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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 up to 91% from the reactions involving 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. Complementarily, the Schiff bases showed low to good quantum fluorescence yield values both 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). Also, compounds 3 confirmed to present good stability under white-LED irradiation conditions and moderate ROS generation properties were observed.

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.

Herein, we explore the synthetic potential of tetrazolo[1,5-a]pyrimidines to obtain new pyrimidine derivatives by click chemistry and hydrogenation. Click chemistry reactions of the trifluoromethyltetrazolo[1,5-a]pyrimidines with terminal acetylenes produced unprecedented trifluoromethylated triazolylpyrimidines in excellent yields (84-98 %) in which one of them was active against all tested microorganisms, presenting moderate MIC values (62.5-15.62 mg/ml). Hydrogenation was carried out using Pd/C-H2 in MeOH under conventional, photochemical, and pressure (5 bar) conditions. The hydrogenation was an excellent method to obtain 2-amino-6-aryl-4-trifluoromethyl pyrimidines and/or 2-amino-6-aryl-4-trifluoro methyltetrahydro pyrimidines with a preference for 2-aminopyrimidine formation. The photochemical hydrogenation was the fastest and only pathway to reduce aryl-brominated substrate for the product without dehalogenation. Trifluoromethyl-substituted tetrazolo[1,5-a]pyrimidines reacted to 2-amino-6-aryl-4-trifluoromethyl pyrimidine formation in preference to the formation of the corresponding tethaydropyrimidines. However, the hydrogenation of non-trifluoromethylated tetrazolo[1,5-a]pyrimidines showed a preference for tetrahydropyrimidine formation.

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.

The synthetic potential of 5-bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one toward the catalyst-free synthesis of N-pyrrolyl(furanyl)-piperazines, 1,4-diazepanes, and 1,4-diazocanes through a telescoped protocol is reported. This three-component one-pot method provided 23 examples with high chemo- and regioselectivity at yields up to 96%.

A systematic investigation to assess the degree of similarity between polymorphs was carried out. A similarity indices (IX) approach was applied in ten series of polymorphs with different characteristics and number of molecules in the asymmetric unit. Geometric (ID), contact area (IC), and stabilization energy (IG) parameters were used. It was possible to situate each comparison in different regions of similarity within the polymorphism phenomenon and determine the boundaries between quasi-isostructural polymorphs and polymorphs of low similarity. The multiparameter IDCG index was used as a robust tool to determine the total similarity within the polymorphism phenomenon. The highest contribution of the stabilization energy parameter (45%) toward the final value of similarity (IDCG) was observed, followed by the contact area index (32%). The geometric index contributed approximately 23% to the final value of IDCG. This information reinforces the importance of the contact area and stabilization energy in assessing the degree of similarity between crystalline structures. A new descriptor (IQ) based on the comparison of the energetic contribution of intermolecular interaction types present in each crystal structure is presented. IQ can be a versatile tool and applicable even for systems that do not share any similarity.

This paper describes the synthesis of a novel series of 2-aryl-6-(1H-indol-1-yl)-4-(trifluoromethyl)quinolines, in which aryl = C6H5, 4-CH3C6H4, 4-FC6H4, 4-CF3C6H4 and heteroaryl = 2-thienyl, by an Ullmann-type cooper-catalyzed amination cross-coupling reaction. Photophysical properties of indolyl-quinolines were investigated using absorption and emission analysis. The emission fluorescence analysis showed a blue to cyan region emission in the 400–650 nm range. Large Stokes shifts values were observed for all new quinolines and attributed to the ICT state and to the electron-substituent properties. The ability to generate 1O2 species after being exposed to white light and biomolecule-binding DNA / HSA properties were also investigated.

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.

The use of β-enamino diketones as an easy entry to the regioselective synthesis of [1,2,4]triazolo[1,5-a]pyrimidines is reported. These ketones reacted with 3-amino-1H-1,2,4-triazoles to furnish exclusively 6-substituted 5-(trifluoromethyl)[1,2,4]triazolo[1,5-a]pyrimidines in yields of up to 95%. The regioselectivity of the reactions performed was maintained regardless of the substituent in the starting ketone or aminoazole.

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.

