Malcolm S.,Eiden, Carter G.,Aldrich, Courtney C.
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p. 3583 - 3594
(2020/09/15)
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- Palladium Ion Catalysed Oxidative C–C Bond Formation Reactions in Arylboronic Acid: Application of Cordierite Monolith Coated Catalyst
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Abstract: Catalytic efficiency of palladium ion substituted in TiO2, Ti0.97Pd0.03O1.97 is successfully exploited for the oxidative homocoupling of arylboronic acid and oxidative Heck coupling reactions between arylboronic acid and olefins. The reaction protocol provides direct approach to synthesize biphenyls and cinnamates from moderate to good yield with good functional group tolerance. As a result, 11 symmetrical biaryls and 14 cinnamates were synthesized from readily available arylboronic acids. Ti0.97Pd0.03O1.97 powder catalyst is synthesized by solution combustion method and characterized by powder X-ray diffraction. The C–C bond formation reactions were carried out by catalyst cartridge method using Ti0.97Pd0.03O1.97 catalyst coated cordierite monolith. Coating of the catalyst on a cordierite monolith enhanced the applicability of the catalyst and made handling and recycling of the catalyst very easy. Catalyst was recovered and recycled for eight times in both homocoupling and oxidative Heck coupling reactions. The turnover number for both the reactions found to be 443 and 424, respectively. Graphic Abstract: [Figure not available: see fulltext.].
- Bhat, Shrikanth K.,Prasanna,Dasappa, Jagadeesh Prasad,Hegde
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p. 2911 - 2927
(2020/03/31)
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- Structure?Activity Relationships of Cinnamate Ester Analogues as Potent Antiprotozoal Agents
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Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model.
- Bernal, Freddy A.,Kaiser, Marcel,Wünsch, Bernhard,Schmidt, Thomas J.
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- Synthesis of new Pro-PYE ligands as co-catalysts toward Pd-catalyzed Heck-Mizoroki cross coupling reactions
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The present research work describes the synthesis of five new ligands containing pyridinium amine, [H2L1][OTf]2-[H2L5][I]2 from two new precursors, [P3Et][I] and [P2Me][CF3SO3]. The structure elucidations of the compounds were confirmed by multinuclear NMR (1H, 13C), FT-IR and by single crystal XRD techniques. Theoretical DFT studies were carried out to get better insight into the electronic levels and structural features of all the molecules. These synthesized new Pro-PYE ligands [H2L1][OTf]2-[H2L5][I]2 were found to be significantly active as co-catalysts for Pd(CH3CO2)2 toward Heck-Mizoroki coupling reactions with wide substrate scope in the order of [H2L1][OTf]2 ? [H2L2][OTf]2 > [H2L3][OTf]2 > [H2L4][OTf]2 > [H2L5][I]2.
- Munir, Naima,Masood, Sara,Liaqat, Faroha,Tahir, Muhammad Nawaz,Yousuf, Sammer,Kalsoom, Saima,Mughal, Ehsan Ullah,Sumrra, Sajjad Hussain,Maalik, Aneela,Zafar, Muhammad Naveed
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p. 37986 - 38000
(2019/12/03)
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- Threonine stabilizer-controlled well-dispersed small palladium nanoparticles on modified magnetic nanocatalyst for Heck cross-coupling process in water
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We report the synthesis of magnetically separable Fe3O4@Silica-Threonine-Pd0 magnetic nanoparticles with a core–shell structure. After synthesis of Fe3O4@Silica, threonine as an efficient stabilizer/ligand was bonded to the surface of Fe3O4@Silica. Then, palladium nanoparticles were generated on the threonine-modified catalyst. The threonine stabilizer helps to generate palladium nanoparticles of small size (less than 4?nm) with high dispersity and uniformity. Magnetically separable Fe3O4@Silica-Threonine-Pd0 nanocatalyst was fully characterized using various techniques. This nanocatalyst efficiently catalysed the Heck cross-coupling reaction of a variety of substrates in water medium as a green, safe and inexpensive solvent at 80°C. The Fe3O4@Silica-Threonine-Pd0 catalyst was used for at least eight successful consecutive runs with palladium leaching of only 0.05%.
