Nanosized MCM-41 supported protic ionic liquid as an efficient novel catalytic system for Friedlander synthesis of quinolines

Friedlӓnder's synthesis of quinolines as a pivotal step in the development of bioactive heterocyclic derivatives in the current era of medicinal chemistry

In the current scenario of medicinal chemistry, quinoline plays a pivotal role in the design of new heterocyclic compounds with several pharmacological properties, so the search for new synthetic methodologies and their application in drug discovery has been widely studied. So far, many procedures have been performed for the preparation of quinoline scaffolds, among which Friedländer quinoline synthesis plays an important role in obtaining these heterocycles. The Friedländer reaction involves condensation between 2-aminobenzaldehydes and keto-compounds. The quinoline nucleus, once obtained through the Friedländer synthesis, has been extensively modified so that these derivatives can exhibit a large number of biological activities such as anticancer, antimalarial, antimicrobial, antifungal, antituberculosis, and antileishmanial properties. In this work, the focus is on the applicability of the Friedländer reaction in the synthesis of various types of bioactive heterocyclic quinoline compounds, which to date has not been reported in the context of medicinal chemistry. The main part of this review selectively focuses on research from 2010 to date and will present highlights of the Friedländer quinoline synthesis procedures and findings to address biological and pharmacological activities.

A combined DFT and FT-IR study on the surface interactions in alumina supported ionic liquid [H-Pyr]+[HSO4]. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020;226:117545. [PMID: 31710889 DOI: 10.1016/j.saa.2019.117545]

The surface interactions in [H-Pyr]⁺[HSO₄]^-/γ-Al₂O₃ system (prepared by wetness impregnation method) are investigated theoretically and experimentally. For that purpose, atoms in molecules theory, natural bond orbital and natural charge population analyses in a combination with a vibrational spectroscopy (FT-IR) are used. It is established that a bond formation between the hydrogen sulfate anion and the alumina influences the IL-support interaction in a great extent. However, a support-cation and a cation-anion interaction in the immobilized [H-Pyr]⁺[HSO₄]^- present as well. A comparative analysis between the experimental and the calculated vibrational modes is carried out and a significant number of infrared bands are assigned. The results indicate a good correlation between the experimental and the theoretical IR frequencies. It is found that the aforementioned interactions affected the vibrational frequencies in the supported IL.

Recent Advances in Applications of Supported Ionic Liquids

:

The supported ionic liquids have shown immense potential for numerous applications in catalysis and separation science. In the present review, the remarkable contribution of supported ionic liquids has been highlighted. The main emphasis has been laid on describing the facile separation of gas from binary gas mixtures owing to the capability of selective transport of permeable gases across supported membranes and removal of environmentally hazard sulfur compounds from fuels. The catalytic action of supported ionic liquids has been discussed in other applications such as biodiesel (biofuel) synthesis by transesterification/esterification processes, waste CO2 fixation into advantageous cyclic carbonates, and various chemical transformations in organic green synthesis. This review enclosed a maximum of the published data of the last ten years and also recently accomplished work concerning applications in various research areas like separation sciences, chemical transformations in organic green synthesis, biofuel synthesis, waste CO2 fixation, and purification of fuels by desulfurization.

Potentiality of PARAFAC approaches for simultaneous determination of N-acetylcysteine and acetaminophen based on the second-order data obtained from differential pulse voltammetry

