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3D-Printing of Hierarchical Porous Copper-Based Metal-Organic-Framework Structures for Efficient Fixed-Bed Catalysts. CHEM & BIO ENGINEERING 2024; 1:264-273. [PMID: 38689655 PMCID: PMC11056925 DOI: 10.1021/cbe.4c00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/13/2024] [Accepted: 02/21/2024] [Indexed: 05/02/2024]
Abstract
Metallic structures with hierarchical open pores that span several orders of magnitude are ideal candidates for various catalyst applications. However, porous metal materials prepared using alloy/dealloy methods still struggle to achieve continuous pore distribution across a broad size range. Herein, we report a printable copper (Cu)/iron (Fe) composite ink that produces a hierarchical porous Cu material with pores spanning over 4 orders of magnitude. The manufacturing process involves four steps: 3D-printing, annealing, dealloying, and reannealing. Because of the unique annealing process, the resulting hierarchical pore surface becomes coated with a layer of Cu-Fe alloy. This feature imparts remarkable catalytic ability and versatile functionality within fixed bed reactors for 4-nitrophenol (4-NP) reduction and Friedländer cyclization. Specifically, for 4-NP reduction, the porous Cu catalyst demonstrates an excellent reaction rate constant (kapp = 86.5 × 10-3 s-1) and a wide adaptability of the substrate (up to 1.26 mM), whilst for Friedländer cyclization, a conversion over 95% within a retention time of only 20 min can be achieved by metal-organic-framework-decorated porous Cu catalyst. The utilization of dual metallic particles as printable inks offers valuable insights for fabricating hierarchical porous metallic structures for applications, such as advanced fixed-bed catalysts.
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Preparation of Copper-Based Catalysts for Obtaining Methanol by the Chemical Impregnation Method. MATERIALS (BASEL, SWITZERLAND) 2024; 17:847. [PMID: 38399098 PMCID: PMC10890475 DOI: 10.3390/ma17040847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/06/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024]
Abstract
This paper presents the preparation of heterogeneous catalysts for the direct hydrogenation process of CO2 to methanol. The development of the modern chemical industry is inextricably linked to the use of catalytic processes. As a result, currently over 80% of new technologies introduced in the chemical industry incorporate catalytic processes. Since the basic factor of catalytic processes is the catalysts, the studies for the deepening of the knowledge regarding the nature of the action of the catalysts, for the development of new catalysts and catalytic systems, as well as for their improvement, represent a research priority of a fundamental or applied nature. The Cu/ZnO/Al2O3 catalyst for the synthesis of green methanol, using precursors of an inorganic (copper nitrate, denoted by Cu/ZnO/Al2O3-1) and organic (copper acetate, denoted by Cu/ZnO/Al2O3-2) nature, are obtained by chemical impregnation that includes two stages: preparation and one of calcination. The preparation methods and conditions, as well as the physico-chemical properties of the catalyst precursor, play a major role in the behavior of the catalysts. The prepared catalysts were characterized using atomic adsorption analysis, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, specific surface area and pore size analyses, adsorption, and the chemisorption of vapor (BET).
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Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N, N-diacyl-β-amino esters. Beilstein J Org Chem 2024; 20:212-219. [PMID: 38318462 PMCID: PMC10840549 DOI: 10.3762/bjoc.20.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/23/2024] [Indexed: 02/07/2024] Open
Abstract
An efficient multicomponent reaction of newly designed β-trifluoromethyl β-diazo esters, acetonitrile, and carboxylic acids via an interrupted esterification process under copper-catalyzed conditions has been developed, which affords various unsymmetrical β-trifluoromethyl N,N-diacyl-β-amino esters in good to excellent yields. The reaction features mild conditions, a wide scope of β-amino esters and carboxylic acids, and also applicability to large-scale synthesis, thus providing an efficient way for the synthesis of β-trifluoromethyl β-diacylamino esters. Furthermore, this reaction represents the first example of a Mumm rearrangement of β-trifluoromethyl β-diazo esters.
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Copper-catalyzed reaction of aziridine for the synthesis of substituted imidazolidine and imidazolidinone. Front Chem 2023; 11:1272034. [PMID: 37841205 PMCID: PMC10570437 DOI: 10.3389/fchem.2023.1272034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 09/18/2023] [Indexed: 10/17/2023] Open
Abstract
Herein we report a copper-catalyzed synthesis of imidazolidine by employing the reaction of aziridine with imine. The reaction smoothly provided a diverse range of 2-substituted imidazolidines with high compatibility with various functional groups. Moreover, during our investigation, we discovered that isocyanate also reacted with aziridine to yield substituted imidazolidinones efficiently. The versatility of these reactions was further demonstrated by their application in the synthesis of hybrid molecules derived from two pharmaceutical compounds. This approach opens new possibilities for the discovery of novel classes of bioactive molecules.
