Resorcinarene supramolecular organocatalyst for functionalized 1-tetralone synthesis in aqueous medium

An efficient, straightforward and environmentally benign process has been developed for the synthesis of fluorenone and 1-tetralone derivatives using cyclic 1,3-dione, malononitrile and dialkylacetylenedicarboxylate as starting materials in aqueous medium. The reaction is favoured in presence of resorcin[4]arene which is effective as a reusable organocatalyst. The catalyst has been easily synthesized and characterized by ¹H, ¹³C NMR, IR, XRD and HRMS analyses. Resorcin[4]arene afforded the resulted products in a shorter time and in good yields. The recyclability of the catalyst was established up to 6th cycle by FT-IR and SEM images.     

New aqua rhenium oxocomplex; synthesis,characterization, thermal studies,DFT calculations and catalytic oxidations

The aqua rhenium oxocomplex [ReO(OH)(H₂O)₄]^2? (1) has been prepared and characterized by spectroscopy, thermogravimetry, and elemental analysis and its reactivity towards triphenylphosphine has been evaluated. Complex (1) acts as a catalyst precursor in the presence of molecular oxygen for the oxidation of PPh₃ to OPPh₃. This proceeds through complex intermediates like [Re(PPh₃)_n]³⁺ (2), and [ReO(PPh₃)_n]³⁺ (3). The newly prepared complex (1) was also employed as catalyst for catalytic oxidation of cyclohexane. The geometry of [ReO(OH)(H₂O)₄]^2? has also been optimized in the singlet state by the DFT method with B3LYP level of theory.     

Green synthesis of 3,4-dihydropyrimidinones using nano Fe3O4@meglumine sulfonic acid as a new efficient solid acid catalyst under microwave irradiation

Design, synthesis and characterization of nano Fe₃O₄@meglumine sulfonic acid as a new solid acid catalyst for the simple and green one pot multicomponent synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones was studied. New solid acid catalyst was prepared through a clean and simple protocol and characterized using FTIR, VSM, TGA, SEM, elemental analysis (CHN) and XRD techniques. Heterogenization of homogeneous catalyst as a green approach is a useful method for enhancing the efficiency of catalyst. Presented study was a new method for attachment of homogeneous highly soluble catalyst (meglumine sulfate) to the magnetite nanoparticle surfaces for preparing a heterogeneous and effective catalyst. Obtained heterogeneous and reusable solid acid catalyst has high performance in the synthesis of Biginelli compounds. The reaction was performed under microwave irradiation as a rapid and green condition. Easy work up as well as excellent yield (90–98%) of products in short reaction times (40–200 s) and reusable catalyst are the main advantages of presented procedure. Reaction products were characterized in details using physical and chemical techniques such as melting point, ¹H NMR, ¹³C NMR and FTIR.     

Banana pulp extract mediated synthesis of Cu2O nanoparticles: An efficient heterogeneous catalyst for the ipso-hydroxylation of arylboronic acids

A green and facile novel procedure has been developed for the synthesis of Cu₂O nanoparticles within a very short reaction time using banana pulp extract as a reducing agent. The synthesized nanoparticles are well characterized by SEM (Scanning Electron Microscope), TEM (Transmission Electron Microscope) and powder XRD (X-ray Diffraction) methods. An environmental benign and highly efficient protocol for the ipso-hydroxylation of aryl and hetero arylboronic acids using bio-fabricated Cu₂O nanoparticles as a catalyst and aqueous H₂O₂ as an oxidant has also been developed. The main advantages of this protocol are the base free reaction condition, reusable and heterogeneous catalytic system, and short reaction time with excellent yields.     

Co(II) anchored glutaraldehyde crosslinked magnetic chitosan nanoparticles (MCS) for synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles

A simple, highly efficient and green synthesis of 2,4,5‐trisubsituted and 1,2,4,5‐tetrasubstituted imidazoles was developed using a novel MCS‐GT@Co(II) magnetically recoverable and recyclable catalyst under refluxing conditions with ethanol as a solvent. The catalyst was prepared by immobilization of chitosan onto Fe₃O₄ using glutaraldehyde as crosslinker followed by Co(II) ion immobilization via cobalt acetate. The catalyst was characterized using various techniques. For organic products determination, ¹H NMR, ¹³C NMR and Fourier transform infrared spectroscopies were used. The reaction was also tried with individual components of the catalyst, but the synergistic effect of the components in the prepared catalyst showed the highest yield and shortest reaction time.     

