Visible-light-mediated C3-ethoxycarbonylmethylation of imidazo[1,2-a]pyridines and convenient access to Zolpidem

Xiao, Yuanjiu; Lin, Ying‐Chu; Yu, Yongqi; Tan, Ze; Deng, Wei

doi:10.1016/j.tetlet.2020.152606

Cited by 8 publications

(5 citation statements)

References 33 publications

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“…Various imidazopyridines and other imidazoheterocycles furnish products 62 in high to excellent yields (Scheme ). The mechanism of this reaction is in analogy to the one described by Gryko et al Shortly afterward, Deng et al further expanded the scope of diazo compounds suitable for this transformation to other α-diazo esters …”

Section: X–h Insertionsmentioning

confidence: 99%

“…The mechanism of this reaction is in analogy to the one described by Gryko et al 45 Shortly afterward, Deng et al further expanded the scope of diazo compounds suitable for this transformation to other α-diazo esters. 51 Nicewicz et al took advantage of the nucleophilic reactivity of diazo compounds and applied them in a photocatalytic C−H alkylation of arenes (Scheme 16). 52 In this approach, arene 19 is first oxidized to radical cation A via photoinduced electron transfer and then directly reacts with diazo compound 27.…”

Section: ■ X−h Insertionsmentioning

confidence: 99%

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Lightening Diazo Compounds?

Durka

Turkowska

Gryko

2021

ACS Sustainable Chem. Eng.

149

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The development of new sustainable reactions and protocols is essential to fulfill the growing demands of every branch of organic chemistry for greener synthetic methodologies. In this context, the use of visible light as the only source of energy is highly appealing. Since diazo compounds are valuable reagents in organic synthesis, their transformations realized in a sustainable manner are of interest. High reactivity and easy availability make them suitable for solar-driven transformations. Indeed, photochemical reactions of diazo compounds have recently proven a valuable alternative to transition metal catalysis. In this perspective, we highlight applications of these reagents under visible irradiation, particularly focusing on recent advancements. These include photochemical generation of carbenes and radicals which involve many relevant reactions, [2+1]-cycloadditions, X−H and C−H insertions, Wolff rearrangement, and more. Mechanistic aspects of these processes are briefly addressed to give readers a deeper understanding of rules underlying photoreactivity of diazo compounds. We conclude by emphasizing significant advancements and discussing challenges for future developments in the photochemistry of these valuable reagents.

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Section: X–h Insertionsmentioning

confidence: 99%

Section: ■ X−h Insertionsmentioning

confidence: 99%

Lightening Diazo Compounds?

Durka

Turkowska

Gryko

2021

ACS Sustainable Chem. Eng.

149

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“…Similarly, Yu, Tan, and Deng expanded Hajra’s methodology to a wide range of diazo derivatives and imidazo[1,2- a ]pyridine substrates (28 examples) [ 60 ]. Subsequently, the reaction showed its applicability with a gram-scale reaction ( Scheme 25 , Equation (1)) and the Zolpidem preparation ( Scheme 25 , Equation (2)).…”

Section: C–h Functionalizationmentioning

confidence: 99%

“… C–H carbonylalkylation of imidazo[1,2- a ]pyridines by Yu, Tan, and Deng and the method’s applicability [ 60 ]. …”

Section: Figure and Schemesmentioning

confidence: 99%

Recent Developments in the Photochemical Synthesis of Functionalized Imidazopyridines

Tran

Hamzé

2022

Molecules

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Imidazopyridines constitute one of the most important scaffolds in medicinal chemistry, as their skeleton could be found in a myriad of biologically active molecules. Although numerous strategies were elaborated for imidazopyridine preparation in the 2010s, novel eco-compatible synthetic approaches have emerged, conscious of climate change concerns. In this framework, photochemical methods have been promoted to conceive this heterocyclic motif over the last decade. This review covers the recently published works on synthesizing highly functionalized imidazopyridines by light induction.

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“…咪唑并吡啶杂环化合物还是一类富电子的自由基受体, 因此可以接受亲电性自由基的进攻得到 C3-取代的官能团化产物. 谭泽、邓伟 [26] 以及 Hajra 课题组 [27] 几乎同时报道了可见光促进下咪唑并吡啶衍生物的 C3-烷基化反应 (Scheme 14 汪舰等 [32] 当重氮化合物没有被分解时, 亲核性自由基则更倾向于加成到重氮基团的氮原子一端. 余永耀等 [34] 草酸酯是一类常见的化合物, 广泛存在于天然产物和药物分子中, 同时还具有很好的反应性, 成为了重要的有机合成中间体 [35] .…”

Section: 质子化随后单电子还原产生unclassified

Visible Light-Promoted Radical Reactions of Diazo Compounds

Li¹,

Zhou²

2022

Chinese Journal of Organic Chemistry

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Diazo compounds have rich reactivity and are important synthetic intermediates in organic synthesis. Diazo compounds are commonly used as the precursors of transition metal carbenes, and the relative transition metal catalyzed reactions have achieved many important progresses in the past decades. In sharp contrast, radical reactions with diazo compounds as a key component are still less explored. Owing to the easy generation of diverse radical intermediates under mild conditions, visible-light photoredox catalysis has emerged as a powerful tool for organic synthesis. By the combination of visible light photoredox catalysis and diazo compounds, some novel reactions that different from the classical carbene processes have been developed, which further extend the synthetic applications of these reagents. The progresses of radical reactions of diazo compounds enabled by visible light photoredox catalysis in the past five years are summarized, including:(1) diazo compounds as the nucluophiles, (2) diazo compounds as the equivalents of carbyne precursors, (3) diazo compounds as the radical acceptors, and (4) diazo compounds as the radical precursors. We wish that the detailed discussion on the mechanism of the reactions would help the audiences to understand the features of radical reactions of diazo compounds and the realative visible light chemistry.

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Visible-light-mediated C3-ethoxycarbonylmethylation of imidazo[1,2-a]pyridines and convenient access to Zolpidem

Cited by 8 publications

References 33 publications

Lightening Diazo Compounds?

Lightening Diazo Compounds?

Recent Developments in the Photochemical Synthesis of Functionalized Imidazopyridines

Visible Light-Promoted Radical Reactions of Diazo Compounds

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