RESUMEN

This study reports the synthesis of a new series of pyrazole-isoxazolines, at very good yields, from the cyclocondensation reaction of pyrazole-enaminones with hydroxylamine hydrochloride. Dehydration of the pyrazole-isoxazolines furnished another new series of the respective pyrazole-isoxazoles, at excellent yields. Both series of the obtained compounds were screened for antimycobacterial activity, and compounds 4f and 5c showed significant inhibition of bacterial growth with a time- and concentration-dependent bactericidal effect. Cytotoxicity tests in VERO cell line did not indicate toxicity of compounds 4f and 5c regarding cellular prediction, NO production or dsDNA release. However, both compounds were associated with an increase in total ROS levels, providing induction of oxidative stress, but without compromising cellular targets. These results highlight compounds 4f and 5c as promising candidates for antimycobacterial treatment with a favorable safety profile.

RESUMEN

Pyrimidinone scaffolds are present in a wide array of molecules with synthetic and pharmacological utility. The inherent properties of these compounds may be attributed to intermolecular interactions analogous to the interactions that molecules tend to establish with active sites. Pyrimidinones and their fused derivatives have garnered significant interest due to their structural features, which resemble nitrogenous bases, the foundational building blocks of DNA and RNA. Similarly, pyrimidinones are predisposed to forming N-H···O hydrogen bonds akin to nitrogenous bases. Given this context, this study explored the supramolecular features and the predisposition to form hydrogen bonds in a series of 18 substituted 4-(trihalomethyl)-2(1H)-pyrimidinones. The formation of hydrogen bonds was observed in solution via nuclear magnetic resonance (NMR) spectroscopy experiments, and subsequently confirmed in the crystalline solid state. Hence, the 18 compounds were crystallized through crystallization assays by slow solvent evaporation, followed by single-crystal X-ray diffraction (SC-XRD). The supramolecular cluster demarcation was employed to evaluate all intermolecular interactions, and all crystalline structures exhibited robust hydrogen bonds, with an average energy of approximately -21.64 kcal mol-1 (∼19% of the total stabilization energy of the supramolecular clusters), irrespective of the substituents at positions 4, 5, or 6 of the pyrimidinone core. To elucidate the nature of these hydrogen bonds, an analysis based on the quantum theory of atoms in molecules (QTAIM) revealed that the predominant intermolecular interactions are N-H···O (average of -16.55 kcal mol-1) and C-H···O (average of -6.48 kcal mol-1). Through proposing crystallization mechanisms based on molecular stabilization energy data and contact areas between molecules and employing the supramolecular cluster and retrocrystallization concepts, it was determined that altering the halogen (F/Cl) at position 4 of the pyrimidinone nucleus modifies the crystallization mechanism pathway. Notably, the hydrogen bonds present in the initial proposed steps were confirmed by 1H NMR experiments using concentration-dependent techniques.

RESUMEN

An efficient [4 + 2] cyclization protocol to synthesize a series of twelve examples of 1,2,3-triazolo[4,5-b]aminoquinolines (5) as novel structurally modified tacrines was obtained by reacting readily accessible precursors (i.e., 3-alky(aryl)-5-amino-1,2,3-triazole-4-carbonitriles (3)) and selected cycloalkanones (4) of five-, six-, and seven-membered rings. We evaluated the AChE and BChE inhibitory activity of the novel modified tacrines 5, and the compound derivatives from cyclohexanone (4b) showed the best AChE and BChE inhibitory activities. Specifically, 1,2,3-triazolo[4,5-b]aminoquinolines 5bb obtained from 3-methyl-carbonitrile (3b) showed the highest AChE (IC50 = 12.01 µM), while 5ib from 3-sulfonamido-carbonitrile (3i) was the most significant inhibitor for BChE (IC50 = 1.78 µM). In general, the inhibitory potency of compound 5 was weaker than the pure tacrine reference, and our findings may help to design and develop novel anticholinesterase drugs based on modified tacrines.