Modified palladium-catalyzed regioselective ortho-arylation of sp C-H bond substrates with a low catalyst loading

A novel and generally applicable system for ortho-arylation of a broad range of sp² C-H bond substrates such as arylated benzoxazoles, acylated anilines, and pyridines has been developed. The arylation was performed in trifluoroacetic acid (TFA) under air by using PdCl₂ as the catalyst with a low catalyst loading of 1 mol %. And it was found for the first time that the addition of weak base K₃PO₄ to the acidic solvent could remarkably enhance the reaction rate. The arylated products were isolated in moderate to good yields with high regioselectivity for the substrates containing a meta-substituent. This arylation is tolerant with various functional groups such as CH₃, CH₃O, CH₃CO, Br, and Cl.     

Fe3O4 Nanoparticles as an Efficient and Magnetically Recoverable Catalyst for the Synthesis of α,β-Unsaturated Heterocyclic and Cyclic Ketones under Solvent-Free Conditions

An efficient and green procedure has been developed for the synthesis of monoarylidenes of cyclic and heterocyclic ketones. The reaction was carried out under solvent-free conditions in the presence of a catalytic amount of nanosized magnetite (Fe₃O₄). The catalyst was easily removed by using an external magnet. The structures of the products were deduced from their ¹H NMR, ¹³C NMR, and infrared spectroscopy and mass spectrometry.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications^® for the following free supplemental resource(s): Full experimental and spectral details.]     

Preparation of 1,3-dienyl organotrifluoroborates and their Diels-Alder/cross-coupling reactions

2-BF₃-substituted 1,3-butadienes with potassium and tetrabutyl ammonium counterions have been prepared in gram quantities from chloroprene via a simple synthetic procedure. The potassium salt of this new main group element substituted diene has been characterized by ¹H, ¹³C, ¹¹B, and ¹⁹F NMR and the tetra n-butyl ammonium salt was also characterized by X-ray crystallography. Diels-Alder reactions of these dienes with dienophiles such as ethyl acrylate, methyl vinyl ketone, and N-phenylmaleimide are reported as well as subsequent Pd-catalyzed cross-coupling reactions of those Diels-Alder adducts. 4-Phenyl-2-BF₃-substituted 1,3-diene was prepared by magnesium-halogen exchange from the corresponding 2-bromo and iodo dienes. The 4-phenyl-2-bromo-1,3-butadiene was also characterized by X-ray crystallography. 4-Phenyl-2-BF₃-1,3-butadiene was used in Diels-Alder/cross-coupling reactions and the product of a Diels-Alder reaction with N-phenylmaleimide followed by cross-coupling with 4-bromo-benzonitrile was also characterized by X-ray crystallography.     

Peroxidative bromination and oxygenation of organic compounds: Synthesis, X-ray crystal structure and catalytic implications of mononuclear and binuclear oxovanadium(V) complexes containing Schiffbase ligands

Treatment of of (R,R)-N,N-salicylidene cyclohexane 1,2-diamine(H₂L¹) in methanol with aqueous NH₄VO₃ solution in perchloric acid medium affords the mononuclear oxovanadium(V) complex [VOL¹(MeOH)]·ClO₄ (1) as deep blue solid while the treatment of same solution of (R,R)-N,N-salicylidene cyclohexane 1,2-diamine(H₂L¹) with aqueous solution of VOSO₄ leads to the formation of di-(μ-oxo) bridged vanadium(V) complex [VO₂L²]₂ (2) as green solid where HL² = (R,R)-N-salicylidene cyclohexane 1,2-diamine. The ligand HL² is generated in situ by the hydrolysis of one of the imine bonds of HL¹ ligand during the course of formation of complex [VO₂L²]₂ (2). Both the compounds have been characterized by single crystal X-ray diffraction as well as spectroscopic methods. Compounds 1 and 2 are to act as catalyst for the catalytic bromide oxidation and C-H bond oxidation in presence of hydrogen peroxide. The representative substrates 2,4-dimethoxy benzoic acid and para-hydroxy benzoic acids are brominated in presence of H₂O₂ and KBr in acid medium using the above compounds as catalyst. The complexes are also used as catalyst for C-H bond activation of the representative hydrocarbons toluene, ethylbenzene and cyclohexane where hydrogen peroxide acts as terminal oxidant. The yield percentage and turnover number are also quite good for the above catalytic reaction. The oxidized products of hydrocarbons have been characterized by GC Analysis while the brominated products have been characterized by ¹H NMR spectroscopic studies.     