- Sarvi, Iraj,Gholizadeh, Mostafa,Izadyar, Mohammad
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- Ultra-small and highly dispersed Pd nanoparticles inside the pores of ZIF-8: Sustainable approach to waste-minimized Mizoroki–Heck cross-coupling reaction based on reusable heterogeneous catalyst
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The rapid development of nanomaterials, particularly advanced hybrid nanoparticles, has made new opportunities for the design and fabrication of high-performance metal-based catalysts. However, generating metal nanoparticles of desired size without aggregation is an important challenge for enhancing the catalytic activity of metal nanoparticles supported in the host matrix. In this work, a hybrid nanoporous material, namely Pd nanoparticles@N-heterocyclic carbene@ZIF-8, with a high internal surface area was successfully prepared using a dispersed anionic sulfonated N-heterocyclic carbene–Pd(II) precursor inside the cavities of zeolitic imidazolate framework (ZIF-8) using an impregnation approach followed by reduction with NaBH4. The anionic sulfonated N-heterocyclic carbene was found to be a superb ligand for the stabilization of Pd nanoparticles in the pores of ZIF-8. The resulting system was applied to the Mizoroki–Heck cross-coupling reaction, in which the catalyst showed high catalytic activity under mild reaction conditions.
- Azad, Mohammad,Rostamizadeh, Shahnaz,Estiri, Hamid,Nouri, Fatemeh
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- Synthesis, structure, computational and catalytic activities of palladium complexes containing hydrazide based amino-phosphine ligands
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Two new N, N-bis(diphenylphosphino)-amine ligands [where amine = N-Aminophthalimide (in L1) and Hydrazine dihydrochloride (in L2)] and their Pd(II) complexes, C1 and C2 have been synthesized and characterized by IR and NMR spectroscopies. Single crystal X-ray diffraction techniques have been used to determine the crystal structures of the complexes. Moreover, the catalytic activities of mentioned complexes in Heck coupling reactions have been assessed. The NBO analysis has been used to investigate the nature of the metal-ligand interactions. In the case of L2, preparation route could have produced two different products (Pro.1 and Pro.2), but only one structure has been gained which has been prepared in high purity. To address the reason for this manner, kinetics and thermodynamics of two different pathways that could have led to possible products have been investigated theoretically.
- Gholivand, Khodayar,Kahnouji, Mohammad,Maghsoud, Yazdan,Hosseini, Mahdieh,Mark Roe, Stephen
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p. 281 - 292
(2018/11/26)
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- Asymmetric Synthesis of γ-Amino Alcohols by Copper-Catalyzed Hydroamination
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Asymmetric synthesis of γ-amino alcohols from unprotected allylic alcohols by a copper-catalyzed hydroamination strategy has been developed. Using easily accessible starting materials, a range of chiral 1,3-amino alcohols were prepared with excellent regio- and enantioselectivity. Further, this protocol provided an efficient one-step method for the enantioselective synthesis of γ-amino alcohols in an intermolecular manner.
- Ichikawa, Saki,Buchwald, Stephen L.
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supporting information
p. 8736 - 8739
(2019/11/03)
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- Synthesis of Allylsilanes via Nickel-Catalyzed Cross-Coupling of Silicon Nucleophiles with Allyl Alcohols
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NiCl2(PMe3)2-catalyzed reaction of allyl alcohols with silylzinc reagents, including PhMe2SiZnCl, Ph2MeSiZnCl, and Ph3SiZnCl, was performed, achieving allylsilanes in high yields. Aryl- and heteroaryl-substituted allyl alcohols, (E)-3-arylprop-2-en-1-ols, 1-aryl-prop-2-en-1-ols, and (E)-1-phenylpent-1-en-3-ol can be employed in the transformation. A range of functional groups as well as heteroaryl groups were tolerated. Reaction exhibited high regioselectivity and E/Z-selectivity when 1- or 3-aryl-substituted allyl alcohols were used as the substrates. Reaction of chiral allyl alcohol, (S,E)-1-phenylpent-1-en-3-ol, yielded a configuration-inversion product (R,E)-dimethyl(phenyl)(1-phenylpent-1-en-3-yl)silane.
- Yang, Bo,Wang, Zhong-Xia
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supporting information
p. 7965 - 7969
(2019/10/19)
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- Boron-Templated Dimerization of Allylic Alcohols to Form Protected 1,3-Diols via Acid Catalysis
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We report an unprecedented boron-templated dimerization of allylic alcohols that generates a 1,3-diol product with two stereogenic centers in high yield and diastereoselectivity. This acid-catalyzed reaction is achieved via in situ formation of a boronic ester intermediate that facilitates selective cyclization and formation of a cyclic boronic ester product. High yields are observed with a variety of allylic alcohols, and mechanistic studies confirm the role of boron as a template for the reaction.
