Synthesis of Quinolines and Pyrido[3,2-g or 2,3-g]quinolines Catalyzed by Heterogeneous Propylphosphonium Tetrachloroindate Ionic Liquid

Triazine diphosphonium tetrachloroferrate ionic liquid immobilized on functionalized halloysite nanotubes as an efficient and reusable catalyst for the synthesis of mono-, bis- and tris-benzothiazoles

Aminopropyl-1,3,5-triazine-2,4-diphosphonium tetrachloroferrate immobilized on halloysite nanotubes [(APTDP)(FeCl4)2@HNT] was prepared and fully characterized using different techniques such as FT-IR, thermogravimetric analysis (TGA), SEM/EDX, elemental mapping, TEM, ICP-OES, and elemental analysis (EA). This nanocatalyst was found to be highly effective for synthesis of various benzothiazole derivatives in excellent yields under solvent-free conditions. Furthermore, bis- and tris-benzothiazoles were smoothly synthesized from dinitrile and trinitrile in the presence of this catalytic system. High yields and purity, easy work up procedure, high catalytic activity (high TON and TOF) and easy recovery and reusability of the catalyst make this method a useful and important addition to the present methodologies for preparation of these vital heterocyclic compounds.

Diphenhydramine Hydrochloride-CuCl as a New Catalyst for the Synthesis of Tetrahydrocinnolin-5(1H)-ones

The current study deals with the synthesis and characterization of a novel catalyst made from diphenhydramine hydrochloride and CuCl ([HDPH]Cl-CuCl). The prepared catalyst was thoroughly characterized using various techniques, such as ¹H NMR, Fourier transform-infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis and derivative thermogravimetry. More importantly, the observed hydrogen bond between the components was proven experimentally. The activity of this catalyst was checked in the preparation of some new derivatives of tetrahydrocinnolin-5(1H)-ones via a multicomponent reaction between dimedone, aromatic aldehydes, and aryl/alkyl hydrazines in ethanol as a green solvent. Also, for the first time, this new homogeneous catalytic system was effectively used for the preparation of unsymmetric tetrahydrocinnolin-5(1H)-one derivatives as well as mono- and bis-tetrahydrocinnolin-5(1H)-ones from two different aryl aldehydes and dialdehydes, respectively. The effectiveness of this catalyst was further confirmed by the preparation of compounds containing both tetrahydrocinnolin-5(1H)-one and benzimidazole moieties from dialdehydes. The one-pot operation, mild conditions, rapid reaction, and high atom economy, along with the recyclability and reusability of the catalyst, are other notable features of this approach.

3-(Propylthio)propane-1-sulfonic acid immobilized on functionalized magnetic nanoparticles as an efficient catalyst for one-pot synthesis of dihydrotetrazolo[1,5-a]pyrimidine and tetrahydrotetrazolo[5,1-b]quinazolinone derivatives

An efficient and reusable catalyst, which is 3-(propylthio)propane-1-sulfonic acid immobillized on functionalized magnetic nanoparticles [PTPSA@SiO2-Fe3O4], has been synthesized. For the first time, it is highlighted under solvent-free conditions for the catalytic activity in multicomponent synthesis of dihydrotetrazolo[1,5-a]pyrimidines, dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylates and tetrahydrotetrazolo[5,1-b]quinazolinones. The structure of the catalyst was well confirmed by characterization techniques, such as FT-IR, TGA, SEM-EDX, elemental mapping, TEM, VSM and elemental analysis. Besides, this unique catalyst was found to be effectual up to six cycles, which made it spotlighted. Recyclability of catalyst, excellent yield of the products, short reaction time and clean reaction profile are the advantages of the present protocol.

Advances in polymer based Friedlander quinoline synthesis

Nitrogen containing heterocyclic compounds has acquired their remarkable and distinct place in the wide area of organic synthesis due to the broad range of applications. Among them, quinoline motifs have attracted researchers in the synthetic chemistry because of its presence in the large number of pharmacologically active compounds. Different methods for synthesis of quinoline derivatives are reported, among them the Friedlander synthesis have provided comparatively more efficient approach. Many of the reported conventional Friedlander methodologies have some problems such as difficult product isolation procedures, poor yields and use of expensive catalysts, etc. Recently, polymer or solid supported synthetic approaches have attracted the attention of researchers because of their easy execution, greater selectivity, increased product yields, simple work-up procedures, recoverability and reusability of the catalysts. In consideration with the advantages of polymer supported synthetic strategies, the proposed review covers the role of polymers in the Friedlander synthesis; which may use polymers of organic, inorganic or hybrid in nature and of nanolevel as well.

Synthetic and medicinal perspective of quinolines as antiviral agents

In current scenario, various heterocycles have come up exhibiting crucial role in various medicinal agents which are valuable for mankind. Out of diverse range of heterocycle, quinoline scaffold have been proved to play an important role in broad range of biological activities. Several drug molecules bearing a quinoline molecule with useful anticancer, antibacterial activities etc have been marketed such as chloroquine, saquinavir etc. Owing to their broad spectrum biological role, various synthetic strategies such as Skraup reaction, Combes reaction etc. has been developed by the researchers all over the world. But still the synthetic methods are associated with various limitations as formation of side products, use of expensive metal catalysts. Thus, several efforts to develop an efficient and cost effective synthetic protocol are still carried out till date. Moreover, quinoline scaffold displays remarkable antiviral activity. Therefore, in this review we have made an attempt to describe recent synthetic protocols developed by various research groups along with giving a complete explanation about the role of quinoline derivatives as antiviral agent. Quinoline derivatives were found potent against various strains of viruses like zika virus, enterovirus, herpes virus, human immunodeficiency virus, ebola virus, hepatitis C virus, SARS virus and MERS virus etc.

Triazine bis(pyridinium) hydrogen sulfate ionic liquid immobillized on functionalized halloysite nanotubes as an efficient catalyst for one-pot synthesis of naphthopyranopyrimidines

1,1′-(6-(Propyl amino)-1,3,5-triazine-2,4-diyl)bis(pyridinium) hydrogen sulfate immobillized on halloysite nanotubes [(PATDBP)(HSO₄)₂@HNT] as a solid acid nanocatalyst was successfully synthesized and characterized by various analysis techniques such as FT-IR, TGA, SEM/EDX, elemental mapping, TEM and elemental analysis. This catalyst was found to be highly efficient for the convenient synthesis of naphthopyranopyrimidine derivatives through a one-pot three-component reaction of β-naphthol, aldehydes and N,N-dimethylbarbituric acid in excellent yields under solvent-free conditions. Furthermore, the catalyst could be recovered and reused five times without any notable loss of its activity.

A novel method for synthesis of naphthopyranopyrimidines, using [(PATDBP)(HSO₄)₂@HNT] as a green and reusable catalyst is reported.

DFT investigation on the mechanisms of Csp3–H functionalization of glycine derivatives induced by radical cation salt

The mechanism of Csp³–H functionalization between ethyl 2-(p-tolylamino)acetate and phenylethylene initiated by tris(4-bromophenyl)aminium hexachloroantimonate was elaborated based on DFT calculations.