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Highly Selective and Stable Cu Catalysts Based on Ni-Al Catalytic Systems for Bioethanol Upgrading to n-Butanol. Molecules 2023; 28:5683. [PMID: 37570654 PMCID: PMC10419762 DOI: 10.3390/molecules28155683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/19/2023] [Accepted: 07/23/2023] [Indexed: 08/13/2023] Open
Abstract
The catalytic upgrading of ethanol into butanol through the Guerbet coupling reaction has received increasing attention recently due to the sufficient supply of bioethanol and the versatile applications of butanol. In this work, four different supported Cu catalysts, i.e., Cu/Al2O3, Cu/NiO, Cu/Ni3AlOx, and Cu/Ni1AlOx (Ni2+/Al3+ molar ratios of 3 and 1), were applied to investigate the catalytic performances for ethanol conversion. From the results, Ni-containing catalysts exhibit better reactivity; Al-containing catalysts exhibit better stability; but in terms of ethanol conversion, butanol selectivity, and catalyst stability, a corporative effect between Ni-Al catalytic systems can be clearly observed. Combined characterizations such as XRD, TEM, XPS, H2-TPR, and CO2/NH3-TPD were applied to analyze the properties of different catalysts. Based on the results, Cu species provide the active sites for ethanol dehydrogenation/hydrogenation, and the support derived from Ni-Al-LDH supplies appropriate acid-base sites for the aldol condensation, contributing to the high butanol selectivity. In addition, catalysts with strong reducibility (i.e., Cu/NiO) may be easily deconstructed during catalysis, leading to fast deactivation of the catalysts in the Guerbet coupling process.
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Cu-Catalyzed Polychloromethylamination of Styrenes through C(sp 3 )-H Bond Cleavage. Chemistry 2023; 29:e202203079. [PMID: 36573558 DOI: 10.1002/chem.202203079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Indexed: 12/28/2022]
Abstract
A copper-catalyzed three-component coupling reaction has been developed allowing the rapid building of valuable complex highly functionalized β-polychloromethyl amines from simple styrenes, arylamines, and dichloromethane/chloroform. Using aryldiazonium salts as a radical initiator, a series of corresponding products are obtained with moderate to good yields under a carbon dioxide or nitrogen atmosphere (50 psi). In addition, good functional group tolerance can be observed.
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Copper-Catalyzed Aerobic C(sp 3)-H Oxidation of β-(Alkoxy)imino Carbonyl Compounds. Chem Pharm Bull (Tokyo) 2023; 71:83-92. [PMID: 36724984 DOI: 10.1248/cpb.c22-00403] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Direct oxidation of the C(sp3)-H bond of β-(alkoxy)imino carbonyl compounds using copper acetate and molecular oxygen has been established. The protocol features a broad substrate scope and generates 1-imino-2,3-dicarbonyls in good to excellent yields.
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Electrochemical Generation of Nitric Oxide for Medical Applications. ELECTROCHEMICAL SCIENCE ADVANCES 2022; 2:e2100156. [PMID: 36386004 PMCID: PMC9642980 DOI: 10.1002/elsa.202100156] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/06/2021] [Indexed: 12/31/2022] Open
Abstract
Over the past 30 years, the significance of nitric oxide (NO) has become increasingly apparent in mammalian physiology. It is biosynthesized by three isoforms of nitric oxide synthases (NOS): neuronal (nNOS), endothelial (eNOS), and inducible (iNOS). Neuronal and eNOS both produce low levels of NO (nM) as a signaling agent and vasodilator, respectively. Inducible (iNOS) is present in activated macrophages at sites of infection to generate acutely toxic (μM) levels of NO as part of the mammalian immune defense mechanism. These discoveries have led to numerous animal and clinical studies to evaluate the potential therapeutic utility of NO in various medical operations/treatments, primarily using NO gas (via gas-cylinders) as the NO source. In this review, we focus specifically on recent advances in the electrochemical generation of NO (E-NOgen) as an alternative means to generate NO from cheap and inert sources, and the fabrication and testing of biomedical devices that utilize E-NOgen to controllably generate NO for medical applications.
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Reverse Microemulsion-Synthesized High-Surface-Area Cu/γ-Al 2O 3 Catalyst for CO 2 Conversion via Reverse Water Gas Shift. ACS APPLIED MATERIALS & INTERFACES 2022; 14:22082-22094. [PMID: 35522907 DOI: 10.1021/acsami.2c01959] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Reverse microemulsion method was implemented to synthesize a CuO/γ-Al2O3 catalyst (18 wt % Cu) with a specific surface area (SSA) of 328 m2/g (after calcination at 400 °C). Catalytic performance was evaluated in the range of temperatures and space velocities (300-600 °C and 10,000-200,000 mL/(g h)). The catalyst was 100% selective to CO generation while attaining a nearly equilibrium CO2 conversion at 500 °C (ca. 50% at 10,000 mL/(g h) and H2/CO2 = 4). Despite the initial reduction of surface area under the reaction conditions, the reduced Cu/γ-Al2O3 catalyst demonstrated a stable performance for 80 h on stream, attaining a nearly equilibrium CO2 conversion at 600 °C (ca. 60% at 60,000 mL/(g h) and H2/CO2 = 4). The selectivity to CO generation remained complete during the stability test, and no significant carbon deposition was detected.
