Visible-light promoted one-pot synthesis of pyrazoles from alkynes and hydrazines

Meng, Yunge; Zhang, Te; Gong, Xinchi; Zhang, Min; Zhu, Chunyin

doi:10.1016/j.tetlet.2018.12.009

Cited by 23 publications

(7 citation statements)

References 54 publications

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“…Zhu and co-workers in 2019 demonstrated a dual photoredox/Cu catalysis approach to the aerobic synthesis of pyrazoles from a hydrazine and terminal alkyne via tandem photochemical Glaser reaction and intermolecular annulation ( Scheme 114 ). 343 Optimal conditions consisted of blue-light irradiation of a solution of alkyne, [Ru(bpy) 3 ]Cl 2 photocatalyst ([ Ru-1 ]Cl 2 ), and CuI co-catalyst in DMSO under air atmosphere facilitating alkyne dimerization. Addition of the hydrazine partway through the reaction then leads to pyrazole formation.…”

Section: N -Centered Radical Generation From N–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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We present here a review of the photochemical and electrochemical applications of multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms in which both an electron and a proton are exchanged together, often in a concerted elementary step. As such, MS-PCET can function as a non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from a wide variety of common organic functional groups. We present an introduction to MS-PCET and a practitioner’s guide to reaction design, with an emphasis on the unique energetic and selectivity features that are characteristic of this reaction class. We then present chapters on oxidative N–H, O–H, S–H, and C–H bond homolysis methods, for the generation of the corresponding neutral radical species. Then, chapters for reductive PCET activations involving carbonyl, imine, other X=Y π-systems, and heteroarenes, where neutral ketyl, α-amino, and heteroarene-derived radicals can be generated. Finally, we present chapters on the applications of MS-PCET in asymmetric catalysis and in materials and device applications. Within each chapter, we subdivide by the functional group undergoing homolysis, and thereafter by the type of transformation being promoted. Methods published prior to the end of December 2020 are presented.

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Section: N -Centered Radical Generation From N–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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“…In a work published a year later (Table 9B), 59 the Zhu group described a visible-light-promoted cascade reaction of alkynes ( 239 ) with hydrazines ( 240 ) to produce poly-substituted pyrazoles ( 241 ) with a yield of up to 84%. Under the illumination of a 12 W blue LED lamp, 239 was exposed to air in the presence of CuI and Ru(bpy) 3 Cl 2 ( PC16 ), and then hydrazine hydrate was added.…”

Section: Alkynes As Synthonsmentioning

confidence: 99%

Photocatalysis as a green alternative toolkit for the construction of nitrogen-enriched heterocycles via the direct and indirect activation of alkynes/alkenes

Das,

Gouthaman,

Justin Thomas

2024

Green Chem.

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“…Xu et al [12] reported the synthesis of 5-aryl-3-trifluoromethyl pyrazoles, which involved a silver-catalyzed reaction using N -benzylidene tolylsulfonohydrazides 7 and ethyl 4,4,4-trifluoro-3-oxobutanoate 8 as precursors. The process entailed sequential steps of nucleophilic addition, intramolecular cyclization, elimination, and ultimately, [1,5]-H shift, resulting in the formation of trifluoromethylated pyrazole derivatives 9 in yields ranging from moderate to excellent (Scheme 3). During the optimization process, the yield of the product improved when the reaction temperature was raised to 60 • C. However, increasing the temperature beyond 60 • C led to a decrease in the yield.…”

Section: Pyrazoles From 13-diketonesmentioning

confidence: 99%

“…Furthermore, the pyrazole fragment plays a crucial role in numerous organic ligands and serves as an essential coordinator. Recent research has uncovered intriguing applications of the pyrazole structure in organic synthesis, where it acts as both a directing and transforming group [4,5]. Pyrazole serves as a fundamental element present in various small molecules, exhibiting a diverse array of agricultural and pharmaceutical activities [3].…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in the Synthesis of Pyrazole Derivatives: A Review

Ameziane El Hassani,

Rouzi,

Assila

et al. 2023

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Pyrazole, characterized by a five-membered heterocyclic structure featuring two neighboring nitrogen atoms, serves as a core element. Pyrazoles hold a privileged status as versatile frameworks in various sectors of the chemical industry, including medicine and agriculture. Previous reviews have extensively highlighted the significance of pyrazoles and their diverse biological activities, encompassing roles such as antituberculosis, antimicrobial, antifungal, anti-inflammatory, anticancer, and antidiabetic agents. Consequently, they have garnered substantial interest from researchers. The aim of this review is to offer a comprehensive overview of the published research related to the synthesis of pyrazole derivatives, encompassing a discussion of diverse methods for accessing the pyrazole moiety. These methods span from utilizing transition-metal catalysts and photoredox reactions to employing one-pot multicomponent processes, novel reactants, and innovative reaction types. It encompasses studies conducted by numerous scientists worldwide, showcasing collective efforts in advancing the methodologies and applications of pyrazole derivatives.

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Visible-light promoted one-pot synthesis of pyrazoles from alkynes and hydrazines

Cited by 23 publications

References 54 publications

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Photocatalysis as a green alternative toolkit for the construction of nitrogen-enriched heterocycles via the direct and indirect activation of alkynes/alkenes

Recent Advances in the Synthesis of Pyrazole Derivatives: A Review

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