H_6P_2W_（18）O_（62）á18H_2O： A green and reusable catalyst for one-pot synthesis of pyrano[4,3-b]pyrans in water

A convenient,effcient and environmentally benign procedure has been developed for the synthesis of pyrano[4,3-b]pyran derivatives via a one-pot,three-component reaction of 4-hydroxy-6-methylpyran-2-one,aldehydes and malononitrile in water using H6P2W18O62á18H2O as catalyst.Reusability of the catalyst and reaction media,short reaction times and easy isolation of products are some added advantages of the present methodology.     

A simple conversion of azlactones into indenones via H3PW12O40/Al2O3 catalyzed intramolecular Friedel-Crafts reaction

A rapid and simple procedure for the synthesis of the indenone derivatives, N-(1-oxo-1H-inden-2-yl)benzamides, via intramolecular Friedel-Crafts (IFC) reaction of (Z)-4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) catalyzed by H₃PW₁₂O₄₀ supported on neutral alumina under microwave irradiation has been developed. The reaction is straightforward and allows easy isolation of the product. The catalyst could be re-used up to four times after simple filtration.     

The catalysis, synthesis and characterization of ferrocenylchalcone

Eight kinds of ferrocenylchalcone derivatives were synthesized by the reaction of acetylferrocene and aromatic aldehyde using solid as catalyst in the experiment. The influrence of the catalysts, the raw material molar ratios and reaction times on the yield of ferrocenylchalcone derivatives are discussed. The optimal conditions of synthesis reaction have been selected: the catalyst was KF/Al₂O₃, n(acetyl ferrocene)/n(formal dehyde) = 1:1.2. The structures of the products were characterized by melting point test, IR, ¹HNMR, ¹³CNMR and elemental analysis.     

Keplerate巨型纳米多孔聚氧钼酸盐作为可重复使用催化剂用于合成1,2,4,5-四取代咪唑(英文)

The Keplerate‐type giant nanoporous isopolyoxomolybdate (NH4)42[MoVI72MoV60O372‐(CH3COO)30(H2O)72], denoted {Mo132}, has been used as a catalyst for the synthesis of1,2,4,5‐tetrasubstituted imidazoles by the one‐pot, four‐component thermal reaction of benzil with aromatic aldehydes, primary amines, and ammonium acetate under solvent‐free conditions. The catalyst was prepared according to a previously published literature procedure using inexpensive and readily available starting materials, and subsequently characterized by FT‐IR, UV and X‐ray diffraction spectroscopy, as well as microanalysis. The results showed that {Mo132} exhibited high catalytic activity towards the synthesis of 1,2,4,5‐tetrasubstituted imidazoles, with the desired products being formed in good to high yields. Furthermore, the catalyst was recyclable and could be reused at least three times without any discernible loss in its catalytic activity. Overall, this new catalytic method for the synthesis of 1,2,4,5‐tetrasubstituted imidazoles provides rapid access to the desired compounds following a simple work‐up procedure, and avoids the use of harmful organic solvents. This method therefore represents a significant improvement over the methods currently available for the synthesis of tetrasubstituted imidazoles.     

Presence or absence of a nonlinear effect according to the asymmetric catalyst preparation in the alkylation of benzaldehyde

The addition of Et₂Zn on benzaldehyde in the presence of a stoichiometric amount of Ti(Oi-Pr)₄ catalysed by (1R,2R)-bis(trifluoromethanesulfonamido)-cyclohexane 1a has been revisited. A nonlinear effect was present or absent, depending on the catalyst preparation. An asymmetric amplification has been observed when Ti(Oi-Pr)₄ was added to 1a followed by Et₂Zn and then benzaldehyde (Ohno procedure). In the alternate procedure (Walsh), where Et₂Zn and 1a were premixed, there is linearity. Mechanistic implications are discussed.     

Vanadium(IV) tetrachloride catalyzed oxidative homo-coupling of aryl lithium under mild reaction condition

A novel efficient strategy to prepare symmetrical diaryls via VCl₄ catalyzed homo-coupling of aryl lithium has been developed. In which, organometallic reagent n-BuLi was applied as the strong base to form aryl lithium from aryl halogen in anhydrous diethyl ether, then it was followed by the addition of catalytic amount of VCl₄ at room temperature to afford diaryls. All the diaryls have been characterized by ¹H and ¹³C NMR.     

