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A simple procedure for the synthesis and characterization of new 3-alkoxy-3-(1H-tetrazol-5-yl)propionic acids and 2-(1H-tetrazol-5-yl)tetrahydrofuran- and -(1H-tetrazol-5-yl)-2H-pyran-3-carboxylic acids from the [2 + 3] cycloaddition reactions between the nitrile group of β-cyanocarboxylic acids with sodium azide in the presence of zinc chloride is described. The tetrazolic acids were isolated in moderate to good yields and are structurally analogous to succinic acid.

This paper describes firstly the synthesis of a new series of 3-hydroxy-2-[(3(5)-(methyl/phenyl)-5(3)-(trifluoromethyl)-1 H -pyrazol-4-yl)arylmethyl]-cyclohex-2-en-1-ones (2), where aryl = C 6 H 5 , 4-NO 2 C 6 H 4 , 4-OCH 3 C 6 H 4 , from an ANRORC ring transformation reaction of 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2 H -chromen-5(6 H )-ones (1), where acyl = acetyl and benzoyl, in the presence of hydrazine hydrate, at 63–90% yields. In subsequent steps, an oxidative aromatization reaction from 2 was done in an iodine/methanol medium for the preparation of 3(5)-trifluoromethyl-5(3)-methyl-4-[(2,6-dimethoxyphenyl)-(4-methoxyphenylmethyl)]-1 H -pyrazole (3) at 72% yields. Also, the alkylation reaction using benzyl chloride easily converted a pyrazole like 2 to its N -benzyl derivative (4), at 69% yield. Finally, the structural assignment of compounds 2–4 was deduced by mass spectrometry, X-ray crystal diffraction and density functional theory (DFT) calculations, which clearly and unambiguously furnished values very close to those determined from 1 H, 13 C and 19 F NMR data.

1-(Pentafluorophenyl)-4,5-dihydro-1H-pyrazoles were synthesized from the cyclocondensation reactions of 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (CX3C(O)CH=C(R1)OR, where X = F, Cl; R = Me, Et; R1 = H, Me, Et, n-Pr, i-Pr, n-Bu, i-Pent, Ph, 4-Cl-C6H4, 4-Br-C6H4, 4-F-C6H4) with pentafluorophenyl hydrazine. Pyrazoles were obtained under microwave irradiation in solvent-free conditions or under conventional heating in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4]. These procedures furnished products in moderate to good yields in a short reaction time. Atom economy, reaction mass efficiency (RME), and environmental factor (E-factor) were determined for the cyclocondensation reaction performed under microwave (MW)/solvent-free and under conventional thermal heating/[BMIM][BF4] conditions. RME and E-factor indicated that the solvent-free procedure is invariably less green than [BMIM][BF4] when the isolated product was considered.

This paper describes a mild method for regioselective reduction of 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2 H -chromen-5(6 H )-ones, where acyl = Ac, Bz, 2-thenoyl; and aryl = Ph, 4-NO 2 C 6 H 4 , 4-OCH 3 C 6 H 4; employing sodium borohydride as the reducing reagent for successful preparation of a series of nine new 3-acyl-4-aryl-2-(trifluoromethyl)-8a-hydroxy-octahydrochromen-5-ones. Yields in the range of 25–63% were obtained when the reduction reactions were performed at room temperature using ethanol as the solvent. When 3-acetyl-2-hydroxy-5-methoxy-4-phenyl-2-(trifluoromethyl)chromane was also tested under similar conditions, the 3-(1-hydroxyethyl)-3,4-dihydro-2 H -chromane derivative was obtained at 83% yield. A representative X-ray diffraction ORTEP for an example of 2-(trifluoromethyl)-octahydrochromen-5-one is shown and the reduction mechanisms discussed.

