1575-27-5Relevant articles and documents
Preparation method of polysubstituted pyrazole compound
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Paragraph 0082-0087, (2021/01/04)
The invention relates to the technical field of organic synthesis, in particular to a preparation method of a polysubstituted pyrazole compound. The method comprises the following steps: carrying outa condensation reaction on alkynyl ketone compounds and
An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes
Khairnar, Pankaj V.,Lung, Tsai-Hui,Lin, Yi-Jung,Wu, Chi-Yi,Koppolu, Srinivasa Rao,Edukondalu, Athukuri,Karanam, Praneeth,Lin, Wenwei
, p. 4219 - 4223 (2019/06/17)
α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.
Efficient Copper-Catalyzed Synthesis of Substituted Pyrazoles at Room Temperature
Wang, Haifeng,Sun, Xiangli,Zhang, Shuangling,Liu, Guanglu,Wang, Chunjie,Zhu, Lili,Zhang, Hui
supporting information, p. 2689 - 2692 (2018/12/14)
An efficient method for the synthesis of pyrazoles through a copper-catalyzed condensation reaction has been developed. The new catalytic system not only maintained a broad substrate scope but was also active under acid-free reaction conditions, overcoming the conventional requirement for an acid-catalyzed system. Furthermore, the copper catalyst enabled this reaction to be performed at room temperature and in a short reaction time.
Metal-Free Synthesis of Pyrazoles from 1,3-Diarylpropenes and Hydrazines via Multiple Inter-/Intramolecular C–H Aminations
Tang, Li,Ma, Minyan,Zhang, Qi,Luo, Huan,Wang, Tao,Chai, Yonghai
, p. 2610 - 2620 (2017/08/16)
A facile and metal-free access to pyrazoles from 1,3-diarylpropenes and hydrazines via multiple inter-/intramolecular C-H aminations was described. Under the neutral and mild 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) oxidative conditions, various disubstituted pyrazoles were synthesized in moderate to excellent yields. This method provides a pot- and step-economic strategy for the construction of pyrazoles, especially those for drug discovery. (Figure presented.).
Method for preparing pyrazole compound
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Paragraph 0024; 0025; 0026; 0027, (2017/08/28)
The invention discloses a method for preparing a pyrazole compound. A substituted propylene compound and p-toluenesulfonhydrazide serve as raw materials, 2,3-dichloro-5,6-dicyan-1,4-benzoquinone serves as an oxidant, and the pyrazole compound is synthesized through a dehydrogenation coupling reaction. The method is easy to operate, reaction conditions are mild, no catalysts need to be added, and the pyrazole compound can be synthesized by means of a simple substrate not needing functionalization at a medium or high yield.
Copper-Mediated Domino Cyclization/Trifluoromethylation/Deprotection with TMSCF3: Synthesis of 4-(Trifluoromethyl)pyrazoles
Wang, Quande,He, Lisi,Li, Kin Keung,Tsui, Gavin Chit
, p. 658 - 661 (2017/02/10)
A copper-mediated synthesis of 4-(trifluoromethyl)pyrazoles is described. In one step from readily accessible α,β-alkynic tosylhydrazones, a remarkable domino sequence of cyclization, trifluoromethylation, and detosylation takes place to furnish the 4-CF3 N-H pyrazole cores with good functional group compatibility. The reaction conditions are mild and convenient, at room temperature in air, using the commercially available trifluoromethyltrimethylsilane (TMSCF3) as the CF3 source. The method can be applied to the synthesis of a 4-CF3 analogue of the anti-inflammatory drug celecoxib.
Base-promoted ecofriendly synthesis of trisubstituted pyrazoles from α,β-alkynyl N-tosylhydrazones under metal- and solvent-free conditions
Li, Ning,Li, Baoguo,Chen, Shufeng
, p. 1597 - 1601 (2016/06/14)
A simple and green method is described for the synthesis of trisubstituted pyrazoles from α,β-alkynyl N-tosylhydrazones under metal- and solvent-free conditions. Notably, only diisopropylamine is required as a promoter, and the reaction can be easily perf
Propargyl hydrazides: Synthesis and conversion into pyrazoles through hydroamination
Yoshimatsu, Mitsuhiro,Ohta, Katsuki,Takahashi, Nami
, p. 15602 - 15606 (2013/01/16)
Pyrazoles direct: Propargyl alcohols undergo hydrazination when treated with p-tosyl hydrazide in the presence of catalytic amounts of either Sc(OTf)3 or La(OTf)3 (see scheme; Tf= trifluoromethanesulfonyl). Propargyl hydrazides are converted into either N-tosyl or N-H pyrazoles when treated with an acid or a base, respectively. The one-step acid-catalyzed hydrazination/cyclization of propargyl alcohols directly affords pyrazoles in high yields. Copyright
Thermal rearrangement of cis-N-alkyl-3-phenylaziridin-2-yl-phenyl ketone tosylhydrazones in dimethoxyethane. Preparation of 5-alkylamino-2-pyrazoline derivatives
Morioka, Motonobu
, p. 1173 - 1181 (2007/10/03)
Thermal rearrangement of cis-aziridinyl ketone tosyl-hydrazones (4) in refluxing dimethoxyethane produced 5-alkylamino-3,5-diphenyl-1-tosyl-2-pyrazolines (5) in good to excellent yields. The reaction of cis-1-isopropyl-3-phenyl-aziridin-2-yl phenyl ketone tosyl hydrazone (4a) in refluxing chloroform in the presence of acetic acid yielded 3, 5-diphenyl-1-tosyl-pyrazole (6a). Under the similar conditions, 5-isopropylamino-3, 5-diphenyl-1-tosyl-2-pyrazoline (5a) was rearranged into 6a. The rearrangement from 4 to 5 was assumed to be initiated with ionic cleavage of the bond between ring nitrogen and C2 carbon.
