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A new series of ten examples of Schiff bases, namely (E)-2-(((2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenols 3, was easily synthesized with yields of up to 91% from the reactions involving a series of 2-(R-substituted) 6-amino-4-(trifluoromethyl)quinolines 1 and 4(5)-R1-substituted salicylaldehydes 2 – in which alkyl/aryl/heteroaryl for 2-R-substituents are Me, Ph, 4-MeC6H4, 4-FC6H4, 4-NO2C6H4, and 2-furyl, and R1-substituents are 5-NEt2, 5-OCH3, 4-Br, and 4-NO2. Complementarily, the Schiff bases showed low to good quantum fluorescence yield values in CHCl3 (Φf = 0.12–0.80), DMSO (Φf = 0.20–0.75) and MeOH (Φf = 0.13–0.85). Higher values of Stokes shifts (SS) were observed in more polar solvents (DMSO; 65–150 nm and MeOH; 65–130 nm) than in CHCl3 (59–85 nm). Compounds 3 presented good stability under white-LED irradiation conditions and moderate ROS generation properties were observed.

A series of seven 5-aryl-1-(1,1-dimethylethyl)-3-trifluoromethyl-1H-pyrazoles [in which aryl: C6H5 (1); C6H4-4-F (2); C6H4-4-Cl (3); C6H4-4-Br (4); C6H4-4-I (5); C6H4-4-CH3 (6), C6H4-4-OCH3 (7)] and 5-aryl-1-(1,1-dimethylethyl)-1H-pyrazole [C6H4-4-NO2 (8)] was studied at the molecular and supramolecular level. X-ray diffraction, thermal analysis, sublimation enthalpy data, NMR spectroscopy, and DFT calculations were used in this systematic study. The supramolecular cluster was used as demarcation and furnished energetic and contact area data of each compound, which allowed proposals of crystallization mechanisms. Two different mechanisms were observed: (i) compounds 1–4 had 2 stages, where initially the monomers formed a 2-D block, followed by the formation of the 3-D block; (ii) compounds 5–8 also had 2 stages, where initially the monomers formed a 1-D block, followed by formation of the 3-D block. The packing observed in the crystal was corroborated by data from 1H NMR experiments. The types of interactions observed were evaluated using Hirshfeld surface and QTAIM analysis and showed slight differences in both methods. Lastly, energetic and topologic data obtained from the clusters were correlated with crystal properties such as crystal packing efficiency, sphericity, and sublimation enthalpy and presented good trends between data.

An efficient protocol for the assembly of a new series of 1,3-disubstituted 4,5-bis(trifluoromethyl)-1H-pyrazoles – through a concise sequential iodination-trifluoromethylation reaction at the C-4 position of an initial series of 1-aryl-3-(alkyl/aryl)-5-trifluoromethyl-1H-pyrazoles (electronically deactivated heterocycles), using NIS and MFSDA, at good conversion yields and in short reaction times – is reported.

This paper presents a new family of pyrimidine-based BF2 complexes. The series contains six examples of 1,1-difluoro-3-aryl(heteroaryl)-1H-pyrimido[1,2-c][1,3,5,2]oxadiazaborinin-9-ium-1-uides (2) — in which aryl(heteroaryl) = phenyl, 4-MeC6H4, 4-N(CH3)2C6H4, 4-NO2C6H4, 2-naphthyl, and 2-thienyl. The heterocycles 2 were easily synthesized at yields of 50–68% from reactions — at room temperature for 24 h — of simple N-(pyrimidin-2-yl)benzamides (1) with BF3·Et2O, and they were fully characterized by 1H-, 13C-, 19F, 11B-NMR, GC–MS, and X-ray diffractometry. Moreover, the photophysical properties, TD-DFT analysis, BSA-binding experiments, and molecular docking studies for the new organoboron complexes 2 were determined, presented, discussed, and compared with similar compounds that have already been described.

The synthesis and structural elucidation of a new series of six 6-amino-2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl) quinolines are reported, yielding 22 to 87% isolated products. This was achieved through a regioselective intramolecular cyclization reaction of novel (Z)-4-((4-aminophenyl)amino)-1,1,1-trifluoro-but-3-en-2-ones in an acidic solvent-free medium, in which alkyl/aryl/heteroaryl = methyl, phenyl, 4-MeC6H4, 4-FC6H4, 4-NO2C6H4, and 2-furyl. The novel compounds were fully characterized by 1H-, 13C- and 19F-NMR spectroscopy, GC-MS and single-crystal X-ray diffraction. In addition, the preliminary investigation of photophysical properties of the 6-aminoquinolines (UV-Vis, fluorescence, quantum yield calculations, Stokes shifts, and TD-DFT analysis) and inhibitory activity against M. tuberculosis H37Rv strain was also presented. Thermal analyses were carried out to assess their properties as new materials.

A new series of ten examples of (E)-2-(((2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenols (Schiff bases), was easy synthesized at yields of up to 91% from the reactions between a series of 2-(R-substituted) 6-amino-4-(trifluoromethyl)quinolines and 4(5)-R1-substituted salicylaldehydes – in which alkyl/aryl/heteroaryl for 2-(R)-substituents are Me, Ph, 4-MeC6H4, 4-FC6H4, 4-NO2C6H4, and 2-furyl, and (R1)-substituents are 5-NEt2, 5-OCH3, 4-Br, and 4-NO2. The compounds are fully characterized by 1H-, 13C-, and 19F-NMR spectroscopy and SC-XRD. Complementarily, the photophysical, photostability, and reactive oxygen species (ROS) generation properties of these novel trifluoromethylated Schiff bases are evaluated.