N-acetylcysteine (N-AC) has widespread application such as pharmaceutical drug and nutritional supplement. Its adverse effects are rash, urticaria, and itchiness and large doses of N-AC could potentially cause damage to the heart and lungs. Therefore, in this work, a sensitive voltammetric sensor based on a carbon paste electrode modified with silica nano particles (i.e. Mobil Composition of Matter (No. 41) modified with Boron Trifluoride or BF₃@MCM-41) with a combination of 4,4'-dihydroxybiphenyl (DHB) (BF₃@MCM-41/DHB/CPE) was designed for determination of N-AC. The electrochemical oxidation of N-AC was examined using various techniques such as cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV). Under the optimum conditions, some parameters such as electron transfer coefficient (α) and heterogeneous rate constant (k_s) were estimated for N-AC. Due to the use of N-AC for the treatment of acetaminophen (AC) overdose, the application of modified electrode was investigated for the simultaneous determination of N-AC and AC in blood serum and tablet samples. Since, the signals of these species overlap and due to the presence of interfering species in blood samples, the simultaneous determination of mentioned species is difficult or impossible. To overcome this challenge, parallel factor analysis (PARAFAC) was used for the analysis of the complex matrices to obtain the spectral profile of each component and interference. To achieve this goal, electrochemical second-order data were generated using a simple change in pulse height of differential pulse voltammetry. The results of the presently proposed strategy for the real samples analysis are similar to those obtained with HPLC. Thus, the proposed method has acceptable performance for simultaneous determination of the two species in real samples.

Ultrasonic-assisted synthesis of novel nanocomposite of poly(vinyl alcohol) and amino-modified MCM-41: A green adsorbent for Cd(II) removal

Amino-modified MCM-41/poly(vinyl alcohol) nanocomposite (M-MCM-41/PVOH NC) was developed for the adsorption of Cd(II) from aqueous media. M-MCM-41/PVOH NC was prepared through ultrasonic-assisted and simple blending procedure with economical and environmentally friendly polymer. The as-prepared adsorbent was characterized by FT-IR, TEM, FE-SEM and TGA. The contact time, solution pH and initial concentration of Cd(II) were found to affect the adsorption of Cd(II) from aqueous media. Kinetic studies were carried out and pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and intra-particle diffusion (IPD) reaction kinetic models were examined. The kinetic results revealed that the adsorption of Cd(II) onto M-MCM-41/PVOH NC followed PSO kinetic model and is a chemical adsorption. The equilibrium adsorption data were evaluated by different isotherms viz. Langmuir, Freundlich, and Dubinin Radushkevich (D-R) equations. The equilibrium data fitted better with the Langmuir isotherm and the maximum adsorption capacity of M-MCM-41/PVOH NC at 298K was calculated to be 46.73mgg^-1 for Cd(II) on a typical saturated monomolecular layer with a fixed number of localized adsorption sites.

Cu(ii) immobilized on Fe3O4@APTMS-DFX nanoparticles: an efficient catalyst for the synthesis of 5-substituted 1H-tetrazoles with cytotoxic activity

Cu(ii) immobilized on deferasirox loaded amine functionalized magnetic nanoparticles (Cu(ii)/Fe₃O₄@APTMS-DFX) as a novel magnetically recyclable heterogeneous catalyst is able to catalyze the [3 + 2] cycloaddition reactions of various organic nitriles with sodium azide. Using this method, a series of 5-substituted-1H-tetrazoles under mild conditions in DMSO were prepared. The reaction involves mild reaction conditions with efficient transformation capability. The developed catalyst could be easily separated by applying an external magnetic field. Furthermore, it could be recycled for 5 runs with negligible leaching of copper from the surface of the catalyst. The catalyst was characterized by various techniques such as FT-IR, TGA, VSM, SEM-EDX, and ICP-OES. Several derivatives of 1H-tetrazoles were prepared using this catalyst, and their structures were confirmed using different techniques. Then, the synthesized anthraquinones were evaluated for their cytotoxicity against several cell lines including MCF-7, MAD-MD-231, HT-29, HeLa, neuro-2a and L-929. The results obtained from the MTT assay revealed that the 6 derivatives exhibited a high level of cytotoxicity. In order to determine the cytotoxicity mechanism, 2 derivatives with the highest cytotoxic activity were selected, and an apoptosis assay was carried out by flow cytometry, which supported that apoptosis is the major mechanism.