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

5-Bromo[5,5-dibromo]-1,1,1-trihalo-4-methoxy-3-penten[hexen]-2-ones are explored as precursors to the synthesis of 3-ethoxymethyl-5-trifluoromethyl-1H-pyrazoles from a cyclocondensation reaction with hydrazine monohydrate in ethanol. 3-Ethoxymethyl-carboxyethyl ester pyrazoles were formed as a result of a substitution reaction of bromine and chlorine by ethanol. The dibrominated precursor furnished 3-acetal-pyrazole that was easily hydrolyzed to formyl group. In addition, brominated precursors were used in a nucleophilic substitution reaction with sodium azide to synthesize the 3-azidomethyl-5-ethoxycarbonyl-1H-pyrazole from the reaction with hydrazine monohydrate. These products were submitted to a cycloaddition reaction with phenyl acetylene furnishing the 3-[4(5)-phenyl-1,2,3-triazolyl]5- ethoxycarbonyl-1H-pyrazoles and to reduction conditions resulting in 3-aminomethyl-1H-pyrazole-5-carboxyethyl ester. The products were obtained by a simple methodology and in moderate to good yields.

A simple procedure to obtain 4-acyl-1-substituted-1,2,3-triazoles, using a deep eutectic solvent (DES), ChCl and ethylene glycol at a 1 : 2 ratio, as the reaction medium is described. The products were obtained in high selectivity and good yields (70–84%). The advantages of the method include easy work-up, metal-free conditions, inexpensiveness, and the ability to be used four times without a loss in yield.

An efficient one-pot transition metal-free procedure for the synthesis of new pyrazolo[1,5-a]quinoxalin-4(5H)-ones from easily prepared 1-(2-chlorophenyl-5-ethylcarboxylate)pyrazoles and various primary alkylamines is described. The key steps involved in the synthesis of the new 5,6-fused ring system are the formation of an amide intermediate followed by an intramolecular N-arylation reaction via nucleophilic aromatic substitution.

A simple and regioselectively controlled method for the preparation of both 1,4- and 1,6-regioisomers of 1-substituted 4(6)-trifluoromethyl-pyrimidin-2(1H)-ones is described. Both regioisomers were synthesized from the cyclocondensation reaction of 4-substituted 1,1,1-trifluoro-4-methoxybut-3-en-2-ones: with nonsymmetric ureas for the 1-substituted 4-(trifluoromethyl)pyrimidin-2(1H)-ones (1,4-isomer) and with nonsymmetric 1-substituted 2-methylisothiourea sulfates for the synthesis of 1-substituted 6-(trifluoromethyl)pyrimidin-2(1H)-ones (1,6-isomer). Each method furnished only the respective isomer in very good yields. The structure of the products was assigned based on the 1H and 13C NMR as well as 2D HMBC spectral analysis.

A mild and efficient protocol for the assembly of tetra-substituted 5-trifluoromethylpyrazoles is presented, involving halogenation at the 4-position of readily prepared tri-substituted 5-trifluoromethylpyrazoles to give 4-halo-1-phenyl-5-trifluoromethyl pyrazoles, and subsequent palladium-catalyzed Negishi or Buchwald–Hartwig cross-couplings to install carbon or nitrogen-based 4-substituents. Key to the success of these challenging cross-couplings is the use of XPhos and JosiPhos CyPF-tBu ligands, respectively.

The title pyrimidinones are highly regioselectively obtained by cyclocondensation of trichloro-alkenones with non-symmetric substituted isothiourea sulfates under mild basic conditions.

A concise method to synthesize 1-substituted 4-amino-2-(trifluoromethyl)-1H-pyrroles from the heterocyclization reaction of 5-bromo-4-methoxy-1,1,1-trifluoropent-3-en-2-ones with amines is described. This method has the following advantages: it uses a wide range of primary amines, starting materials are easily available, it is simple to perform, the reaction conditions are mild, it is environmentally friendly, and it furnishes yields of up to 98%.

This Letter reports the first series of seven examples of novel 7-amine-spiro[chromeno[4,3-b]quinoline- 6,1′-cycloalkanes], where cycloalkane is cyclopentane, cyclohexane, cycloheptane, 2-methyl-, 3-methyl-, 4-methyl-, and 4-t-butyl-cyclohexane. These new compounds were synthesized at yields of 30–65% by a one-pot cyclocondensation reaction of 2-aminobenzonitrile and seven examples of spiro[chroman-2,1′-cycloalkan]-4-ones, using AlCl3 as the catalyst, without solvent and under conventional thermal heating. Subsequently, these spirochromeno-quinolines were subjected to AChE and cytotoxicity activity, and molecular docking studies. Both results for these new tacrine analogues were correlated with the structural features and showed the best results for the tacrine hybrid that possesses the spirocyclopentane moiety.