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Spray-Assisted Interfacial Polymerization to Form Cu II/I@CMC-PANI Film: An Efficient Dip Catalyst for A 3 Reaction. NANOMATERIALS 2022; 12:nano12101641. [PMID: 35630864 PMCID: PMC9146272 DOI: 10.3390/nano12101641] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/01/2022] [Accepted: 05/02/2022] [Indexed: 02/01/2023]
Abstract
A novel and interesting method for the preparation of carboxymethylcellulose–polyaniline film-supported copper catalyst (CuII/I@CMC-PANI) has been developed via spray-assisted interfacial polymerization. Using copper sulfate as an initiator, spraying technology was introduced to form a unique interface that is perfectly beneficial to the polymerization of aniline monomers onto carboxymethylcellulose macromolecule chains. To further confirm the composition and structure of the as-prepared hybrid film, it was systematically characterized by inductively coupled plasma (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA) techniques. The Cu content in the fresh CuII/I@CMC-PANI film was determined to be 1.805 mmol/g, and spherical nanoparticles with an average size of ca. 10.04 nm could be observed in the hybrid film. The CuII/I@CMC-PANI hybrid film was exerted as a dip catalyst to catalyze the aldehyde–alkyne–amine (A3) coupling reactions. High yields of the products (up to 97%) were obtained in this catalytic system, and the catalyst could be easily picked up from the reaction mixture by tweezers and reused for at least six consecutive runs, without any discernible losses in its activity in the model reaction. The dip catalyst of CuII/I@CMC-PANI, with easy fabrication, convenient deployment, superior catalytic activity, and great reusability, is expected to be very useful in organic synthesis.
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Selective, Stable Production of Ethylene Using a Pulsed Cu-Based Electrode. ACS APPLIED MATERIALS & INTERFACES 2022; 14:19388-19396. [PMID: 35442619 DOI: 10.1021/acsami.2c01230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ethylene (C2H4) is an important product in carbon dioxide electroreduction (CO2RR) because of the essential role it plays in chemical industry. While several strategies have been proposed to tune the selectivity of Cu-based catalysts in order to achieve high C2H4 faradaic efficiency, maintaining high selectivity toward C2H4 in CO2RR remains an unresolved problem hampering the deployment of CO2 conversion technology due to the lack of stable electrocatalysts. Here, we develop a facile method to deposit a layer of Cu2O on Cu foil by an electrochemical pulsed potential treatment. This method is capable to easily scale up and synthesize multiple electrodes in one step. After the synthesis, the pulsed copper foil, denoted as P-Cu, exhibits good C2H4 faradaic efficiency of ∼50% in CO2RR at a potential around -1.0 V vs. RHE. The C2H4 selectivity is also found to be quantitatively correlated with the roughness factor (RF) of Cu-based catalysts. More importantly, for the first time, we demonstrate that the P-Cu electrode is quite durable in CO2RR to produce C2H4 for more than 6 months.
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Scalable Gas Diffusion Electrode Fabrication for Electrochemical CO 2 Reduction Using Physical Vapor Deposition Methods. ACS APPLIED MATERIALS & INTERFACES 2022; 14:7731-7740. [PMID: 35128928 DOI: 10.1021/acsami.1c17860] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electrochemical CO2 reduction (ECR) promises the replacement of fossil fuels as the source of feedstock chemicals and seasonal storage of renewable energy. While much progress has been made in catalyst development and electrochemical reactor design, few studies have addressed the effect of catalyst integration on device performance. Using a microfluidic gas diffusion electrolyzer, we systematically studied the effect of thickness and the morphology of electron beam (EB) and magnetron-sputtered (MS) Cu catalyst coatings on ECR performance. We observed that EB-Cu outperforms MS-Cu in current density, selectivity, and energy efficiency, with 400 nm thick catalyst coatings performing the best. The superior performance of EB-Cu catalysts is assigned to their faceted surface morphology and sharper Cu/gas diffusion layer interface, which increases their hydrophobicity. Tests in a large-scale zero-gap electrolyzer yielded similar product selectivity distributions with an ethylene Faradaic efficiency of 39% at 200 mA/cm2, demonstrating the scalability for industrial ECR applications.
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Insight into the Activity and Selectivity of Nanostructured Copper Titanates during Electrochemical Conversion of CO 2 at Neutral pH via In Situ X-ray Absorption Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:2742-2753. [PMID: 34982523 DOI: 10.1021/acsami.1c19298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The electrochemical conversion of carbon dioxide (CO2) to useful chemical fuels is a promising route toward the achievement of carbon neutral and carbon negative energy technologies. Copper (Cu)- and Cu oxide-derived surfaces are known to electrochemically convert CO2 to high-value and energy-dense products. However, the nature and stability of oxidized Cu species under reaction conditions are the subject of much debate in the literature. Herein, we present the synthesis and characterization of copper-titanate nanocatalysts, with discrete Cu-O coordination environments, for the electrochemical CO2 reduction reaction (CO2RR). We employ real-time in situ X-ray absorption spectroscopy (XAS) to monitor Cu species under neutral-pH CO2RR conditions. Combination of voltammetry and on-line electrochemical mass spectrometry with XAS results demonstrates that the titanate motif promotes the retention of oxidized Cu species under reducing conditions for extended periods, without itself possessing any CO2RR activity. Additionally, we demonstrate that the specific nature of the Cu-O environment and the size of the catalyst dictate the long-term stability of the oxidized Cu species and, subsequently, the product selectivity.