- Nazari, S. Hadi,Forson, Kelton G.,Martinez, Erin E.,Hansen, Nicholas J.,Gassaway, Kyle J.,Lyons, Nathan M.,Kenney, Karissa C.,Valdivia-Berroeta, Gabriel A.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 9589 - 9593
(2019/12/02)
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- Arene Trifunctionalization with Highly Fused Ring Systems through a Domino Aryne Nucleophilic and Diels–Alder Cascade
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A convenient and efficient domino aryne process was developed under transition-metal-free conditions to generate a range of tetra- and pentacyclic ring systems. This transformation was realized via a 1,2-benzdiyne through a nucleophilic and Diels–Alder reaction cascade using styrene as the diene moiety. Three new chemical bonds, namely one C?N and two C?C bonds, and two benzofused rings could be constructed concomitantly, which was made possible by distinct chemoselective control at both the 1,2-aryne and 2,3-aryne stages. Moreover, in-depth studies were carried out on the domino aryne precursors and controlling the diastereoselectivity.
- He, Jia,Jia, Zizi,Tan, Hongcheng,Luo, Xiaohua,Qiu, Dachuan,Shi, Jiarong,Xu, Hai,Li, Yang
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supporting information
p. 18513 - 18518
(2019/11/19)
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- Palladium catalyst immobilized on functionalized microporous organic polymers for C-C coupling reactions
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Two microporous organic polymer immobilized palladium (MOP-Pd) catalysts were prepared from benzene and 1,10-phenanthroline by Scholl coupling reaction and Friedel-Crafts reaction, respectively. The structure and composition of the catalyst were characterized by FT-IR, TGA, N2 sorption, SEM, TEM, ICP-AES and XPS. MOP-Pd catalysts were found to possess high specific surface areas, large pore volume and low skeletal bone density. Moreover, the immobilized catalyst also had advantages, such as readily available raw materials, chemical and thermal stability, and low synthetic cost. The Pd catalyst is an effective heterogeneous catalyst for carbon-carbon (C-C) coupling reactions, such as the Heck reaction and Suzuki-Miyaura reaction, affording good to high yields. In these reactions, the catalyst was easily recovered and reused five times without significant activity loss.
- Xu, Wei,Liu, Cijie,Xiang, Dexuan,Luo, Qionglin,Shu, You,Lin, Hongwei,Hu, Yangjian,Zhang, Zaixing,Ouyang, Yuejun
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p. 34595 - 34600
(2019/11/11)
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- Palladium-melamine complex anchored on magnetic nanoparticles: A novel promoter for C-C cross coupling reaction
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A palladium-melamine complex deposited on Fe3O4@SiO2 nanoparticles (MNPs-Mel-Pd) was considered as an effective catalyst for C-C cross-coupling (Mirozoki-Heck) reaction. Surface and magnetic properties of the prepared core-shell hybrid nanocatalyst was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, energy-dispersive X-ray, vibrating sample magnetometry, transmission and scanning electron microscopy techniques and ICP/OES analysis. It was found that the heterogeneous nanocatalyst could be recovered simply and reused numerous times without loss of its catalytic activity. The advantages of this new methodology are: isolation of highly pure products without chromatography techniques, reusability of the catalyst using a magnet, easy workup procedure and negligible leaching of palladium.
- Bodaghifard, Mohammad Ali
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- Recyclable Pd ionic catalyst coated on cordierite monolith for high TOF Heck coupling reaction
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Abstract : Pd 2 + ionic catalyst, Ti 0.97Pd 0.03O 1.97 was coated over cordierite monolith by solution combustion method. The catalyst coated on the cordierite is nano-crystalline as seen from XRD studies. Coated catalyst was used for Heck coupling reactions with different substrates of aryl halides and olefins. Thus handling nano-crystalline catalyst powder is avoided by fixing it on a solid catalyst cartridge. Heck coupled products were characterized using 1H NMR, 13C NMR, Mass and FTIR spectroscopy. This catalyst showed high selectivity towards Heck coupling reaction. Turnover frequencies (TOF) for each of the reactions were found to be very high. The catalyst was recycled up to 7 times with total TOF 3017 h - 1, which is found to be a new green technique in the Heck coupling reaction. Graphical abstract: Ti 0.97Pd 0.03O 1.97 catalyst is coated on cordierite monolith honeycomb (HC) by solution combustion method and it is used in the Heck coupling reaction. Reactions are done in a specially designed flask. Catalyst is recycled for 7 times. The total turnover frequency (TOF) after 7 cycles was 3017 h - 1. [Figure not available: see fulltext.].