Deep eutectic solvents (DES) have been used as sustainable media for the synthesis of more efficient nanoparticle-based catalysts. However, the effects of DES deposition on the catalytic activity of metal oxide nanoparticles like TiO2 are unknown. Thus, the goal of this study was to facilitate the deposition of DES onto TiO2 surfaces and investigate how this coating modulates the catalytic activity of TiO2 in the photodecomposition of organic dyes. Results for the thermal and spectroscopic properties of the TiO2 coated with DES in relation to pure materials indicated interactions between these two materials, confirming the deposition of DES onto the TiO2 surface. Different choline chloride : HBD molar ratios had little impact on the thermal stability, phase transitions, crystallization and amorphization of the mixture. In general, the catalytic activity of TiO2 coated with DES was reduced. However, TiO2 covered with ChCl : malonic acid (1 : 2) showed the best catalytic activity and it was better as greater the amount of DES used in the surface deposition.

Reaction of 5-bromo enones with pyrazoles provided a series of unexpected N,O-aminal derivatives, through a 1,4-conjugated addition at the β-carbon of the 5-bromo enones instead of the expected nucleophilic substitution of the bromine. This reaction also furnished the 1,3-regioisomer of the pyrazole. A similar reaction of pyrazoles using 5-bromo enaminones furnished only N-alkylated pyrazoles-with high regioselectivity and at good yields-through nucleophilic substitution of the bromine.

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 present work reports the biological assays between synthetic BF

This paper describes the synthesis, structural study, and evaluation of electrochemical and photophysical properties by UV-Vis absorption and fluorescence emission analysis (solution and solid-state) of a series of eight 3,5-aryl-substituted 1-phenyl-2-pyrazolines (5), where 3-aryl = 2-OH-C

A series of seven N-phenylamides [R–C(O)NHPh, in which R: CH3, C(CH3)3, Ph, CF3, CCl3, CBr3, and H] were used as models in this study. Molecular packing and intermolecular interactions were evaluated by theoretical calculations, solution NMR, and quantum theory of atoms in molecules analyses. Crystallization mechanisms were proposed based on the energetic and topological parameters using the supramolecular cluster as demarcation. Concentration-dependent 1H NMR experiments corroborated the proposed interactions between molecules. For all compounds (except for R: H, which initially formed tetramers), layers (two-dimensional) or chains (one-dimensional) were formed in the first stage of the proposed crystallization mechanisms. The presence of strong intermolecular NH···O═C interactions promoted the first stages. The study in solution provided different values of association constant (Kass) governed by the hydrogen bond NH···O═C, showing that the stronger interactions are directly influenced by the substituen...

The synthetic versatility of 4-alkoxy-4-alkyl/aryl-1,1,1-trichloroalk-3-en-2-ones (enones) for the synthesis of [1,2,4]triazolo[1,5-a]pyrimidines, in which the trichloromethyl group is either maintained or eliminated from the product by simply controlling the reaction medium, is reported. These enones react with 3-amino-1H-1,2,4-triazoles under acidic conditions to furnish exclusively 7-(trichloromethyl)-[1,2,4]triazolo[1,5-a]pyrimidines, whereas under basic conditions [1,2,4]triazolo[1,5-a]pyrimidin-5/7(1H)-ones are obtained with elimination of the trichloromethyl group. The regioselectivity of the reactions performed under basic conditions is highly influenced by the substituents present in the starting enones. Twenty-one examples are synthesized using these two methodologies, with yields of up to 86%.

Glioblastoma is the most common and aggressive glioma, characterized by brain invasion capability. Being very resistant to the current therapies, since even under treatment, surgery, and chemotherapy with temozolomide (TMZ), patients achieve a median survival of one year. In the search for more effective therapies, new molecules have been designed. For nervous system cancers, molecules able to cross the blood-brain barrier are handled with priority. Accordingly, tacrine was chosen for this study and the inclusion of spiro-heterocyclic rings was done in its structure resulting in new compounds. Cytotoxic activity of tacrine derivatives was assayed using glioblastoma cell line (SF295) as well as analyzing cell death mechanism. Increased caspases activities were observed, confirming apoptosis as cell death type. Some derivatives also increased reactive oxygen species formation and decreased the mitochondrial membrane potential. Moreover, compounds acted on several glioblastoma-related proteins including p53, HLA-DR, beta-catenin, Iba-1, MAP2c, Olig-2, and IDH1. Therefore, tacrine derivatives presented promising results for the development of new glioblastoma therapy, particularly to treat those patients resistant to TMZ.

