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Two series of 4,6-disubstituted 1,3,5-triazin-2-amines were prepared by cesium carbonate-promoted cotrimerization of aromatic nitriles with guanidine and the reaction of (hetero)aryl nitriles with N-acetylguanidine. The first series of 4,6-bis(hetero)aryl-1,3,5-triazin-2-amines was synthesized in yields of 56–85% by adapting a traditional approach that starts from readily available substrates but requires strong and hard-to-handle bases as well as presents serious scope limitations. In this line, the method developed here used a mild base and overcame the scope limitation for p-substituted benzonitrile with electron-releasing group. The second series of 4-(hetero)aryl-6-methyl-1,3,5-triazin-2-amines comprises unsymmetrically substituted symmetrical triazines, which were synthesized in yields of 58–75%. In summary, this work highlighted a synthetic method, which tolerates broad range of substrates, including o- and p-substituted benzonitriles as well as heteroaromatic nitriles.

The broad application of 1

A convenient domino route for the synthesis of novel 1,3-dihydrofuro[3,4-c]pyridines from pyridoxal and alkyl, aryl or heteroaryl ketones under basic conditions is reported. A series of nine derivatives is obtained in 53–90% yields after stirring reactants for 48 hours at room temperature. Most products are easily isolated by filtration followed by recrystallization from ethanol. All products were fully characterized by FTIR, HRMS, and 1H and 13C NMR spectroscopy. The X-ray crystal structure of a representative example of the 1,3-dihydrofuro[3,4-c]pyridine series is also presented.

2-(2-Furyl)-3-hydroxychromone (HL) reacts with MII ions in the formation of quadratic [Cu(L)2] (3), octahedral [M(L)2(OH2)2] (M = Co (1), Ni (2), Zn (4), Mn (5)) and seesaw [M(L)2] (M = Sn (6), Pb (7)) complexes. Recrystallization of complexes 1-3 in presence of pyridine lead to [M(L)2(py)2] (1a-3a) adducts. All compounds were characterized by Fourier transform infrared spectroscopy (FTIR). Complexes 1-7 were analyzed by UV-Vis and diffuse reflectance spectroscopies. The estimated band gap energies range from 2.90-3.15 eV. The crystal structure of complexes 6 and 7 revealed the influence of the stereochemically active lone pair due to their electronic configuration ns2. An intense fluorescence emission band centered at approximately 600 nm (λexc centered at 340 nm) has been observed for complex 6 in the solid state. In N,N‑dimethylformamide (DMF) solution, complex 6 showed two emission bands (468 and 538 nm) when excited from 300 to 380 nm, and only one emission band (468 nm) when excited from 385 to 420 nm.

Novel mononuclear silver(I) complexes based on thiocarbamoyl-pyrazoline ligands were synthesized and structurally characterized. Complexes 1 and 2 were prepared in good yields using a sonochemical method. X-ray diffraction studies revealed trigonal coordination geometry for the AgI atom in complex 1 and distorted trigonal pyramidal geometry in complex 2, according to τ4 parameter analysis. Investigation of photophysical properties revealed intense blue-greenish emissions both in solution and in the solid state when excited at 300 nm. This emission was tentatively attributed to mixed (M+X)LCT and IL electronic transitions taking place after ligand metalation, as shown by DFT calculations. Complete characterization of the prepared compounds was also performed, including 1H and 13C NMR experiments, elemental analysis, infrared spectroscopy, absorption/emission studies, and time-resolved luminescence experiments. The synthesized ligands and complexes 1 and 2 were also tested as antibacterial agents against two standard bacterial strains (Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922) and a panel of clinical S. aureus strains with distinct antibiotic-resistance profiles. Antitumor activity was investigated against melanoma cells (B16F10) and mammary carcinoma cells (4T1).

