DABCO‐Catalyzed Double Cascade Cycloaddition of Maleimides with Bisarylhydrazones: Access to Fused Pyrazolo[5,1‐<i>c</i>][1,2,4]triazole Derivatives

Zhu, Jia-Nan; Yang, Zhenhua; Qi, Ming; Zhao, Sheng‐Yin

doi:10.1002/adsc.201801260

Cited by 19 publications

(8 citation statements)

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“…However, until now, the construction of this analogous frame containing maleimides has been extremely rare. ,, To the best of our knowledge, related single electron oxidation of (NCH) of diverse hydrazones to maleimides in dihydropyrazoles or pyrazoles formation was not explored so far. Our previous study has smoothly accessed pyrazolo[5,1- c ][1,2,4] triazole derivatives through bisarylhydrazones and maleimides (see Scheme c) . Unfortunately, the pyrazole framework was not observed.…”

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confidence: 99%

Pyrrolo[3,4-c]pyrazole Synthesis via Copper(Ι) Chloride-Catalyzed Oxidative Coupling of Hydrazones to Maleimides

et al. 2019

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A variety of pyrrolo[3,4-c]pyrazole derivatives from readily available aldehyde hydrazones and maleimides via direct oxidative coupling under radical cascade reaction have been reported. This method offers satisfactory chemical yields and good functional group compatibility. Moreover, this practical approach is catalyzed by CuCl utilizing air as the oxidant and some control experiments were performed to elaborate the mechanism.

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confidence: 99%

Pyrrolo[3,4-c]pyrazole Synthesis via Copper(Ι) Chloride-Catalyzed Oxidative Coupling of Hydrazones to Maleimides

et al. 2019

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“…In the same year, a metal-free cycloaddition reaction of maleimides 391 with diarylhydrazones 392 to synthesize triazole derivatives was presented by the Zhao's group (Scheme 61). [116] The reaction is not limited to the N-protected maleimide and the desired product can be obtained from NH maleimide with an appropriate yield. The transformation proceeds via a cascade that includes DABCO-induced hydrogen atom transfer, nucleophilic addition, dehydrogenation oxidation, intramolecular cyclization, and proton capture.…”

Section: Intermolecular Cyclizationmentioning

confidence: 99%

Update on the Synthesis of N‐Heterocycles via Cyclization of Hydrazones (2017–2021)

Meng

et al. 2021

Adv Synth Catal

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Hydrazones, as universal structural units, are useful synthons for the formation of carbonnitrogen and nitrogenÀ heteroatom bonds. Thus, they provide new methods of constructing nitrogen-containing heterocycles. In recent years, especially between 2017 and 2021, many efforts have been made to exploit hydrazone-based reactions in efforts to develop more powerful and effective pathways towards the synthesis of various multifunctional heterocyclic compounds. However, despite the tremendous amount of work that has been published over the past five years, no review has been published that summarizes the significant progress in the preparation of nitrogen heterocycles via intramolecular cyclization of hydrazones with adjacent unsaturated bonds or intermolecular cyclization of hydrazones with unsaturated systems. Therefore, this review summarizes the hydrazone-based cyclization strategies used to synthesize nitrogen-containing heterocycles over the past five years. It discusses the corresponding reaction scopes, limitations, mechanisms, and problems. Cyclization of Hydrazones with Unsaturated Systems 3.3. Cyclization of Hydrazones with Unsaturated Systems Under Metal-Free Conditions 4. Conclusion

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“…Oxygen is used as oxidant. As maleimides are unstable and undergo polymerization in the presence of strong bases and acids, this method proved to be a new approach towards the synthesis of pyrazolo[5,1‐ c ][1,2,4]triazole derivatives (Scheme ) …”

Section: Preparation Of 124‐triazole Derivativesmentioning

confidence: 99%

Exploring recent developments on 1,2,4‐triazole: Synthesis and biological applications

Sathyanarayana

Poojary

2020

J Chinese Chemical Soc

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Triazoles are nitrogen-bearing heterocycles. In the last few decades, researchers have focused on fused heterocycles, as they have better pharmacological effect compared to triazoles alone. Among the two isomers of triazole, this article aims to explore the work carried out on 1,2,4-triazole and N-bridged heterocycles derived from 1,2,4-triazole in last 18 years, highlight different synthetic pathways, and present a brief summary of the different biological activities possessed by 1,2,4-triazole derivatives. The information collected in this article is expected to help researchers to discover novel therapeutic agents for better applications in the field of pharmaceutical science. K E Y W O R D Sbio-organic chemistry, medicinal chemistry, organic chemistry

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DABCO‐Catalyzed Double Cascade Cycloaddition of Maleimides with Bisarylhydrazones: Access to Fused Pyrazolo[5,1‐c][1,2,4]triazole Derivatives

Cited by 19 publications

References 47 publications

Pyrrolo[3,4-c]pyrazole Synthesis via Copper(Ι) Chloride-Catalyzed Oxidative Coupling of Hydrazones to Maleimides

Pyrrolo[3,4-c]pyrazole Synthesis via Copper(Ι) Chloride-Catalyzed Oxidative Coupling of Hydrazones to Maleimides

Update on the Synthesis of N‐Heterocycles via Cyclization of Hydrazones (2017–2021)

Exploring recent developments on 1,2,4‐triazole: Synthesis and biological applications

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