The present paper describes first an efficient methodology for an easy O -functionalization (alkylation) of tetracyclic hydroxyisoxazolines 1 applied to the synthesis of eight examples of new 3-(alkoxy)-3-(trifluoromethyl)-3,3a-dihydrospiro[chromeno [4,3- c ]isoxazole-4,1′-cycloalkanes] ( 6-9 ) at 61–84% yields, in which the alkoxy substituents were methoxy, benzyloxy, allyloxy, or prop-2-yn-1-yloxy; while the cycloalkanes were 5-, 6-, and 7-membered carbocycles, as well as 4′-methyl- and 4′- t -butyl-cyclohexane. The reaction medium used 1 , four alkyl halides ( 2 - 5 ), K 2 CO 3 , and KI in DMF at room temperature. The selected 3-(prop-2-yn-1-yloxy)-substituted isoxazolines 6 were successfully used as a CC -fragment in the construction of another series of five examples of 3-((1-benzyl-1 H -1,2,3-triazol-4-yl)methoxy)-3-(trifluoromethyl)-3,3a-dihydrospiro[chromeno[4,3- c ]isoxazole-4,1′-cycloalkanes] ( 10 ), at 36–84% yields, through a regioselective 1,3 dipolar cycloaddition reaction catalyzed by copper iodide (CuAAC), using benzyl azide as an NNN -building block (Click Chemistry).

The structure of four spiro[chromeno[4,3-b]quinoline-6,1′-cycloalkan]-7-amine (1–4) was determined by X-ray diffraction methods. The quinoline rings were obtained as almost planar structures, with an RMS deviation within a range of 0.0345–0.0641 A, while the chromene rings are not planar. Moreover, the cycloalkane rings are attached to the chromene in spiro form. Three of the four compounds crystallize as solvates—one with ethanol and the other two with water. The crystal packing for compounds 1–4 is discussed in terms of intermolecular interactions, and it is shown that the crystal packing of these heterocycles is governed by: strong O–H···N and N–H···O hydrogen bonds; weak C–H···O and C–H···N hydrogen bonds; and very weak C–H···Cl, C–H···Br, and C–H···π interactions. Also, π···π and lone pair···π interactions are present in the crystal packing of the heterocycles. These interactions lead to the formation of endless chains along a plane, as well as supramolecular dimers and the arrangement of molecules in layers. Additionally, UV–Vis absorption spectra properties are also discussed. The structure of four spiro[chromeno[4,3-b]quinoline-6,1’-cycloalkan]-7-amines are determined by single crystal X-ray diffraction. The crystal packing is discussed in terms of intermolecular interactions (strong O–H···N and N–H···O hydrogen bonds; weak C–H···O and C–H···N hydrogen bonds; and very weak C–H···Cl, C–H···Br, and C–H···π interactions). Also, π···π and lone pair π interactions are present in the crystal packing of the heterocycles.

This study reports a comparison between conventional methods, ionic liquids, microwave (MW) irradiation, and combinations thereof for the synthesis of a series of fourteen 1-aryl-2-arylamino-5-trifluoroacetyl-1,2,3,4-tetrahydropyridines. In all of the reactions tested, the products were obtained at very good yields (87–97%), but the reaction times were very different, depending on the method used. Comparing to other methods, the time decreased to 1 min when [BMIM]BF 4 under MW irradiation was used, thus evidencing a synergic effect.

The quest for concepts of isostructurality in organic crystals has been long and mostly based on geometric data, even with the development of modern software. This field of study is of great interest to the pharmaceutical industry and for the prediction of crystal structures. Despite this, there is still no methodology that provides broad quantitative and comparable similarity data between two complete crystalline structures. The present study demonstrated that the similarity between two crystalline structures could be estimated from the similarity between the two "supramolecular clusters". Quantitative indexes for similarity comparisons of crystal structures were shown using nine 5-aryl-1-(1,1-dimethylethyl)-1H-pyrazoles as a model. This proposal includes the quantitative data of a geometric parameter (ID), a contact area parameter (IC), and an energetic parameter (IG). The proposed indexes exhibited good perspective regarding the similarity data and distinct regions of similarity. The range of similarity was set at IX ≥ 0.80, 0.80 > IX > 0.60, and IX ≤ 0.60 (X = D, C, or G). Indexes with a value near 1.0 indicate systems with isostructural, isocontact, and isoenergetic behavior. The results indicated that supramolecular structures with high similarity must have high values for all three indexes (ID, IC, and IG).

