Pyridinium Ylids in Heterocyclic Synthesis

Jacobs, Jan; Hende, Eva Van; Claessens, Sven; Kimpe, Norbert De

doi:10.2174/138527211795378209

Cited by 97 publications

(32 citation statements)

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“…Indolizines are rather scarce in nature whereas the reduced form of these heteroaromatic bicyclic compounds, the indolizidines, are quite common, see: Michael (2007) and references therein. Well defined substitution patterns are required (Sarkunam & Nallu, 2005;Swinbourne et al, 1978;Uchida & Matsumoto, 1976) and therefore, different transition-metal mediated and metal-free strategies for the synthesis of substituted indolizines have been developed (Jacobs et al, 2011;Swinbourne et al, 1978;Kel'in et al, 2001;Kim et al, 2010;Liu et al, 2007;Morra et al, 2006;Seregin & Gevorgyan, 2006;. Pyridinium N-methylides react with acetylenes or with ethylenes in the presence of an oxidant to make indolizines (Miki et al, 1984;Padwa et al, 1993;Wei et al, 1993).…”

Section: Related Literaturementioning

confidence: 99%

[1-Methoxy-3-(pyridin-2-yl)indolizin-2-yl](pyridin-2-yl)methanone

et al. 2012

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Methylation of [1-hydroxy-3-(pyridin-2-yl)indolizin-2-yl](pyridin-2-yl)methanone was performed via metalation with potassium tert-butanolate in toluene and a subsequent metathesis reaction with methyl iodide yielded the yellow title compound, C20H15N3O2. The substituents at the indolizine unit are twisted [the indolizine ring system makes dihedral angles of 34.67 (7) and 77.49 (5)°, respectively, with the pyridyl and pyridinoyl rings] with single bonds between the central unit and the attached pyridine ring [1.459 (3) Å] and the pyridinoyl group [1.483 (3) Å]. There are no classical hydrogen bonds in the crystal structure.

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Section: Related Literaturementioning

confidence: 99%

[1-Methoxy-3-(pyridin-2-yl)indolizin-2-yl](pyridin-2-yl)methanone

et al. 2012

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“…Such deprotonation reactions can be plausibly assumed to be the origin of the CPC carbonization process leading to the CDs [23]. In general, pyridinium ylides are known to be versatile reagents in a broad range of reactions [55]. In particular, it is well documented that such ylides can give aromatic heterocyclic compounds in ring closure reactions with double-bond-containing dipolarophile molecules.…”

Section: Chemical Insights On the Cpc Carbonization Processmentioning

confidence: 99%

Oil-Dispersible Green-Emitting Carbon Dots: New Insights on a Facile and Efficient Synthesis

et al. 2020

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Carbon dots (CDs) have been progressively attracting interest as novel environmentally friendly and cost-effective luminescent nanoparticles, for implementation in light-emitting devices, solar cells, photocatalytic devices and biosensors. Here, starting from a cost-effective bottom-up synthetic approach, based on a suitable amphiphilic molecule as carbon precursor, namely cetylpyridinium chloride (CPC), green-emitting CDs have been prepared at room temperature, upon treatment of CPC with concentrated NaOH solutions. The investigated method allows the obtaining, in one-pot, of both water-dispersible (W-CDs) and oil-dispersible green-emitting CDs (O-CDs). The study provides original insights into the chemical reactions involved in the process of the carbonization of CPC, proposing a reliable mechanism for the formation of the O-CDs in an aqueous system. The ability to discriminate the contribution of different species, including molecular fluorophores, allows one to properly single out the O-CDs emission. In addition, a mild heating of the reaction mixture, at 70 °C, has demonstrated the ability to dramatically decrease the very long reaction time (i.e. from tens of hours to days) at room temperature, allowing us to synthesize O-CDs in a few tens of minutes while preserving their morphological and optical properties.

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“…Azomethine ylides, consisting of an iminium ion adjacent to a carbanion, are allyl-anionic-type dipoles that can be applied to dipolar cycloaddition reactions (for reviews see [68][69][70][71]). Since their discovery by Kröhnke in 1935 [72], the properties and reactions of pyridinium ylides, a special subclass of azomethine ylides, have been intensively studied (for reviews see [11,73,74]).…”

Section: Pyridinium Ylidesmentioning

confidence: 99%

Nucleophilic Dearomatization of Activated Pyridines

2018

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Amongst nitrogen heterocycles of different ring sizes and oxidation statuses, dihydropyridines (DHP) occupy a prominent role due to their synthetic versatility and occurrence in medicinally relevant compounds. One of the most straightforward synthetic approaches to polysubstituted DHP derivatives is provided by nucleophilic dearomatization of readily assembled pyridines. In this article, we collect and summarize nucleophilic dearomatization reactions of - pyridines reported in the literature between 2010 and mid-2018, complementing and updating previous reviews published in the early 2010s dedicated to various aspects of pyridine chemistry. Since functionalization of the pyridine nitrogen, rendering a (transient) pyridinium ion, is usually required to render the pyridine nucleus sufficiently electrophilic to suffer the attack of a nucleophile, the material is organized according to the type of N-functionalization. A variety of nucleophilic species (organometallic reagents, enolates, heteroaromatics, umpoled aldehydes) can be productively engaged in pyridine dearomatization reactions, including catalytic asymmetric implementations, providing useful and efficient synthetic platforms to (enantioenriched) DHPs. Conversely, pyridine nitrogen functionalization can also lead to pyridinium ylides. These dipolar species can undergo a variety of dipolar cycloaddition reactions with electron-poor dipolarophiles, affording polycyclic frameworks and embedding a DHP moiety in their structures.

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Pyridinium Ylids in Heterocyclic Synthesis

Cited by 97 publications

References 0 publications

[1-Methoxy-3-(pyridin-2-yl)indolizin-2-yl](pyridin-2-yl)methanone

[1-Methoxy-3-(pyridin-2-yl)indolizin-2-yl](pyridin-2-yl)methanone

Oil-Dispersible Green-Emitting Carbon Dots: New Insights on a Facile and Efficient Synthesis

Nucleophilic Dearomatization of Activated Pyridines

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