The synthesis, antimicrobial activity evaluations, biomolecule-binding properties (DNA), and absorption The synthesis, antimicrobial activity evaluations, biomolecule-binding properties (DNA), and absorption and emission properties of a new series of (Z)-1,1,1-trichloro-4-alkyl(aryl)amino-4-arylbut-3-en-2-ones (4,5) and 2,2-difluoro-3-alkyl(aryl)amino-4-aryl-6-(trichloromethyl)-2H-1,3,2-oxazaborinin-3-ium-2-uides (6,7) in which 3(4)-alkyl(aryl) = H, Me, iso-propyl, n-butyl, C6H5, 4-CH3C6H4, 4-CH3OC6H4, 4-NO2C6H4, 4-FC6H4, 4-BrC6H4, 2-naphthyl, is reported. A series of β-enaminoketones (4,5) is synthesized from the O,N-exchange reaction of some amines (3) with (Z)-1,1,1-trichloro-4-methoxy-4-aryl-but-3-en-2-ones (1,2) at 61–90% yields. Subsequently, reactions of the resulting β-enaminoketones with an appropriate source of boron (BF3.OEt2) gave the corresponding oxazaborinine derivatives (6,7) at 50-91% yields. UV-Vis and emission properties of biomolecule-binding properties for the DNA of these new BF2-β-enamino containing CCl3 units were also evaluated. Some compounds from the present series also exhibited potent antimicrobial effects on various pathogenic microorganisms at concentrations below those that showed cytotoxic effects. Compounds 4d, 4e, 6e, and 6f showed the best results and are very significant against P. zopfii, which causes diseases in humans and animals.

This paper firstly describes the synthesis of a series of (Z)-4-((3-chloro-4-fluorophenyl)amino)-1,1,1-trifluorobut-3-en-2-ones (3a–f) as well as 1-(1-((3-chloro-4-fluorophenyl)amino)-3,4-dihydronaphthalen-2-yl)-2,2,2-trifluoroethanone (3g), from the O,N-exchange reaction of some 4-methoxy-4-alkyl(aryl)-1,1,1-trifluoroalk-3-en-2-ones (1) with 3-chloro-4-fluoroaniline (2), at 70–90% yields. Subsequently, in concentrated sulfuric acid, the enaminoketones 3 underwent a successful and regioselective intramolecular cyclocondensation reaction, which furnished a novel series of 2-alkyl(aryl)-7-chloro-6-fluoro-4-(trifluoromethyl)-quinolines (4) at 70–85% yields. To demonstrate synthetic applicability through the Sonogashira coupling reaction for obtaining quinolines with potential antimicrobial activity, the synthesis of a novel series of 2-alkyl(aryl)-6-fluoro-7-(phenylethynyl)-4-(trifluoromethyl)-quinolines (5) was performed, using quinolines 4 and phenylacetylene, via a regioselective Sonogashira coupling reaction (25–50% yield). Unfortunately, the new series of heterocycles 4 and 5 did not produce significant results against bacteria and fungi at the concentrations of 80–0.31 μg/mL.

This paper reports the results of the synthesis and structural elucidation by multinuclear NMR spectroscopy and single crystal X-ray diffraction of a new series of four examples of 1,1-difluoro-3-methyl-9-(aryl/heteroaryl)-7-(trifluoromethyl)-1H-[1,3,5,2]oxadiazaborinino[3,4-a][1,8]naphthyridin-11-ium-1-uides, which were obtained, at good yields (60–66%), from the reaction of 7-substituted N-(5-(trifluoromethyl)-1,8-naphthyridin-2-yl)acetamides — in which the 7-substituents are C6H5, 4-CH3C6H4, 4-FC6H4, and 2-Thienyl — with BF3·Et2O solution. One-dimensional multinuclear NMR spectroscopy (1H, 13C, 19F, and 11B) and two-dimensional 1H–15N HMBC are presented as powerful tools for an easy and secure NMR chemical shift assignments and structural characterization of fluorinated 1,8-naphthyridine-based boron complexes. Additionally, investigations of photophysical, electrochemical and DNA-binding properties were done.

This work reports a successful synthesis of two new series of 2-(aryl/heteroaryl)-6-(morpholin-4-yl/pyrrolidin-1-yl)-(4-trifluoromethyl)quinolines via the Buchwald–Hartwig amination, at 60–88% yields, starting from 2-(aryl/heteroaryl)-6-bromo-4-trifluoromethyl-quinolines and heteroarylamines (morpholine and pyrrolidine). The 6-bromoquinoline precursors were obtained from an easy intramolecular cyclization reaction of (Z)-4-((4-bromophenyl)amino)-1,1,1-trifluoro-but-3-en-2-ones, which were previously prepared through the reaction of 4-methoxy-(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones with 4-bromoaniline. Photophysical analyses indicated intraligand and charge-transfer type transitions, in agreement with the aromatic structures of the heterocycle moieties. In the case of ct-DNA titrations (via the absorption and emission method), morpholinyl- and pyrrolydinyl-substituted quinolines had strong interactions with ct-DNA, which could be attributed to π-stacking and/or hydrogen-bonding interactions.

