N.m.r. Spectra and Stereoisomerism in Pyrazolines

Häßner, Alfred; Michelson, M.J.

doi:10.1021/jo01058a052

Cited by 48 publications

(8 citation statements)

References 1 publication

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“…The configuration of 8b and 8b′ can be established unambiguously by NMR using comparison with literature data. 4,5- cis -Disubstituted pyrazolines exhibit larger 3 J (HH) coupling constants (10–14 Hz) than trans -isomers (3–10 Hz) . These data are in perfect agreement with observed coupling values of cis -pyrazoline 8b′ (11.9 Hz) and trans -pyrazoline 8b (6.5 Hz).…”

Section: Resultsmentioning

confidence: 99%

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α,β-Disubstituted CF₃-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF₃-Pyrazoles

et al. 2021

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An efficient pathway toward a novel class of trifluoromethyl building blocks was elaborated. The reaction of α-CF3-enamines with arylaldehydes resulted in direct synthesis of α,β-diaryl-CF3-enones isolated in up to 93% yield as E-isomers. The possible reaction mechanism was proposed using the Zimmerman–Traxler model. The reaction of α,β-diaryl-CF3-enones with hydrazines opens a novel pathway to trifluoromethylated pyrazolines. Oxidation of pyrazolines with DDQ opened access to totally regioselective preparation of 3-CF3-pyrazoles isolated in high yield. Using this strategy, 4-arylated derivatives of known drugs Celebrex, Mavacoxib, and SC-560 can be synthesized.

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Section: Resultsmentioning

confidence: 99%

“…4,5-cis-Disubstituted pyrazolines exhibit larger 3 J(HH) coupling constants (10−14 Hz) than transisomers (3−10 Hz). 31 These data are in perfect agreement with observed coupling values of cis-pyrazoline 8b′ (11.9 Hz) and trans-pyrazoline 8b (6. 5 Hz).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

α,β-Disubstituted CF₃-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF₃-Pyrazoles

et al. 2021

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“…With semicarbazide two diastereoisomers were obtained in each case except in the reaction of 2-benzylidenecyclo-octanone. The differences in the chemical shift of 3-H in the diastereoisomeric pairs ( 3 j ( 4 ) , and (6)-- (7), can be attributed to the diamagnetic anisotropy of the neighbouring C(3a)-C(4) bond and to the preferential orientation of the phenyl group.' For these compounds, the CHy2HCI I are greater than those of J3,3a(tran~) and are in the ranges reported by Hassner and Michelson (10)(11)(12)(13)(14) Hz for the cis, and 3-10 Hz for the trans isomer).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and stereochemistry of substituted bi- and tri-cyclic 4,5-dihydropyrazoles

Lóránd¹,

Szabó²,

Földesi³

et al. 1985

J. Chem. Soc., Perkin Trans. 1

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“…But the lower J values compared to what is described in the literature [22][23] may be attributed to electronic environment effects. There is some indication that J trans decreases with increasing polarity of substituents on C-5 [24], but a generalization is still premature. It is therefore not surprising that, due to the polarity of the tiophen ring, the J values of our compounds (2.96-3.12 Hz) are lower than those bearing a phenyl ring [22][23].The geminal coupling constants (H a ,H b ) were 17.32-17.56 Hz, while the vicinal ones were 10.96-11.16 Hz and 2.96-3.12 Hz.…”

Section: Chemistrymentioning

confidence: 99%

1‐N‐Substituted Thiocarbamoyl‐3‐phenyl‐5‐thienyl‐2‐pyrazolines: Synthesis and Evaluation as MAO Inhibitors

Gökhan

Yeşilada

Uçar

et al. 2003

Archiv der Pharmazie

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Twelve new 1-N-substituted thiocarbomoyl-3-phenyl-5-thienyl-2-pyrazoline derivatives were synthesized and evaluated their for antidepressant, anxiogenic and mammalian monoamine oxidase (MAO)-A and Binhibitory activities by in vivo and in vitro tests. MAO was isolated and purified from the mitochondrial pellet of bovine liver homogenates and human platelets. All of the new compounds inhibited the total MAO activity of liver homogenates and the inhibition was found to be time-dependent. Four compounds (3 i-3 l) inhibited MAO-B selectively and irreversibly in a classical non-competitive manner with IC(50) values in the range of 22.00-91.50 microM. The rest of the compounds appeared to be non-selective reversible inhibitors. It was suggested that the p-methoxy group on the phenyl ring in the compounds increased the inhibitory effect and selectivity toward MAO-B. The reversible and unselective inhibition of MAO by the remaining compounds was suggested to be related to their properties of acting ability to act as both as substrate and inhibitor at the same time. However, none of the novel compounds showed antidepressant activity as expected suggesting formation of inactive metabolites. We conclude that the compounds appeared as which functioned as selective MAO-B inhibitors might have promising features as therapeutic properties in the treatment of Parkinson disease. In vivo studies are needed to verify this hypothesis.

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N.m.r. Spectra and Stereoisomerism in Pyrazolines

Cited by 48 publications

References 1 publication

α,β-Disubstituted CF₃-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF₃-Pyrazoles

α,β-Disubstituted CF₃-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF₃-Pyrazoles

Synthesis and stereochemistry of substituted bi- and tri-cyclic 4,5-dihydropyrazoles

1‐N‐Substituted Thiocarbamoyl‐3‐phenyl‐5‐thienyl‐2‐pyrazolines: Synthesis and Evaluation as MAO Inhibitors

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N.m.r. Spectra and Stereoisomerism in Pyrazolines

Cited by 48 publications

References 1 publication

α,β-Disubstituted CF3-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF3-Pyrazoles

α,β-Disubstituted CF3-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF3-Pyrazoles

Synthesis and stereochemistry of substituted bi- and tri-cyclic 4,5-dihydropyrazoles

1‐N‐Substituted Thiocarbamoyl‐3‐phenyl‐5‐thienyl‐2‐pyrazolines: Synthesis and Evaluation as MAO Inhibitors

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α,β-Disubstituted CF₃-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF₃-Pyrazoles

α,β-Disubstituted CF₃-Enones as a Trifluoromethyl Building Block: Regioselective Preparation of Totally Substituted 3-CF₃-Pyrazoles