Asunto(s)

Acetilcolinesterasa , Butirilcolinesterasa , Acetilcolinesterasa/metabolismo , Butirilcolinesterasa/metabolismo , Tacrina/farmacología , Simulación del Acoplamiento Molecular , Relación Estructura-Actividad , Inhibidores de la Colinesterasa/química , Estructura Molecular

RESUMEN

In this work, we present a regiocontrolled methodology to prepare 1-substituted-3(5)-carboxyalkyl-1H-pyrazoles using trichloromethyl enones as starting materials. It was found that the selectivity of the reaction depends on the nature of the hydrazine: when using arylhydrazine hydrochlorides, synthesis of the 1,3-regioisomer was achieved (22 examples, 37-97% yields), while the corresponding free hydrazine led exclusively to the 1,5-regioisomer (12 examples, 52-83% yields). The trichloromethyl group was used as a precursor for the carboxyalkyl moiety, furnishing a one-pot three-component regioselective protocol suitable for preparing both isomers at moderate to excellent yields. The selectivity of the reaction was investigated through NMR analyses and the structures of the products were unambiguously determined by SCXR analyses.

RESUMEN

Aim: The aim of the present preliminary case-control study was to test the sensitivity and specificity of salivary pipecolic acid in predicting head and neck squamous cell carcinoma (HNSCC). Methods: High-performance liquid chromatography was used for the analysis of non-stimulated saliva samples from 40 individuals: 20 in the case group (recently diagnosed with untreated HNSCC) and 20 in the control group (individuals without cancer). Both groups included patients taking daily oral hypoglycemic drugs (comorbidity). The case and control groups were matched at a proportion of 1:1 for sex and comorbidity. Results: Mean salivary levels of pipecolic acid were 169.38 ng/ mL in the case group and 114.66 ng/mL in the control group (p<0.001). Individuals who took oral hypoglycemic drugs had higher levels of pipecolic acid in both the case and control groups (p<0.001). The receiver operating characteristic curve analysis revealed 90% sensitivity and 65% specificity for head and neck cancer, with an area under the curve of 0.838 between the case and control groups. Conclusions: Pipecolic acid had high sensitivity for the diagnosis of HNSCC but low specificity in the sample analyzed. Our findings suggest that salivary pipecolic acid levels are associated with glucose homeostasis. Studies with larger samples are required to evaluate the specificity of this metabolite

Asunto(s)

Humanos , Masculino , Femenino , Saliva , Biomarcadores , Carcinoma de Células Escamosas de Cabeza y Cuello

RESUMEN

Due to several obstacles in treating tuberculosis (TB), the search for new therapeutic alternatives remains a global priority. The nitrogenous heterocyclic compounds are promising in searching for new anti-Mycobacterium tuberculosis molecules, and our previous results highlight the potential of tetrahydropyridines. After exploring the antimycobacterial potential and putative mechanism of action of a tetrahydropyridine derivative (NUNL02), we seek to measure the oxidative stress caused by NUNL02 inside the extracellular replicating M. tuberculosis since it could be the reason for the NUNL02 bactericidal effect against replicating and starved M. tuberculosis; and to evaluate the anti-M. tuberculosis activity of NUNL02 against the intracellular bacillus (even combined with an anti-TB drug) to explore the potential of this tetrahydropyridine as a promising adjuvant for TB therapy. Briefly, we assessed the activity of NUNL02 against the H37Rv strain and evaluated the combination of NUNL02 and rifampicin (RIF), at previously defined subinhibitory concentrations, against intramacrophage M. tuberculosis. NUNL02, in addition to promote the oxidative stress inside the extracellular replicating M. tuberculosis as a possible indirect mechanism of action, also presented bactericidal potential as promising as RIF against intracellular bacilli. Thus, our findings reinforce NUNL02 as a promising scaffold for the development of new options for TB.

Asunto(s)

Mycobacterium tuberculosis , Tuberculosis Ganglionar , Antituberculosos/farmacología , Antituberculosos/uso terapéutico , Humanos , Pruebas de Sensibilidad Microbiana , Pirrolidinas/farmacología , Rifampin/farmacología

RESUMEN

This study reports two strategies for preparing O-alkyl derivatives of 6-substituted-4-(trifluoromethyl)pyrimidin-(1H)-ones: a linear protocol of alkylation, using a CCC-building block followed by [3 + 3]-type cyclocondensation with 2-methylisothiourea sulfate and a convergent protocol based on direct alkylation, using 4-(iodomethyl)-2-(methylthio)-6-(trihalomethyl)pyrimidines. It was found that the cyclocondensation strategy is not feasible; thus, the direct chemoselective O-alkylation was performed, and 18 derivatives of the targeted pyrimidines were obtained in 70-98% yields. The structure of the products was unambiguously determined via single crystal X-ray analyses and two-dimensional nuclear magnetic resonance experiments.

