- Condensation of methylhydrazine with 4-ethoxy-1,1,1-trifluoro-3-buten-2-one. A reinvestigation
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In contrast to previous reports, 4-ethoxy-1,1,1-trifluoro-3-buten-2-one (1) was observed to react with methylhydrazine (2) in refluxing ethanol to yield 1-methyl-3-(trifluoromethyl)pyrazole (6) and 4,5-dihydro-1-methyl-5-(trifluoromethyl)pyrazol-5-ol (4). The later compound undergoes acid catalyzed dehydration to 1-methyl-5-(trifluoromethyl)pyrazole (3).
- Pavlik, James W.,Ayudhya, Theppawut Israsena Na,Tantayanon, Supawan
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- Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
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In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
- Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
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supporting information
p. 15396 - 15405
(2021/10/12)
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- Practical synthetic method for functionalized 1-methyl-3/5-(trifluoromethyl)-1H-pyrazoles
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A new, high-yielding, and practical method for synthesis of 1-methyl-3-(trifluoromethyl)-1H-pyrazole and 1-methyl- 5-(trifluoromethyl)-1H-pyrazole, key intermediates for important building blocks relevant to medicinal and agrochemistry, is developed. A one-step procedure for synthesis of the regioisomeric mixture of target pyrazoles was proposed starting from 4-ethoxy- 1,1,1-trifluoro-3-buten-2-one. The procedure for separation of this mixture was elaborated on the basis of the boiling point vs pressure diagram analysis. The efficient synthetic strategies for regioisomeric building blocks bearing CF3 groups at the 3rd and 5th positions were demonstrated. A set of 1-methyl-3-(trifluoromethyl)-1H-pyrazoles containing such a functional group as aldehyde, acid, boron pinacolate, lithium sulfinate, and sulfonyl chloride was synthesized based on lithiation of 1-methyl-3-(trifluoromethyl)- 1H-pyrazole in a flow reactor. Bromination of both 1-methyl-3-(trifluoromethyl)-1H-pyrazole and 1-methyl-5-(trifluoromethyl)-1Hpyrazole by NBS in mild conditions was performed. The introduction of the functional group at the 4th position of 1-methyl-5- (trifluoromethyl)-1H-pyrazole was illustrated by the optimized synthesis of the corresponding aldehyde and acid based on the Br-Li exchange in an appropriate bromide. Alternatively, the introduction of the functional group (acid and boron pinacolate) at the 5th position of 1-methyl-5-(trifluoromethyl)-1H-pyrazole was performed based on the direct ortho-metalation (DoM) reaction of 4- bromo-1-methyl-5-(trifluoromethyl)pyrazole followed by catalytic reductive debromination.
- Tairov, Maxim A.,Levchenko, Vitalina,Stadniy, Ivan A.,Dmytriv, Yurii V.,Dehtiarov, Serhii O.,Kibalnyi, Mykola O.,Melnyk, Anton V.,Veselovych, Stanislav Y.,Borodulin, Yurii V.,Kolotilov, Sergey V.,Ryabukhin, Sergey V.,Volochnyuk, Dmitriy M.
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p. 2619 - 2632
(2020/12/29)
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- Ionic Liquids, Method for manufacturing thereof, and Electrochemical Devices Comprising the Same
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The present invention concerns ionic liquids comprising at least one pyrazolium cation which are substituted by at least one fluorine atom and at least one anion obtainable from 4-ethoxy-1,1,1-trifluoro-3-butene-2-one (ETFBO). The ionic liquids according to the present invention can be used as electrolytes for electrochemical and/or optoelectronic devices.
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Page/Page column 6; 10
(2013/12/02)
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- IONIC LIQUIDS, METHOD FOR MANUFACTURING THEREOF, AND ELECTROCHEMICAL DEVICES COMPRISING THE SAME
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The present invention concerns ionic liquids comprising at least one pyrazolium cation which are substituted by at least one fluorine atom and at least one anion obtainable from 4-ethoxy- 1,1,1 -trifluoro-3-butene-2-one (ETFBO). The ionic liquids accordin
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Page/Page column 10
(2013/12/03)
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- Synthesis of Some Trifluoromethyl Substituted 1-Methylpyrazoles
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The major products from the reaction of β-alkoxyvinyl trifluoromethyl ketones 1a-c with methylhydrazine (2) in absolute ethanol are the 3-(trifluoromethyl)-substituted-1-methylpyrazoles 3a-3c with lesser amounts of the 5-(trifluoromethyl)-substituted prod
- Pavlik, James W.,Ayudhya, Theppawut Israsena Na,Tantayanon, Supawan
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p. 1087 - 1089
(2007/10/03)
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- Switchable reactivity: The site-selective functionalization of trifluoromethyl-substituted pyrazoles
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Modern organometallic methods enable the regioflexible conversion of simple heterocyclic starting materials into families of isomers and congeners. Depending on the choice of the reagent, 1-methyl-5-(trifluoromethyl)pyrazole (1) undergoes deprotonation and subsequent carboxylation mainly or exclusively at either the 4-position of the heterocycle or at the nitrogen-attached methyl group. Similarly, 1-phenyl-5-(trifluoromethyl)pyrazole (5) and 3-methyl-l-phenyl-5-(trifluoromethyl)pyrazole (8) are selectively attacked by lithium diisopropylamide at the heterocyclic 4-position and by butyllithium concomitantly at the 4-position and the ortho position of the phenyl ring. In contrast, metalation of 1-methyl-3-(trifluoromethyl)pyrazole (2) occurs only at the 5-position, whatever the organometallic or metal amide base. Further sites become accessible to functionalization if bromine is introduced into the heterocyclic or aromatic ring. This has been demonstrated with 4-bromo-1-methyl-5-(trifluoromethyl)pyrazole (3), 4-bromo-l-methyl-3-(trifluoromethyl)pyrazole (4), 4-bromo-1-methyl-5-(trifluoromethyl)pyrazole (7) and 1-(2-bromophenyl)-5-(trifluoromethyl)pyrazole (6). Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Schlosser, Manfred,Volle, Jean-Noel,Leroux, Frederic,Schenk, Kurt
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p. 2913 - 2920
(2007/10/03)
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- A convenient method to obtain 4,5-dihydro-1H-1- methylpyrazoles by a ring transformation reaction
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A convenient method for the synthesis of alkyl[aryl]- substituted 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1- methylpyrazole (2) from a new ring transformation reaction of alkyl[aryl]-substituted-5-hydroxy-5-trifluoromethyl-4,5-dihydro- 1H-1-pyrazolethi
- Bonacorso, Helio Gauze,Wastowski, Arci Dirceu,Zanatta, Nilo,Martins, Marcos Antonio Pinto
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p. 1457 - 1465
(2007/10/03)
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- Haloacetylated Enol Ethers. 2. Synthesis of 5-Trifluoromethylpyrazoles
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1-Methyl-5-(trifluoromethyl)-1H-pyrazoles 2,3 and 4,5-dihydro-1-phenyl-5-(trifluoromethyl)-1H-pyrazol-5-ol 4 were prepared by reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones 1 and hydrazine, methylhydrazine, and phenylhydrazine, respectively, in good yields.Compound 1 proved to be a versatile building block for the regiospecific construction of pyrazole rings having an 5-trifluoromethyl substituent.
- Braibante, Mara E. F.,Clar, Gunter,Martins, Marcos A. P.
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p. 1159 - 1160
(2007/10/02)
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