- Bhat, Shrikanth K,Prasad, Jagadeesh D,Hegde
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- METHOD FOR THE SYNTHESIS AND PURIFICATION OF ARYL ACID ESTERS
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The general inventive concepts are directed to the discovery that certain aryl acids can be esterified under particular conditions to provide the resulting ester as a solid that precipitates in good yield from the reaction mixture. The esters may then be isolated and purified with relative ease. Accordingly, a method for the esterification, isolation, and purification of aryl acids is provided.
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Paragraph 0028
(2019/10/17)
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- PHOTOCHEMICAL METHODS OF MAKING CYCLOBUTANE BORONATES AND RELATED COMPOUNDS
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The present technology relates generally cyclobutane boronates, including methods of preparation by exposing a mixture of a compound of Formula I in a solvent and a catalytic amount of a visible light sensitizer to provide a compound of Formula II, stereoisomers thereof, and/or salts of any of the foregoing. The cyclobutane boronate compounds are useful intermediates in the preparation of pharmaceutically active compounds as well as other other useful compounds.
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Paragraph 0123; 0124; 0129
(2019/02/19)
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- Synthesis and biological evaluation of 4-arylcoumarins as potential anti-Alzheimer's disease agents
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Alzheimer's disease (AD) is a progressive neurological degenerative disease that has complex pathogenesis. A variety of studies in humans indicate that several enzymes inhibitors can be useful in the treatment of AD, including acetylcholinesterase (AchE), butyrylcholinesterase (BuChE) and monoamine oxidase (MAO). Various substituted 4-arylcoumarin derivatives were synthesised, and their activity in vitro were investigated, including AChE/BuChE inhibitory activity, MAO inhibitory activity, and antioxidant activity. Most of the compounds were found to exhibit high inhibitory activity, and individual compounds have extremely excellent activities. Therefore 4-arylcoumarins provides an idea for drugs design for the development of therapeutic or preventive agents for AD.
- Miao, Yuhang,Sun, Jie,Wang, Xiaojing,Yang, Jie,Yun, Yinling
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- Water as a Hydrogenating Agent: Stereodivergent Pd-Catalyzed Semihydrogenation of Alkynes
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Palladium-catalyzed transfer semihydrogenation of alkynes using H2O as the hydrogen source and Mn as the reducing reagent is developed, affording cis- and trans-alkenes selectively under mild conditions. In addition, this method provides an efficient way to access various cis-1,2-dideuterioalkenes and trans-1,2-dideuterioalkenes by using D2O instead of H2O.
- Zhao, Chuan-Qi,Chen, Yue-Gang,Qiu, Hui,Wei, Lei,Fang, Ping,Mei, Tian-Sheng
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supporting information
p. 1412 - 1416
(2019/03/07)
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- One-pot synthesis of new N-(1-methylpyridin-4(1H)-ylidene)amine ligands for palladium-catalyzed heck coupling reaction
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A series of new derivatives of N -(1-methylpyridin-4(1 H) -ylidene)amines, [L1 ]–[L 5 ], were synthesized and characterized by FTIR, NMR, MS, and XRD analysis. These targeted compounds were synthesized by the melt reaction between N -methylated-4-chloropyridinium triflate and corresponding amines (1-naphthyl amine, o-ansidine, 2-nitroaniline, p-ansidine, and cyclohexyl amine) followed by the addition of sodium hydride in dichloromethane in the same pot. These highly electron-donating N -(1-methylpyridin-4(1 H) -ylidene)amine ligands considerably improve the catalytic activity of palladium acetate towards Heck–Mizoroki carbon–carbon cross-coupling reactions.
- Zafar, Muhammad,Zahra, Sabeen,Tahir, Muhammad,Mughal, Ehsan,Nazar, Muhammad,Rafique, Hummera
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- Pd(II)-NHDC-Functionalized UiO-67 Type MOF for Catalyzing Heck Cross-Coupling and Intermolecular Benzyne-Benzyne-Alkene Insertion Reactions
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A novel palladium N-heterocyclic bis-carbene dicarboxylate ligand (Pd-NHDC-H2L) was successfully synthesized. In addition, an Pd-NHDC-containing UiO-67 type MOF (UiO-67-Pd-NHDC) was prepared on the basis of a size-matched ligand mixture of biphenyl-4,4′-dicarboxylic acid/Pd-NHDC-H2L (9/1) and ZrCl4 under solvothermal conditions. The obtained UiO-67-Pd-NHC MOF can be a highly heterogeneous catalyst to promote Heck cross-coupling and intermolecular benzyne-benzyne-alkene insertion reactions.