Deep eutectic solvents (DESs) have attracted the attention of the researchers as alternative solvents due to desirable properties such as easy preparation and high thermal stability. In this work, it was reported the preparation of five DESs from benzyltriethylammonium chloride (BTEAC) as quaternary ammonium salt (QAS) and carboxylic acids (oxalic, malonic or benzoic) as hydrogen bonding donor (HBD), which four were not reported so far. Furthermore, it was presented the first type III liquid DES at room temperature from benzoic acid and shown by interaction energy calculations why the formation of benzyltriethylammonium chloride:benzoic acid (BTEAC:BA) is favored over choline chloride:benzoic acid (ChCl:BA). The optimized geometries showed the Cl···π interaction is determining for decreasing the freezing point of benzyltriethylammonium chloride:benzoic acid mixture. Infrared spectra showed evidence for the existence of hydrogen bonds in DESs. Physical (freezing point, density and refractive index), thermal (thermogravimetric analysis) and rheological characterizations were performed for all solvents. The structure of HBDs affected the results on all evaluated properties and proved that it could be tunable. The prepared DESs were stable thermically and can be used in a wide range of temperature. Finally, rheological studies showed that Newtonian or non-Newtonian behavior can be observed by the nature of HBD.

Candida spp. cause invasive fungal infections. One species, Candida glabrata, may present intrinsic resistance to conventional antifungal agents, thereby increasing mortality rates in hospitalized patients. In this context, metal complexes present an alternative for the development of new antifungal drugs owing to their biological and pharmacological activities demonstrated in studies in the last decades. Accordingly, in this study we have synthesized and characterized two new Co(II) complexes with thiocarbamoyl-pyrazoline ligands to assess their antimicrobial, mutagenic, and cytotoxic potential. For antimicrobial activity, the broth microdilution method was performed against ATCC strains of Candida spp. and fluconazole dose-dependent isolates of C. glabrata obtained from urine samples. The Ames test was used to assess mutagenic potential. The reduction method of the MTS reagent (3 [4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium) was performed with HeLa, SiHa, and Vero cells to determine cytotoxicity. Both complexes exhibited fungistatic and fungicidal activity for the yeasts used in the study, demonstrating greater potential for C. glabrata ATCC 2001 and the C. glabrata CG66 isolate with a Minimum Inhibitory Concentration MIC from 3.90 to 7.81 μg mL−1 and fungicidal action from 7.81 to 15.62 μg mL−1. The complexes inhibited and degraded biofilms by up to 90% and did not present mutagenic and cytotoxic potential at the concentrations evaluated for MIC. Thus, the complexes examined herein suggest promising alternatives for the development of new antifungal drugs.

Background: Heterocyclic compounds containing nitrogen atoms such as pyrazoles have a long history and applicability in the field of medicinal chemistry. Many compounds containing pyrazole moiety have been reported in the available literature for their prominent biological activities, including antimicrobial activity against different microorganisms. Over the years, there has been a concern with the many health problems associated with the dramatic increase of microbial infections and resistance to standard drugs, so there is a need for the development of more effective antimicrobial agents. Pyrazoles and their derivatives are promising candidates to bypass these problems with good safety profiles, and there is a wide range of synthetic methodologies for their obtainment. This review aims to compact a literature survey (2012-2017) very informative and helpful for researchers who wish to study or continue the development of new, potent and broad-spectrum antimicrobial compounds. Methods: This review encompasses reports on the synthesis and antimicrobial evaluation of synthetic pyrazoles from the year 2012 to 2017, which were extracted from bibliographic databases such as PubMed, scielo, sciencedirect, scifinder, and scopus. The main keywords in our search were “pyrazole” and “antimicrobial activity”, in which we made efforts to include synthetic and biological methodologies that can be useful for laboratories of different levels of infrastructure. Moreover, inclusion/ exclusion criteria was applied to select quality reports which could demonstrate different tools of antimicrobial evaluation, focusing on the advances made in the area, such as evaluation in silico and exploration of the possible mechanism of action for active compounds. Results: Thirty-four papers were included in this work, which was displayed chronologically from the year 2012 to 2017 in order to enhance the advances made in the area, with at least five reports from each year. We found that the most commonly tested bacterial strains are Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and from the year 2016 onwards Mycobacterium tuberculosis. The most common tested fungal strains are Candida albicans, Aspergillus flavus, and Aspergillus niger. The majority of articles expressed the antimicrobial results as a zone of inhibition, leading to the determination of the Minimum Inhibitory Concentration (MIC) and a probable mechanism of action for the most prominent compounds, considering cytotoxicity. Aromatic aldehydes and ketones are key reactants to obtain important precursors for the synthesis of pyrazoles, such as chalcones, together with alkyl or phenylhydrazines and thiosemicarbazide. A great variation in the reported MICs was found as there is no standard maximum limit, but many compounds exhibited antimicrobial activity comparable or better than standard drugs, from which 10 reports active compounds with MIC lower than 5 μg mL-1. Conclusion: The findings of this work support the importance of pyrazole moiety in the structure of antimicrobial compounds and the versatility of synthetic methodologies to obtain the target products. Results clearly indicate that they are attractive target compounds for new antimicrobial drugs development. We hope that this information will guide further studies on continuing the search for more effective, highly active antimicrobial agents.