One-Pot,Facile, Highly Efficient,and Green Synthesis of Acridinedione Derivatives Using Vitamin B1

An efficient methodology for the synthesis of acridinedione derivatives 4a–o has been achieved by one-pot, multicomponent condensation of dimedone 1, various amines 2a–d, and substitute aromatic aldehydes 3a–k, in the presence of the easily available, inexpensive, and nontoxic catalyst vitamin B₁ (VB₁) as a versatile biodegradable. Synthesis of acridine-type compounds was performed in good yields in water as green solvent. Its high-yield efficiency; clean, ecofriendly, simple workup procedure; and easy purification are regarded as the main advantages of this method besides its green solvent. The synthesized compounds are characterized using spectroscopic analyses (FTIR, ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry) techniques.     

Highly stable magnetically separable copper nanocatalyst as an efficient catalyst for C(sp2)–C(sp) and C(sp2)–C(sp2) cross‐coupling reactions

A copper catalyst has been explored as an efficient and recyclable catalyst to effect Sonogashira and Suzuki cross‐coupling reactions. After modification of 2‐(((piperazin‐1‐ylmethyl)imino)methyl)phenol (PP) on the surface of amorphous silica‐coated iron oxide (Fe₃O₄@SiO₂@Cl) magnetic core–shell nanocomposite, copper(II) chloride was employed to synthesize the Fe₃O₄@SiO₂@PP‐Cu catalyst, affording a copper loading of 1.52 mmol g⁻¹. High yield, low reaction times, non‐toxicity and recyclability of the catalyst are the main merits of this protocol. The catalyst was characterized using Fourier transform infrared, X‐ray photoelectron, energy‐dispersive X‐ray and inductively coupled plasma optical emission spectroscopies, X‐ray diffraction, scanning and transmission electron microscopies, and vibrating sample magnetometry.     

Asymmetric reduction of aromatic ketones in pyridinium-based ionic liquids

The asymmetric reduction of aromatic ketones has been studied in pyridinium-based room temperature ionic liquids, namely, 1-ethyl-pyridinium tetrafluoroborate, [EtPy]⁺[BF₄]⁻ and 1-ethyl-pyridinium trifluoroacetate, [EtPy]⁺[CF₃COO]⁻. Ionic liquids were employed as solvents, while (R)-BINOL and (R)-BINOL-Br were used as chiral promoters. The effects of solvent, reaction time, temperature, catalyst loading and substituents were investigated. The reduction could be easily carried out in both ionic liquids with lower catalyst loading. 1-Ethyl-pyridinium tetrafluoroborate was recycled and reused efficiently.     

1-D copper(I) coordination polymer based on bidentate 1,3-dithioether ligand: Novel catalyst for azide-alkyne-cycloaddition (AAC) reaction

A novel 1,3-bis(4-fluorophenylthio)-propane ligand based CuI 1-D polymeric coordination complex having formula ([(CuI)₂{ArS(CH₂)₃SAr}₂]_n, Ar?=?4-F-C₆H₄) has been synthesized and characterized by ¹H NMR, ¹³C NMR and single crystal XRD techniques. This complex has been employed for the first time as suitable catalyst for base-free one-pot three-component regioselective azide-alkyne cycloaddition (AAC) reaction. A novel 1,2,3-triazole compound with sulfur functionalized pendant arms has also been prepared using our catalytic system in a multicomponent manner via one-pot two-step reaction.     

Synthesis of isotactic copolymers of 4-methyl-1-pentene by living polymerization catalyzed by zirconium non-metallocene complexes

Amorphous isotactic poly(4-methyl-1-pentene) was synthesized from 4-methyl-1-pentene in the presence of the zirconium complex (η⁵-C₅Me₅)ZrMe[PhCH₂NC(Me)N-tert-Bu][B(C₆H₅)₄] as a catalyst of living polymerization and characterized. A number of linear isotactic copolymers of 4-methyl-1-pentene with 1-hexene and functionalized olefins, such as 5-(trialkylsiloxy)-1-pentene, were prepared under similar conditions. The feasibility of chemical modification of the functionalized copolymers to yield hydroxylated copolymers was studied. All the polymers obtained were characterized by means of the GPC, DSC, X-ray diffraction, and ¹³C and ¹H NMR techniques.