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Catalytic Asymmetric Allylic Substitution with Copper(I) Homoenolates Generated from Cyclopropanols. Angew Chem Int Ed Engl 2021; 60:26351-26356. [PMID: 34617380 DOI: 10.1002/anie.202110709] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/30/2021] [Indexed: 12/23/2022]
Abstract
By using copper(I) homoenolates as nucleophiles, which are generated through the ring-opening of 1-substituted cyclopropane-1-ols, a catalytic asymmetric allylic substitution with allyl phosphates is achieved in high to excellent yields with high enantioselectivity. Both 1-substituted cyclopropane-1-ols and allylic phosphates enjoy broad substrate scopes. Remarkably, various functional groups, such as ether, ester, tosylate, imide, alcohol, nitro, and carbamate are well tolerated. Moreover, the present method is nicely extended to the asymmetric construction of quaternary carbon centers. Some control experiments argue against a radical-based reaction mechanism and a catalytic cycle based on a two-electron process is proposed. Finally, the synthetic utilities of the product are showcased by means of the transformations of the terminal olefin group and the ketone group.
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Design, Microwave-Assisted Synthesis and In Silico Prediction Study of Novel Isoxazole Linked Pyranopyrimidinone Conjugates as New Targets for Searching Potential Anti-SARS-CoV-2 Agents. Molecules 2021; 26:molecules26206103. [PMID: 34684683 PMCID: PMC8537412 DOI: 10.3390/molecules26206103] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/27/2021] [Accepted: 10/06/2021] [Indexed: 11/25/2022] Open
Abstract
A series of novel naphthopyrano[2,3-d]pyrimidin-11(12H)-one containing isoxazole nucleus 4 was synthesized under microwave irradiation and classical conditions in moderate to excellent yields upon 1,3-dipolar cycloaddition reaction using various arylnitrile oxides under copper(I) catalyst. A one-pot, three-component reaction, N-propargylation and Dimroth rearrangement were used as the key steps for the preparation of the dipolarophiles3. The structures of the synthesized compounds were established by 1H NMR, 13C NMR and HRMS-ES means. The present study aims to also predict the theoretical assembly of the COVID-19 protease (SARS-CoV-2 Mpro) and to discover in advance whether this protein can be targeted by the compounds 4a–1 and thus be synthesized. The docking scores of these compounds were compared to those of the co-crystallized native ligand inhibitor (N3) which was used as a reference standard. The results showed that all the synthesized compounds (4a–l) gave interesting binding scores compared to those of N3 inhibitor. It was found that compounds 4a, 4e and 4i achieved greatly similar binding scores and modes of interaction than N3, indicating promising affinity towards SARS-CoV-2 Mpro. On the other hand, the derivatives 4k, 4h and 4j showed binding energy scores (−8.9, −8.5 and −8.4 kcal/mol, respectively) higher than the Mpro N3 inhibitor (−7.0 kcal/mol), revealing, in their turn, a strong interaction with the target protease, although their interactions were not entirely comparable to that of the reference N3.
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Synthesis of Carbohydrate Based Macrolactones and Their Applications as Receptors for Ion Recognition and Catalysis. Molecules 2021; 26:3394. [PMID: 34205128 PMCID: PMC8199946 DOI: 10.3390/molecules26113394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 01/23/2023] Open
Abstract
Glycomacrolactones exhibit many interesting biological properties, and they are also important in molecular recognitions and for supramolecular chemistry. Therefore, it is important to be able to access glycomacrocycles with different sizes and functionality. A new series of carbohydrate-based macrocycles containing triazole and lactone moieties have been designed and synthesized. The synthesis features an intramolecular nucleophilic substitution reaction for the macrocyclization step. In this article, the effect of some common sulfonate leaving groups is evaluated for macrolactonization. Using tosylate gave good selectivity for monolactonization products with good yields. Fourteen different macrocycles have been synthesized and characterized, of which eleven macrocycles are from cyclization of the C1 to C6 positions of N-acetyl D-glucosamine derivatives and three others from C2 to C6 cyclization of functionalized D-glucosamine derivatives. These novel macrolactones have unique structures and demonstrate interesting anion binding properties, especially for chloride. The macrocycles containing two triazoles form complexes with copper sulfate, and they are effective ligands for copper sulfate mediated azide-alkyne cycloaddition reactions (CuAAC). In addition, several macrocycles show some selectivity for different alkynes.
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Role of Intermolecular Interactions in the Catalytic Reaction of Formic Acid on Cu(111). SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2008010. [PMID: 33759365 DOI: 10.1002/smll.202008010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Formic acid (HCOOH) can be catalytically decomposed into H2 and CO2 and is a promising hydrogen storage material. As H2 production catalysts, Cu surfaces allow selective HCOOH decarboxylation; however, the on-surface HCOOH decomposition reaction pathway remains controversial. In this study, the temperature dependence of the HCOOH/Cu(111) adsorption structures is elucidated by scanning tunneling microscopy and non-contact atomic force microscopy, establishing the adsorbate chemical species using density functional theory. 2D HCOOH islands at 80 K, linear chains of HCOOH and monodentate formate at 150 K, chain-like assemblies of monodentate and bidentate formate at 200 K, and bidentate formate clusters at 300 K are observed. At each temperature, the adsorbates experience attractive interactions among themselves. Such aggregation stabilizes them against desorption and decomposition. Thus, accurate evaluation of intermolecular interactions is essential to understand catalytic reactivity.