Metal-free electrophilic fluorination, promoted by Selectfluor, of pyrazoles with methylene groups (CH2X), in which X = OH, OMe, F, N3, and NHMe at the C-4 position furnished the 4-fluoro-pyrazole products from unexpected C–C bond cleavage, at moderate to good yields. Otherwise, under the same reaction conditions, when X = NEt2 or SPr, the oxidation product 4-formyl-pyrazole was obtained.

A new one-pot method, for the synthesis of polysubstituted pyrrolo[3,4- d ]pyridazinones, is presented. The protocol consists in cascade reactions performed in the same media: (i) the thermal in situ pyrrole formation by the reaction of vinyl azides with 1,3-dicarbonyl compounds, via the 1,2-addition of 1,3-dicarbonyl compounds to 2 H -azirine intermediates; (ii) the nucleophilic addition of hydrazines to the ketone group present in the pyrroles previously formed, followed by intramolecular cyclization with the bordering ester, which furnishes the respective pyrrolo[3,4- d ]pyridazinones, substituted at the pyrrole and/or pyridazinone rings. All transformations occur in a two-step one-pot methodology, and a series of ten new compounds were obtained at yields of 42–87%.

A study is presented for the synthesis of a series of 1-tert-butyl-3(5)-(trifluoromethyl)-1H-pyrazoles from the reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF3C(O)CH=C(R1)(OR), where R = Et and R1 = H or R = Me and R1 = Me, Ph, 4-Me-C6H4, 4-MeO-C6H4, 4-F-C6H4, 4-Cl-C6H4, 4-Br-C6H4, 4-I-C6H4, fur-2-yl, thien-2-yl, or naphth-2-yl] with tert-butylhydrazine hydrochloride. When [BMIM][BF4] (1-butyl-3-methylimidazolium tetrafluoroborate) and pyridine were used as the reaction media, we obtained a mixture of 1-tert-butyl-3(5)-trifluoromethylpyrazoles. The formation of 5-trifluoromethyl-1-tert-butyl-1H-pyrazoles with high regioselectivity occurred when the reaction was carried out with NaOH in EtOH. The formation of 1-tert-butyl-3-trifluoromethyl-1H-pyrazoles occurred, after hydrolysis of the 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones in H2O and H2SO4, followed by cyclization in [BMIM][BF4] and pyridine.

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

This paper describes the one-pot simple and efficient oxidative aromatization reaction employing an iodine/alcohol medium for the preparation of a series of 11 new 3-acyl-2-hydroxy-5-alkoxy-4-aryl-2-(trifluoromethyl)chromanes, where acyl = Ac, Bz, furan-2-oyl; aryl = Ph, 4-NO 2 C 6 H 4 , 4-OCH 3 C 6 H 4 and alkoxy = OMe, O-Pr n , EtO and OBn from the respective 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2 H -chromen-5(6 H )-ones. Yields in the range of 50–89% were obtained when the oxidative reactions were performed using both conventional thermal heating (CTH) and microwave (MW) procedures. In general, the MW method produced similar yields with shorter reaction times and easier reaction workups. As an example, a representative X-ray diffraction ORTEP for 3-benzoyl-2-hydroxy-5-methoxy-4-methoxyphenyl-2-(trifluoromethyl)chromane is also shown.

