- Structure and photoluminescence of silver(i) trinuclear halopyrazolato complexes
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Five halogen substituted pyrazolates, 4-chloro-3,5-diisopropylpyrazole (4-Cl-3,5-iPr2pzH), 4-bromo-3,5-diisopropylpyrazole (4-Br-3,5-iPr2pzH), 4-iodo-3,5-diisopropylpyrazole (4-I-3,5-iPr2pzH), 4-chloro-3,5-diphenylpyrazole
- Morishima, Yui,Young, David James,Fujisawa, Kiyoshi
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- An Efficient Synthesis of Substituted Pyrazoles from One-Pot Reaction of Ketones, Aldehydes, and Hydrazine Monohydrochloride
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An efficient, one-pot and metal-free process for the preparation of 3,5-disubstituted and 3,4,5-trisubstituted pyrazoles on multi-gram scale was developed. One-pot condensation of ketones, aldehydes and hydrazine monohydrochloride readily formed pyrazoline intermediates under mild conditions. Oxidation of pyrazolines, in situ, employing bromine afforded a wide variety of pyrazoles. The methodology offers a fast, and often chromatography-free protocol for the synthesis of 3,4,5-substituted pyrazoles in good to excellent yields. Alternatively, a more benign oxidation protocol affords 3,5-disubstituted or 3,4,5-trisubstituted pyrazoles by simply heating pyrazolines in DMSO under oxygen.
- Lellek, Vit,Chen, Cheng-Yi,Yang, Wanggui,Liu, Jie,Ji, Xuebao,Faessler, Roger
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supporting information
p. 1071 - 1075
(2018/02/26)
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- Michael cyclization of polarized systems: Synthesis and in vitro anti-diabetic evaluation of some novel pyrimidine, pyridine, pyrazole and pyrazolo[3, 4-b]pyridine derivatives
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Various interesting heterocycle skeletons were synthesized via Michael type addition reaction with 1, 2; 1, 3-bidentate nitrogen and carbon nucleophiles. Cycloaddition of different α, β-unsaturated systems afforded bromopyrimidinone 3/5, bromothiazine 4 and bromopyrazole 6a/6b pyrazole-1-carboxylate 8, pyridinylmethanone 9, nicotinonitrile 10, pyrazolopyridine 11a/11b, pyran-3-carbonitrile 12/13, chromenopyridine 14 and N-butyrylpyrazolyl-1-butanone 15 derivatives. The structures of the synthesized compounds were elucidated based on IR, NMR and mass spectral analyses. Group of the newly synthesized compounds were screened for their anti-diabetic activities, whereas compounds 8 and 11b exhibited promising anti-diabetic activities at micro molar concentration against α-glucosidase inhibitor with IC50 values ranging between 13.80-500 μM. On the other hand compound 10 showed a week effect as compared to the standard anti-diabetic agent.
- Soylem, Essam A.,Assy, Mohammed G.,Morsi, Ghania M.
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p. 461 - 469
(2018/01/26)
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- An efficient one-pot synthesis of 3,5-diaryl-4-bromopyrazoles by 1,3-dipolar cycloaddition of in situ generated diazo compounds and 1-bromoalk-1-ynes
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A simple, highly efficient, one-pot synthesis of 3,5-di-aryl-4- bromopyrazoles via 1,3-dipolar cycloaddition of diazo compounds and alkynyl bromides has been developed. The diazo compounds and alkynyl bromides were generated in situ from tosylhydrazones and gem-dibromoalkenes, respectively. When ketone-derived hydrazones were used, 3,5-diaryl-4-bromo-3H-pyrazoles were obtained and the isomerization products 3,5-diaryl-4-bromo-1H-pyrazoles were formed when using aldehyde-derived hydrazones. The reaction system exhibited high regioselectivity and good functional group tolerance. Both electron-rich and electron-deficient-substituents on the aromatic ring of the hydrazones or the gem-dibromoalkenes gave desired products in moderate to good yields (67-86%). Georg Thieme Verlag Stuttgart - New York.
- Sha, Qiang,Wei, Yunyang
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p. 413 - 420
(2013/03/14)
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- Halogenation of pyrazoles using N-halosuccinimides in CCl4 and in water
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Reaction of pyrazoles with N-halosuccinimides (NXS, X=Br, Cl) in either CCl4 or water gave 4-halopyrazoles in excellent yields. The reaction was carried out under mild conditions and did not require any catalysts or special precautions. The reaction provides an efficient method for 4-C halogenation of pyrazoles. Copyright Taylor & Francis Group, LLC.
- Zhao, Zhi-Gang,Wang, Zhong-Xia
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p. 137 - 147
(2007/10/03)
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- Organocatalysis in conjugate amine additions. Synthesis of β-amino acid derivatives
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Conjugate addition of O-protected hydroxylamines to pyrazole-derived enoates proceeds with high efficiency and enantioselectivity when chiral thioureas are used as activators. A wide variety of substrates undergo conjugate amine addition providing access to enantioenriched β-amino acid derivatives. Structural requirements for the optimal thiourea catalyst have been established, and the results suggest that it operates as a bifunctional catalyst. Copyright
- Sibi, Mukund P.,Itoh, Kennosuke
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p. 8064 - 8065
(2008/02/09)
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- Reactions of N-Aminopyrazoles with Halogenating Reagents and Synthesis of 1,2,3-Triazines
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Reactions of N-aminopyrazoles with halogenating reagents (Cl2, Br2, I2, BrCl, ICl, IBr, N-chlorosuccinimide, and N-bromosuccinimide) were examined.Some of these reagents preferentially lead to oxidation of the amino group to give the corresponding 1,2,3-triazines as major products, while others mainly gave either or both of 1-amino-4-halopyrazoles and 5-halo-1,2,3-triazines as the result of halogenation of the 4-position of the pyrazole ring prior to the oxidation of the amino group.In some cases, the oxidation of the amino group and the halogenation of the pyrazole ring proceeded concurrently to form not only the unhalogenated triazines but also the 1-amino-4-halopyrazoles and the 5-halotriazines.Various reagents and reaction conditions were explored to utilize the reaction for the synthesis of halogenated and unhalogenated 1,2,3-triazines.Keywords - 1,2,3-triazine; halo-1,2,3-triazine; pyrazole; 1-aminopyrazole; 1-aminohalopyrazole; synthesis; oxidation; halogenation; ring expansion
- Ohsawa, Akio,Kaihoh, Terumitsu,Itoh, Takashi,Okada, Mamiko,Kawabata, Chikako,et al.
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p. 3838 - 3848
(2007/10/02)
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