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PROMETHEUS: A Copper-Based Polymetallic Catalyst for Automotive Applications. Part I: Synthesis and Characterization. MATERIALS (BASEL, SWITZERLAND) 2021; 14:622. [PMID: 33572954 PMCID: PMC7866378 DOI: 10.3390/ma14030622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/20/2021] [Accepted: 01/26/2021] [Indexed: 11/22/2022]
Abstract
According to the strict European exhaust emissions standards that have been imposed by European legislation there is an elevated need for the decrease of the toxic gas emissions from vehicles. Therefore, car manufacturers have implemented a series of catalytic devices in the aftertreatment of the engine to comply with the standards. All catalytic devices (such as three-way catalysts, diesel particulate filters and diesel oxidation catalysts) accumulate concentrated loading of platinum group metals (PGMs, platinum, palladium, rhodium) as the active catalytic phase. Thus, the demand for PGMs is constantly increasing with a subsequent increase in their market prices. As a result, the research on catalytic converters of high activity and reduced cost/PGM loading is of great interest. In the present work, the Prometheus catalyst, a polymetallic nanosized copper-based catalyst for automotive emission control applications, is presented in two different metal loadings (2 wt% and 5 wt%) and metal ratios (Cu/Pd/Rh = 21/7/1 and Cu/Pd/Rh = 21/7/3). For the first time, a three-metal (copper, palladium, rhodium) nano-catalyst has been synthesized and characterized on a large scale. By using copper as an active catalytic phase, a reduction of PGMs loading is achieved (up to 85%) resulting in a novel catalytic device with similar or improved catalytic performance compared to commercial ones. The Prometheus catalyst is prepared by a wet impregnation method, using as a carrier an inorganic mixed oxide (CeZrO4) exhibiting elevated oxygen storage capacity (OSC). The heterogeneous catalytic powders produced were characterized by both spectroscopic and analytical methods. The metal content and ratio were determined by inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF) and energy-dispersive X-ray spectroscopy (EDS). The morphology and the catalyst particle size were determined with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The investigation revealed homogeneous particle formation and dispersion. The deposition of the metal nanoparticles on the porous inorganic carrier was verified with N2 sorption. Catalytic performance and reactivity of a catalyst (pure wash coat) with molar ratio 21/7/1 and a full-scale Prometheus catalyst with the desired loading of 15 g/ft3 were tested on an in-house synthetic gas bench (SGB) for the abatement of CO, CH4 and NO, both presenting high catalytic activity.
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CO 2 Hydrogenation to Methanol with Ga- and Zn-Doped Mesoporous Cu/SiO 2 Catalysts Prepared by the Aerosol-Assisted Sol-Gel Process*. CHEMSUSCHEM 2020; 13:6409-6417. [PMID: 32996706 DOI: 10.1002/cssc.202001951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/25/2020] [Indexed: 06/11/2023]
Abstract
The preparation of copper-based heterogeneous catalysts dedicated to the hydrogenation of CO2 to methanol typically relies on multi-step procedures carried out in batch. These steps are precisely tailored to introduce the active phase (Cu) and the promoters (e. g., zinc, gallium) onto a preformed support to maximize catalyst performance. However, each process step can be associated with the formation of waste and with the consumption of energy, thereby negatively impacting the environmental performance of the overall catalyst preparation procedure. Here, a direct and continuous production process is proposed for the synthesis of efficient catalysts for the CO2 -to-methanol reaction. Gallium- and zinc-promoted mesoporous Cu-SiO2 catalysts were prepared in one step by the aerosol-assisted sol-gel process. The catalysts consisted of spherical microparticles and featured high specific surface area and pore volume, with interconnected pores of about 6 nm. A strong promoting effect of Ga and Zn was highlighted, boosting the selectivity for methanol at the expense of CO. Upon calcination, it was shown that Cu species (initially trapped in the silica matrix) underwent a migration towards the catalyst surface and a progressive sintering. After optimization, the catalysts obtained via such direct, continuous, simple, and scalable route could compete with the best catalysts reported in the literature and obtained via multi-step approaches.
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Catalytic Halogen Exchange in Supplementary Activator and Reducing Agent Atom Transfer Radical Polymerization for the Synthesis of Block Copolymers. Macromol Rapid Commun 2020; 42:e2000532. [PMID: 33289265 DOI: 10.1002/marc.202000532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/24/2020] [Indexed: 11/08/2022]
Abstract
Synthesis of block copolymers (BCPs) by catalytic halogen exchange (cHE) is reported, using supplemental activator and reducing agent Atom Transfer Radical Polymerization (SARA ATRP). The cHE mechanism is based on the use of a small amount of a copper catalyst in the presence of a suitable excess of halide ions, for the synthesis of block copolymers from macroinitiators with monomers of mismatching reactivity. cHE overcomes the problem of inefficient initiation in block copolymerizations in which the second monomer provides dormant species that are more reactive than the initiator. Model macroinitiators with low dispersity are prepared and extended to afford well-defined block copolymers of various compositions. Combined cHE/SARA ATRP is therefore a simple and potent polymerization tool for the copolymerization of a wide range of monomers allowing the production of tailored block copolymers.