A series of functionalized 1,1,1-trihalo-4-methoxy-3-alken-2-ones [CX3C(O)CR1=CROMe, where X = F or Cl; R = n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-tridecyl, (CH2)2CH=C(Me)2, (CH2)2Ph, (CH2)2-(4-HOC6H4), (CH2)2-(4-MeOC6H4), (CH2)2CO2Me, (CH2)3CO2Me, CH(SMe)CH3, CH2(2-MeOC6H4), and R1 = H, and R = H and R1 = n-decyl] were synthesized from respective alkyl methyl ketones or aldehyde via acetal acylation using trifluoroacetic anhydride and trichloroacetyl chloride. 1,1,1-Trihalo-4-methoxy-3-alken-2-ones with acid-compatible substituents were easily hydrolyzed to respective trihalomethyl-1,3-diketones. The 1,1,1-trihalo-4-methoxy-3-alken-2-ones and/or respective trihalomethyl-1,3-diketones were reacted regiospecifically with hydroxylamine hydrochloride, leading to isoxazole derivatives, and with hydrazines, leading to respective 1H-pyrazole derivatives. The structures of all compounds were assigned based on nuclear magnetic resonance (NMR) and mass spectrometric data. This method represents an efficient pathway for the regioselective trihaloacetylation of asymmetrically substituted alkyl methyl ketones and highly self-condensing aldehydes. Moreover, this approach allows the introduction of biologically recognizable moieties, such as those from levulinic acid, sulcatone (prenyl), benzylacetone, anisylacetone, and raspberry ketone, as synthetic molecular targets.

New mononuclear cadmium (II) complexes based on thiocarbamoyl-pyrazoline ligands were synthesized and structurally characterized. Complexes 1, 2 and 3 possess similar structural behavior around the cadmium (II) atom which presented a distorted tetrahedral coordination geometry determined by using the τ4 (tau four) parameter analysis. Interesting photophysical properties as bluish emission at spectral range (330–450 nm) and nanoseconds fluorescence lifetime (1.05 up to 1.42 ns) were observed upon excitation of the prepared compounds at λex = 300 nm. This emission was tentatively assigned to the LLCT transitions of the type XLCT I(5p6) → π∗(conjugated pyrazoline system) according to the frontier orbital molecular calculations. The complete characterization of the prepared compounds also included X-ray structure determination, elemental analyses, IR spectroscopy, 1H and 13C NMR experiments, molecular absorption (UV–Vis) and luminescence studies.

This paper describes the synthesis and structural characterization of a novel, cheap and simple CoII complex (CoII(L)2Cl2) based on the 1,3,5-trisubstituted-pyrazoline ligand along with the electrochemical production of metal–organic electroactive films derived from this new complex. These systems were applied as electrocatalysts for hydrogen production (ACN/ACA or ACN/TFA medium) where both materials presented high performance toward hydrogen evolution. Compared to the CoII complex, the electroactive films exhibited significant electroactivity toward hydrogen evolution, presenting a remarkable TOF for H2 production (312 900 s−1, corrected by Faraday efficiency) in the presence of TFA. In addition, the generated metal–organic film showed high stability toward the electrocatalytic hydrogen production, supporting at least 1000 cycles at 20 mV s−1 in the large potential range investigated, as well as good performance and stability in the presence of 0.5 M H2SO4. Relevant insights into the mechanistic details and the role played by the CoII complex and the films during the catalytic hydrogen production are also discussed in light of the structural features and electrochemical experiments.