Synthesis of magMCM-41 with rice husk silica as cadmium sorbent from aqueous solutions: parameters' optimization by response surface methodology

The magnetic mesoporous silica of magMCM-41 with large surface area (695 m² g^-1) and high magnetization (10.79 emu g^-1) was synthesized using extracted amorphous silica from rice husk. The synthesized materials were applied for adsorption of Cd(II) ions from aqueous solution in batch operation systems. A highly selective adsorbent was obtained by grafting 3-aminopropyltrimethoxysilane on the pores of the magMCM-41 in which the adsorption capacity of Cd(II) ions increased from 41.8 to 86 mg g^-1, under the same conditions. A total of 20 sets of experiments were planned by the central composite design under response surface methodology. The effects of three independent variables pH, initial Cd(II) ion concentration and sorbent dosage were investigated on the adsorption capacity (q_e) and removal efficiency (R) of cadmium. The best responses for Cd(II) adsorption capacity and removal efficiency were 493.21 mg g^-1 and 60.25%, respectively, which was achieved at pH of 5.05, sorbent dosage of 0.1 g L^-1 and Cd(II) concentration of 150 mg L^-1. Additionally, the obtained value for desirability was equal to 0.807. The theoretical isotherm models were applied to describe the adsorption process that the Langmuir model provides the best correlation of the equilibrium data. The kinetics study revealed that data from the experiments fitted well to the pseudo-second-order equation than the pseudo-first-order equation. The thermodynamic parameters revealed that the adsorption process strongly depended on temperature and indicated the exothermic behavior and spontaneous nature of the adsorption.

Introduction of a new ionic liquid solid acid based on clay as an efficient, recyclable and thermally stable catalyst for organic transformations

Ammonium hydrogen sulfate based ionic liquid immobilized on Na⁺–montmorillonite (AHS@MMT) was prepared via anchoring ammonium hydrogen sulfate propyltriethoxysilane onto sodium montmorillonite by covalent bonds.

Multi-component one-pot reaction of aldehyde, hydroxylamine and sodium azide catalyzed by Cu-MCM-41 nanoparticles: a novel method for the synthesis of 5-substituted 1H-tetrazole derivatives

A new method was developed for the synthesis of 5-substituted 1H-tetrazoles in the presence of copper modified MCM-41, as a heterogeneous and reusable nanostructured catalyst.

Friedländer annulation: scope and limitations of metal salt Lewis acid catalysts in selectivity control for the synthesis of functionalised quinolines

In(OTf)₃ is the most effective catalyst among metal halides, tetrafluoroborates, perchlorates, and triflates for Friedländer quinoline synthesis in 75–92% yields.

New pyridinium-based ionic liquid as an excellent solvent-catalyst system for the one-pot three-component synthesis of 2,3-disubstituted quinolines

The synthesis of a variety of 2,3-disubstituted quinolines has been achieved successfully via a one-pot three-component reaction of arylamines, arylaldehydes and aliphatic aldehydes in the presence of butylpyridinium tetrachloroindate(III), [bpy][InCl4], ionic liquid as a green catalyst and solvent. Mild conditions with excellent conversions, and simple product isolation procedure are noteworthy advantages of this method. The recyclability of the ionic liquid makes this protocol environmentally benign.

Copper modified spherical MCM-41 nano particles: an efficient catalyst for the three-component coupling of aldehydes, amines and alkynes in solvent-free conditions

Cu-MCM-41 nano particles have been shown to effectively catalyze the multi-component synthesis of propargylamines by the reaction of aldehydes, amines, and alkynes (A³ coupling) effectively at 100 °C under solvent-free conditions.

BF3/MCM-41 as nano structured solid acid catalyst for the synthesis of 3-iminoaryl-imidazo[1,2-a]pyridines

Multi-component reaction of various types of aldehydes, 2-aminopyridines and trimethylsilyl cyanide was carried out in the presence of MCM-41 supported boron trifluoride (BF₃/MCM-41) as a nanostructured solid acid catalyst for the synthesis of 3-iminoaryl-imidazo[1,2-a]pyridine derivatives.