RESUMEN

A convenient synthesis of a broad series of thirteen examples of alkyne-spacer derivatives 2 from the well-known Sonogashira cross-coupling reaction on diazenyl-pyrazolo[1,5-a]pyrimidin-2-amine compounds 1 is reported. The reactivity of heterocycles 1 due the presence of selected electron-donor (EDG) and electron-withdrawing (EWG) groups attached to different alkynes was evaluated. Also, the reactional versatility due the position variation of the bromo atom at the scaffolds 1 was also investigated. In general, derivatives presented strong absorption bands at the 250-500 nm optical window and UV to cyan emission properties. Also, the redox analysis was recorded by electrochemical cyclic voltammetry technique. For HSA biomacromolecule assays, spectroscopic studies by UV-Vis, steady-state and time-resolved emission fluorescence, and molecular docking calculations evidenced the ability of each compound to establish interactions with human serum albumin (HSA). Finally, the behavior presented for this new class of heterocycles makes them a promising tool as optical sensors for albumins.

Asunto(s)

Aminas , Albúmina Sérica Humana , Alquinos/química , Humanos , Simulación del Acoplamiento Molecular , Espectrometría de Fluorescencia

RESUMEN

The selective N- or O-alkylation of 4-(trihalomethyl)pyrimidin-2(1H)-ones, using 5-bromo enones/enaminones as alkylating agents, is reported. It was found that the selectivity toward the N- or O-regioisomer is driven by the substituent present at the 6-position of the pyrimidine ring, thus enabling the preparation of each isomer as the sole product, in 60-95% yields. Subsequent cyclocondensation of the enaminone moiety with nitrogen dinucleophiles led to pyrimidine-azole conjugates in 55-83% yields.

Asunto(s)

Alquilación , Isomerismo

RESUMEN

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-C6H4 (5a-g) or Ph (5h), and 5-aryl = Ph (a, h), 1-naphthyl (b), 4-Br-C6H4 (c), 4-F-C6H4 (d), 4-OCH3-C6H4(e), 4-NO2-C6H4 (f), 4-(N(CH3)2)-C6H4(g). The UV-Vis absorption properties of 2-pyrazolines were evaluated in DCM, MeCN, AcOEt, EtOH, and DMSO as the solvent and showed a fluorescence shift for the polar aprotic solvents. The steady-state fluorescence emission exhibited a band in the blue region when excited at the least energetic transition of each compound, although the excited-state intramolecular proton (ESIPT) effect was not detected. In the solid state, compounds presented similar behavior regarding absorption and emission properties compared to the solution assays. With the electrochemical analyses performed for the synthesized 2-pyrazolines, it was possible to conclude that the redox potentials were influenced by the electronic and steric effects of the substituents on the aryl rings and, according to the electronic nature of the substituents, which electron-donating groups were favored. Finally, the TD-DFT analyses revealed that all compounds had delocalized electron density throughout the 2-pyrazolines unit and were not influenced by the substituent bonded at C-5. Nonetheless, LUMO orbital analysis showed that only derivatives 5b and 5f have this localized density over the substituents.

Asunto(s)