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Chemical Fixation of CO 2 Using Highly Dispersed Cu on Hierarchically Porous N-Doped Carbon. ACS APPLIED MATERIALS & INTERFACES 2020; 12:40236-40247. [PMID: 32805818 DOI: 10.1021/acsami.0c08001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Chemical transformation of carbon dioxide (CO2) into fine chemicals such as oxazolidinones and carbamates is mainly reported using transition-metal complexes as homogeneous catalysts. Herein, we demonstrate that a heterogeneous catalyst of highly dispersed Cu (Cu/NHPC) supported on hierarchically porous N-doped carbon (NHPC) can efficiently promote CO2 fixations to oxazolidinones and β-oxopropylcarbamates. The obtained NHPC, assembled by ultrathin nitrogen-doped carbon nanosheets with a three-dimensional (3D) structure, is readily prepared by pyrolysis of a nitrogen-containing polymer gel (NPG) in the presence of an activator of potassium bicarbonate (KHCO3). The resulting NHPC shows specific Brunauer-Emmet-Teller (BET) surface areas up to 2054 m2 g-1 with a mean micro/mesopore size of 0.55/3.2 nm and a broad macropore size distribution from 50 to 230 nm. The Cu/NHPC can efficiently promote three-component coupling of CO2, amines, and propargyl alcohols for syntheses of various oxazolidinones and β-oxopropylcarbamates with yields up to 99% and a wide substrate scope. Moreover, the Cu/NHPC exhibits excellent recyclability in CO2-to-oxazolidinone transformation during nine-time recycling. The research thus develops an NHPC-based heterogeneous Cu catalyst for green transformation of CO2.
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Amine-Mediated Bond Cleavage in Oxidized Lignin Models. CHEMSUSCHEM 2020; 13:4660-4665. [PMID: 32539209 DOI: 10.1002/cssc.202001228] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/14/2020] [Indexed: 06/11/2023]
Abstract
Introducing amines/ammonia into lignin cracking will allow novel bond cleavage pathways. Herein, a method of amines/ammonia-mediated bond cleavage in oxidized lignin β-O-4 models was studied using a copper catalyst at room temperature, demonstrating the effect of the amine source on the selectivity of products. For primary and secondary aliphatic amines, lignin ketone models underwent oxidative Cα -Cβ bond cleavage and Cα -N bond formation to generate aromatic amides. For ammonia, the competition between oxygen and ammonia determined the selectivity between Cα -N and Cβ -N bond formation, generating amides and α-keto amides, respectively. For tertiary amines, the lignin models underwent oxidative Cα -Cβ bond cleavage to benzoic acids. Control experiments indicated that amines act as nucleophiles attacking at the Cα or Cβ position of the oxidized β-O-4 linkage to be cleaved. This study represents a novel example that the breakage of oxidized lignin model can be regulated by amines with a copper catalyst.
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Fabrication of Fe 3O 4@PVA-Cu Nanocomposite and Its Application for Facile and Selective Oxidation of Alcohols. Front Chem 2020; 8:615. [PMID: 32850642 PMCID: PMC7396633 DOI: 10.3389/fchem.2020.00615] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/11/2020] [Indexed: 11/30/2022] Open
Abstract
Fe3O4@PVA-Cu nanocomposite was introduced as an affordable catalyst for selective oxidation of alcohols into various aldehydes and ketones. The synthesized nanocomposite was characterized by applying essential analyses. The peaks that are appeared in FT-IR spectroscopy confirmed the production of the Fe3O4@PVA-Cu nanocomposite. In addition, EDX analysis proved the presence of oxygen, carbon, iron, and copper elements in the catalyst. Further, TGA analysis showed high thermal stability of the nanocomposite. VSM technique was applied to examine the magnetic property of the nanocomposite. The results demonstrated a high magnetic property in the catalyst, which enables easy separation of it from the reaction solution. TEM and SEM imaging showed the nanoscale size of the particles (~20 nm) in the catalyst. Additionally, XRD data was compatible with that of Fe3O4 nanoparticles. The application of the nanocomposite has been studied in the selective oxidation of alcohols in the presence of acetonitrile as solvent, and hydrogen peroxide as a supplementary oxidizing agent. This technique is remarkably facile and inexpensive. Further, the products showed high yields. In addition, the calculated TON and TOF values indicated the phenomenal efficiency of the nanocomposite in preparation of targeted products.