A series of 5(3)-aryl-3(5)-carboxyethyl-1-tert-butylpyrazoles (aryl, 4-X-C6H4, where X = H, F, Cl and Br) were studied in the solid state. The 1,3-regioisomers (carboxyethyl group in 3-position) of t-butylpyrazoles crystalized in three different forms: s-cis, s-trans or s-cis + s-trans. On the other hand, the 1,5-regioisomers (carboxyethyl group in 5-position) of t-butylpyrazoles showed only s-trans conformation. The 13C CPMAS and SCXRD data confirmed that each 1,3- and 1,5-regioisomers of t-butylpyrazoles crystallized only one of the three mentioned forms. The potential energy surface (PES) yielded insights regarding the formation of each conformer. In general, quantum mechanical calculations showed that the conformer s-trans is more stable than s-cis, and the calculated stability difference was 0.7 kcal mol−1 for the 1,3-regioisomers and 3.5 kcal mol−1 for the 1,5-regioisomers. Moreover, 1,5-regioisomers of t-butylpyrazoles showed intramolecular interactions of type CH⋯OC between the carbonyl and t-butyl group, which was obtained by QTAIM analysis. This interaction can influence the stabilization for s-trans conformation in the solid state. In contrast, the 1,3-regioisomers did not show intramolecular interaction with the COOEt group, and the conformation adopted in the solid state should be the consequence of the crystalline packing. The QTAIM analysis of the more stable dimers of s-trans-conformation for X = Cl, Br showed that the halogen atoms interact with the COOEt group, helping stabilize this conformation. On the other hand, in the s-cis⋯s-cis conformation dimer (X = Cl, Br), the COOEt group was stabilized by the phenyl group, which is the same stabilization for X = H.

This paper presents a series of six examples of 1,1-difluoro-3-aryl(heteroaryl)-1H-pyrido[1,2-c][1,3,5,2]oxadiazaborinin-9-ium-1-uides (2)—in which aryl(heteroaryl) = phenyl, 4-MeC6H4, 4-N(CH3)2C6H4, 4-NO2C6H4, 2-naphthyl, and 2-thienyl—as pyridine-based boron heterocycles with variable ligand structures. The heterocycles 2 were easily synthesized at yields of 51–70% from reactions—at room temperature for 24 h—of simple N-(pyridin-2-yl)benzamides (1) with BF3·Et2O, and they were fully characterized by 1H-, 13C-, 19F-, and 11B-NMR spectroscopy, GC-MS, and X-ray diffractometry. The optical and electrochemical properties of 2 (UV-vis spectra, fluorescence spectra, quantum yield calculations, Stokes’ shifts, redox potentials, and DFT calculations) were determined and discussed. BSA-binding experiments and molecular docking studies of new complexes 2 were performed and correlated between each other.

A series of seven novel scaffolds of 2-substituted 4-trifluoromehyl-5H-chromeno[4,3-b]pyridin-5-ones (3a-g), where R (2-substituents) = Me, Ph, 4-tolyl, 4-NO2C6H4, 4-FC6H4, 4-BrC6H4, and 2-thienyl, were easily and regioselectively synthesized by employing a [3 + 3] cyclocondensation reaction of 4-methyl(aryl/thienyl)-4‑methoxy-1,1,1-trifluoroalk-3-en-2-ones (1) with 4-aminocoumarin (2) in up to 66% yields. The photophysical and electrochemical analysis of 3a-g revealed large Stokes shifts (30 to 130 nm) due to the ICT state and low redox oxidation processes. Additionally, the antioxidant activity evaluated by DPPH assays (aided by cyclic voltammetry) showed that compounds 3b (R = Ph, EC50 (µM) = 19.6) and 3e (R = 4-FC6H4, EC50 (µM) = 19.1) had the most significant radical scavenging capacity (ref. ascorbic acid = 10.9 µM).

An efficient synthesis methodology for a series of tetrazolo[1,5-a]pyrimidines substituted at the 5- and 7-positions from the cyclocondensation reaction [CCC + NCN] was developed. The NCN corresponds to 5-aminotetrazole and CCC to β-enaminone. Two distinct products were observed in accordance with the β-enaminone substituent. When observed in solution, the compounds can be divided into two groups: (a) precursor compounds with R = CF3 or CCl3, which leads to tetrazolo[1,5-a]pyrimidines in high regioselectivity with R at the 7-position of the heterocyclic ring; and (b) precursor compounds with R = aryl or methyl, which leads to a mixture of compounds, tetrazolo[1,5-a] pyrimidines (R in the 5-position of the ring) and 2-azidopyrimidines (R in the 4-position of the ring), which was attributed to an equilibrium of azide–tetrazole. In the solid state, all compounds were found as 2-azidopyrimidines. The regiochemistry of the reaction and the stability of the products are discussed on the basis of the data obtained by density functional theory (DFT) for energetic and molecular orbital (MO) calculations.

A new series of 3,6-disubstituted 2-(methylthio)-4-(trifluoromethyl)-3,4-dihydropyrimidin-4-ols displaying methyl, phenyl, aryl, and heteroaryl groups at the 6-position; and methyl, ethyl, allyl, and phenyl groups at the 3-position of the dihydropyrimidine ring, were synthesized and evaluated in vitro for acetylcholinesterase (AChE) inhibitory activity. Seven compounds showed activity with IC50 values in the lower micromolar range. The compound 4-trifluoromethyl-6-(4-fluorophenyl)-3-methyl-2-methylthio-3,4-dihydropyrimidin-4-ol (6e) had the best inhibitory activity (IC50 2.2±0.9 μM) and this inhibition was characterized as competitive. The molecular docking study showed that the AChE enzyme accommodates compound 6e in its catalytic site. The enantiomers of compound 6e, present similar interactions: π–π stacking interactions between the aromatic ring of the ligand's 4-fluorophenyl moiety and the aromatic rings of the electron-rich Trp84; and H-bonds between the hydroxyl group of Tyr121 and the hydroxyl moiety from 6e. The antioxidant effect of the dihydropyrimidin-4-ols was also investigated. This article is protected by copyright. All rights reserved.

