Metal-Free Tandem Oxidative Cyclization for the Synthesis of 1,2-Dihydropyridazines and Pyrazoles
作者:Dongping Cheng、Yinqiang Shen、Ziliang Wu、Xiaoliang Xu、Jizhong Yan
DOI:10.1021/acs.joc.1c00020
日期:2021.7.2
disclosed to generate appealing β,γ-unsaturated hydrazones, which further undergo 5-exo-trig or 6-endo-trig cascade cyclization to give the respective 1,2-dihydropyridazines or pyrazoles selectively under metal-free conditions. The mechanisms of the coupling and subsequent cyclization are proposed.
在 2,3-二氯-5,6-二氰基-1,4-苯醌 (DDQ) 介导下,腙和 1,3-二芳基丙烯的新型氧化偶联已被公开,可生成有吸引力的 β,γ-不饱和腙,这进一步在无金属条件下进行5- exo -trig或6- end -trig级联环化,选择性地生成各自的1,2-二氢哒嗪或吡唑。提出了偶联和随后环化的机制。
Pyrolysis of 3-hydroxy-2-arylhydrazonoalkanoic acid derivatives
作者:Nouria A. Al-Awadi、Yehia A. Ibrahim、Elizabeth John、Aneesha Parveen
DOI:10.1016/j.tet.2010.11.074
日期:2011.2
conditions including pyrolysis, dehydration under Mitsunobu conditions or with aceticanhydride or aceticacid. According to their method of synthesis these 1,2-diaza-1,3-butadienes underwent subsequent reactions to give interesting products, and in the presence of proper dienophiles gave the corresponding cycloaddition products. Also, a new approach to pyrazole-3-carboxylic acid derivatives was discovered
Electrochemical Synthesis of Pyrazolines and Pyrazoles via [3+2] Dipolar Cycloaddition
作者:Martin Linden、Silja Hofmann、Antonia Herman、Nicole Ehler、Robin M. Bär、Siegfried R. Waldvogel
DOI:10.1002/anie.202214820
日期:2023.2.20
Electrochemically initiated [32] cycloaddition reactions of readily available and less toxic starting materials enable a facile synthesis of pyrazolines and pyrazoles. Application of a biphasic system and sodium iodide in a dual role as mediator and electrolyte allows for selective reactions with outstanding robustness towards scalability.
Electrochemically enabled oxidative aromatization of pyrazolines
作者:Silja Hofmann、Martin Linden、Julian Neuner、Felix N. Weber、Siegfried R. Waldvogel
DOI:10.1039/d3ob00671a
日期:——
Pyrazoles are a very important structural motif widely found in pharmaceuticals and agrochemicals. An electrochemically enabled approach for the sustainable synthesis of pyrazoles via oxidativearomatization of pyrazolines is presented. Inexpensive sodium chloride is employed in a dual role as a redox mediator and supporting electrolyte in a biphasic system (aqueous/organic). The method is applicable
Vinylogous Reactivity of Enol Diazoacetates with Donor–Acceptor Substituted Hydrazones. Synthesis of Substituted Pyrazole Derivatives
作者:Xinfang Xu、Peter Y. Zavalij、Wenhao Hu、Michael P. Doyle
DOI:10.1021/jo302696y
日期:2013.2.15
A regiospecific synthesis of multifunctional pyrazoles has been developed from a cascade process triggered by Rh(II)-catalyzed dinitrogen extrusion from enol diazoacetates with vinylogous nucleophilic addition followed by Lewis acid catalyzed cyclization and aromatization.