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The synthesis of 5-trifluoromethyl-1-phenyl-1H-pyrazoles from the reactions of 4-alkoxy-1,1,1-trifluoro-Ph, 4-MeC 6 H 4 , 4-FC 6 H 4 , 4-ClC 6 H 4 , 4-BrC 6 H 4, 4-IC 6 H 4, fur-2-yl] with phenyl hydrazine in the presence of ionic liquid [BMIM][BF 4 ] is reported. Synergic effects of ionic liquid and microwave irradiation in promoting pyrazole synthesis have been shown for the first time.

Ultrasonic irradiation was used in the synthesis of a series of novel 1,2,4-triazolo[1,5-a]pyrimidines. The products were synthetized from the cyclocondensation reaction of 1,1,1-trifluoro-4-metoxy-3-alken-2-one [CF3C(O)CHC(R)OMe, where R=Ph, 4-F-C6H4, 4-Br-C6H4, 4-I-C6H4, 4-CH3-C6H4, 4-CH3O-C6H4, Thien-2-yl, Biphen-4-yl] or β-enaminones [RC(O)CHCHNMe2, where R=Ph, 4-F-C6H4, 4-Br-C6H4, 4-I-C6H4, 4-CH3-C6H4, 4-CH3O-C6H4, 4-NO2-C6H4, Thien-2-yl, Biphen-4-yl, Naphth-2-yl, Pyrrol-2-yl, CCl3] with 5-amino-1,2,4-triazole in acetic acid at 99°C with 5-17 min of ultrasound irradiation. This methodology has shown several advantages, such as shorter reaction times, mild conditions, high regioselectivity, and excellent yields, when compared with conventional thermal heating (oil bath).

Este trabalho descreve a reação de ciclocondensação de 3-amino-5-metil-1H-pirazol com 1,1,1-tricloro-4-alcóxi-3-alquen-2-onas [CCl 3 C(O)CH=C(R 1 )OR, onde R 1 /R = H/Me, Me/Et, Et/Me, Pr/Et, Bu/Me, iso-Bu/Me] e β-dimetilaminovinil cetonas [R 2 C(O)CH=CHNMe 2 , onde R 2 = Ph, Ph-4-Me, Ph-4-F, Ph-4-Cl, Ph-4-Br, Ph-4-NO 2 , fur-2-il, tien-2-il, pirrol-2-il, pyrid-2-il], em refluxo de ácido acético para a obtenção de uma série de catorze pirazolo [1,5-a]pirimidinas. Os produtos foram obtidos em bons rendimentos (65-98%). Este trabalho apresenta ainda uma metodologia simples e seletiva para a obtenção de 3-bromo-pirazolo [1,5-a] IntroductionAmong the broad range of templates, heterocycle scaffolds represent the most promising molecules as lead structures in the discovery of novel synthetic drugs 1 and the revision of synthetic methods for their obtainment are intense.2 In particular, the pyrazolo[1,5-a]pyrimidine heterocyclic can be found in a large number of pharmaceutical agents with a diverse range of activities. Pyrazolo [1,5-a] 13 However, a facile procedure that can incorporate diversity structural it is high desirable. There are a limitedness number and variety of pyrazolo pyrimidines trifluoromethyl substituted described in literature.14 Conversely, pyrazolo[1,5-a] pyrimidines trichloromethyl substituted are rare. 15 The most convenient method to construct trihalogenated compounds is to use halogen-containing building blocks as starting reagents. 16,17 Our research group developed a general procedure for preparing β-alkoxyvinyl trihalomethyl ketones by acylation of enol ethers and acetals using 2-Methyl-7-Substituted Pyrazolo[1,5-a]pyrimidines J. Braz. Chem. Soc. 206 functionalized acyl groups CX 3 CO (where X = F and Cl). 16In addition, we have exhaustively studied the versatility of the β-alkoxyvinyl trihalomethyl ketones on heterocyclic synthesis and our research have resulting in outstanding contributions to heterocyclic synthesis. 2,16 On the other hand, aminopyrazoles are known to be highly reactive heterocyclic compounds, e.g., the nucleophilic attack of C-4 of the aminopyrazoles on the carbonyl groups, 18 and the N-nucleophilic attack on aromatic aldehydes yielding aldimines, have been extensively reported.19 Aminopyrazoles also react as electron-rich dienophiles in the inverse electron demand Diels-Alder [4+2] cycloaddition reactions. 20The use of 3-and 5-aminopyrazoles as precursors of fused heterocycles, such as pyrazolo[1,5-a]pyrimidines 21 and pyrazolo [3,4-b]pyridines 22 has also been described. Additionally, halogenation of pyrazolo[1,5-a]pyrimidines can be used to obtain key substructures in a large variety of compounds with important biological activities, and the halogenated compounds also can be used as reagents in cross-coupling reactions with terminal acetylenes, organotin aryl derivatives or aryl boronic acids. 23 Thus, in the course of our investigations on heterocyclic chemistry and in view of the growing importance of halogenated heterocycles, the aim of this study is to show...

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.