Electrospray ionization mass spectrometry with variable collision-induced dissociation (CID) was used to conduct a comprehensive study of cation-anion interaction strength in dicationic ionic liquids (ILs). This investigation reports the influence of anion structure (Cl−, Br−, NO3−, BF4−, and SCN−) and spacer chain length (n = 4, 6, 8, and 10) on the interaction strength of dicationic ILs derived from 1,n-bis(3-methylimidazolim-1-yl)alkane. The anion-cation interaction strength was determined from the binary mixture of ILs and from the center-of-mass energy (Ecm). Moreover, two novel models were proposed, based on the extended first order and zero order equations, which allow determining the order of stability from the constant dissociation (Kd) and decay rate (k0), respectively. Additionally, quantum chemical calculations of cation-anion energy were done in order to support experimental results. The order of energy of the anion-cation interaction determined by both Ecm,1/2 and Kd followed the same trend, while the order of the cation-anion interaction strength observed in the binary mixtures was in accordance with quantum chemical calculations. The model based on zero order process did not show good agreement with either the Ecm,1/2 or Kd, thus indicating that it is a very simplified model that does not result in an appropriate order for the cation-anion energy interaction. Orders were not comparable; however, it was the first time that binary mixture experiments and Ecm were used with the same set of ILs.

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.

The first Quantum Theory of Atoms in Molecules (QTAIM) analysis of [2]rotaxanes was used in combination with quantum mechanical calculations and variable temperature NMR experiments. The study shows all the intramolecular interactions of tetraalkylsuccinamide[2]rotaxanes with different templates. The threads have different stoppers [R1R2NC(O)-CH2CH2-C(O)NR2R1, in which R2/R1 = CH2cy-Hex/CH2Ph, i-Bu, Bu, and Pr]. The different threads used allowed us verify that the contact area between the submolecular components (CMcy···Thr) is closely correlated with the interaction energy (GMcy···Thr) in the [2]rotaxanes studied. Furthermore, the QTAIM data and quantum mechanical calculations confirmed that, in all of the compounds, the hydrogen bonds are responsible for most of the energy from the intramolecular interactions that follow the C–H···π and H···H interactions, independent of the thread used. In the liquid state, using NMR 1H some intramolecular interactions were observed, which is in agreement with the dat...

A new, simple, and efficient method for the synthesis a novel series of 1-substituted 4-(trifluoromethyl)-5-(alkan-1-ol)-pyridin-2(1 H )-imines from the reaction of 3-(5,6-dihydro-4 H -pyran-3-yl)-4,4,4-trifluorobut-2-enenitrile and 3-(4,5-dihydrofuran-3-yl)-4,4,4-trifluorobut-2-enenitrile with primary amines – is described. The products were obtained in 29–82% yield.

This work reports the synthesis of a series of (1H-1,2,3-triazol-4-yl)carbohydrazides (2), which were obtained from 4-trichloroacetyl-1H-1,2,3-triazoles (1). Triazoles 1 were synthesized by 1,3-dipolar cycloaddition reaction, starting from 4-alkoxy-1,1,1-trichloroalk-3-en-2-ones and benzyl azides and easily (15 min) converted to 2 by reaction with hydrazine hydrate (73–82% yield). Carbohydrazides 2 proved to be a versatile building block for constructing a series of fluorinated heterocycles analogous to rufinamide, i.e., 1H-1,2,3-triazol-4-yl-1,3,4-oxadiazoles, a pyrrole derivative, and a 2-pyrazoline, through [4+1]–, [1+4]–, and [3+2]–cyclocondensation reactions, respectively. Finally, and according to the Lipinski’s rule of five, 2,6-difluorobenzylated 1,2,3-triazoles can be considered as potential candidates for further biological activity assays.

