Heterocycle Syntheses with Anionic N-Heterocyclic Carbenes : Ring Transformations of Sydnone Imine Anions

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Freese , T , Luecke , A-L , Namyslo , J C , Nieger , M & Schmidt , A 2018 , ' Heterocycle Syntheses with Anionic N-Heterocyclic Carbenes : Ring Transformations of Sydnone Imine Anions ' , European Journal of Organic Chemistry , no. 14 , pp. 1646-1654 . https://doi.org/10.1002/ejoc.201800028

Title: Heterocycle Syntheses with Anionic N-Heterocyclic Carbenes : Ring Transformations of Sydnone Imine Anions
Author: Freese, Tyll; Luecke, Ana-Luiza; Namyslo, Jan C.; Nieger, Martin; Schmidt, Andreas
Contributor: University of Helsinki, Department of Chemistry
Date: 2018-04-17
Language: eng
Number of pages: 9
Belongs to series: European Journal of Organic Chemistry
ISSN: 1434-193X
URI: http://hdl.handle.net/10138/324828
Abstract: Sydnone imines were deprotonated at the C4 position to give lithium-stabilized anions, which proved to be stable for several months in solution. These anions are elements of the intersection of the substance classes of N-heterocyclic carbenes and mesomeric betaines. They can be formulated as anionic N-heterocyclic carbenes. The negative charge translates into high-field shifts of the C-13 NMR resonance frequencies of C4 in comparison to other NHCs. Similar to the chemistry of N-heterocyclic carbenes, reactions with isocyanates and isothiocyanates gave 4-(N-carbamoyl)-benzoylsydnone imines in trapping reactions. As a result of ring transformations involving the characteristic p-architecture of the mesoionic framework, imidazolidine-2,4-dithiones, imidazolin-2,4-diones and 1,2,4-triazol-5-ones were formed depending on the substitution pattern of the starting materials and the reaction conditions.
Subject: Betaines
Carbenes
Anions
1,2,4-Triazolones
Imidazolidine-2,4-diones
CONJUGATED MESOMERIC BETAINES
HEILMITTELCHEMISCHE STUDIEN
CYCLOADDITION REACTIONS
PALLADIUM COMPLEXES
UBER SYDNONIMINE
ORGANOLITHIUM
CHEMISTRY
PYRAZOLE
CO2
DECARBOXYLATION
116 Chemical sciences
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