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Copper-Catalyzed Electrophilic Etherification of Arylboronic Esters with Isoxazolidines. Chem Asian J 2020; 15:1869-1872. [PMID: 32352205 DOI: 10.1002/asia.202000270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/29/2020] [Indexed: 11/10/2022]
Abstract
A copper-catalyzed electrophilic etherification of arylboronic esters is reported. Isoxazolidines are utilized as easily available and stable [RO]+ surrogates to give 1,3-amino aryl ethers. The O-selective arylation of isoxazolidines takes place without causing competitive N-arylation. In contrast to previously reported anionic conditions, our copper-catalyzed conditions are mild enough to achieve high functional group tolerance. Preliminary mechanistic studies and DFT calculations support that the reaction proceeds via a transmetalation/oxidative addition pathway, followed by a Lewis acid-promoted reductive elimination to induce the crucial O-selectivity.
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Synthesis and anticancer activity of bis(2-arylimidazo[1,2- a]pyridin-3-yl) selenides and diselenides: the copper-catalyzed tandem C-H selenation of 2-arylimidazo[1,2- a]pyridine with selenium. Beilstein J Org Chem 2020; 16:1075-1083. [PMID: 32550922 PMCID: PMC7277930 DOI: 10.3762/bjoc.16.94] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/04/2020] [Indexed: 11/23/2022] Open
Abstract
Most heteroaryl selenides and diselenides are biologically active, with some reported to act as antioxidants and show activities that are medicinally relevant; hence, the development of efficient methods for their synthesis is an important objective. Herein, a simple method for the synthesis of selenides and diselenides bearing imidazo[1,2-a]pyridine rings and their anticancer activity are described. The double C-H selenation of imidazo[1,2-a]pyridine with Se powder was catalyzed by CuI (10 mol %) ligated with 1,10-phenanthroline (10 mol %) at 130 °C under aerobic conditions. The selenides or diselenides were prepared almost selectively using selenium powder in an appropriate quantity under otherwise identical reaction conditions. The prepared selenides and diselenides bearing two imidazo[1,2-a]pyridine rings were all novel compounds. Among the prepared diselenides and selenides that exhibited cytotoxicity against cancer cells, bis[2-(4-methoxyphenyl)imidazo[1,2-a]pyridin-3-yl] diselenide showed an excellent anticancer activity and low cytotoxicity toward noncancer cells, suggesting that this diselenide is a potential lead compound for anticancer therapy.
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Copper-Promoted One-Pot Approach: Synthesis of Benzimidazoles. Molecules 2020; 25:molecules25081788. [PMID: 32295143 PMCID: PMC7221555 DOI: 10.3390/molecules25081788] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/06/2020] [Accepted: 04/09/2020] [Indexed: 01/31/2023] Open
Abstract
A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C-N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C-N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.
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Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons. Beilstein J Org Chem 2020; 16:502-508. [PMID: 32273910 PMCID: PMC7113556 DOI: 10.3762/bjoc.16.45] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/13/2020] [Indexed: 01/06/2023] Open
Abstract
A terminal alkyne is one of the most useful reactants for the synthesis of alkyne and alkene derivatives. Because an alkyne undergoes addition reaction at a C-C triple bond or cross-coupling at a terminal C-H bond. Combining those reaction patterns could realize a new reaction methodology to synthesize complex molecules including C-C multiple bonds. In this report, we found that the reaction of 3 equivalents of terminal alkyne 1 (aryl substituted alkyne) and an α-bromocarbonyl compound 2 (tertiary alkyl radical precursor) undergoes tandem alkyl radical addition/Sonogashira coupling to produce 1,3-enyne compound 3 possessing a quaternary carbon in the presence of a copper catalyst. Moreover, the reaction of α-bromocarbonyl compound 2 and an alkyne 4 possessing a carboxamide moiety undergoes tandem alkyl radical addition/C-H coupling to produce indolinone derivative 5.
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Cu(II)-Catalyzed Homocouplings of (Hetero)Arylboronic Acids with the Assistance of 2- O-Methyl-d-Glucopyranose. MOLECULES (BASEL, SWITZERLAND) 2019; 24:molecules24203678. [PMID: 31614791 PMCID: PMC6832226 DOI: 10.3390/molecules24203678] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/08/2019] [Accepted: 10/11/2019] [Indexed: 11/16/2022]
Abstract
This is the first report of a natural ligand improving the copper-catalyzed homocouplings of (hetero)arylboronic acids. Various important synthetic biaryl intermediates in organic synthesis could be assembled via this method. To gain insight into this reaction, in situ React IR technology was used to confirm the effectivity of this catalyst system. This protocol could provide important biaryl compounds in high yields within a short time.
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Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc. Beilstein J Org Chem 2018; 14:576-582. [PMID: 29623119 PMCID: PMC5852614 DOI: 10.3762/bjoc.14.44] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/19/2018] [Indexed: 11/23/2022] Open
Abstract
The catalytic asymmetric methylation of fluoroalkylated pyruvates is shown with dimethylzinc as a methylating reagent in the presence of a copper catalyst bearing a chiral phosphine ligand. This is the first catalytic asymmetric methylation to synthesize various α-fluoroalkylated tertiary alcohols with CF3, CF2H, CF2Br, and n-C n F2n+1 (n = 2, 3, 8) groups in good-to-high yields and enantioselectivities. Axial backbones and substituents on phosphorus atoms of chiral phosphine ligands critically influence the enantioselectivity. Moreover, the methylation of simple perfluoroalkylated ketones is found to be facilitated by only chiral phosphines without copper.