Electrones , Protones , Colorantes , Solventes , Espectrometría de Fluorescencia

RESUMEN

The synthesis, structural analysis, and evaluation of the photophysical properties of twelve novel 2-aryl(heteroaryl)-6-(4-alkyl(aryl)-1H-1,2,3-triazol-1-yl)-4-(trifluoromethyl)quinolines (6-8), where aryl(heteroaryl)=Ph, 4-Me-C6 H4 , 4-F-C6 H4 and 2- furyl; 4-alkyl(aryl)=-CH2 OH, -(CH2 )5 CH3 and Ph, are reported. Hybrid scaffolds 6-8 were synthesized at 77-95 % yields by regioselective copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction of unpublished 6-azido-4-(trifluoromethyl)quinolines (2) with selected terminal alkynes (3-5). Azido intermediates 2 were obtained from the reaction of 6-amino-4-(trifluoromethyl)quinolines (1) and sodium azide at good yields (78-87 %). Compounds 6-8 were structurally fully characterized by 1 H-, 13 C- and 19 F- and 1 H-13 C 2D-NMR (HSQC, HMBC) spectroscopy, X-ray diffraction (SC-XRD) and HRMS analysis. Moreover, the photophysical properties, DNA- and HSA-binding experiments (bio-interactions), and molecular docking studies for compounds 6-8 were performed. These are discussed and compared with similar compounds from recent research.

Asunto(s)

ADN/química , Simulación del Acoplamiento Molecular , Albúmina Sérica Humana/química , Animales , Bovinos , Humanos , Procesos Fotoquímicos

RESUMEN

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.

RESUMEN

Imidazolium-based dicationic ILs (DILs) presenting antimicrobial activity and relatively low toxicity are highly desirable and are envisioned for use in live tissue to prevent bacterial or fungal infections. In this context, we present here DILs with dicarboxylate anions [Cn(MIM)2[Cn(MIM)2][CO2-(CH2)mCO2], in which n = 4, 6, 8, and 10, and m = 0, 1, 2, 3, 4, and 5. The results showed that DILs with an alkyl chain spacer of ten carbons were active against yeasts and the bacterial strains tested. However, most of the DILs were cytotoxic and toxic at 1 mM. By contrast, DILs with alkyl chains possessing less than ten carbons were active against some specific Candidas and bacteria (mainly S. aureus), and they showed moderate cytotoxicity. The best activity against Gram-positive bacteria was observed for [C4(MIM)2][Pim] toward MRSA. For the DILs described herein, their level of toxicity against C. elegans was lower than that of most of the mono- and dicationic IL analogs with other anions. Our results showed that the presence of carboxylate anions reduces the toxicity of DILs compared to DILs containing halide anions, which is particularly significant to the means of designing biologically active compounds in antimicrobial formulations.

RESUMEN

Prostate cancer is among the most common cancer diagnoses in men, and the best treatment for patients with metastatic disease in advanced stages is still unclear. Previously, we have demonstrated that the three 1-(3-(aryl-4,5-dihydroisoxazol-5-yl)methyl)-4-trihalomethyl-1H-pyrimidin-2- ones derivatives (8a, 8e and 9c) present important cytotoxicity and selectivity for tumoral cells. Considering that various cytotoxic drugs have been assessed in patients with prostate cancer, but few drugs show survival advantage, we decided to study these three compounds (8a, 8e and 9c) in prostate cancer cells, androgen receptor (AR)-positive 22Rv-1 and AR-negative PC-3 cells. We obtained the half maximal inhibitory concentration (IC50) of 8a, 8e and 9c in prostate cancer cells and based on high selectivity of 9c to PC-3 cells, we determined the mechanism of this compound to induce cell death through different methods. We show here that 9c compound induces cell cycle arrest in G2/M, increasing the levels of reactive oxygen species and DNA damage, and triggers DNA damage response by ataxia-telangiectasia mutated (ATM) and histone H2AX phosphorylation induction. The compound also led PC-3 to lipid peroxidation and mitochondrial depolarization which triggered the activation of intrinsic pathway, confirmed by increase of cleaved caspase-9 and 3. In this work we also show the ability of 9c in reducing vascular endothelial growth factor expression (VEGF) and inhibiting topoisomerase I enzyme, therefore indicating a potential new molecule to be further investigated for prostate cancer management.