The essential oil of leaves and barks of Nectandra lanceolata, obtained by hydrodistillation, was characterized in terms of its chemical composition by GC-FID, GC-MS and NMR. The analyses and identiucation pointed by mass fragmentation pattern and retention index revealed the presence of 30 compounds in the oil from leaves and 36 compounds in oil from barks, representing 91.8 % of the total leaf oil and 96.5 % of the bark oil. The major compounds of the leaf oil were E-caryophyllene (12.45 %), biciclogermacrene (18.2 %) and spathulenol (16.7 %). In the oil from barks, the major compounds were guaiol (13.2 %), cubenol (7.6 %), α- epi-cadinol (4.8 %), γ-cadinene (7.6 %), α-pinene (6.9 %). Moreover, were evaluated the potential of inhibition against the resistant bacteria Acinetobacter baumannii and antitumor properties of oils. It was possible to conclude that oil from bark of Nectandra lanceolata present more potent activity than oil from leaves. The essential oil from bark of Nectandra lanceolata ...

An efficient synthesis of aromatic pyrazoles via cyclocondensation of epoxy chalcones with hydrazine is reported. When aminoguanidine hydrochloride is the dinucleophilic specie the reaction leads to a mixture of amidino pyrazole and a minor amount (15%) of an interesting co-product identified as 2,2'-(1,3-diphenylpropane-1,2-diylidene)bis(hydrazinecarboximidamide) dihydrochloride by X-ray diffraction and NMR. A plausible mechanism for the co-product formation via rearrangement of the epoxy chalcone into 1,2-diketone followed by the condensation with aminoguanidine reaction is proposed. DOI: http://dx.doi.org/10.17807/orbital.v9i3.972

The aim of this work was the production and characterization of films prepared from starch, gelatin and methyl esters of epoxidized macauba (Acrocomia aculeata), corn (Zea mays), pacu (Piaractus mesopotamicus), pintado (Pseudoplatystoma corruscans) and soybean (Glycine max) and also multilayer films of polyhydroxyalkanoates (PHA) conjugated with two of the epoxides that presented the best results in characterizations. The two types of films EEF (Epoxidized esters films) and EEFPHA (Epoxidized esters and PHA conjugated films) were both characterized for their visual aspects, solubility in water and acid, width, color, opacity, water vapor permeability, tensile strength and elongation. EEFPHA were also characterized by differential scanning calorimetry, scanning electron microscopy and X-ray diffraction analyses. The epoxidation reaction was successfully carried out; with the GC-MS analysis indicating the formation of epoxidized esters derived from linoleic and oleic acids. The addition of the epoxidized esters to the EEF films caused an increase in film thickness, opacity, solubility in water, tensile strength and elongation, while the solubility in acid presented the same value as compared to the blank sample. In the EEFPHA samples, addition of filmogenic solution of epoxidized esters from corn and macauba presented a value exceeding the standard in the thickness, opacity, water solubility, water vapor permeability and tensile strength analyses. In the analysis of solubility in acid these samples showed results below the standard, and the elongation test showed values very close. DSC, SEM and XRD results showed that there was a polymeric incorporation between the starch and the PHA.

This work describes the synthesis, structural characterization and emissive behavior of a new copper (I) complex based on 1-thiocarbamoyl-5-(4-methoxiphenyl)-3-phenyl-4,5-dihydro-1H-pyrazole ligand. A dimeric self-assembling via hydrogen bonding was determined by analyzing the short contacts present in the solid-state structure by means of X-ray crystallography. The spectroscopic properties were determined using UV-Vis and fluorescence experiments and an interesting behavior as bluish luminescence was assigned mainly to the mixed (MLCT + IL) electronic transitions of the Cu(I)d10 ® (S=C–Nligand) type. The complete characterization of the new copper (I) complex also included elemental analyses and IR spectroscopy. DOI: http://dx.doi.org/10.17807/orbital.v9i1.952

Fingerprints are unique to each individual, contributing to human identification in forensic cases. The powder technique being widely used is considered one of the most important in latent fingermarks analysis. In this sense, the present work aimed to synthesize 1-thiocarbamoyl-4,5-dihydro-1H-pyrazoles and apply them as powder agents to develop latent fingermarks. The compounds were prepared from an effective and green synthesis via the condensation of chalcones with thiosemicarbazide in ethanol under microwave irradiation. Pyrazoles were tested and compared with a standard white powder (Sirchie®) on glass surfaces using sebaceous and natural fingermarks so that molecule 2c has been shown to be more promising providing image clarity. The derivatives of pyrazoles were promising as an alternative latent fingermark, presenting high quality images for fingermarks, proving to be a great tool for forensic sciences.