- Wei, Yong-Liang,Li, Yue,Chen, Yun-Qi,Dong, Ying,Yao, Jia-Jia,Han, Xin-Yue,Dong, Yu-Bin
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supporting information
p. 4379 - 4386
(2018/04/25)
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- Halogen Bond Catalyzed Bromocarbocyclization
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A halogen bond catalyzed bromo-carbocyclization of N-cinnamyl sulfonamides and O-cinnamyl phenyl ethers has been developed. N-methyl 4-iodopyridinium triflate is used as the halogen-bonding organocatalyst and the reaction is highly chemoselective. This report represents the first proof-of-concept for halogen-bonding organocatalyst-promoted electrophilic halogenation. Mechanistic study suggests the autocatalytic nature of this reaction.
- Chan, Yuk-Cheung,Yeung, Ying-Yeung
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supporting information
p. 3483 - 3487
(2018/02/28)
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- Fabrication of Pd/CuFe2O4 hybrid nanowires: A heterogeneous catalyst for Heck couplings
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The development of environmentally benign transformations is indispensable in organic synthesis. Herein, a hybrid heterogeneous catalyst, palladium(0) on copper ferrite nanowires, has been synthesized, characterized, and for the first time, employed in the Jeffrey Heck reaction between iodoarenes and allylic alcohols, and good to excellent yields have been obtained. In addition, the catalyst was found to be suitable for the usual Heck coupling. The nanocatalyst was recovered and reused up-to multiple runs without any noticeable loss of its catalytic activity.
- Lakshminarayana,Mahendar,Ghosal,Sreedhar,Satyanarayana,Subrahmanyam, Ch.
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p. 1646 - 1654
(2018/02/09)
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- Probing the Evolution of Palladium Species in Pd@MOF Catalysts during the Heck Coupling Reaction: An Operando X-ray Absorption Spectroscopy Study
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The mechanism of the Heck C-C coupling reaction catalyzed by Pd@MOFs has been investigated using operando X-ray absorption spectroscopy (XAS) and powder X-ray diffraction (PXRD) combined with transmission electron microscopy (TEM) analysis and nuclear magnetic resonance (1H NMR) kinetic studies. A custom-made reaction cell was used, allowing operando PXRD and XAS data collection using high-energy synchrotron radiation. By analyzing the XAS data in combination with ex situ studies, the evolution of the palladium species is followed from the as-synthesized to its deactivated form. An adaptive reaction mechanism is proposed. Mononuclear Pd(II) complexes are found to be the dominant active species at the beginning of the reaction, which then gradually transform into Pd nanoclusters with 13-20 Pd atoms on average in later catalytic turnovers. Consumption of available reagent and substrate leads to coordination of Cl- ions to their surfaces, which causes the poisoning of the active sites. By understanding the deactivation process, it was possible to tune the reaction conditions and prolong the lifetime of the catalyst.
- Yuan, Ning,Pascanu, Vlad,Huang, Zhehao,Valiente, Alejandro,Heidenreich, Niclas,Leubner, Sebastian,Inge, A. Ken,Gaar, Jakob,Stock, Norbert,Persson, Ingmar,Martín-Matute, Belén,Zou, Xiaodong
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supporting information
p. 8206 - 8217
(2018/06/22)
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- Phosphine-mediated partial reduction of alkynes to form both (E)- and (Z)-alkenes
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A mild, phosphine-mediated partial reduction of alkynyl carbonyls to the corresponding alkenes was developed. Tuning of the reaction conditions led to either the (E)- or (Z)-diastereomer with high selectivity. A range of alkynyl esters, amides, and ketones were reduced to form alkenes in good to high yields and with excellent functional group tolerance.
- Pierce, Brett M.,Simpson, Brittany F.,Ferguson, Kane H.,Whittaker, Rachel E.
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p. 6659 - 6662
(2018/09/29)
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- One-Pot Synthesis of α,β-Unsaturated Esters, Ketones, and Nitriles from Alcohols and Phosphonium Salts
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A general method for the synthesis of α,β-unsaturated esters, ketones, and nitriles is successfully achieved by a one-pot copper-catalyzed oxidation with O 2 in air as oxidant. The solvent mixture of acetonitrile and formamide (1:1) is optimized to ensure the oxidation of alcohols, deprotonation of phosphonium salt, and Wittig reaction occur efficiently in one pot. A broad range of substrates has been explored for this process, including three electron-withdrawing group (CO 2 Et, COPh, CN) functionalized phosphonium salts. They reacted not only with benzylic and heteroaromatic alcohols, but also with aliphatic alcohols, forming the corresponding α,β-unsaturated esters, ketones, and nitriles in moderate to excellent yields.