Three new series of compounds, 5-alkoxy-3-(trifluoromethyl)penta-2,4-dienenitriles, 5-(phenylthio)-3-(trifluoromethyl)penta-2,4-dienenitriles, and ethyl 4-alkoxy-2-(cyanomethylene)but-3-enoates, obtained from the olefination reaction of the respective enones with diethyl cyanomethylphosphonate via the Horner–Wadsworth–Emmons olefination are reported. All products were obtained as single regioisomers; however, the composition of the stereoisomers changed according to the enone substituents. A study based on 1H and 13C NMR chemical shifts, 1H–19F and 13C–19F NMR coupling constants, 1H NMR signal integrals, and HSQC, HMBC, and NOESY experiments was performed in order to assign the structure and percentage of each stereoisomer obtained.

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.

This paper describes firstly an effective protocol for the synthesis of a new series of five examples of 3-(trifluoromethyl)-3,3a-dihydrospiro[chromeno[4,3-c]isoxazole-4,1′-cycloalkan]-3-ols (4), in which the cycloalkanes — cyclopentane, cyclohexane, cycloheptane, and 4′-methyl- and 4′-t-butyl-cyclohexane — were isolated at yields of 65–84%. The dihydro-isoxazolinols 4 were obtained regioselectively from the reactions of 2,2,2-trifluoro-1-[4-methoxy-spiro(2H-chromen-2,1′-cycloalkane)-3-yl]ethanones (3) with hydroxylamine hydrochloride, in the presence of sodium bicarbonate and methanol as solvent, for 24 h at 60 °C. The ethanone precursors 3 were synthesized by trifluoroacetylation reaction, employing trifluoroacetic anhydride and mixtures of enolethers and/or acetals derived from spiro[chroman-2,1′-cycloalkan]-4-ones (2) (Kabbe’s adducts), which were obtained beforehand from the reaction of cycloalkanones 1 with 2-hydroxyacetophenone and pyrrolidine. Subsequently, dehydration reactions of isoxazolinols 4, employing thionyl chloride and pyridine, enabled the isolation of another series of five novel spiro-isoxazoles 5 (76–95% yield). The structural features of the two series of new spiro heterocycles (4 and 5) were unequivocally determined with the aid of: one-dimensional 1H, 13C, and 19F NMR spectroscopy; two-dimensional 1H and 13C NMR spectroscopy (NOESY, gHMBC, and gHMQC); single crystal X-ray diffraction; and GC–MS.

Herein we report the synthesis of twelve 2,5-substituted 4-(trifluoromethyl)-spirochromeno[4,3-d]pyrimidines (7–10), as well as an evaluation of their analgesic effect in a mouse pain model. The nine new chromeno[4,3-d]pyrimidines (7–9) were synthesized from the cyclocondensation reactions of three 2,2,2-trifluoro-1-(4-methoxyspiro[chromene-2,1′-cycloalkane]-3-yl)ethanones (3) containing 5-, 6- and 7-membered spirocycloalkanes, with some well-known amidine salts (4–6) [NH2CR( NH)]—in which R = Me, Ph, and NH2—at yields of 60–95%. Subsequently, three new 2-(pyrrol-1-yl)-4-(trifluoromethyl)-chromeno[4,3-d]pyrimidines (10) were obtained through a Clauson-Kaas reaction between the respective 2-(amino)-4-(trifluoromethyl)-chromeno[4,3-d]pyrimidines (9) and 2,5-dimethoxy-tetrahydrofuran. The analgesic evaluation showed that these 4-(trifluoromethyl)chromeno[4,3-d]pyrimidines (100 mg/kg, p.o.) and Ketoprofen (100 mg/kg, p.o.) significantly reduced capsaicin-induced spontaneous nociception. Moreover, the 2-pyrrolyl-spirocyclohexane derivative 10b (100 and 300 mg/kg, p.o.) had an anti-allodynic effect comparable to Ketoprofen (100 and 300 mg/kg, p.o.) in the arthritic pain model, without causing locomotor alterations in the mice. These results suggest that the compound 10b is a promising molecule for new analgesic drugs in the treatment of pathological pain, such as in arthritis.