Three novel highly photoluminescent mononuclear AuI compounds (1, 2, and 3) based on mixed phosphine/thiocarbamoyl-pyrazoline materials were synthesized at good yields using a sonochemical method and then structurally characterized. X-ray diffraction studies revealed the compounds to be mononuclear cationic complexes of the [Ph3PAu(L)]PF6 type with linear coordination geometry around AuI atoms. Investigation of photophysical properties showed an intense greenish blue emission when the complexes were excited at 305 nm in solution. The emission was attributed to mixed MLCT + IL and LLCT electronic transitions taking place after ligand complexation, as shown by DFT calculations. Full characterization of the compounds also comprised 1H and 13C NMR experiments, elemental analyses, infrared spectroscopy, and absorption–emission studies. Additionally, compounds 1, 2, and 3 and respective ligands were investigated as antibacterial agents against five Streptococcus aureus strains (Gram-positive) and one Escherichia coli strain (Gram-negative) with distinct antibiotic-resistance profiles. Cytotoxic activity was assessed using the MTT method against B16F10 melanoma, 4T1 mammary carcinoma, and normal BHK-21 baby hamster kidney cell lines. The synthesized AuI compounds proved more active than the respective precursors and free ligands. Tested as probes for cellular bioimaging, the complexes showed good biodistribution in the cytoplasm of MCF-7 and MDA-MB-231 (human breast adenocarcinoma cell lines).

Two novel mononuclear heteroleptic Cu(I) complexes based on mixed phosphine/thiocarbamoyl-pyrazoline ligands were synthesized and structurally characterized. For both complexes, similar structural behavior was observed around Cu(I) atoms, which exhibited a distorted tetrahedral coordination geometry identified using τ4 parameter analysis. Interesting photophysical properties, including strong absorption in the UV–Vis spectral range (200–450 nm) and orange-red emission, were observed in the solid state upon excitation of the prepared compounds at λex = 290 nm. As shown by TD-DFT studies, the absorption and emission behavior of the Cu(I) complexes proved primarily related to HOMO and HOMO−1 to LUMO ((M+X)LCT Cu(d10) → π∗(S C N)) transitions. Complete characterization of the compounds also included X-ray studies, elemental analysis, IR spectroscopy, cyclic voltammetry, and absorption/emission investigation.

Aminoguanidine and its derivatives have shown antiglycation activity and are effective antioxidants. Complexes with ligands derived from aminoguanidine are relevant to both medicinal and bioinorganic chemistry. In this article, we describe the synthesis and characterization of a new mononuclear complex of copper(II) with a chelating ligand derived from aminoguanidine. Single crystals of the resulting complex were obtained by recrystallization from isopropanol. The molecular structure of the complex was obtained by X-ray diffraction which shows a distorted square pyramidal geometry, where copper(II) is coordinated to four nitrogen atoms (base of the pyramid) and to one chlorine atom (pyramid peak). The spectroscopic behavior (FT-IR and UV–vis) of both the complex and the ligand were examined.

In this chapter, the main aspects about biodiesel synthesis and established quality parameters are reviewed and discussed in the perspective of oxidative stability. First, the characteristics, which define biodiesel as a promising, renewable green fuel, are listed. On the other hand, the propensity of biodiesel to oxidation is explained as one of the limitations to its application. Along this line of thought, the majority of natural and synthetic antioxidants usually applied in the industry are discussed, in which it can be noted that phenolic compounds are very representative. Chalcones containing hydroxyl groups in its structure are phenolic compounds, and so, their origins, sources, and synthetic approaches to obtain these types of molecules are presented. Antioxidant effects of hydroxychalcones already reported in the literature are pointed, and then an experimental topic shows the influence of two synthetic hydroxychalcones, namely (E)-1-(2-hydroxyphenyl)-3-phenylprop-2-en-1-one and (E)-1-(2-hydroxyphenyl)-3-(3-hydroxyphenyl) prop-2-en-1-one, on the oxidative stability of biodiesel obtained from frying soybean oil. The effects assessed by calorimetric analysis revealed interesting effects on the enhancement of biodiesel oxidative stability.

