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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.

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%.

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

Reaction of trifluoroacetylated Kabbe adducts (IV) with phenylhydrazine or methylhydrazine proceeds with apposite regioselectivity furnishing chromenopyrazoles (VI) or (VIII), respectively.

Title compounds are synthesized in high yields from butenones (I) and urea in short reaction times compared to other known methods.

The reaction proceeds via in situ prepared (Me-CH=CH-CH2)Al2Br3 and (H2C=CH-CH2)Al2Br3, respectively.

Rufinamide analogues of type (III)/(IV) are prepared by 1,3-dipolar cycloaddition and/or electrocyclization reactions of trifluoroalkenones of type (I) with 2,6-difluorobenzyl azide (II).

Cycloaddition reactions between the nitrile group of β-cyanocarboxylic acids with sodium azide in the presence of zinc chloride afford tetrazolic acids, structural analogues of succinic acid.

Title compounds (IV) are obtained in a two-step procedure that involves the reaction of enones (I) with hydrazones (II), followed by deprotective hydrolysis and intramolecular nucleophilic heterocyclization.

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.

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 highly regioselective and inexpensive method is developed for the synthesis of 1,2-dihydropyridines.

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.

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%).

Synthesis of 4-alkoxy-1,1-dichloro-3-alken-2-ones [CHCl 2 C(O)C(R 2 ) C(R 1 )-OR, where R, R 1 , R 2 = Et, H, H; Me, Me, H; Et, H, Me; Me, –(CH 2 ) 2 –; Me, –(CH 2 ) 3 –; Et, Et, H; Et, Bu, H; Et, i -Pr, H; Et, i -Bu, H; Me, Ph, H; Me, thien-2-yl, H] from acylation of enol ethers and acetals with dichloroacetyl chloride, in ionic liquid ([BMIM][BF 4 ] or [BMIM][PF 6 ]) is reported. The synthesis of alkenones [R 3 –C(O)C(R 2 ) C(R 1 )-OR], where R/R 1 /R 2 /R 3 = Et/H/H/Ph, t -Bu/H/H/Ph, Me/-(CH 2 ) 4 /Ph, Me/-(CH 2 ) 4 /Me] from the reaction of enol ethers with benzoyl chloride or acetyl chloride, in ionic liquid [BMIM][BF 4 ], is also reported. Last products are described for the first time.

11 Pyridone derivatives of type (III) are prepared using triethylamine as catalyst and [bmim]BF4 as solvent.

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).

In this study, diethylaminosulfur trifluoride (DAST) was successfully applied in monofluorination reactions of some trifluoromethyl substituted 2-hydroxy-2H-chromenones, employing a general, mild, and efficient methodology. The fluorinated compounds (2-fluoro-2H-chromenones) were synthesized as unique products by a chemoselective reaction in 63–81% yield despite the presence of different reactive sites subjected to reactions with DAST.

A series of fluorine-containing 4,5-dihydro-1H-pyrazoles (III) are obtained in a efficient and green synthesis using microwave irradiation and solvent-free conditions.

All products are purified by recrystallization and subsequent drying in a desiccator under reduced pressure over phosphorous pentoxide.

A facile and convenient access to a new series of succinyl-spaced pyrazoles via regioselective cyclocondensation of alkenone (I) with succinic acid dihydrazide (II) is reported.

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 reaction of cyclic enones (I) with diamines or amino alcohols affords the products with high purity in good to excellent yields.

The preparation of NH-pyrazoles according to A) is superior to the classical conditions in EtOH [cf.

The mechanism for the dehydration and unexpected loss of the methyl carboxylate group at higher temperatures is discussed.

The regiochemistry of the acylation of enol ethers, generated in situ, from acetals of unsymmetrical ketones is reported. These results demonstrate a convenient one-pot method to obtain a series of β-methoxyvinyl trichloromethyl ketones [CCl3COCHC(OMe)R, where R=Et, n-Bu, i-Pr, (CH2)2C(OMe)CHC(O)CCl3 and (CH2)5CO2CH3)] in high yields.

A convenient method to obtain β-alkyl-β-methoxyvinyl trifluoromethyl ketones [CF 3 COCHC(OMe)R, where R = Et, n -Pr, i -Pr, i -Bu, t-Bu, –(CH 2 ) 2 OMe] from the regiospecific acylation of kinetic enol ether generated in situ is reported. The unsymmetrical ketone dimethyl acetals react with trifluoroacetic anhydride in the presence of pyridine using dry chloroform as solvent with a temperature range of 25–60°C. These acetals [R–C(OMe) 2 Me] are obtained from the reaction of alkyl methyl ketones with trimethyl orthoformate in the presence of p -toluenesulfonic acid as catalyst in pure methanol as solvent. The new acetylated enol ethers proved to be versatile building blocks for the construction of interesting alkyl trifluoromethyl substituted heterocycles. Thus, examples of isoxazoline, pyrazoline, pyrazole and pyrimidinone have been obtained in good yields (62–79%).