First synthesis of novel 2,4-bis((E)-styryl)quinoline-3-carboxylate derivatives and their antitumor activity

Iron(III)-Catalyzed Carboannulations of Homopropargylic Alcohols: A One-Pot General Synthesis of 4-(2,2-Diarylvinyl)quinolines and 4-(2,2-Diarylvinyl)-2H-chromenes

A simple and efficient approach for the general synthesis of 4-(2,2-diarylvinyl)quinolines 5 and 4-(2,2-diarylvinyl)-2H-chromenes 6 has been developed using Fe(III)-catalyzed intramolecular annulations of homopropargyl substrates 1 and 2, respectively. The high yields (up to 98%) achieved using simple substrates, an environmentally benign low-cost catalyst, and less hazardous reaction conditions make the methodology inherently attractive.

Microwave and Cs+-assisted chemo selective reaction protocol for synthesizing 2-styryl quinoline biorelevant molecules

The reaction protocols and their continuous development to achieve the desired selectivity remain a primary target of organic chemistry, which is addressed here with the specific role of the cesium ion. The pharmacophore “2-styryl quinoline” was taken as a reference here because of the continuation of our work, where it was found fit as fusion inhibitors and anti-viral agents. The present protocol defines its importance for the synthesis of O-alkylated products. However, in most cases, N-alkylation proceeds because of nitrogen atoms’ more nucleophilic nature and electronic density. The cesium effect makes this possible because of the large cationic size and its affection for the oxygen atom. The plausible mechanism and its progression were demonstrated here with the help of density function theory calculation by analyzing the energy of intermediates. The protocol is also found suitable with microwave irradiation. Moreover, it gives the product a better yield in less reaction time. The present reaction protocol and its importance will address some of the crucial issues related to the synthesis of the complex molecule, and the present protocol will open up hope, where the selectivity and product yield would be a concern.

Conversion of 2-methyl-4-styrylquinolines into 2,4-distyrylquinolines: synthesis, and spectroscopic and structural characterization of five examples

Four new 2,4-distyrylquinolines and one 2-styryl-4-[2-(thiophen-2-yl)vinyl]quinoline have been synthesized using indium trichloride condensation reactions between aromatic aldehydes and the corresponding 2-methylquinolines, which were themselves prepared using Friedländer annulation reactions between mono- or diketones and (2-aminophenyl)chalcones: the products have all been fully characterized by spectroscopic and crystallographic methods. 2,4-Bis[(E)-styryl]quinoline, C₂₅H₁₉N, (IIa), and its dichloro analogue, 2-[(E)-2,4-dichlorostyryl]-4-[(E)-styryl]quinoline, C₂₅H₁₇Cl₂N, (IIb), exhibit different orientations of the 2-styryl unit relative to the quinoline nucleus. In each of the 3-benzoyl analogues {2-[(E)-4-bromostyryl]-4-[(E)-styryl]quinolin-3-yl}(phenyl)methanone, C₃₂H₂₂BrNO, (IIc), {2-[(E)-4-bromostyryl]-4-[(E)-4-chlorostyryl]quinolin-3-yl}(phenyl)methanone, C₃₂H₂₁BrClNO, (IId), and {2-[(E)-4-bromostyryl]-4-[(E)-2-(thiophen-2-yl)vinyl]quinolin-3-yl}(phenyl)methanone, C₃₀H₂₀BrNOS, (IIe), the orientation of the 2-styryl unit is similar to that in (IIa), but the orientation of the 4-arylvinyl units show considerable variation. The thiophene unit in (IIe) is disordered over two sets of atomic sites having occupancies of 0.926 (3) and 0.074 (3). There are no hydrogen bonds of any kind in the structure of (IIa), but in (IId), a single C-H...O hydrogen bond links the molecules into cyclic centrosymmetric R₂²(20) dimers. A combination of C-H...N and C-H...π hydrogen bonds links the molecules of (IIb) into a three-dimensional framework structure. A combination of three C-H...π hydrogen bonds links the molecules of (IIc) into sheets, and a combination of C-H...O and C-H...π hydrogen bonds forms sheets in (IIe). Comparisons are made with the structures of some related compounds.

A three-step pathway from (2-aminophenyl)chalcones to novel styrylquinoline-chalcone hybrids: synthesis and spectroscopic and structural characterization of three examples