- Ding, Weijie,Hu, Juan,Jin, Huile,Yu, Xiaochun,Wang, Shun
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p. 107 - 118
(2017/09/28)
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- Facile synthesis of α, β-unsaturated esters through a one-pot copper-catalyzed aerobic oxidation-Wittig reaction
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An efficient one-pot synthesis of α, β-unsaturated esters through the aerobic oxidation – Wittig tandem reaction of alcohols and phosphorous ylide is developed. This new method operates under mild reaction conditions, and uses CuI/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) as co-catalyst and air (O2) as the oxidant. It tolerates a wide range of functionalized benzylic alcohol and aliphatic alcohols.
- Ren, Cheng,Shi, Zhenyu,Ding, Weijie,Liu, Zhiqing,Jin, Huile,Yu, Xiaochun,Wang, Shun
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supporting information
p. 14 - 17
(2017/12/06)
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- ATP3 and MTP3: Easily Prepared Stable Perruthenate Salts for Oxidation Applications in Synthesis
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The Ley–Griffith tetra-n-propylammonium perruthenate (TPAP) catalyst has been widely deployed by the synthesis community, mainly for the oxidation of alcohols to aldehydes and ketones, but also for a variety of other synthetic transformations (e.g. diol cleavage, isomerizations, imine formation and heterocyclic synthesis). Such popularity has been forged on broad reaction scope, functional group tolerance, mild conditions, and commercial catalyst supply. However, the mild instability of TPAP creates preparation, storage, and reaction reproducibility issues, due to unpreventable slow decomposition. In search of attributes conducive to catalyst longevity an extensive range of novel perruthenate salts were prepared. Subsequent evaluation unearthed a set of readily synthesized, bench stable, phosphonium perruthenates (ATP3 and MTP3) that mirror the reactivity of TPAP, but avoid storage decomposition issues.
- Moore, Peter W.,Read, Christopher D. G.,Bernhardt, Paul V.,Williams, Craig M.
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supporting information
p. 4556 - 4561
(2018/03/13)
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- Method for preparing ethyl p-methoxy cinnamate
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The invention provides a method for preparing ethyl p-methoxy cinnamate. The method is characterized by comprising the following steps: adding metered p-methoxybenzaldehyde, toluene and solid super-strong alkali into a flask; heating and reflowing while stirring; after raising the temperature of the materials to pre-set temperature, slowly dropwise adding a toluene solution (with the concentrationof 20 percent) of diethyl malonate; after adding the toluene solution, reacting at the pre-set temperature to pre-set time; filtering a catalyst and evaporating to remove the toluene; cooling residues and slowly separating out light yellow solids, namely the ethyl p-methoxy cinnamate.
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Paragraph 0011; 0012; 0013; 0014-0022
(2018/03/28)
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- Synthesis and characterization of N-heterocyclic carbene–PdCl2–1H-benzotriazole complexes and their catalytic activities toward Mizoroki–Heck and Sonogashira reactions
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Four heteroleptic palladium complexes containing both N-heterocyclic carbenes and 1H-benzotriazole were synthesized and characterized. The solid-state structures show mononuclear carbene palladium complexes with each palladium coordinated by an NHC, the 3-position nitrogen of 1H-benzotriazole and two trans chlorides. The catalytic performance of the complexes for Mizoroki–Heck and Sonogashira reactions were further investigated. The results reveal that the complexes show high catalytic activities for coupling of aryl bromides with alkenes and alkynes.
- Yang, Jin
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p. 441 - 450
(2017/01/28)
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- Suzuki and Heck cross-coupling reactions using ferromagnetic nanoparticle-supported palladium complex as an efficient and recyclable heterogeneous nanocatalyst in sodium dodecylsulfate micelles
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A novel heterogeneous Pd catalyst was synthesized by anchoring Pd(II) onto 4′-(4-hydroxyphenyl)-2,2′:6′,2″-terpyridine-coated Fe3O4 (FMNPs@TPy-Pd). This catalyst has been demonstrated for the first time as a recoverable and reusable heterogeneous nanocatalyst in Suzuki and Heck cross-coupling reactions. The catalyst is very easy to handle and is environmentally safe and economical. FMNPs@TPy-Pd was characterized using transmission and scanning electron microscopies, X-ray diffraction, and Fourier transform infrared and energy-dispersive X-ray spectroscopies.
