A new route for the synthesis of 1,3,4-trisubstituted pyrazolo[4,3-c]quinolines via a multicomponent reaction

Colorimetric detection of fluoride and mercury (II) ions using isatin Schiff base skeleton bearing pyridine-2-carboxamidine moiety: Experimental and theoretical studies

An isatin-Schiff base ligand (ISS) bearing a pyridine-2-carboxamidine moiety was synthesized through a facile and convenient method for the highly selective colorimetric detection of Hg+2 and F- ions. The sensing ability of the synthesized ISS sensor toward Hg+2 and F- was established using colorimetric and UV-visible techniques. The developed sensor showed excellent selectivity in the presence of other competing ions for Hg+2 and F-, with a color change from yellow to red. The limits of the detection for sensing Hg+2 and F- were calculated to be 2.9 ×10-6 M and 1.4 ×10-5 M, respectively. Job's plot based on spectroscopic data revealed a 1:1 binding stoichiometry between ISS and Hg+2 or F- ion. Furthermore, the binding mechanism, optimized structures and electronic properties of ISS, ISS-F- adduct and ISS-Hg+2 complex were investigated using density functional theory (DFT) calculations. DFT results indicated a decrease of the HOMO-LUMO energy gap for ISS upon interaction with the F- and Hg+2 species which were in good agreement with the experimental outcomes.

Engaging Isatins in Multicomponent Reactions (MCRs) - Easy Access to Structural Diversity

Multicomponent reactions (MCRs) are a valuable tool in diversity-oriented synthesis. Its application to privileged structures is gaining relevance in the fields of organic and medicinal chemistry. Isatin, due to its unique reactivity, can undergo different MCRs, affording multiple interesting scaffolds, namely oxindole-derivatives (including spirooxindoles, bis-oxindoles and 3,3-disubstituted oxindoles) and even, under certain conditions, ring-opening reactions occur that leads to other heterocyclic compounds. Over the past few years, new methodologies have been described for the application of this important and easily available starting material in MCRs. In this review, we explore these novelties, displaying them according to the structure of the final products obtained.

Ring expansion and ring opening of 3-halooxindoles with N-alkoxycarbonyl-O-tosylhydroxylamines for divergent access to 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas

The reaction of N-alkoxycarbonyl-O-tosylhydroxylamines with indol-2-ones in situ generated from 3-halooxindoles has been developed for divergently accessing 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas in good to excellent yields.

Crystal Structure and Computational Study on Methyl-3-Aminothiophene-2-Carboxylate

Methyl-3-aminothiophene-2-carboxylate (matc) is a key intermediate in organic synthesis, medicine, dyes, and pesticides. Single crystal X-ray diffraction analysis reveals that matc crystallizes in the monoclinic crystal system P21/c space group. Three matc molecules in the symmetric unit are crystallographically different and further linked through the N–H⋯O and N–H⋯N hydrogen bond interactions along with weak C–H⋯S and C–H⋯Cg interactions, which is verified by the three-dimensional Hirshfeld surface, two-dimensional fingerprint plot, and reduced density gradient (RDG) analysis. The interaction energies within crystal packing are visualized through dispersion, electrostatic, and total energies using three-dimensional energy-framework analyses. The dispersion energy dominates in crystal packing. To better understand the properties of matc, electrostatic potential (ESP) and frontier molecular orbitals (FMO) were also calculated and discussed. Experimental and calculation results suggested that amino and carboxyl groups can participate in various inter- and intra-interactions.

Organocatalyzed Synthesis of Functionalized Quinolines

As one of the most widely investigated compound skeleton, quinolines possess important medicinal and biological activities. As such, a great number of literatures, including reviews, have reported various methodologies to construct quinolines. Recently, organocatalyzed reactions have attracted the attention of organic chemists due to its being "green" because the reactions avoid the use of toxic metals. In this review, various distinctive contributions are surveyed with specific emphasis on organocatalyzed reactions for quinoline core constructions.

An efficient cascade synthesis of substituted 6,9-dihydro-1H-pyrazolo[3,4-f]quinoline- 8-carbonitriles

The synthesis of pyrazolo[3,4-f]quinoline-8-carbonitriles 4a–h and 6a–k involves the reaction of an aromatic aldehyde, 1H-indazol-6-amine and 3-(1H-indol-3-yl)-3-oxopropanenitrile or 3-oxo-3-arylpropanenitrile in ethanol under mild conditions.

Simple access to spirooxadiazole compounds containing a quinoxaline moiety using a nitrile imine intermediate generated in situ

A convenient method for the synthesis of spiro[indeno[1,2-

Synthesis of spiro[pyrazole-4,8′-pyrazolo [3,4-f]quinolin]-5(1H)-ones by the reaction of aldehydes with 1H-indazol-6-amine and 1H-pyrazol-5(4H)-one

A four-component reaction including two equivalents of aldehyde, 1

Metal-free domino one-pot protocols for quinoline synthesis

Metal-free domino one-pot protocols for quinoline synthesis have been reviewed.