In this work, 3-haloacetyl-4-methylquinolines were synthesized from the reaction of 4-alkoxy-3-alken-2-ones [R¹C(O)CH=C(R²)OCH3, where R¹ = CF3, CCl3, CHCl2, CF2Cl, CF2CF3 and R² = Me, Et, Pr, Bu, i-Bu and i-Pe] and 2-aminoacetophenone. The reaction was performed in ionic liquid and 4-toluene sulfonic acid under microwave irradiation. Results showed that the catalytic method was effective. Products were formed in a short time (10-20 min) and presented good yields (70-91%). Neste trabalho, 3-haloacetil-4-metilquinolinas foram sintetizadas a partir da reação de 4-alcóxi-3-alquen-2-onas [R¹C(O)CH=C(R²)OCH3, onde R¹ = CF3, CCl3, CHCl2, CF2Cl e CF2CF3 e R² = Me, Et, Pr, Bu, i-Bu e i-Pe] e 2-aminoacetofenona. A reação foi realizada em líquido iônico e ácido 4-toluenosolfônico sob irradiação de micro-ondas. Os resultados mostraram que o método catalítico foi efetivo e os produtos foram formados em tempos de reação curtos (10-20 min) e com bons rendimentos (70-91%).

A simple and convenient procedure for the synthesis of a new series of 3-ethoxypyrrolidine-2,5- diones and cis-2,3,3a,6a-tetrahydrofuro(2,3-c)pyrrole-4,6(5H)-diones derivatives is described. All compounds were obtained from the direct cyclization of two β-cyanocarboxylic acids with primary amines and amino alcohols in short reaction time and good yields.

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

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

The X-ray diffraction data determined for eight 3-(R3), 4-(R4), 4,4-(R4/R4′) and/or 5-(R5) 5-hydroxy-4,5-dihydroisoxazoles [where R3 = Ph, R4/R4′ = H/H, R5 = CCl3 (1); R3 = 4-Br-C6H4, R4/R4′ = H/H, R5 = CCl3 (2); R3 = thien-2-yl, R4/R4’ = H/H, R5 = CCl3 (3); R3 = Ph, R4 = Ph, R4’ = OH, R5 = Me (4); R3 = Me, R4/R4′ = N–OH, R5 = Me (5); R3 = CF3, R4/R4’ = H/H, R5 = CMe2CH2OH (6); R3 = H, R4 = 4-I-C6H4, R4’ = H, R5 = 4-I-C6H4 (7); R3/R4 = –(CH2)3–, R4′ = H, R5 = CF2CF2H (8);] are discussed. The crystalline structure of compounds 1–3 is described for the first time and crystalline structure of compounds 4–8 has already been described in literature. It was found that the supramolecular auto-organization of 1–8 is characterized by hydrogen bonds invariably involving the hemiacetal hydroxyl group. Compound 5 is the only exception, where the hydroxyl oxime group is the participant in the hydrogen bond. Compounds 4 and 8 present intermolecular contact between the hydroxyl group of the hemiacetal and the nitrogen atom of the 4,5-dihydroisoxazole ring. Compound 7 presents similar interaction, where the hydroxyl contact is with the oxygen atom of the 4,5-dihydroisoxazole ring. Moreover, the crystal structure of compound 6 was stabilized by O–H⋯O interaction between the hydroxyl group of hemiacetal and the hydroxyl group of the alcohol function attached at the 5-position of 4,5-dihydroisoxazole. The crystal structure of compounds 1–3, as described here for the first time, was similar to that of compounds 4 and 7, showing a hydrogen bond O(51)-H(51)⋯N(2) between the hydroxyl group and the nitrogen atom of the isoxazoline ring. This means that the crystal structure of these compounds was governed by hydrogen bonds O–H⋯N, involving the hydroxyl of the hemiacetal group and the nitrogen atom of the 4,5-dihydroisoxazole ring. This interaction is relatively robust, showing a pattern in the crystal packing. Compounds 1–3 also have their crystal stabilized by more weak interactions of type Cl⋯Cl, involving the chlorine atom of the trichloromethyl group.