The nickel-catalyzed cyclization of in situ generated ortho-chlorobenzophenone hydrazone derivatives, to afford 3-(hetero)aryl-1H-indazoles, is documented for the first time. The product 1H-indazoles can be transformed subsequently in a one-pot procedure into 1,3-di(hetero)aryl-1H-indazoles via copper-catalyzed N-arylation with (hetero)aryl bromides.

5-Bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one was used as an efficient precursor for the synthesis of a new series of (1,2,3-triazol-1-yl)methyl-pyrimidine biheterocycles. For this stepwise synthesis, the 5-bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one was first converted into 5-azido-1,1,1-trifluoro-4-methoxypent-3-en-2-one through a nucleophilic substitution of the bromine by an azide group. This was then followed by an azide–alkyne cycloaddition reaction (click chemistry) to give the key intermediate 5-[4-alkyl(aryl)-1H-1,2,3-triazol-1-yl]-1,1,1-trifluoro-4-methoxypent-3-en-2-ones. These were cyclocondensed with 2-methylisothiourea sulfate to give a series of 2-(methylthio)-4-(1,2,3-triazol-1-yl)methyl-6-(trifluoromethyl)pyrimidines. Additionally, the 2-methylthiopyrimidine products were used to prepare a new series of 2-amino-4-(1,2,3-triazol-1-yl)methyl-6-(trifluoromethyl)pyrimidines.

A new series of nine examples of 9-aryl-3-(aryl/heteroaryl)-1,1-difluoro-7-(trifluoromethyl)-1H-[1,3,5,2]oxadiazaborinino[3,4-a][1,8]naphthyridin-11-ium-1-uides, which contained 1,8-naphthyridine-based boron complexes with variable ligand structures, were synthesized at yields of 50–65% from the reaction of unpublished 2-benzoylamino-7-aryl(heteroaryl)-5-trifluoromethyl-1,8-naphthyridines—in which aryl(heteroaryl) = phenyl, 4-MeC6H4, 4-FC6H4, 4-BrC6H4, 4-OMeC6H4, 4-NO2C6H4, and 2-thienyl—with BF3·Et2O and fully characterized by 1H-, 13C-, 19F-, and 11B NMR spectroscopy and X-ray diffractometry. The optical and electrochemical properties of the new complexes were investigated, and the results for quantum yield calculations, Stokes shift, UV–vis, fluorescence, and redox potential data analysis indicated an important relationship with the aryl(heteroaryl) substituents attached to the 3- and 9-position of the naphthyridine boron complexes.

A convergent synthesis of a series of 16 new polysubstituted (5-hydroxy-5-(trifluoromethyl)-4,5-dihydro-1H-pyrazol-1-yl)(quinolin-4-yl)methanones, starting from isatin and alky(aryl/heteroaryl) ketones, is described. The diheteroaryl methanones were achieved at yields of up to 95% by a [3 + 2] cyclocondensation reaction involving 4-alkyl(aryl/heteroaryl)-4-methoxy-1,1,1-trifluorobut-3-en-2-ones (by two-step reaction) and 2-alkyl(aryl/heteroaryl)-4-carbohydrazides (by three-step reaction). Subsequently, representative dehydrated heterocyclic derivatives were obtained from the respective 5-hydroxy-2-pyrazoline moieties by classical dehydration reactions, which resulted in the corresponding (5-(trifluoromethyl)-1H-pyrazol-1-yl)(quinolin-4-yl)methanones (three examples) at yields of 69–82%. The subsequent cytotoxicity evaluation showed that compounds with aromatic groups at the 2-position of the quinoline and a methyl moiety at the 3-position of the pyrazole have significant cytotoxicity in human leukocytes at high concentrations (200 μM).

A convenient and environmentally benign procedure for the synthesis of a new series of trifluoromethyl-substituted N-(pyrimidin-2-yl)benzo[d]thiazol-2-amines by the cyclocondensation reaction of (benzo[d]thiazolyl)guanidine with either 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones or 2,2,2-trifluoro-1-(2-methoxycyclohexen-1-en-1-yl)ethanone is described. The main reactions were performed in refluxing water as the solvent (8–24 h), without catalysts, and the corresponding new N-(pyrimidinyl)-1H-(benzo[d]thiazolyl)amines were obtained at a 60–88 % yield. Subsequently, some di(hetero)arylamines were derivatized to the respective tertiary amines via easy N-alkylation and N-alkenylation reactions at 55–82 % yields. Finally, the Lipinski parameters and the total antioxidant activity of the new series of secondary arylamines were also evaluated.