- Bahrami, Kiumars,Khodaei, Mohammad M.,Meibodi, Farhat Sadat
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- Unsymmetrical pincer CNN palladium complex of 7-ferrocenylmethyl-3-methyl-3,7-diazabicyclo[3.3.1]nonane
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The new unsymmetrical ferrocenyl containing bispidine derivative 7 was synthesized as a ligand precursor in five steps starting from N-Boc-4-oxopiperidine. The corresponding palladium CNN pincer complex 8 was prepared by direct cyclopalladation of the ligand 7 with Li2PdCl4 in MeOH. The molecular structure of the obtained palladacycle was determined by multinuclear NMR (1H, 13C, 15N) and confirmed by X-ray diffraction analysis. The pincer complex 8 demonstrated high catalytic activity in some cross-coupling reactions of aryl halides with phenylboronic acid, norbornene and ethyl acrylate.
- Bulygina, Ludmila A.,Kagramanov, Nikolay D.,Khrushcheva, Natalya S.,Lyssenko, Konstantin A.,Peregudov, Aleksander S.,Sokolov, Viacheslav I.
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p. 169 - 175
(2017/06/20)
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- Palladium on Polydopamine: Its True Potential in Catalytic Transfer Hydrogenations and Heck Coupling Reactions
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The application of Pd–polydopamine and magnetic Fe3O4@Pd–polydopamine catalysts in catalytic transfer hydrogenation reactions and the Heck arylation is reported. The reduction of a wide range of aromatic nitro-compounds bearing both electron-donating and -withdrawing substituents to the corresponding anilines could be efficiently performed, although the reduction of carbonyl compounds was found to be less general. In the latter case, only aromatic ketones could be reduced to the corresponding alcohols, whereas aldehyde substrates were unaffected, which may be owing to their reaction with the catalyst support leading to catalyst deactivation. By using magnetic Fe3O4@Pd–polydopamine system, facilitated catalyst recovery and reuse for five consecutive cycles without considerable loss of activity in nitro-group reduction. The efficiency of the catalyst in Heck reactions was comparable to that in transfer hydrogenation, however, no catalytic activity was observed upon reuse in this case, likely as a result of metal leaching. We also explored tandem Heck reaction/catalytic transfer hydrogenation sequences, however, the two reactions showed limited compatibility under the applied conditions.
- Kunfi, Attila,Szabó, Vivien,Mastalir, ágnes,Bucsi, Imre,Mohai, Miklós,Németh, Péter,Bertóti, Imre,London, Gábor
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p. 3236 - 3244
(2017/08/29)
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- Bioactivity and structure-activity relationship of cinnamic acid esters and their derivatives as potential antifungal agents for plant protection
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A series of cinnamic acid esters and their derivatives were synthesized and evaluated for antifungal activities in vitro against four plant pathogenic fungi by using the mycelium growth rate method. Structure-activity relationship was derived also. Almost all of the compounds showed some inhibition activity on each of the fungi at 0.5 mM. Eight compounds showed the higher average activity with average EC50 values of 17.4-28.6 μg/mL for the fungi than kresoxim-methyl, a commercial fungicide standard, and ten compounds were much more active than commercial fungicide standards carbendazim against P. grisea or kresoxim-methyl against both P. grisea and Valsa Mali. Compounds C1 and C2 showed the higher activity with average EC50 values of 17.4 and 18.5 μg/mL and great potential for development of new plant antifungal agents. The structure-activity relationship analysis showed that both the substitution pattern of the phenyl ring and the alkyl group in the alcohol moiety significantly influences the activity. There exists complexly comprehensive effect between the substituents on the phenyl ring and the alkyl group in the alcohol moiety on the activity. Thus, cinnamic acid esters showed great potential the development of new antifungal agents for plant protection due to high activity, natural compounds or natural compound framework, simple structure, easy preparation, low-cost and environmentally friendly.
- Zhou, Kun,Chen, Dongdong,Li, Bin,Zhang, Bingyu,Miao, Fang,Zhou, Le
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- Gold-Catalyzed [2,3]-Sigmatropic Rearrangement: Reaction of Aryl Allyl Alcohols with Diazo Compounds
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A gold-catalyzed [2,3]-sigmatropic rearrangement reaction has been developed. The intermolecular rearrangement occurs between in situ generated donor-acceptor gold-carbenes and cinnamyl alcohols via tandem oxonium ylide formation. The desired rearranged product has been accomplished selectively over more conventional O-H insertion, cyclopropanation, cycloaddition, and C-H functionalization products under mild, open-air conditions. The scope of the work has been illustrated by synthesizing a new class of substrates that can be used for constructing complex molecular targets.