Pyrazoles have a representative history in medicinal chemistry. These nucleuses, molecules of synthetic origin, constitute a group of nitrogen heterocyclic compounds. Available literature particularly shows a variety of pyrazoles with antioxidant effect. In this connection, this review describes the advances on the green synthesis of pyrazoles with antioxidant activity, mainly covering the data published over the last seven years (2008-2014).

An electrophilic iodocyclization reaction involving alkynylated 2-iodoanisoles and molecular iodine in the presence of sodium bicarbonate was developed and diiodo-functionalized benzo[b]furans were obtained in yields from 45 to 99%.

3-(Thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carboximidamides were efficiently prepared through a cyclocondensation of thiophenylchalcones with aminoguanidine hydrochloride under ultrasonic conditions in the presence of KOH and ethanol as a green solvent in short reaction times (15-35 min) and good yields (62-95%). All compounds produced were evaluated against the human Jurkat and RS4;11 acute lymphoblastic leukemia cell lines of T- and B-cell origin, respectively, and the K562 myelogenous leukemia cell line. Six compounds presented half maximal inhibitory concentration (IC50) values around 15 µmol L-1 and five compounds presented IC50 values around 40 µmol L-1 for at least one of the three cell lines analyzed. One compound was not significantly cytotoxic, presenting IC50 value > 100 µmol L-1.

Whole mycelia of marine fungal strain Penicillium citrinum CBMAI 1186, both free and immobilized on cotton (Gossypium sp.), fibroin (Bombyx mori) and a local kapok (Ceiba speciosa), catalyzed the chemoselective reduction of chalcones [(E)-3-(4-fluorophenyl)-1-phenylprop-2-en-1-one 3a, (E)-3-(4-bromophenyl)-1-phenylprop-2-en-1-one 3b, (E)-3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one 3c, (E)-3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one 3d, (E)-3-(3-nitrophenyl)-1-phenylprop-2-en-1-one 3e] to dihydrochalcones [3-(4-fluorophenyl)-1-phenylpropan-1-one 4a, 3-(4-bromophenyl)-1-phenylpropan-1-one 4b, 3-(4-methoxyphenyl)-1-phenylpropan-1-one 4c, 1-(4-methoxyphenyl)-3-phenylpropan-1-one 4d, 3-(3-nitrophenyl)-1-phenylpropan-1-one 4e] in good yields. The immobilized fungus and free whole mycelium showed a similar behavior in the conversion of the chalcones. The hyphae immobilized on biopolymers were active in biotransforming the chalcones after being preserved for 30 days in refrigerator. Scanning electron micrographs showed that the cells of marine fungus P. citrinum CBMAI 1186 were intertwined with the fibers of the supports, allowing fast separation from the reaction media and easing reuse of the biocatalyst. It is concluded that marine fungus P. citrinum CBMAI 1186 presents potential for the biotransformations of reduction of chalcones (3a–e). This paper describes the first reported use of immobilized marine fungus in reactions catalyzed by enoate reductases.

Efficient heterocyclization of methyl 7,7,7-trifluoro-4-methoxy-6-oxo-4-heptenoate and methyl 7,7,7-trichloro-4-methoxy-6-oxo-4-heptenoate into isoxazole and pyrazole derivatives that represent a new type of glutamate-like 3-(trihalomethylated-1,2-azol-3-yl)propanoate is reported. Preparation of the key methyl 7,7,7-trihalo-4-methoxy-6-oxohept-4-enoate precursors from levulinic acid is also described. The synthetic potential of this synthetic protocol was indicated by the production of several methyl and ethyl 3-(isoxazol-3-yl)propanoates and 3-(1H-pyrazol-3-yl)propanoates, and the respective acid derivatives, in good (70–95%) yields. The crystal structure for ethyl 5-(3-ethoxy-3-oxopropyl)-1H-pyrazole-3-carboxylate (10c) has been determined by monocrystal X-ray diffraction analysis. The N–H…H intermolecular hydrogen bonds join the molecules into catamer.

