Cancer preventive agents, Part 2: Synthesis and evaluation of 2-phenyl-4-quinolone and 9-oxo-9,10-dihydroacridine derivatives as novel antitumor promoters

Reagent-Free Intramolecular Hydroamination of Ynone-Tethered Aryl-sulfonamide: Synthesis of Polysubstituted 4-Quinolones

An efficient reagent-free method for the synthesis of polysubstituted 4-quinolone from 2-substituted alkynoyl aryl-sulfonamide was developed. This developed method tolerates various functional groups and gives the corresponding 4-quinolones. We have successfully extended this method to the synthesis of dihydro-4-quinolones from 2-alkenoyl aryl sulfonamide derivatives.

Organocatalytic Csp2-O Amination of Quinolin-4(1H)-ones with 3-Alkynyl-3-hydroxyisoindolinones

The Brønsted acid catalytic Csp2-O amination of quinolin-4(1H)-ones with 3-alkynyl-3-hydroxyisoindolinones as animation reagents has been developed. The cascade dehydration/conjugate addition/intramolecular annulation/ring-opening reaction proceeded smoothly to afford a broad scope of aminated products with high efficiency. Furthermore, the enantioselective construction of Csp2-N atropisomers was also investigated in the presence of chiral phosphoric acid. Importantly, this work not only realized the organocatalytic Csp2-O amination of quinolin-4(1H)-ones but also laid the foundation for directly asymmetric synthesis of Csp2-N atropisomers.

Hydrogen Bond Assisted Three-Component Tandem Reactions to Access N-Alkyl-4-Quinolones

Hydrogen-bonding catalytic reactions have gained great interest. Herein, a hydrogen-bond-assisted three-component tandem reaction for the efficient synthesis of N-alkyl-4-quinolones is described. This novel strategy features the first proof of polyphosphate ester (PPE) as a dual hydrogen-bonding catalyst and the use of readily available starting materials for the preparation of N-alkyl-4-quinolones. The method provides a diversity of N-alkyl-4-quinolones in moderate to good yields. The compound 4h demonstrated good neuroprotective activity against N-methyl-ᴅ-aspartate (NMDA)-induced excitotoxicity in PC12 cells.

[4 + 2]-Annulation of Prop-2-ynylsulfonium Salts and Isatoic Anhydrides: Access to 3-Methylthio-4-quinolones

An unparalleled [4 + 2]-annulation of prop-2-ynylsulfonium salts with isatoic anhydrides was developed, affording a series of 4-quinolones with a alkylthio group in medium to good yields under mild conditions. In this reaction type, the prop-2-ynylsulfonium salt serves as a C2 synthon and sulfide does not act as a leaving group, providing facile access to organosulfur compounds. The resulting quinolone products could be further transformed to a diverse range of synthetically useful compounds.

Synthesis of aryl-substituted quinolines and tetrahydroquinolines through Suzuki–Miyaura coupling reactions

The synthesis and characterization of substituted (trifluoromethoxy, thiomethyl, and methoxy) phenyl quinolines is described. Dichlorobis(triphenylphosphine)palladium(II)-catalyzed Suzuki–Miyaura cross-coupling of 6-bromo- and 6,8-dibromo-1,2,3,4-tetrahydroquinolines, 5-bromo-8-methoxyquinoline, and 5,7-dibromo-8-methoxyquinoline with substituted phenylboronic acids affords the corresponding 6-aryl- (13a–d), 6,8-diaryl- (14a–c), 5-aryl- (15), and 5,7-diaryl- (16b, c) tetrahydroquinolines and quinolines in high yields (68%–82%). The structures of all the products are characterized by 1H NMR, 13C NMR,19F NMR, and Fourier transform infrared spectroscopy and by elemental analysis.

Creation of thio and selenocyanate derivatives of 4-quinolone via regioselective C–H bond functionalization under ambient conditions

An operationally simple C–SCN and C–SeCN bond formation technique to generate different SCN/SeCN substituted 4-quinolone derivatives using NH₄SCN/KSeCN in excellent yields was developed.