- Rao, Santhosh,Prabhu, Kandikere Ramaiah
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supporting information
p. 846 - 849
(2017/02/26)
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- A Gold- and Br?nsted Acid Catalytic Interplay Towards the Synthesis of Highly Substituted Tetrahydrocarbazoles
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The reaction of indoles and stabilized cyclopropyl alkynes under gold- and/or gold & Br?nsted acid-catalysis provided access to highly substituted tetrahydrocarbazoles. A mechanistic study revealed the complex mechanism underlying these processes and the opportunistic cooperation of Lewis and Br?nsted acid-catalysts towards the formation of complex molecular scaffolds.
- Garayalde, David,Rusconi, Giulia,Nevado, Cristina
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- Stereodivergent allylic substitutions with aryl acetic acid esters by synergistic iridium and lewis base catalysis
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The preparation of all possible stereoisomers of a given chiral molecule bearing multiple stereocenters by a simple and unified method is a significant challenge in asymmetric catalysis. We report stereodivergent allylic substitutions with aryl acetic acid esters catalyzed synergistically by a metallacyclic iridium complex and benzotetramisole. Through permutations of the enantiomers of the two chiral catalysts, all four stereoisomers of the products bearing two adjacent stereocenters are accessible with high diastereoselectivity and enantioselectivity. The resulting chiral activated ester products can be converted readily to enantioenriched amides, unactivated esters, and carboxylic acids in a onepot manner.
- Jiang, Xingyu,Beiger, Jason J.,Hartwig, John F.
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supporting information
p. 87 - 90
(2017/05/16)
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- Iridium-Catalyzed Enantioselective Allylic Substitution of Aliphatic Esters with Silyl Ketene Acetals as the Ester Enolates
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Enantioselective allylic substitution with enolates derived from aliphatic esters under mild conditions remains challenging. Herein we report iridium-catalyzed enantioselective allylation reactions of silyl ketene acetals, the silicon enolates of esters, to form products containing a quaternary carbon atom at the nucleophile moiety and a tertiary carbon atom at the electrophile moiety. Under relatively neutral conditions, the allylated aliphatic esters were obtained with excellent regioselectivity and enantioselectivity. These products were readily converted into primary alcohols, carboxylic acids, amides, isocyanates, and carbamates, as well as tetrahydrofuran and γ-butyrolactone derivatives, without erosion of enantiomeric purity.
- Jiang, Xingyu,Hartwig, John F.
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supporting information
p. 8887 - 8891
(2017/07/17)
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- Preparation method and application of octyl methoxycinnamate
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The invention discloses a preparation method of octyl methoxycinnamate (OMC). The preparation method comprises the following steps: firstly, uniformly stirring p-methoxybenzaldehyde, acetate, organic amine substances and a solvent, and controlling the temperature to be from 20 DEG C below zero to 10 DEG C; then dropwise adding a titanium tetrachloride catalyst, and after dropwise addition, rising the temperature to 10 to 40 DEG C, and carrying out reaction for 2 to 16h; after the reaction is completed, washing a reaction solution with dilute acid until being neutral, washing with water, drying an organic phase with anhydrous sodium sulfate, and carrying out solvent removal to obtain the octyl methoxycinnamate, wherein the yield reaches 98 percent or above. The preparation method has the characteristics of simpleness, convenience, easiness in control and industrial production, small environmental pollution, low energy consumption, capability of recycling materials, high purity and the like. The prepared octyl methoxycinnamate has the advantages of being colorless and transparent, high purity and the like and can be applied to the field of sun-screening cosmetics, chemical industry for daily supplies, plastics, rubber, coatings and the like.
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Paragraph 0037; 0038; 0039; 0040; ,0041; 0042
(2017/07/20)
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- A class of 1, 2, 5 - oxadiazole - 2 oxide analogs, its preparation and use
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The invention provides 1,2,5-oxadiazole-2 oxide analogue with a structure shown as general formula I, and a preparation method and an application thereof. The 1,2,5-oxadiazole-2 oxide analogue has the activity for resisting schistosome thioredoxin glutathione reductase, kills schistosome by blocking a normal redox equilibrium physiological metabolism process of schistosome cells, can be used as a drug lead for development of drugs for treating schistosomiasis, and provides novel means for preventing and treating schistosomiasis. The general formula I is shown in the description.
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Paragraph 0079; 0080; 0081; 0082
(2017/04/21)
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