Novel gold(I) complexes based on thiocarbamoyl-pyrazoline ligands were synthetized for the first time and their structural/photophysical properties were determined. Two new monocationic complexes of the type [(Ph)3PAu(L)]PF6 (L = 1-thiocarbamoyl-5-(4-halophenyl)-3-phenyl-pyrazoline) were prepared by reacting (Ph)3PAuCl and ligands in the presence of KPF6 in a 1:1:1 molar ratio in a MeOH/CH2Cl2 (1:1) medium in good yields. The two cationic units from both complexes possess similar structural behaviour around the Au(I) atom which presents a two-coordinate and an almost linear coordination geometry. It was found good correlation between absorption and emission spectra and the photophysical properties were described. The prepared complexes (1 and 2) are representative examples of Au(I)/d10 compounds that present bluish luminescence in the solid state at room temperature when excited at λex = 320 nm. The bluish emission that appears at ca. 415 nm for both cationic complexes was tentatively assigned to the LMCT excitations arising from sulphur based orbitals to the Au(I) atom (S → Au–P). Besides X-ray studies, the complete structural characterization of the prepared compounds also includes elemental analyses, IR spectroscopy, 1H and 13C NMR, UV–Vis absorption and luminescence studies.

In this review article we have gathered relatively recent publications involving modern methodologies for iodi- nation reactions of aromatic and heteroaromatic compounds using pure water or mixtures containing water as environ- mentally friendly media.

The reaction of aromatic and heteroaromatic compounds with molecular iodine in the presence of aqueous hydrogen peroxide using water without any co-solvent at 50 °C for 24 h produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in very good yields. In addition, a mechanistic investigation for the iodination process was carried out by mass spectrometry.

The Biginelli reaction is a multicomponent reaction involving the condensation between an aldehyde, a β-ketoester, and urea or thiourea, in the presence of an acid catalyst, producing dihydropyrimidinones (DHPMs). Owing to their important pharmacological properties, the DHPMs have been studied by many authors. However, most of the methodologies used for the synthesis of these compounds require drastic reaction conditions. In the current study, we report an efficient and clean procedure for preparing DHPMs by the use of citric acid or tartaric acid as a promoter of the Biginelli synthesis in ethanol as solvent. In addition, we have evaluated the antioxidant capacity of the compounds synthesized by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and the thiobarbituric acid-reactive species test. Two compounds presented antioxidant activity and also reduced lipid peroxidation at concentrations of 200 and 300 µM. In summary, we report an environmentally friendly procedure for the preparation of DHPMs and demonstrate the antioxidant capacity of some of the compounds. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:155–161, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20424

A rapid and cleaner procedure for the synthesis of a series of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles under ultrasonic irradiation in ethanol is described.

The antioxidant capacity of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles was evaluated. The values of antioxidant capacities of compounds 2d and 2e were found to be, respectively, 2,700 ± 150 and 3,135 ± 230 TE by the ORAC method, corresponding to a significant antioxidant capacity. recent publication, we reported the antioxidant capacity of phenylpyrazole using the ORAC method (14). In continua- tion of our research program, we report here the antioxidant evaluation of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4- phenylthiazoles, synthetic derivatives compounds of facile preparation (Scheme 1).

An ultrasound-assisted preparation of a series of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides that proceeds via the efficient reaction of chalcones with aminoguanidine hydrochloride under clean conditions is described.

A facile, one-pot, ultrasound-promoted synthesis of N-substituted 5-(3,3,3-trifluoro-2-oxopropylidene)pyrrolidin-2-ones from methyl 7,7,7-trifluoro-4-methoxy-6-oxohept-4-enoate and a wide range of primary alkyl(aryl)amines using ethanol as a green solvent and employing triethylamine as a base is described.

Pyrazoles have a representative history in medicinal chemistry. These nucleuses, molecules of synthetic origin, constitute a group of nitrogen heterocyclic compounds. Available literature particularly shows a variety of pyrazoles with antioxidant effect. In this connection, this review describes the advances on the green synthesis of pyrazoles with antioxidant activity, mainly covering the data published over the last seven years (2008-2014).

Heterocyclization of 1,1,1-trifluoro[chloro]-4-methoxy-4-[2-tienyl]-3-buten-2-one and 1,1,1-trifluoro[chloro]-4-methoxy-4-[2-furyl]-3-buten-2-ones into isoxazoles and pyrazoles derivatives as a new type of trihalomethylated bicyclic heterocycles is reported.