Rhodium(iii)-catalyzed [3 + 3] annulation reactions of N-nitrosoanilines and cyclopropenones: an approach to functionalized 4-quinolones

We report Rh(iii)-catalyzed [3 + 3] annulation reactions for the preparation of functionalized 4-quinolones from available N-nitrosoanilines and cyclopropenones.

2-(2-Chlorobenzoyl)-1-(3,4-dimethoxyphenyl)-3-iodoquinolin-4(1H)-one

In the title compound C24H17ClINO4, the iodoquinolinyl moiety (r.m.s. deviation = 0.044 Å) makes dihedral angles of 87.44 (10) and 88.64 (10)° with the chloro- and methoxy-substituted benzene rings, respectively. The methoxy groups are present in synperiplanar and antiperiplanar conformations with respect to the benzene ring they are bound to, as indicated by the C—C—O—C torsion angle values of −16.2 (3) and 177.6 (2)°, respectively. The crystal structure features relatively strong methoxybenzene-C—H...O(quinolinyl) hydrogen bonds, leading to helical supramolecular chains along thea-axis direction. Additional C—H...O interactions along with π-stacking [inter-centroid distance = 3.6070 (16) Å between quinolyl-NC5and C6rings] consolidate the three-dimensional molecular packing.

Efficient synthesis of novel N-substituted 2-carboxy-4-quinolones via lithium bis(trimethylsilyl)amide (LiHMDS)-induced in situ cyclocondensation reaction

Efficient synthesis ofN-aryl-2-carboxy-substituted 4-quinolones with broad substrate scope and high regioselectivity.

Photo-Fries rearrangement of aryl acetamides: regioselectivity induced by the aqueous micellar green environment

NMR spectroscopy shows the location of acetanilides within the shells and hydrophobic cores in micellar solutions. Irradiation of acetanilides in aqueous micellar solutions involves C–N homolytic cleavage to yield singlet radical pairs that selectively provide 2-aminoacetophenone derivatives.

Quinolone-Hydroxyquinoline Tautomerism in Quinolone 3-Esters. Preserving the 4-Oxoquinoline Structure To Retain Antimalarial Activity

Recent publications report in vitro activity of quinolone 3-esters against the bc1 protein complex of Plasmodium falciparum and the parasite. Docking studies performed in silico at the yeast Qo site established a key role for the 4-oxo and N-H groups in drug-target interactions. Thus, the possibility of 4-oxoquinoline/4-hydroxyquinoline tautomerism may impact in pharmacologic profiles and should be investigated. We describe the synthesis, structure, photochemistry, and activity against multidrug-resistant P. falciparum strain Dd2 of ethyl 4-oxo-7-methylquinoline-3-carboxylate (7Me-OQE) and ethyl 4-hydroxy-5-methylquinoline-3-carboxylate (5Me-HQE), obtained from diethyl 2-[((3-methylphenyl)amino)methylene]malonate. Theoretically (B3LYP/6-311++G(d,p)), 5Me-HQE and 7Me-OQE show clear preference for the hydroxyquinoline form. The difference between the lowest energy hydroxyquinoline and quinolone forms is 27 and 38 kJ mol(-1), for 5Me-HQE and 7Me-OQE, respectively. Calculations of aromaticity indexes show that in 5Me-HQE both rings are aromatic, while in the corresponding oxo tautomers the nitrogen-containing ring is essentially non-aromatic. The structure of monomeric 5Me-HQE was studied using matrix isolation coupled to FTIR spectroscopy. No traces of 4-oxoquinoline tautomers were found in the experimental IR spectra, revealing that the species present in the crystal, 5Me-HQE·HCl, was lost HCl upon sublimation but did not tautomerize. Continuous broadband irradiation (λ > 220 nm; 130 min) of the matrix led to only partial photodecomposition of 5Me-HQE (ca. 1/3).