Supramolecular gels present several applications in which the gelator properties are closely dependent on their structure and solvent. Despite this, there are few studies on the effect of the gelation ability of gelators with slight molecular changes. Therefore, N-arylestearamides (in which aryl = phenyl (1), 4-tolyl (2) and 4-acetylphenyl (3)) were evaluated in different solvents. The critical gelefication concentration (CGC) values indicated that the substituents can significantly affect the concentration at which the supramolecular gels are formed, mainly in non-aromatic solvents (e.g. cyclohexane, acetonitrile and DMSO). From UV-Vis and DSC data, we verified that the gel-sol and sol-gel transitions (Tgel-sol and Tsol-gel) increase in the order of 123. Organogel strength was evaluated for 1-3 as a function of concentration and solvent type using rheology data. Gel strength is concentration-dependent and a strength order was found in acetonitrile, cyclohexane and DMSO, in which: 1 ∼ 23. Dynamic viscoelastic measurements as a function of temperature sweeps indicate a predominantly enthalpic contribution to the elasticity of the organogels formed from 1-3. Temperature-dependent 1H NMR indicates that NHO interactions may be responsible for the molecular association of molecules into 1D fibers, while 3D fibers were formed from van der Waals interactions.

This study reports a simple and highly regioselective synthesis of a new series of 3,6-disubstituted 2-(methylsulfanyl)pyrimidin-4(3H)-ones, in which the 6-substituents are methyl or aryl groups and the 3-substituents are alkyl, allyl, phenyl, benzyl, or 2-phenylethyl groups. The products are obtained in good yields by cyclocondensation of the appropriate 4-substituted 4-methoxy-1,1,1-trichloroalk-3-en-2-ones with nonsymmetric 1-substituted 2-methylisothiourea sulfates under mild basic conditions.

This study describes a simple, efficient, and environmentally benign procedure for synthesizing a novel series of 13 N-(pyrimidinyl)-N-(1H-benzo[d]imidazolyl)amines, from the cyclocondensation reaction of (benzo[d]imidazolyl)guanidine with 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones or 2,2,2-trifluoro-1-(2-methoxycyclohexen-1-en-1-yl)ethanone. The (benzo[d]imidazolyl)guanidine precursor was earlier obtained from the reactions of cyanoguanidine with o-phenylenediamine. The trifluoroacetylated enol ethers were synthesized from the trifluoroacetylation reaction of enol ethers or acetals with trifluoroacetic anhydride. The main reactions were performed in pure refluxing water as the solvent (1–24 h), without catalysts, and the corresponding new N-(pyrimidinyl)-N-(1H-benzo[d]imidazolyl)amines were obtained at good to excellent yields (60–90 %). Subsequently, N-alkylation reactions were performed to obtain tertiary amines and to increase the solubility of the amines.

This paper reports a synthetic and NMR spectroscopic studies of two new series of 4-fluorinated 1,3,5-substituted 1H-pyrazoles. Firstly, an efficient synthesis of new series of 3-aryl-4-(di)fluoromethyl-1H-1-phenylpyrazoles, where [aryl = Ph, 4-NO2C6H4, 4-CH3OC6H4] is described, from fluorination reactions of 4-(formyl)- and 4-(hydroxymethyl)-1H-1-phenylpyrazoles in dichloromethane as solvent at room temperature, employing diethylaminosulfur trifluoride (DAST) as fluorinating agent in 41 to 73% yield. The 4-formyl-pyrazoles are obtained in 54–58% yield by Vilsmeier–Haack reaction using a mixture of POCl3/DMF with arylhydrazones, which were derived from the respective aryl methyl ketones and phenylhydrazine. The 4-hydroxymethyl-pyrazole precursors were easily obtained from the reduction of 4-formyl-pyrazoles by sodium borohydride (NaBH4) in 52–87% yield. Subsequently, the present work also discusses the 1H, 13C and 19F NMR spectroscopic data.

A simple and efficient procedure for the synthesis of ethyl 2-methylthio- and ethyl 2-benzylthio-6-methyl(aryl)-pyrimidine-4-carboxylates and their corresponding acid derivatives is reported. The products are obtained in good yields via the cyclocondensation reaction of ethyl 4-alkoxy-2-oxo-4-methyl(aryl)-but-3-enoates with 2-meth­ylisothiourea sulfate or 2-benzylisothiourea hydrochloride, under mild, basic, aqueous conditions.

This work reports the synthesis of a new series of 2-aryl-6-(phenylethynyl)-4-(trifluoromethyl) quinolines (2), where aryl = 4-(phenylethynyl)phenyl (2a), Ph (2b), 4-MeC6H4 (2c), 4-FC6H4 (2d). These were obtained by the Sonogashira coupling reaction producing 42–88% yield, utilizing 6-bromoquinolines and phenylacetylene as precursors in the presence of catalyst systems of Pd(OAc)2 and PPh3. The precursor 6-bromoquinolines were obtained from an intramolecular cyclisation reaction of (Z)-4-[(4-bromophenyl)amino]-1,1,1-trifluorobut-3-en-2-ones, which were previously prepared though the reaction of 4-methoxy-4-aryl-1,1,1-trifluoroalk-3-en-2-ones with 4-bromoaniline. Liquid crystal (LCs) properties were evaluated using thermal data and mesophase texture. Only compound 2a displayed monotropic nematic mesophase with very narrow liquid crystal window. Compounds 2b, 2c and 2d only displayed transition between the crystal phase to a liquid state. Nematic behavior was mainly dependent on the molecular length, as proved for 2a, which has the longest molecular length. Torsional angles between quinoline and aryl moieties at the 2-position were significant on hysteresis observed during the crystallization process.