The objectives of this study were to evaluate tetrahydropyridine derivatives as efflux inhibitors and to understand the mechanism of action of the compounds by in silico studies. Minimum inhibitory concentration (MIC) determination, fluorometric methods and docking simulations were performed. The compounds NUNL02, NUNL09 and NUNL10 inhibited efflux, and NUNL02 is very likely a substrate of the transporter protein AcrB. Docking studies suggested that the mechanism of action could be by competition with substrate for binding sites and protein residues. We showed for the first time the potential of tetrahydropyridines as efflux inhibitors and highlighted compound NUNL02 as an AcrB-specific inhibitor. Docking studies suggested that competition is the putative mechanism of action of these compounds.

The syntheses of several polyazaheterocycles are demonstrated. The cyclocondensation reactions between β-enaminodiketones [CCl3C(O)C(=CNMe2)C(O)-CO2Et] and aromatic amidines resulted in glyoxalate-substituted pyrido[1,2-a]pyrimidinone, thiazolo[3,2-a]pyrimidinone and pyrimido[1,2-a]benzimidazole. Pyrazinones and quinoxalinones were obtained through the reaction of these glyoxalates with ethylenediamine and 1,2-phenylenediamine derivatives. On the other hand, the reaction of glyoxalates with amidines did not lead to the formation of imidazolones, but rather N-acylated products were obtained. All the products were isolated in good yields. DFT-B3LYP calculations provided HOMO/LUMO coefficients, charge densities, and the stability energies of the intermediates, and from these data it was possible to explain the regiochemistry of the products obtained. Additionally, the data were a useful tool for elucidating the reaction mechanisms.

A series of novel trifluoromethylated tetrazolo[1,5-a]pyrimidines were easily prepared via a highly regioselective cyclocondensation reaction between β-alkoxyvinyl trifluoromethyl ketones [CF3C(O)CH=C(R)OMe] (in which R = Ph, 4-F–C6H4, 4-Cl–C6H4, 4-Br–C6H4, 4-I–C6H4, 4-CH3–C6H4, 4-OCH3–C6H4, Thien-2-yl, 4-Ph–C6H4, Me) and 5-aminotetrazole, using conventional heating in an oil bath or microwave irradiation. The results showed that when ionic liquid was used as the reaction medium, the reaction time drastically decreased and the yield improved. Additionally, all the newly synthesized compounds were evaluated to determine their antimicrobial activity. Two of the compounds tested were the most promising because they displayed activity against the Gram-positive and Gram-negative bacteria used in the tests, and they were moderately active against the yeast Candida albicans. And finally, the cytotoxicity of lymphocytes of the two compounds was evaluated by using MTT assay. Results showed at active concentration such compounds would be safe.

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.

This work reports a successful one-pot three-step protocol for the synthesis of a new series of 15 examples of polysubstituted 4-(5-(trifluoromethyl)-1H-pyrazol-4-yl)-1H-1,2,3-triazoles, in which sequential Sonogashira cross-coupling, desilylation, and a copper(I)-catalyzed azide–alkyne cycloaddition reaction (CuAAC) with an overall yield of up to 72% were used. The presence of a trifluoromethyl substituent attached to the pyrazole moiety made the Sonogashira cross-coupling reaction challenging. Additionally, the selection of the ancillary ligand XPhos was essential and indispensable for the desired heterocyclic construction.

The synthesis of benzylic amide [2]rotaxanes using 1,2-bis(aminocarbonyl-(1′-tert-butyl-1H-pyrazole-[3′]5′-yl))-ethanes as templates is reported. These templates are equipped with tert-butyl pyrazole-based stoppers and have donor (N–H) and acceptor (CO) hydrogen bond groups. The synthesis of [2]rotaxanes has been shown to be highly dependent on the tert-butylpyrazole stoppers. While the thread with 1′,3′-disubstituted pyrazoles as stopper units was shown to be an excellent template for the synthesis of [2]rotaxanes, the thread with 1′,5′-disubstituted pyrazoles as stopper units did not yield the expected [2]rotaxane. The structure of the synthesized [2]rotaxanes was characterized using NMR experiments and X-ray diffraction, with the latter showing that the macrocycle adopts a distorted chair conformation. An in-depth study of the isolated thread's X-ray structures and concentration-dependent NMR experiments seem to explain the dependence of the rotaxane formation on the substitution pattern of the thread's pyrazole stoppers.