Solid-Phase Synthesis of Substituted Pyrazolones from Polymer-Bound β-Keto Esters

Tietze, Lutz F.; Evers, Holger; Hippe, Thomas; Steinmetz, Adrian; Töpken, Enno

doi:10.1002/1099-0690(200105)2001:9<1631::aid-ejoc1631>3.3.co;2-r

Cited by 3 publications

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“…The electron rich p -methoxyphenyl ketone further retarded the progress of this reaction, and 27% of starting β-ketoester was isolated upon workup and product purification. Fortunately, we found that TFA, or even better, TiCl 4 , effectively catalyzed this conversion. Isomerization between the E - and Z -hydrazones must also be taken into account as only the Z -configuration is capable of cycloelimination .…”

Section: Resultsmentioning

confidence: 90%

Synthesis of Spiro-Fused (C5)-Isoxazolino-(C4)-pyrazolones (1-Oxa-2,7,8-triazaspiro[4,4]-2,8-dien-6-ones) via 1,3-Dipolar Cycloaddition and Cycloelimination

et al. 2002

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An efficient and selective method for the synthesis of spiro-fused (C5)-isoxazolino-(C4)-pyrazolones (C) is reported. The process consists of utilizing the Baylis-Hillman reaction-or a quicker, stepwise MAC procedure-to give I followed by 1,3-dipolar cycloaddition and Swern oxidation to give beta-ketoesters H, which were condensed with hydrazine derivatives to provide hydrazones that underwent cycloelimination. These novel spiro-fused (C5)-isoxazolino-(C4)-pyrazolones were confirmed by spectroscopic analysis as well as single-crystal X-ray of 5. We also concluded that all condensations/cycloeliminations, except with hydrazine itself, were more effective with catalysts or higher reaction temperatures. For example, TiCl(4) was an efficient catalyst for hydrazone formation and cycloelimination with methylhydrazine, while phenyl-, benzyl-, and (4-methoxyphenyl)hydrazine reacted effectively without catalyst in refluxing xylene.

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Section: Resultsmentioning

confidence: 90%

Synthesis of Spiro-Fused (C5)-Isoxazolino-(C4)-pyrazolones (1-Oxa-2,7,8-triazaspiro[4,4]-2,8-dien-6-ones) via 1,3-Dipolar Cycloaddition and Cycloelimination

et al. 2002

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“…They are traditionally synthesized by treatment of β-ketoesters with substituted hydrazines under acidic conditions at elevated temperature . Some developments include solid-phase synthesis and a two-step reaction of benzoyl hydrazones with silyl enolates in the presence of a catalyst . The use of more environmentally friendly protocols for the synthesis of substituted pyrazolones has been reported .…”

Section: Five-membered Heterocycles With Two Heteroatomsmentioning

confidence: 99%

Solvent-Free Heterocyclic Synthesis

et al. 2009

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Clarissa P. Frizzo was born in Ivora ´, Rio Grande do Sul state, Brazil, in 1983. She received her undergraduate degree in Pharmacy from the Federal University of Santa Maria in 2005, and in 2007 she obtained her M.Sc. degree from the Federal University of Santa Maria, under the supervision of Professor Marcos A. P. Martins, working with the use of ionic liquids in the synthesis of heterocycles. She started her Ph.D. studies under the supervision of Professor Marcos A. P. Martins, and currently she is focusing on her Sandwich Ph.D. in the Universidade Nacional de Educacio ´n a Distancia in Spain, under the guidance of Professor Rosa M. Claramunt Vallespı ´, where she is studying the supramolecular structure of heterocycles. Dayse das Neves Moreira was born in Canguc ¸u, Rio Grande do Sul state, Brazil, in 1984. She received her undergraduate degree in Chemistry from the Federal University of Pelotas, RS, in 2006, and in 2008 she received her M.S. degree, from the Federal University of Santa Maria, RS, Brazil, working under the direction of Professor Marcos A. P. Martins, working with the use of ionic liquids in the synthesis of heterocycles. Currently, she is a Ph.D. student with Professor Marcos A. P. Martins in the Department of Chemistry of the Federal University of Santa Maria. Her major research interest is to develop new methodologies to synthesize heterocyclic compounds. Lilian Buriol was born in Santa Izabel do Oeste, Parana ´(PR) state, Brazil, in 1984. She received her undergraduate degree in Chemistry from the State University of Centro-Oeste (PR). In 2008, she completed her M.S. degree at the same university under the supervision of Professor Yohandra R. Torres, working with oil and ethanol extracts of propolis. After that, she started her Ph.D. studies in the Department of Chemistry of the Federal University of Santa Maria under the supervision of Professor Marcos A. P. Martins. Her research interest is to develop new methodologies to synthesize heterocyclic compounds along the lines of green chemistry.