This paper describes an efficient approach for the synthesis of a new series of 6-[3-alkyl(aryl/heteroaryl)-5-trifluoromethyl-1H-pyrazol-1-yl]nicotinic acids (where alkyl = CH3; aryl = Ph, 4-OCH3Ph, 4,4′-BiPh; and heteroaryl = 2-Furyl) from the hydrolysis reaction of alkyl(aryl/heteroaryl)substituted 2-(5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl)-5-(5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-1-carbonylpyrazol-1-yl)pyridines, under basic conditions and at 70–95% yields. In a subsequent step, the esterification reaction of pyrazolyl-nicotinic acids done in thionyl chloride and methanol led to the isolation of a series of methyl 6-[alkyl(aryl/heteroaryl)-5-trifluoromethyl-1H-pyrazol-1-yl] nicotinates as stable hydrochloride salts at 64–84% yields, which could be easily converted to hydrazides to give new oxadiazolyl-pyrazolyl-pyridine tricyclic scaffolds at good yields from a [4 + 1] cyclocondensation reaction with 1,1,1-triethoxyethane and 1-(triethoxymethyl)benzene as the reagent/solvent.

This paper describes an efficient method for synthesis of rufinamide analogs from the 1,3-dipolar cycloaddition and/or electrocyclization reactions under conventional thermal conditions of 4-alkyl(aryl/heteroaryl)-4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones (1) with 2,6-difluorobenzyl azide, where 4-alkyl = H, Me; 4-aryl = Ph, 4-NO2C6H4, 4-OCH3C6H4, 4-FC6H4, 4,4′-BiPh; and 4-heteroaryl = 2-thienyl; for the efficient preparation of a series of ten new trifluoroacetyl(trifluoromethyl) substituted 1H-1,2,3-triazoles. Yields in the range of 30–71% were obtained when the reactions were performed at high temperatures (130–150 °C) under solvent-free conditions. The pure regioisomers or mixtures of triazoles could be isolate with dependency of the 4-substituent of the enones 1. Finally, two mechanisms are proposed and the results are discussed in accordance with the X-ray diffraction results and FMO theory, which describes the possible HOMO/LUMO interactions via DFT calculations for both precursors.

This article reports a convenient and general method for the regioselective synthesis of a new series of 2-alkyl(aryl)-8-methyl-4-trifluoromethyl-7-aminoquinolines in 86–93% yields, from cycloaromatization reactions of N-(oxotrifluoroalkenyl)-2,6-diaminotoluenes in a strongly acidic medium polyphosphoric acid and absence of solvent. The enaminoketone intermediates were easily isolated from the reaction of 4-alkoxy-4-alkyl(aryl)-1,1,1-trifluoroalk-3-en-2-ones [CF3C(O)CH═C(R)OR1, where R = H, Me, Ph, 4-FPh, 4-BrPh, 4-MePh, and R1 = Me, Et] with 2,6-diaminotoluene (2,6-DAT) in methanol under mild conditions, in 46–70% yields. Another synthetic route also allowed the regioselective synthesis of 2-aryl(heteroaryl)-4-methyl-4-trifluoromethyl-7-aminoquinolines from direct cyclocondensation reactions of 4-alkoxy-4-aryl(heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones with 2,6-diaminotoluene in methanol under mild conditions, in 21–36% yields.

This study describes an improved one-pot, four-step synthesis­ of a new series of 1-aryl-3-trifluoroacetyl pyrroles from the reaction of 3-trifluoroacetyl-4,5-dihydrofuran with arylamines, giving 1,1,1-trifluoro-3-(2-hydroxyethyl)-4-arylamino-3-buten-2-ones, which were directly submitted to Swern oxidation to furnish 1,1,1-trifluoro-3-(2-ethanal)-4-arylamino-3-buten-2-ones. Subsequent intramolecular cyclization of the corresponding enaminoaldehydes followed by aromatization rendered the title compounds in a 30 to 56% overall yield.

A microwave-assisted synthesis of a series of 1-aryl-4-dimethylaminomethylene pyrrolidine-2,3,5-triones from the cyclocondensation reaction of ethyl 5,5,5-trichloro-3-dimethylamino methylene-2,4-dioxopentanoate with aniline, 3- or 4-substituted anilines [where the substituents = 3-Me, 3-OMe, 3-OH, 4-Me, 4-F, 4-Cl, 4-Br, 4-NO 2 , and 4-COMe] is reported. This process is an efficient alternative to the conventional thermal heating and furnishes the products in a short reaction time (ca. 13 min), under mild conditions and in moderate to good yields (50–76%).

A new series of twenty-one trifluoromethyl-containing ( E )- N ′-arylidene-1 H -pyrazole-1-carbohydrazides ( 4 ) was synthesized by the cyclocondensation reactions of six 3-alkyl(aryl/heteroaryl)-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1 H -pyrazole-1-carbohydrazides ( 2 ) with eleven aryl/heteroaryl aldehydes and acetophenone ( 3 ) in 52–97% yields and six new carbohydrazides 2 were easily obtained from the reaction of 1,1,1-trifluoro-4-alkyl(aryl/heteroaryl)-4-methoxy-3-alken-2-ones ( 1 ) with carbohydrazide. Subsequently, four examples of carbohydrazides 4 were fully studied by X-ray diffraction and the twenty-seven pyrazolyl-carbohydrazides 2 and 4 screened for their antioxidant and antimicrobial proprieties and evaluated by DPPH and MIC methods, respectively. Both series 2 and 4 showed ability to capture DPPH free radical for IC 50 from 47.57 to 487 μg/mL. Most of the compounds presented fungistatic and bacteriostatic activity only for high MIC levels ranging from 0.25 mg/mL to 0.5 mg/mL.