Design, synthesis and experimental validation of novel potential chemopreventive agents using random forest and support vector machine binary classifiers

Compared to the current knowledge on cancer chemotherapeutic agents, only limited information is available on the ability of organic compounds, such as drugs and/or natural products, to prevent or delay the onset of cancer. In order to evaluate chemical chemopreventive potentials and design novel chemopreventive agents with low to no toxicity, we developed predictive computational models for chemopreventive agents in this study. First, we curated a database containing over 400 organic compounds with known chemoprevention activities. Based on this database, various random forest and support vector machine binary classifiers were developed. All of the resulting models were validated by cross validation procedures. Then, the validated models were applied to virtually screen a chemical library containing around 23,000 natural products and derivatives. We selected a list of 148 novel chemopreventive compounds based on the consensus prediction of all validated models. We further analyzed the predicted active compounds by their ease of organic synthesis. Finally, 18 compounds were synthesized and experimentally validated for their chemopreventive activity. The experimental validation results paralleled the cross validation results, demonstrating the utility of the developed models. The predictive models developed in this study can be applied to virtually screen other chemical libraries to identify novel lead compounds for the chemoprevention of cancers.

Synthesis and preclinical evaluations of 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one monosodium phosphate (CHM-1-P-Na) as a potent antitumor agent

CHM-1 [2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one] (1) has a unique antitumor mechanism of action. However, because 1 has relatively low hydrophilicity, it was evaluated only via ip administration, which is not clinically acceptable. In this study, we synthesized the monosodium phosphate salt (CHM-1-P-Na, 4) of 1 as a hydrophilic prodrug. Compound 4 was rapidly converted into 1 following iv and po administration and also possessed excellent antitumor activity in a SKOV-3 xenograft nude mice model. Compound 4 also had clear-cut pharmacological effects on enzymes related with tumor cells. Neither 4 nor 1 significantly affected normal biological function in a safety pharmacology profiling study. Compound 1 caused apoptotic effects in breast carcinoma cells via accumulation of cyclin B1, and importantly, the endogenous levels of the mitotic spindle checkpoint proteins BubR1 directly correlated with cellular response to microtubule disruption. With excellent antitumor activity profiles, 4 is highly promising for development as an anticancer clinical trials candidate.

Cytotoxic Activity and Three-Dimensional Quantitative Structure Activity Relationship of 2-Aryl-1,8-naphthyridin-4-ones

A series of substituted 2-arylnaphthyridin-4-one analogues, which were previously synthesized in our laboratory, were evaluated for their in vitro cytotoxic activity against human lung cancer A549 and human renal cancer Caki-2 cells using MTT assay. Some compounds (11, 12, and 13) showed stronger cytotoxicity than colchicine against both tumor cell lines, and compound 13 exhibited the most potent activity with IC(50) values of 2.3 and 13.4 microM, respectively. Three-dimensional quantitative structure activity relationship (3D-QSAR) studies of comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed. Predictive 3D-QSAR models were obtained with q(2) values of 0.869 and 0.872 and r(2) (ncv) values of 0.983 and 0.993 for CoMFA and CoMSIA, respectively. These results demonstrate that CoMFA and CoMSIA models could be reliably used in the design of novel cytotoxic agents.

Design and synthesis of 2-(3-benzo[b]thienyl)-6,7-methylenedioxyquinolin-4-one analogues as potent antitumor agents that inhibit tubulin assembly

As part of our continuing investigation of azo-flavonoid derivatives as potential anticancer drug candidates, a series of 2-aryl-6,7-methylenedioxyquinolin-4-one analogues was designed and synthesized. The design combined structural features of 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one (CHM-1), a previously discovered compound with potent in vivo antitumor activity, and 2-arylquinolin-4-ones, identified by CoMFA models. The newly synthesized analogues were evaluated for cytotoxicity against seven human cancer cell lines, and structure-activity relationship (SAR) correlations were established. Analogues 1, 37, and 39 showed potent cytotoxicity against different cancer cell lines. Compound 1 demonstrated selective cytotoxicity against Hep 3B (hepatoma) cells. Compound 37 was cytotoxic against HL-60 (leukemia), HCT-116 (colon cancer), Hep 3B (hepatoma), and SK-MEL-5 (melanoma) cells. Compound 39 exhibited broad cytotoxicity against all seven cancer cell lines, with IC50 values between 0.07 and 0.19 microM. Results from mechanism of action studies revealed that these new quinolone derivatives function as antitubulin agents.

