- DMSO as a C1 Source for [2 + 2 + 1] Pyrazole Ring Construction via Metal-Free Annulation with Enaminones and Hydrazines
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A cascade reaction between enaminones, hydrazines, and dimethyl sulfoxide (DMSO) for the synthesis of 1,4-disubstituted pyrazoles catalyzed by molecular iodine in the presence of Selectfluor has been realized. DMSO plays a dual role as the C1 source and the reaction medium. In addition, the synthesis of 1,3,4-trisubstituted pyrazoles using aldehydes as alternative C1 building blocks has also been achieved.
- Guo, Haijin,Tian, Lihong,Liu, Yunyun,Wan, Jie-Ping
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supporting information
p. 228 - 233
(2022/01/04)
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- Antispasmodic and antimicrobial activities of pyrazole-containing ferrocenyl alkanols versus their phenyl analogs, and the entry point to potential multitarget treatment for inflammatory bowel diseases
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Inflammatory bowel diseases (IBM), such as Crohn's disease, and their common complications represent a global health challenge. Many pyrazole derivatives, such as the spasmolytic drug metamizole, have already found their place among the frequently used th
- Radulovi?, Niko S.,Nikoli?, Milica G.,Mladenovi?, Marko Z.,Ran?elovi?, Pavle,Stojanovi?, Nikola M.,Stojanovi?-Radi?, Zorica,Jovanovi?, Ljiljana
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- The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- And 1,3,4,5-tetrasubstituted pyrazoles
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In the present work, an efficient regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles via a methanesulfonic acid (MSA)-catalyzed reaction of hydrazones with enaminones or enamines is reported. Mechanistically, the formation of the title compounds involves the [2+3] cycloaddition of hydrazones with enaminones or enamines followed by aromatization with acid and oxygen. This convenient method under mild conditions with various hydrazones, enaminones, and enamines was well-tolerated to afford products in good to excellent yields. Compared with the literature methods, this strategy has advantages such as materials that are available economically, metal-free catalysis, excellent regioselectivity, and high efficiency.
- Duan, Liancheng,Zhou, Hui,Gu, Yucheng,Gong, Ping,Qin, Mingze
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p. 16131 - 16137
(2019/11/03)
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- Copper-Catalyzed Synthesis of Substituted 4-Acylpyrazole Derivatives through a Cascade Transformation from N-Propargylic Sulfonylhydrazones and Diaryliodonium Salts
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A concise strategy for the synthesis of substituted 4-acylpyrazole derivatives from N-propargylic sulfonylhydrazones and diaryliodonium salts has been developed. The pyrazole derivatives are formed through a five-step cascade sequence that includes intramolecular cyclization, hydroxylation, elimination, copper-catalyzed aerobic oxidation, and intramolecular rearrangement.
- Li, Ren-Hao,Fan, Xin-Yang,Hu, Zi-Lin,Liu, Zhi-Kai,Yang, Ying,Tang, Hai-Tao,Chen, Yi-Hui,Chen, Li,Zhan, Zhuang-Ping
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supporting information
p. 2283 - 2287
(2018/10/20)
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- Synthesis of 4-Acylpyrazoles from Saturated Ketones and Hydrazones Featured with Multiple C(sp3)-H Bond Functionalization and C-C Bond Cleavage and Reorganization
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In this paper, an efficient and convenient one-pot synthesis of diversely substituted 4-acylpyrazole derivatives via copper-catalyzed one-pot cascade reactions of saturated ketones with hydrazones is reported. Mechanistically, the formation of the title compounds involves the in situ formation of an enone intermediate through the dehydrogenation of a saturated ketone and the [2 + 3] cyclization of the enone with hydrazone followed by an aromatization-driven C-C bond cleavage and reorganization. To our knowledge, this is the first example in which the biologically and pharmaceutically important yet otherwise difficult-to-obtain 4-acylpyrazole derivatives are directly prepared from saturated ketones and hydrazones featured with multiple aliphatic C-H bond functionalization and C-C bond cleavage and reorganization. Compared with literature methods, this novel process has advantages such as simple and economical starting materials, a sustainable oxidant, excellent regioselectivity, and good efficiency.
- Tian, Miaomiao,Shi, Xiaonan,Zhang, Xinying,Fan, Xuesen
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p. 7363 - 7372
(2017/07/26)
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- Method for synthesizing 4-acyl pyrazole compound from non-cyclic ketone hydrazone
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The invention discloses a method for synthesizing a 4-acyl pyrazole compound from non-cyclic ketone hydrazine, and belongs to the technical field of organic synthesis. The technical scheme of the invention is characterized in that the method for synthesizing the 4-acyl pyrazole compound from the non-cyclic ketone hydrazine specifically comprises the following steps: dissolving an alpha,beta-saturated ketone compound in a solvent; adding a catalyst, a ligand and an oxidizing agent in sequence; stirring for reacting at the temperature of 100 to 140 DEG C in a nitrogen atmosphere; then, adding the non-cyclic ketone hydrazine into a reaction system; continually reacting at the temperature of 100 to 140 DEG C in an air atmosphere to obtain the 4-acyl pyrazole compound. By adopting the method, the alpha,beta-saturated ketone compound and the non-cyclic ketone hydrazine are subjected to a one-pot multi-step serial reaction under the catalysis of a copper salt to obtain the 4-acyl pyrazole compound; the method has the advantages of easiness and convenience in operation, mild conditions and wide substrate application range, and the suitable for industrial production.
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Paragraph 0010; 0011; 0012; 0013; 0014; 0015; 0016-0024
(2017/09/26)
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- 1,3-Dipolar Cycloadditions of Some Nitrilimines and Nitrile Oxides to 3,-N,N-dimethylamino-1-oxopropene Derivatives
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An efficient route for the synthesis of some novel pyrazoles 8a-j, 13a-e, 18a,b, isoxazoles 26a-g, pyrazolo[3,4-d]pyridazines 9a-d and isoxazolo[3,4-d]pyridazines 27a-d via 1,3-dipolar cycloaddition reactions is reported.
- Al-Zaydi, Khadijah Mohamed,Hafez, Ebtisam Abdel Aziz
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p. 1621 - 1633
(2007/10/03)
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- The Cycloaddition of Nitrilimines with 1,2-Dibenzoylethylenes
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The cycloaddition of nitrimines with 1,2-dibenzoylethylenes gave an unexpected 1,3-diaryl-4-benzoylpyrazole and benzoic acid, along with an expected cycloadduct, 1,3-diaryl-4,5-dibenzoyl-2-pyrazoline, and its dehydrogenated product, 1,3-diaryl-4,5-dibenzoylpyrazole.The elimination of the benzoyl group from the pyrazoline followed by dehydrogenation was shown to be the course of the unusual reaction.
- Oida, Tatsuo,Shimizu, Tomio,Hayashi, Yoshiyuki,Teramura, Kazuhiro
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p. 1429 - 1433
(2007/10/02)
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