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“…1 In this context, pyrazolones are traditionally prepared from the reaction of beta-keto esters with hydrazine derivatives in an acidic environment at high temperatures. 15 In addition, the so-lid-phase synthesis reaction, 16 two-step reaction of benzoyl hydrazones with silyl enolates in catalytic medium, 17 microwave synthesis method, 18 solvent-free medium reaction 14 are also available in literature. Some of the features as above stated generally include the synthesis and application of these compounds in the form of small molecules.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization and Thermal Degradation Kinetics of a New Pyrazole Derived Methacrylate Polymer, Poly(1,3-Diphenyl-1H-Pyrazol-5-Yl Methacrylate)

Kurt

Koca²

2022

ACSi

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Since the behavior and properties of macromolecular pyrazole derived polymers differ from their small molecules, such polymers are in the class of well-defined functional polymers due to the fact that the pyrazole ring contains two π-bonds as well as two hetero atoms in its structure, and this feature makes them important in the fields of scientific and technological applications. In present study, therefore, we synthesized a new pyrazole derived methacrylate monomer, 1,3-diphenyl-1H-pyrazol-5-yl methacrylate, from the reaction of 1,3-diphenyl-5-pyrazolone with methacryloyl chloride in the presence of triethylamine. After that, its homopolymerization was carried out by free radical polymerization method at 60 °C initiated with benzoyl peroxide. Spectral characterizations were achieved by 1H-NMR and FTIR spectroscopies. The kinetics of thermal degradation of the new polymer, poly(1,3-diphenyl-1H-pyrazol-5-yl methacrylate), poly(DPPMA), were investigated by thermogravimetric analysis (TGA) at different heating rates. The initial decomposition temperature of the polymer changed from 216.3 °C to 243.5 °C depending on the increasing heating rate. The thermal decomposition activation energies in a conversion range of 7–19% were 79.45 kJ/mol and 81.56 kJ/mol by the Flynn– Wall–Ozawa and Kissinger methods, respectively. Thermodegradation mechanism of the poly(DPPMA) were investigated in detail by using different kinetic methods available in the literature such as Coats-Redfern, Tang, Madhusudanan and Van Krevelen. Among all these methods, the best result was obtained for Coats-Redfern method (E = 90.93 kJ/mol) at the optimum heating rate of 15 °C/min for D1 mechanism that is a one-dimensional diffusion type deceleration mechanism.

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Solid-Phase Synthesis of Substituted Pyrazolones from Polymer-Bound β-Keto Esters

Cited by 3 publications

References 0 publications

Synthesis of Spiro-Fused (C5)-Isoxazolino-(C4)-pyrazolones (1-Oxa-2,7,8-triazaspiro[4,4]-2,8-dien-6-ones) via 1,3-Dipolar Cycloaddition and Cycloelimination

Synthesis of Spiro-Fused (C5)-Isoxazolino-(C4)-pyrazolones (1-Oxa-2,7,8-triazaspiro[4,4]-2,8-dien-6-ones) via 1,3-Dipolar Cycloaddition and Cycloelimination

Solvent-Free Heterocyclic Synthesis

Synthesis, Characterization and Thermal Degradation Kinetics of a New Pyrazole Derived Methacrylate Polymer, Poly(1,3-Diphenyl-1H-Pyrazol-5-Yl Methacrylate)

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