A mild and efficient synthesis of 4-quinolones and quinolone heterocycles

The cycloacylation of aniline derivatives to 4-quinolones in the presence of Eaton's reagent is described. This high-yielding methodology is applicable to a wide variety of functionalized anilines and requires milder conditions than those traditionally employed. This cyclization protocol is used to prepare a host of heterocycles and bis-quinolones and is characterized by relatively low reaction temperature and ease of product isolation.

Synthesis and antiproliferative evaluation of certain 4-anilino-8-methoxy-2-phenylquinoline and 4-anilino-8-hydroxy-2-phenylquinoline derivatives

The present report describes the synthesis and antiproliferative evaluation of certain 4-anilino-8-methoxy-2-phenylquinoline and 4-anilino-8-hydroxy-2-phenylquinoline derivatives. The antiproliferative activity of 4'-COMe-substituted derivatives decreased in an order of 6-OMe (1, 3.89 microM) > 8-OMe (8, 10.47 microM) > 8-OH (9, 14.45 microM), indicating that the position of substitution at the quinoline ring is crucial. For 3'-COMe derivatives, the antiproliferative activity of 8-OH (11, 1.20 microM) is more potent than its 8-OMe counterpart (10, 8.91 microM), indicating that a H-bonding donating substituent is more favorable than that of a H-bonding accepting group. Comparison of 8-OH derivatives, the antiproliferative effect of COMe (11) is more potent than its oxime derivative (15a, 2.88 microM), which in turn is more potent than the methyloxime counterpart (15b, 5.50 microM). Compound 11 is especially active against the growth of certain solid cancer cells such as HCT-116 (colon cancer), MCF7, and MDA-MB-435 (breast cancer) with GI50 values of 0.07, <0.01, and <0.01 microM, respectively. Flow cytometric analyses revealed that growth inhibition by 11 and 15a was due to accumulation in S-phase. This result is interesting because 2-phenylquinolone derivatives have been reported to be antimitotic agents which induced cell cycle arrest in G2/M phase.

Synthesis, cytotoxicity, and anti-inflammatory evaluation of 2-(furan-2-yl)-4-(phenoxy)quinoline derivatives. Part 4

A number of 2-(furan-2-yl)-4-phenoxyquinoline derivatives have been synthesized and evaluated for anti-inflammatory evaluation. 4-[(2-Furan-2-yl)quinolin-4-yloxy]benzaldehyde (8), with an IC(50) value of 5.0 microM against beta-glucuronidase release, was more potent than its tricyclic furo[2,3-b]quinoline isomer 3a (>30 microM), its 4'-COMe counterpart 7 (7.5 microM), and its oxime derivative 13a (11.4 microM) and methyloxime derivative 13b (>30 microM). For the inhibition of lysozyme release, however, oxime derivative 12a (8.9 microM) and methyloxime derivative 12b (10.4 microM) are more potent than their ketone precursor 7 and their respective tricyclic furo[2,3-b]quinoline counterparts 4a and 4b. Among them, 4-[4-[(2-furan-2-yl)-quinolin-4-yloxy]phenyl]but-3-en-2-one (10) is the most active against lysozyme release with an IC(50) value of 4.6 microM, while 8 is the most active against beta-glucuronidase release with an IC(50) value of 5.0 microM. (E)-1-[3-[(2-Furan-2-yl)quinolin-4-yloxy]phenyl] ethanone oxime (11a) is capable of inhibiting both lysozyme and beta-glucuronidase release with IC(50) values of 7.1 and 9.5 microM, respectively. For the inhibition of TNF-alpha formation, 1-[3-[(2-furan-2-yl)quinolin-4-yloxy]phenyl]ethanone (6) is the most potent with an IC(50) value of 2.3 microM which is more potent than genistein (9.1 microM). For the inhibitory activity of fMLP-induced superoxide anion generation, 11a (2.7 microM), 11b (2.8 microM), and 13b (2.2 microM) are three of the most active. None of above compounds exhibited significant cytotoxicity.