The crystalline structure of five 3-(R3) and/or 5-(R5)-substituted 7-trichloromethyl-2-methylpyrazolo[1,5-a]pyrimidines [where R3, R5 = H, Pr (1); Br, H (2); Br, Me (3); H, H (4); and H, Me (5)] were studied from X-ray diffractometry data. It was found that compounds presented themselves as main intermolecular interactions: Cl⋯Cl (1), Br⋯Cl (2,3); and Cl⋯N-pyrimidine (4,5). In compounds 1–3, other interactions reinforce the stabilization of the crystal structure, such as C–H⋯N-pyrimidine (1,2) Cl⋯π-pyrazole (1); C–Br⋯π-pyrimidine (2); and pyrazole-π⋯π-pyrimidine, pyrimidine-π⋯π-pyrimidine (3). This study shows that the Cl⋯N-pyrimidine interactions present in compounds 4 and 5 are a typical halogen⋯base Lewis interaction. Geometric information of Cl⋯Br and Cl⋯Cl interactions could be explained by the σ-hole concept. In compound 2, the chlorine atom participates with its σ-hole, while in compound 3, the σ-hole of the interaction comes from the bromine atom. The Cl⋯π-pyrazole and Br⋯π-pyrimidine interactions have a different nature; while the Br⋯π-pyrimidine interaction is a strong lone pair⋯π interaction, the Cl⋯π-pyrazole is a new interaction: σ-hole⋯π.

In this work, a new catalytic system to synthesize a series of new (E)-1-(benzylideneamino)-3-cyano-6-(trifluoromethyl)-1H-2-pyridones from the cyclocondensation reaction of benzylidene cyanoacetohydrazide with 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF3C(O)C(R2) = C(R1)(OR), where R = Me, Et; R1 = H, Me, Pr, Bu, Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph; R2 = H, Me and R1,R2 = –(CH2)4–] is presented. The products were obtained at room temperature in moderate to good yields (42–87%). Comparison of the catalytic system with a conventional method was not possible, because the products were obtained only when the new catalyst system—consisting of triethylamine and Lewis acid in ionic liquid [BMIM][BF4]—was used.

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

The efficient synthesis of 4,5-dihydro-1H-pyrazoles from the reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF3C(O)CH=C(R1)(OR), where R = Me, Et and R1 = H, Me, Et, Pr, i-Bu, Ph, 4-Me-C6H4, 4-F-C6H4, 4-Cl-C6H4, fur-2-yl, Naphth-2-yl, biphenyl-4-yl] and ethyl 3-hydrazino-3-oxopropionate [NH2NHC(O)CH2C(O)OEt] is reported. The products were obtained in good yields (72–87%). Two protocols were developed: (1) conventional thermal heating using EtOH as solvent and under solvent-free conditions, and (2) a microwave-assisted method using EtOH as solvent and under solvent-free conditions. The E-factor was determined for all protocols, and the results showed that the microwave-assisted method under solvent-free conditions results in a greener process.

The synthesis of 5-trifluoromethyl-1-phenyl-1H-pyrazoles from the reactions of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF3C(O)CH=C(R1)OR, where R = Me, Et; R1 = H, Me, Bu, i-Bu, Ph, 4-MeC6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-IC6H4, fur-2-yl] with phenyl hydrazine in the presence of ionic liquid [BMIM][BF4] is reported. Synergic effects of ionic liquid and microwave irradiation in promoting pyrazole synthesis have been shown for the first time. R = Me, Et R1 = H, Me, Bu, i-Bu, Ph, 4-Me-C6H4, 4-F-C6H4, 4-Cl-C6H4, 4-Br-C6H4, 4-I-C6H4, Fur-2-yl.

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

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

The facile and convenient access by a conventional procedure in ethanol as solvent to a new series of succinyl-spaced pyrazoles including 1,4-bis[5-(trichloromethyl)-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl]butane-1,4-diones (64–82%) and the respective dehydrated derivatives as 1,4-bis[5-(trichloromethyl)-1H-pyrazol-1-yl]butane-1,4-diones in 57–82% yields, from the regioselective cyclocondensation reactions of 4-substituted 4-methoxy-1,1,1-trichloroalk-3-en-2-ones with succinic acid dihydrazide, where the 4-substituents are Me, Ph, 4-FC6H4, 4-ClC6H4, 4-NO2C6H4, 2-furyl, and 2-thienyl, is reported. J. Heterocyclic Chem., 2011.

