Electrochemical Synthesis of [1,2,3]Triazolo[1,5‐<i>a</i>]pyridines through Dehydrogenative Cyclization

Xu, Hai‐Chao

doi:10.1002/celc.201900080

Cited by 26 publications

(11 citation statements)

References 61 publications

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“…Xu's group reported the electrochemical dehydrogenative cyclization towards the synthesis of [1,2,3]triazolo[1,5-a] pyridines in the absence of oxidizing reagents and transitionmetal catalysts (Scheme 21). [35] Cyclic voltammograms of the substrates indicating a proton coupled electron transfer mechanism in presence of a weak base, K 2 CO 3 . Thus, the author proposed the anodic two-electron oxidation of hydrazone with the aid of carbonate giving the diazo intermediate, followed by the intramolecular nucleophilic attack of pyridine ring obtaining the desired products.…”

Section: Electrochemical Dehydrogenative Nà N Bond Formationmentioning

confidence: 99%

Electrochemical Heteroatom‐Heteroatom Bond Construction

Gao

et al. 2021

The Chemical Record

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Heteroatom-heteroatom linkage, with SÀ S bond as a presentative motif, served a crucial role in biochemicals, pharmaceuticals, pesticides, and material sciences. Thus, preparation of the privileged scaffold has always been attracting tremendous attention from the synthetic community. However, classic protocols suffered from several drawbacks, such as toxic and unstable agents, poor functional group tolerance, multiple steps, and explosive oxidizing regents as well as the transitional metal catalysts. Electrochemical organic synthesis exhibited a promising alternative to the traditional chemical reaction due to the sustainable electricity can be employed as the traceless redox agents. Hence, toxic and explosive oxidants and/or transitional metals could be discarded under mild reaction with high efficiency. In this context, a series of electrochemical approaches for the construction of heteroatom-heteroatom bond were reviewed. Notably, most of the cases illustrated the dehydrogenative feature with the clean energy molecules hydrogen as the sole by-product.

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Section: Electrochemical Dehydrogenative Nà N Bond Formationmentioning

confidence: 99%

Electrochemical Heteroatom‐Heteroatom Bond Construction

Gao

et al. 2021

The Chemical Record

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“…Xu and Xu also utilized 2‐acylpyridine hydrazones 431 to access triazolo[1,5‐ a ]pyridines 432 [133] . They carried out electrochemical dehydrogenative cyclization of 2‐acylpyridine hydrazones 431 with RVC cathode (reticulated vitreous carbon) and Pt‐anode at room temperature.…”

Section: Synthesis Of Fused 123‐triazolesmentioning

confidence: 99%

Progress in the Synthesis of Fused 1,2,3‐Triazoles

et al. 2021

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Fused heterocycles display prodigious prominence in diverse field ranging from medicinal chemistry to material science and chemical biology to catalysis. Owing to biological importance, fused 1,2,3‐triazoles have gained much attention and hence, enormous efforts on its synthesis is given by the chemists. Diverse functionalized fused polycyclic 1,2,3‐triazole heterocycles have been designed using Huisgen's thermal intramolecular cycloaddition, copper catalyzed cycloaddition, bimetallic catalytic, greener and other miscellaneous approaches. Novel methodologies that use modified substrates such as ketones, enals, β‐keto esters, olefins, enones, C−H acids etc. in place of alkynes have been developed. Herein, synthetic methodologies to construct fused 1,2,3‐triazoles are briefly discussed.

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“…135 Xu and co-workers report an oxidizing reagent-and transition metal-free synthesis of [1,2,3]triazolo [1,5-a] pyridines 133 through electrochemical dehydrogenative cyclization of pyridyl hydrazones 134 (Scheme 35). 136 The reaction was carried out in two stages: first the hydrazine 132 was obtained by refluxing the respective ketone with hydrazine in MeOH in the presence of AcOH (0.1 equiv.). After complete conversion, the n-Et 4 NPF 6 electrolyte, water, and K 2 CO 3 (1.0 equiv.)…”

Section: Heteroatom-heteroatom Bond Formationmentioning

confidence: 99%