Three new styrylquinoline-chalcone hybrids have been synthesized using a three-step pathway starting with Friedländer cyclocondensation between (2-aminophenyl)chalcones and acetone to give 2-methyl-4-styrylquinolines, followed by selective oxidation to the 2-formyl analogues, and finally Claisen-Schmidt condensation between the formyl intermediates and 1-acetylnaphthalene. All intermediates and the final products have been fully characterized by IR and ¹H/¹³C NMR spectroscopy, and by high-resolution mass spectrometry, and the three products have been characterized by single-crystal X-ray diffraction. The molecular conformations of (E)-3-{4-[(E)-2-phenylethenyl]quinolin-2-yl}-1-(naphthalen-1-yl)prop-2-en-1-one, C₃₀H₂₁NO, (IVa), and (E)-3-{4-[(E)-2-(4-fluorophenyl)ethenyl]quinolin-2-yl}-1-(naphthalen-1-yl)prop-2-en-1-one, C₃₀H₂₀FNO, (IVb), are very similar. In each compound, the molecules are linked into a three-dimensional array by hydrogen bonds, of the C-H...O and C-H...N types in (IVa), and of the C-H...O and C-H...π types in (IVb), and by two independent π-π stacking interactions. By contrast, the conformation of the chalcone unit in (E)-3-{4-[(E)-2-(2-chlorophenyl)ethenyl]quinolin-2-yl}-1-(naphthalen-1-yl)prop-2-en-1-one, C₃₀H₂₀ClNO, (IVc), differs from those in (IVa) and (IVb). There are only weak hydrogen bonds in the structure of (IVc), but a single rather weak π-π stacking interaction links the molecules into chains. Comparisons are made with some related structures.

Substituent-Controlled Structural, Supramolecular, and Cytotoxic Properties of a Series of 2-Styryl-8-nitro and 2-Styryl-8-hydroxy Quinolines

Styryl quinolines are biologically active compounds with properties largely depending on the substituents on the styryl and quinoline rings. The supramolecular aspects of this class of compounds are rarely explored. In this study, two new series of styryl quinoline derivatives, bearing -OH and -NO₂ groups at the eighthposition of the quinoline ring and -SCH₃, -OCH₃, and -Br groups on the styryl ring, have been developed, and their structural, supramolecular, and cytotoxic properties have been analyzed. Crystallographic analyses revealed the exciting substituent-dependent structural and supramolecular features of these compounds. In general, the 8 -OH substituted derivatives (SA series) exhibited a non-planar molecular geometry having larger dihedral angles (5.75-59.3°) between the planes of the aromatic rings. At the same time, the 8 -NO₂ substituted derivatives (SB series) exhibited a more or less planar molecular geometry, as revealed by the smaller dihedral angles (1.32-3.45°) between the aromatic rings. Multiple O-H···O, C-H···O, O-H···N, and π-π stacking interactions among the molecules lead to fascinating supramolecular architectures such as hydrogen-bonded triple helices, zig-zag 1D chains, π-π stacked infinite chains, and so forth in their crystal lattice. Hirshfeld surface analyses confirmed the existence of strong π-π stacking and other weak bonding interactions in these compounds. The preliminary cytotoxic properties of SA and SB series compounds were evaluated against the human cervical cancer cell lines (HeLa cells), which further highlighted the roles of functional substituents on the aromatic rings. The SA series compounds with the -OH substituent on the quinoline ring exhibited better cytotoxicity than the SB series compounds with a -NO₂ substituent. Similarly, the electron-withdrawing group -Br on the styryl ring enhanced the cytotoxicity in both series. The IC₅₀ values were 2.52-4.69 and 2.897-10.37 μM, respectively, for the SA and SB series compounds. Compound S3A having -OH and -Br groups on the quinoline and styryl ring, respectively, exhibited the best IC₅₀ value of 2.52 μM among all the compounds tested. These findings confirm the relevance of the hydroxyl group in the eighth position of quinoline. In short, the present study attempts to provide a systematic analysis of the effects of aromatic ring substituents on the structural, supramolecular, and cytotoxic properties of styryl quinolines for the first time.

Styrylquinolines Derivatives: SAR study and Synthetic Approaches

Abstract:

In the present-day scenario, heterocyclic derivatives have revealed the primary function of various medicinal agents precious for humanity. Out of a diverse range of heterocycles, Styrylquinolines scaffolds have been proved to play an essential role in a broad range of biological activities, includinganti-HIV-1, antimicrobial, anti-inflammatory, anti-Alzheimer activity with antiproliferative effects on tumor cell lines. Due to the immense pharmacological importance, distinct synthetic methods have been executed to attain new drug entities from Styrylquinolines. Various schemes for synthesizing Styrylquinolines derivatives like one-pot, ultrasound-promoted heterogeneous acid-catalysed, microwave-assisted, solvent-free, and green synthesis were discussed in the present review. Some products of Styrylquinolines are in clinical trials, and patents are also granted for the novel synthesis of Styrylquinolines. According to the structure-activity relationship, replacement at the R-7 and R-8 positions is required for various activities. In this review, recent synthetic approaches in the medicinal chemistry of Styrylquinolines and potent Styrylquinolines derivatives based on structural activity relationships (SAR) are outlined. Moreover, their primary methods and modifications are also discussed.

A simple and convenient synthesis of 3-salicyloylquinoline-4-carboxylic esters from chromone and isatin

A simple and convenient synthesis of 3-salicyloylquinoline-4-carboxylic esters has been developed through AlCl₃-catalyzed reaction of Baylis–Hillman adducts from chromones and isatin-derivatives.