The crystalline structure of four enaminones [R 1 C(O)CH C(Me)NR 2 R 3 , where R 1 = CCl 3 , R 2 = H, R 3 = Bn ( 1 ); R 1 = CHCl 2 , R 2 = H, R 3 = Bn ( 2 ); R 1 = CCl 3 , R 2 , R 3 = (CH 2 ) 4 ( 3 ); R 1 = CHCl 2 , R 2 , R 3 = (CH 2 ) 2 O (CH 2 ) 2 ( 4 )] were determined by X-ray diffraction. It was found that compounds 1 – 4 adopted the enaminone tautomeric form. Compounds 1 and 2 displayed intramolecular hydrogen bonds (2.658 ⩽ d (N⋯O) ⩾ 2.726), which are associated with the presence of resonance-assisted hydrogen bonds (RABHs). The bond length data implicated that π-delocalization in 3 and 4 was reduced in comparison to 1 and 2 and this can be interpreted as some gain of the aromatic character in the chelate form. In addition, it was shown that the crystal packing of these enaminones is governed by C H⋯O, C H⋯Cl, Cl⋯Cl weak interactions and these interactions presents interatomic distances in accordance with the reported van der Waals radii of the atoms involved. The energy of these intermolecular interactions was calculated as a difference in energy between the complex on the one hand and the sum of isolated monomers on the other. The energetic contributions of each interaction to the stability of the crystalline packing were determined, firstly for each interaction independently and secondly, for all interactions simultaneously. The additive effect was verified by the fact that the sum of all individual energetic contributions resulted in the same stability as that found when the energetic contribution of all interactions was calculated simultaneously.

Reactions of trihalomethylated enones with dimethylisothiourea sulfate furnish chemoselectivity 2-methylthiotetrahydropyrimidine or -dihydropyrimidine derivatives depending on the reaction conditions and electronic effects of the substituents on the enones.

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

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

A series of NH-pyrazoles was efficiently synthesized from the reaction of b-dimethylaminovinylketones ([R 1 C(O)C(R 2 )@CHN(Me2)], where R

A simple and efficient one-pot synthesis of tetrahydrooxazolo[3,2-a]pyridines and hexahydroimidazo[1,2-a]pyridines, and some related oxa- and aza-condensed tetrahydropyridines, from the reaction of 2-alkoxy-5-(trifluoroacetyl)-2,3-dihydro-2H-pyrans (cyclic enones) with amino alcohols and primary diamines, is reported. Products were isolated with high purity and in very good yields.

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

A simple one-pot procedure to obtain a series of five- and six-membered heterocycles, in three different ionic liquids ([BMIM][BF4], [BMIM][OH] and [HMIM][HSO4]) is described. The synthetic protocol involves the reaction between β-enamino ketone derived from 1,4-diacetylbenzene and hydroxylamine, hydrazines (R1NHNH2, where R1 = H, Ph, 4-O2N-Ph, 2,4-(O2N)2-Ph, C6F5, CO2Me, CONH2, CH2CH2OH, t-Bu) or amidines (R2C(NH)NH2, where R2 = NH2, Ph), furnishing bis-isoxazoles, bis-pyrazoles and bis-pyrimidines in good yields and short reaction times.