The regioselective synthesis and characterization of a new series of 3-aryl-7-trifluoromethyl[1,2,4]triazolo[4,3–a]pyrimidines from the oxidative heterocyclization of 2-(N′-benzylidenehydrazino)-4-trifluoromethylpyrimidines with copper dichloride is described. J. Heterocyclic Chem., (2011).

This work describes the regioselective synthesis of two new series of 1,1′-oxalylbis[3-(alkyl/aryl/heteroaryl)-4,5-dihydro-5-hydroxy-5-(trihalomethyl)-1H-pyrazoles], where the 3-substituents are H, Me, C6H5, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-NO2C6H4, 4,4′-BiPh, and 2-furyl, in a one-pot methodology with ethanol as solvent, from the reaction of 4-alkoxy-4-(alkyl/aryl/heteroaryl)-1,1,1-trihaloalk-3-en-2-ones with oxalyldihydrazide (51–89%). Complementarily, the dehydration reactions of five examples of the described oxalylbispyrazolines are also reported, which furnished the respective 1,1′-oxalylbis[3-(alkyl/aryl/heteroaryl)-5-(trihalomethyl)-1H-pyrazoles] in 53–78% yields without the two C(O)–N bond cleavages. .

This study describes a simple and efficient procedure to synthesize a novel series of fourteen 4-substituted N-(5-pyridinyl-1H-1,2,4-triazol-3-yl)-6-(trifluoromethyl)pyrimidin-2-amines, where the 4-substituents are H, CH3, C6H5, 4-FC6H4, 4-CH3C6H4, 4-CH3OC6H4 and 2-Furyl; from the cyclocondensation reaction of N-[5-(pyridinyl)-1H-1,2,4-triazol-3-yl]guanidines with 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones. The reactions were carried out in ethanol under reflux for 18 h and led to 40–68% yields. N-(Pyridyl-triazolyl)guanidine precursors were further obtained from reactions of cyanoguanidine with nicotinic or isonicotinic acid hydrazides and the halogenated enones from trifluoroacetylation of enolethers or acetals.

A simple, convenient and regioselective one-pot condensation reaction is used for the preparation of the title pyrazoles, e.g. (III).

The unexpected results of the cyclization reactions of N,N′-bis(oxotrifluoroalkenyl)-1,3-phenylenediamines [1,3-C6H4-(NHCR CHC(O)CF3)2], where R = H, Me, and Ph, in a strongly acidic medium (PPA), allowing the synthesis of new trifluoromethylated heterocycles containing the 1,7-phenanthroline nucleus in 32–40% yields and 7-aminoquinolines (38–40% yields), is reported. The bis-enaminoketone intermediates were easily isolated from the reactions of 4-alkoxy-4-alkyl(aryl)-1,1,1-trifluoroalk-3-en-2-ones with 1,3-phenylenediamine in ethanol under mild conditions (68–86% yields).

The structure of three 1-cyanoacetyl-3-alkyl[aryl]-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazoles (1–3) has been determined by X-ray diffractometry. The 4,5-dihydro-1H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0196–0.0736 A. The data demonstrate that the molecular packing is dependent on the substituent present in each molecule. In addition, a computational investigation using semi-empirical AM1 and RM1 methods was performed in order to investigate the correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds. An analysis of the π-electron delocalization by HOMA calculations indicate that there is a hyperconjugation effect in the imine group toward to phenyl group at ring 3-position of compound 2, and that this resonance effect decrease in compounds 1 and 3. In addition, it was showed that bond N(1) and C(6) do not have an amide character. Thus, the O(6)–C(6)–N(1)–N(2)–C(3) fragment is not completely delocalized mainly due to the low π-electron delocalization in N(1)–N(2) bond for all compounds.

The one-pot and regioselective synthesis of a novel series of 3-aryl(heteroaryl)-5trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazolyl-1-carbohydrazides and bis-(3-aryl-5trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl)methanones from the cyclocondensation reactions of 4-alkoxy-4-aryl(heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones, where aryl substituents are H, Me, Ph, 4-OMePh, 4-ClPh, 4-BrPh, 4,4’-biphenyl and heteroaryl are 2-thienyl and 2furyl, with carbohydrazide is reported.

Twelve novel 3-alkyl[aryl]-1-carboxamides-5-trichloromethyl-5-hydroxy-4,5-dihydro-lH-pyrazole have been synthesized in good yields (72–90%) using environmentally benign microwave-induced techniques. The compounds were synthesized from the cyclocondensation of 4-alkoxy-1,1,1-trichloro-3-alkyl[aryl]-2-ones [Cl3CC(O)C(R2) = C(R1)OR, where R = Me, Et; R1 = H, Me, Et, Pr, i-Pr, i-Bu, t-Bu, Ph, Ph-4-NO2, Ph-4-F, Ph-4-Cl, Ph-4-Br; and R2 = H, Me] with semicarbazide hydrochloride in the presence of pyridine and using methanol/water (3:1 v/v) as the solvent. The advantages of using microwave irradiation, rather than a conventional method, were demonstrated.

The one-pot synthesis of a novel series of amino-protected 6-alkyl-, 6-aryl-, 6-heteroaryl- and 5,6-fused-cycloalkane 4-trifluoromethyl-2-acetylaminopyrimidines, where alkyl = Me; aryl = Ph, 4-CH3Ph, 4-FPh, 4-ClPh, 4-BrPh, 4-OCH3Ph, 4-NO2Ph, 4,4′-biphenyl, 1-naphthyl; heteroaryl = 2-thienyl, 2-furyl and cycloalkyl = c-C6H4, c-C7H5 from the reaction of substituted 4-methoxy-1,1,1-trifluoroalk-3-en-2-ones with 1-acetylguanidine in acetonitrile or propan-2-ol as solvent, is reported. The acetylamino group of 2-acetylaminopyrimidines was hydrolyzed under three different conditions to afford the corresponding free 2-aminopyrimidines.