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Effect of Redox "Non-Innocent" Linker on the Catalytic Activity of Copper-Catecholate-Decorated Metal-Organic Frameworks. ACS APPLIED MATERIALS & INTERFACES 2018; 10:635-641. [PMID: 29278492 DOI: 10.1021/acsami.7b15326] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Two new UiO-68 type of Zr-MOFs featuring redox non-innocent catechol-based linkers of different redox activities have been synthesized through a de novo mixed-linker strategy. Metalation of the MOFs with Cu(II) precursors triggers the reduction of Cu(II) by the phenyl-catechol groups to Cu(I) with the concomitant formation of semiquinone radicals as evidenced by EPR and XPS characterization. The MOF-supported catalysts are selective toward the allylic oxidation of cyclohexene and it is found that the presence of in situ-generated Cu(I) species exhibits enhanced catalytic activity as compared to a similar MOF with Cu(II) metalated naphthalenyl-dihydroxy groups. This work unveils the importance of metal-support redox interactions in the catalytic activity of MOF-supported catalysts which are not easily accessible in traditional metal oxide supports.
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Copper-Catalyzed Alkoxycarbonylation of Alkanes with Alcohols. CHEMSUSCHEM 2017; 10:1341-1345. [PMID: 27897401 DOI: 10.1002/cssc.201601587] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 11/25/2016] [Indexed: 06/06/2023]
Abstract
Esters are important chemicals widely used in various areas, and alkoxycarbonylation represents one of the most powerful tools for their synthesis. In this communication, a new copper-catalyzed carbonylative procedure for the synthesis of aliphatic esters from cycloalkanes and alcohols was developed. Through direct activation of the Csp3 -H bond of alkanes and with alcohols as the nucleophiles, the desired esters were prepared in moderate-to-good yields. Paraformaldehyde could also be applied for in situ alcohol generation by radical trapping, and moderate yields of the corresponding esters could be produced. Notably, this is the first report on copper-catalyzed alkoxycarbonylation of alkanes.
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Facile Synthesis for Benzo-1,4-Oxazepine Derivatives by Tandem Transformation of C-N Coupling/C-H Carbonylation. Molecules 2016; 22:E53. [PMID: 28042841 PMCID: PMC6155786 DOI: 10.3390/molecules22010053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 12/22/2016] [Accepted: 12/28/2016] [Indexed: 11/16/2022] Open
Abstract
A tandem transformation of C-N coupling/C-H carbonylation has been developed for the synthesis of benzo-1,4-oxazepine pharmaceutically derivatives. Notably, this reaction was accomplished by various phenylamine with ally halides under carbon dioxide atmosphere employing 2-(2-dimethylamino-vinyl)-1H-inden-1-olcatalyzed. Furthermore, under the optimized conditions, various benzo-1,4-oxazepine derivatives were obtained in good yields. Finally, a plausible CuI/CuIII mechanism of C-N coupling/C-H carbonylation transformation was proposed.
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Copper-catalyzed asymmetric sp 3 C-H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst. Beilstein J Org Chem 2016; 12:2636-2643. [PMID: 28144334 PMCID: PMC5238558 DOI: 10.3762/bjoc.12.260] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/17/2016] [Indexed: 12/14/2022] Open
Abstract
This report describes a highly enantioselective oxidative sp3 C-H arylation of N-aryltetrahydroisoquinolines (THIQs) through a dual catalysis platform. The combination of the photoredox catalyst, [Ir(ppy)2(dtbbpy)]PF6, and chiral copper catalysts provide a mild and highly effective sp3 C-H asymmetric arylation of THIQs.
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Copper-catalyzed [3 + 2] cycloaddition of (phenylethynyl)di-p-tolylstibane with organic azides. Beilstein J Org Chem 2016; 12:1309-13. [PMID: 27559379 PMCID: PMC4979910 DOI: 10.3762/bjoc.12.123] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 06/03/2016] [Indexed: 11/23/2022] Open
Abstract
Trisubstituted 5-stibano-1H-1,2,3-triazoles were synthesized in moderate to excellent yields by the Cu-catalyzed [3 + 2] cycloaddition of a ethynylstibane with organic azides in the presence of CuBr (5 mol %) under aerobic conditions. The reaction of 5-stibanotriazole with HCl, I2, and NOBF4 afforded 1-benzyl-4-phenyltriazole, 1-benzyl-5-iodo-4-phenyltriazole, and a pentavalent organoantimony compound, respectively.
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A concise and efficient synthesis of benzimidazo[1,2-c]quinazolines through CuI-catalyzed intramolecular N-arylations. Beilstein J Org Chem 2015; 11:2365-9. [PMID: 26734086 PMCID: PMC4685915 DOI: 10.3762/bjoc.11.258] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 11/16/2015] [Indexed: 11/23/2022] Open
Abstract
A series of functionalized benzimidazo[1,2-c]quinazoline derivatives was obtained in excellent yields under mild conditions through a CuI-catalyzed Ullmann N-arylation starting from easily available starting materials.
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