Asunto(s)

Inhibidores de la Angiogénesis/farmacología , Apoptosis/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Neovascularización Patológica , Neoplasias de la Próstata/tratamiento farmacológico , Pirimidinonas/farmacología , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Daño del ADN , Regulación hacia Abajo , Puntos de Control de la Fase G2 del Ciclo Celular/efectos de los fármacos , Histonas/metabolismo , Humanos , Peroxidación de Lípido/efectos de los fármacos , Masculino , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Mitocondrias/metabolismo , Mitocondrias/patología , Células PC-3 , Fosforilación , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , Inhibidores de Topoisomerasa I/farmacología , Factor A de Crecimiento Endotelial Vascular/metabolismo

RESUMEN

Five new examples of 9,10-chloro(bromo)-7-amine-spiro[chromeno[4,3-b]quinoline-6,1'-cycloalkanes] - in which cycloalkanes = cyclopentane, cyclohexane, and cycloheptane - were synthesized at yields of 42-56%, using a sequential one-pot two-step cyclocondensation reaction of three different scaffolds of 2-aminobenzonitriles and the respective spiro[chroman-2,1'-cycloalkan]-4-ones, and using AlCl3 as the catalyst in a solvent-free method. Subsequently, the five new spirochromeno-quinolines and nine quinolines previously published by us (14 modified tacrine scaffolds) were subjected to AChE and BChE inhibitory activity evaluation. The molecule containing a spirocyclopentane derivative had the highest AChE and BChE inhibitory activity (IC50 = 3.60 and 4.40 µM, respectively), and in general, the non-halogenated compounds were better inhibitors of AChE and BChE than the halogenated molecules. However, the inhibitory potency of compounds 3a-n was weaker than that of tacrine. By molecular docking simulations, it was found that the size of the spirocarbocyclic moieties is inversely proportional to the inhibitory activity of the cholinesterases, probably because an increase in the size of the spirocyclic component sterically hindered the interaction of tacrine derivatives with the active site of tested cholinesterases. The findings obtained here may help in the design and development of new anticholinesterase drugs.

Asunto(s)

Inhibidores de la Colinesterasa/farmacología , Colinesterasas/metabolismo , Cicloparafinas/farmacología , Quinolinas/farmacología , Animales , Inhibidores de la Colinesterasa/síntesis química , Inhibidores de la Colinesterasa/química , Cicloparafinas/síntesis química , Cicloparafinas/química , Relación Dosis-Respuesta a Droga , Electrophorus , Caballos , Simulación del Acoplamiento Molecular , Estructura Molecular , Quinolinas/síntesis química , Quinolinas/química , Relación Estructura-Actividad

RESUMEN

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 ß-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 ß-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-ß-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.

RESUMEN

Herein, we evaluated tetrahydropyridine (THP) compounds (NUNM) as antimicrobials and inhibitors of the efflux mechanism in M. abscessus. subsp. abscessus. The modulation factor (MF) of efflux inhibitors was calculated from the minimum inhibitory concentrations (MICs) of amikacin (AMI), ciprofloxacin (CIP) and clarithromycin (CLA) in the absence and presence of subinhibitory concentrations of the NUNM compounds and canonical inhibitors carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and verapamil (VP). The kinetics of the intracellular accumulation of the fluorimetric substrate ethidium bromide (EtBr) was evaluated and calculated by the relative final fluorescence (RFF). In addition, molecular modeling simulations for the MmpL5 and Tap efflux transporters with ligands (CLA, NUNM, CCCP, VP and EtBr) were performed to better understand the efflux mechanism. We highlight the NUNM01 compound because it reduced the MICs of AMI, CIP and CLA by 4-, 4- and 16-fold, respectively, had the highest effect on EtBr accumulation (RFF = 3.1) and showed a significant in silico affinity for the evaluated proteins in docking simulations. Based on the analyses performed in vitro and in silico, we propose that NUNM01 is a potential pharmacophore candidate for the development of a therapeutic adjuvant for M. abscessus infections.

Asunto(s)

Antibacterianos/farmacología , Mycobacterium abscessus/efectos de los fármacos , Pirrolidinas/farmacología , Transporte Biológico/efectos de los fármacos , Simulación por Computador , Etidio/farmacocinética , Fluorometría/métodos , Humanos , Pruebas de Sensibilidad Microbiana/métodos , Simulación del Acoplamiento Molecular/métodos , Mycobacterium abscessus/metabolismo

RESUMEN

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.

RESUMEN

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%.

RESUMEN

Reaction of 5-bromo enones with pyrazoles provided a series of unexpected N,O-aminal derivatives, through a 1,4-conjugated addition at the ß-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.