The simple preparation of the title compounds succeeds in moderate to good yields via cyclocondensation of 4-substituted ethyl 4-alkoxy-2-oxobut-3-eneoates with 2-methyl or 2-benzylisothiourea.

The synthesis of a series of 14 new 1-(3-(aryl-4,5-dihydroisoxazol-5-yl)methyl)-4-trihalomethyl-1H-pyrimidin-2-ones from the 1,3-dipolar cycloaddition reaction of 1-allyl-4-(trihalomethyl)pyrimidin-2(1H)-ones with aryl nitrile oxides is described. Also, the antiproliferative activity of the title compounds was tested against five human tumoral cell lines: MCF-7 breast cancer cell line, ER+ (estrogen receptor positive); HepG-2 (hepatoma); T-24 (bladder cancer); HCT-116 cell (colorectal carcinoma); and CACO-2. The preliminary results are promising, since three compounds presented IC50 values below 2 μM, as well as moderate to high selectivity.

This paper describes an efficient approach for the synthesis of a novel series of sixteen 2-(5-trifluoromethyl-1H-pyrazol-1-yl)-5-(5-trihalomethyl-1H-pyrazol-1-yl-1-carbonyl) pyridines, for the first time with non-identical substituents in both pyrazole rings, through the cyclocondensation reaction of 4-methoxy-4-alkyl(aryl/heteroaryl-1,1,1-trihaloalk-3-en-2-ones [CX3C(O)CH=CR1OCH3, in which R1 = CH3, C6H5, 4-CH3C6H4, 4-OCH3C6H4, 2-furyl and X = F, Cl] or acetylacetone with some 6-[3-alkyl(aryl)-5-trifluoromethyl-1H-pyrazol-1-yl]nicotinohydrazides. Optimized yields of 67-91% were obtained when the reactions were performed in ethanol (green solvent) at reflux for 16 h. Subsequent antioxidant and antimicrobial evaluation revealed promising 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibition percentage and exhibited fungiostatic and fungicidal activities against yeasts, dermatophytes and filamentous, especially for the pyridine systems, when the both pyrazole rings attached to a pyridine ring contain CX3 groups (X = H, F, Cl) of different kinds. It is also observed the trichloromethyl substituted compounds presented higher antioxidant activity in comparison to their fluorinated analogous.

The regiospecific synthesis of a novel series of nine 4-phenyl- and 3-alkyl(aryl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-tosylpyrazoles (pyrazolinyl p-tolyl sulfones), as well as their antimicrobial activity against yeast, such as fungi, bacteria, and alga are reported. The 1-p-tosyl-2-pyrazolines were obtained from the cyclocondensation reaction of 3-phenyl- and 4-alkyl(aryl)-1,1,1-trifluoro-4-alkoxy-3-alken-2-ones, [where alkyl = H, Me and aryl are -C6H5, 4-CH3C6H4, 4-OCH3C6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4,] with p-tosylhydrazine in a yield of 58–92% when toluene was employed as solvent. The best activity was obtained when the structure possessed a 4-fluorophenyl substituent linked at the carbon-3 of the pyrazoline ring. Subsequently, the dehydration reaction of 3-(4-fluorophenyl) substituted 2-pyrazoline with thionyl chloride/pyridine in benzene as solvent furnished the corresponding 1H-pyrazole in only a moderate yield (49%).

A new, efficient and easy route for the preparation of a series of 2-alkyl(aryl) substituted 4-oxo-4H-pyrido-[1,2-a]pyrimidines, where alkyl = CH3; aryl = C6H5, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-CH3C6H4, 4-OCH3C6H4, 4-NO2C6H4 in 45–80 % yield from the reaction of β-alkoxyvinyl trichloromethyl ketones with 2-aminopyridine under mild conditions, is then reported.

1,1,1-Trifluoro-4-methoxy-4-aryl-but-3-en-2-ones react with 2-pyridylcarboxamidrazone to produce the corresponding 1,1,1-trifluoro-4-aryl-4-(N1-pyridine-2-carboxamidrazone)-3-buten-2-ones. The butenones react with copper(II) chloride to give 1:1 adducts, in which the donor molecules were shown to isomerize to their cyclic pyrazolic forms. The crystal structure of the 4-fluoro-phenyl derivative, dichloro-[3-(4-fluorophenyl)-1-(imino-pyridin-2-yl-methyl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-pyrazole]-copper(II), was solved by X-ray crystallography. The structural results are compared with those of other copper(II) chloride adducts of similar ligands containing the amidrazone pharmacophore, which have been tested as anticancer drugs.

The synthesis of a novel series of eleven 6-aryl(5-methyl)-4-trifluoromethyl-2(1H)-pyrimidinones, where aryl ¼ Ph, 4-CH3Ph, 4-FPh, 4ClPh, 4-BrPh, 4-OCH3Ph and alkyl ¼ H, CH3, from the reaction of 4-aryl-4-methoxy-1,1,1-trifluoro-3-buten-2-ones with urea in the presence of hydrochloric acid, is reported. Trifluoroacetylation of acetophenone- and propiophenone-dimethylacetals derived from phenones, was employed to obtain the precursors. # 2002 Elsevier Science B.V. All rights reserved.