This paper describes the conventional regioselective synthesis of a series of new succinyl spacer bis-(3,5-substituted 2-pyrazolines and 1H-pyrazoles), namely; 1,4-bis[5-(trifluoromethyl)-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl]butane-1,4-diones (46-88%) and the respective dehydrated system (60-78%), new 1-[5-(trifluoromethyl)-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl]-4-oxobutane hydrazides (52-81%) and the non-symmetrical 2-pyrazolines derivatives thereof as 1-[5-(trifluoromethyl)-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl)-4-(5-(trichloromethyl)-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl]butane-1,4-diones (75-91%). All succinyl substituted bispyrazoles were obtained from the cyclocondensation reactions of 4-substituted 4-alkoxy-1,1,1-trihaloalk-3-en-2-ones, where the 4-substituents are H, Me, Ph, 4-FC6H4, 4-ClC6H4, 4-OMeC6H4, 4-NO2C6H4, 1-naphthyl and 2-furyl, with succinic acid dihydrazide in ethanol as solvent under controlled reaction conditions. Este trabalho apresenta a síntese regiosseletiva de séries de bis-2-pirazolinas e bis-1H-pirazóis succinil intercalados inéditas, denominadas 1,4-bis[5-(trifluormetil)-5-hidróxi-4,5-diidro-1H-pirazol-1-il]butano-1,4-dionas (46-88%), o respectivo sistema desidratado (60-78%), 1-[5-(trifluormetil)-5-hidróxi-4,5-diidro-1H-pirazol-1-il]-4-oxabutano hidrazidas (52-81%) e 2-pyrazolinas derivadas não simétricas, como 1-[5-(trifluormetil)-5-hidróxi-4,5-diidro-1H-pirazol-1-il)-4-(5-(triclorometil)-5-hidróxi-4,5-diidro-1H-pirazol-1-il]butano-1,4-dionas (75-91%). Todos os bis-pirazóis succinil substituídos foram obtidos a partir de reações de ciclocondensação de 4-alcóxi-1,1,1-trialo-3-alquen-2-onas 4-substituídas (4-substituinte = H, Me, fenil, 4-FC6H4, 4-ClC6H4, 4-OMeC6H4, 4-NO2C6H4, 1-naftil and 2-furil), com dihidrazida succínica, em etanol como solvente, sob condições reacionais convencionais controladas.

A convenient method for the synthesis of a novel series of four 5-trilfluoromethyl-1,2,3,4-tetrahydroacridines, by intramolecular cyclization reactions of 2-trifluoroacetyl-1-(arylamino)-cyclohexene using polyphosphoric acid (PPA), is described. The six new enaminoketone intermediates were obtained by an oxygen–nitrogen exchange reaction from 2-trifluoroacetyl-1-methoxycyclohexene with six 4-substituted anilines.

In order to evaluate the effect of a series of 10 different ionic liquids ([BMIM][BF4], [BMIM][Br], [OMIM][BF4], [BMIM][PF6], [DBMIM][Br], [DBMIM][BF4], [BMIM][OH], [BMIM][SCN], [HMIM][HSO4] and [HMIM][CF3CO2]) the cyclocondensation reaction between 4-dimethylamino-1-phenyl-3-alken-2-ones (RC(O)CH CHNMe2, where R = Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-NO2-Ph, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyrid-2-yl, hexyl, dimethoxymethyl) and tert-butylhydrazine was performed. The effects of each ionic liquid are discussed and the best yields for the cyclocondensation reaction studied were obtained using [BMIM][BF4].

Nonsteroidal antiinflammatory drugs (NSAIDs) are commonly used for treatment of arthritis. However, their long-term use has been associated with considerable morbidity, limiting their application. Thus, there remains a need to develop new drugs for the effective and safe relief of chronic inflammatory pain. In this context, the present study was designed to evaluate the antinociceptive and antiedematogenic effects of the 5-trifluoromethyl-4,5-dihydro-1H-pyrazole derivatives EPFCA3 and MPFCA4 after acute (1-1000 micromol/kg) and chronic (100 micromol/kg for 15 days) administration in rats submitted to a model of adjuvant-induced arthritis. We also analyzed some biochemical indicators of toxicity (alanine aminotransferase, aspartate aminotransferase, urea and creatinine levels) after prolonged administration of these compounds. We found that acute and chronic subcutaneuous administration of EPFCA3 and MPFCA4 produces an antinociceptive, but not antiedematogenic, effect on the arthritis animal model induced by complete Freund's adjuvant (CFA). No signs of toxicity were observed in the animals chronically treated with EPFCA3 or MPFCA4. Dipyrone (1-1000 micromol/kg) was used as the positive control and its effect was similar to that of the novel pyrazoles. The activity of tissue myeloperoxidase, the tissue TNF-alpha level and the serum haptoglobin level was increased by intraplantar CFA injection. However, chronic administration of EPFCA3, MPFCA4 or dipyrone was not able to alter the relation between these parameters and inflammation. Our results suggest that EPFCA3 and MPFCA4 are good candidates for the development of new drugs for pain treatment.