- Synthesis of fluorinated pyrazole derivatives from β-alkoxyvinyl trifluoroketones
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1,1,1-Trifluoro-4-ethoxy-3-butene-2-one, 3-trifluoroacetyl-3, 4-dihydro-2H-pyran or furan reacted readily with pentafluorophenylhydrazine or per(poly)fluoroacectylhydrazine RfCO-NHNH2 (Rf: BrCF2, C3F7) to give N-substituted-5-hydroxy-5-trifluoromethyl heterocycles Y-N-N=CH-CH(R)C(OH)CF3 (Y: H, Arf or RfCO), which were dehydrated by treatment with P2O5 or SOCl2 to form N-substituted 5-trifluoromethyl pyrazoles Y-N-N=CH-C(R)=CCF3 (Y: H, Arf or RfCO) in good yields.
- Song,Chu,Zhu
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- The effect of pressurized carbon dioxide on the cyclocondensation reaction between 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones and hydrazines
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The synthesis of 1-unsubstituted and 1-phenyl-5-trifluoromethylpyrazoles from the reaction of 4- alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF 3C(O)CH=C(R1)OR, where R = Me, Et and R1 = H, Me, Ph] with hydrazines [NH2NHR2, where R2 = H, Ph] in pressurized carbon dioxide is reported for the first time. Reaction conditions such as pressure, temperature and time were evaluated. The methodology developed herein was suitable to synthesize products in moderate to excellent yields (60 % - 96 %) and short reaction times (15 - 45 min).
- Rossatto, Marcelo,Casanova, Caroline,Lima, Ana P.,Emmerich, Daniel J.,Oliveira, Vladimir,Dallago, Rogerio M.,Frizzo, Clarissa P.,Moreira, Dayse N.,Buriol, Lilian,Brondani, Sergio,Zanatta, Nilo,Bonacorso, Helio G.,Martins, Marcos A. P.
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p. 224 - 232
(2014/03/21)
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- New strategy for the regioselective synthesis of 1-phenyl-3- trifluoromethyl-1H-pyrazoles
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A regioselective synthesis of 3-trifluoromethyl-1-phenyl-1H-pyrazoles (1,3-isomers) as well as their 1,5-isomers (5-trifluoromethyl-1-phenyl-1H- pyrazoles), is described. The 1,3-isomers were obtained from the reaction of 4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones with arylhydrazones followed by deprotective hydrolysis while the 1,5-isomer was obtained by direct cyclocondensation of 4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones with phenylhydrazine. An unequivocal assignment of the 1,3- and 1,5-isomers of the pyrazole products is given.
- Zanatta, Nilo,Amaral, Simone S.,Dos Santos, Josiane M.,Da Silva, Andréia M.P.W.,Schneider, Juliana M.F.M.,Fernandes, Liana Da S.,Bonacorso, Helio G.,Martins, Marcos A.P.
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p. 4076 - 4079
(2013/07/25)
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- New one-pot, efficient, and regioselective method for the synthesis of 3-Trifluoromethyl-1H-1-phenylpyrazoles and alkyl 3-carboxylate analogs
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An efficient and regioselective procedure for the synthesis of a series of alkyl(aryl/heteroaryl) substituted 3-trifluoromethyl-1H-1-phenylpyrazoles and alkyl 3-carboxylate analogs, from the cyclocondensation reactions of 4-alkoxy-1,1,1-trihaloalk-3-en-2-ones [CX3C(O)CR2=CR 1(OMe/OEt), where R1 = H, Me, Ph, 2-Furyl; R2 = H; R1-R2 = -C4H8- and X = F, Cl] and 1-phenylsemicarbazide in an acidified alcoholic medium (R 3OH/H2SO4), where R3 = Me, Et, Pri was successfully applied and is described here in detail. 2012 Elsevier Ltd. All rights reserved.
- Bonacorso, Helio G.,Correa, Michele S.,Porte, Liliane M.F.,Pittaluga, Everton P.,Zanatta, Nilo,Martins, Marcos A.P.
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p. 5488 - 5491
(2012/11/07)
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- Synergic effects of ionic liquid and microwave irradiation in promoting trifluoromethylpyrazole synthesis
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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(R 1)OR, where R = Me, Et; R1= H, Me, Bu, i-Bu, Ph, 4-MeC6H4, 4-FCsu
- Buriol, Lilian,Frizzo, Clarissa P.,Prola, Lizie D. T.,Moreira, Dayse N.,Marzari, Mara R. B.,Scapin, Elisandra,Zanatta, Nilo,Bonacorso, Helio G.,Martins, Marcos A. P.
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experimental part
p. 1130 - 1135
(2012/06/18)
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- Pyrazole synthesis under microwave irradiation and solvent-free condition
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This paper presents a study of solvent-free reaction conditions using microwave irradiation (MW) to obtain 4,5-dihydro-1H-pyrazoles and dehydrated pyrazoles by the cyclocondensation reaction of 4-alkoxy-1,1,1-trifuoro-3-alken- 2-ones [CF3C(O)CH=C(R1)OR, where R/R1 = Et/H, Me/Me and Me/Ph] with hydrazines [NH2NH-R2, where R2 = CO2Me, Ph, CH2CH2OH]. Some reactions were performed under the same reaction conditions using methanol as solvent. The results obtained using MW equipment for synthesis under solvent-free conditions were also compared with those described in literature for conventional thermal heating and heating with a domestic MW oven. In general, the products furnished by reaction in MW equipment for synthesis presented better yields and shorter reaction times. In addition, it was demonstrated that the reaction temperature altered the formation of products for each hydrazine showing that MW equipment for synthesis is effcient for reacting hydrazines and 4-alkoxy-1,1,1-trifuoro-3- alken-2-ones to procedure the products 4,5-dihydro-1H-pyrazoles and dehydrated pyrazoles.
- Buriol, Lilian,Frizzo, Clarissa P.,Marzari, Mara R. B.,Moreira, Dayse N.,Prola, Lizie? D. T.,Zanatta, Nilo,Bonacorso, Helio G.,Martins, Marcos A. P.
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experimental part
p. 1037 - 1044
(2010/10/21)
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- Microwave assisted regiospecific synthesis of 5-trifluoromethyl-4,5- dihydropyrazoles and - Pyrazoles
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(Chemical Equation Presented) The regiospecific synthesis of a series of twelve 5-trifluoromethyl-4,5-dihydropyrazoles and -pyrazoles from the cyclocondesation reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [F 3CC(O)CH=C(R1)OR,
- Martins, Marcos A. P.,Pereira, Claudio M. P.,Moura, Sidnei,Frizzo, Clarissa P.,Beck, Paulo,Zanatta, Nilo,Bonacorso, Helio G.,Flores, Alex F. C.
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p. 1195 - 1199
(2008/09/17)
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