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Verkhov, Valery A. ; Yakubenko, Artyom A. ; Begović, Benjamin ; Tupikina, Elena Yu. ; Antonov, Alexander S.

Breaking the Aromaticity Trap: N-Silylation-Induced Formation of Stable 2,3-Dihydro-4-dialkylaminopyridin-1-iums

Verkhov, Valery A., Yakubenko, Artyom A. , Begović, Benjamin, Tupikina, Elena Yu. and Antonov, Alexander S. (2026) Breaking the Aromaticity Trap: N-Silylation-Induced Formation of Stable 2,3-Dihydro-4-dialkylaminopyridin-1-iums. The Journal of Organic Chemistry.

Date of publication of this fulltext: 02 Jul 2026 14:16
Article
DOI to cite this document: 10.5283/epub.79749


Abstract

The reactivity of pyridines toward organolithium reagents is dominated by the nucleophilic addition to the C2 position, leading to the formation of labile 1,2-dihydropyridines that readily rearomatize. Herein, we report an unexpected deviation from this classical pathway. Trimethylsilylation of 4-dialkylaminopyridine steers their reaction with alkyl lithium reagents (n-BuLi, s-BuLi, t-BuLi) ...

The reactivity of pyridines toward organolithium reagents is dominated by the nucleophilic addition to the C2 position, leading to the formation of labile 1,2-dihydropyridines that readily rearomatize. Herein, we report an unexpected deviation from this classical pathway. Trimethylsilylation of 4-dialkylaminopyridine steers their reaction with alkyl lithium reagents (n-BuLi, s-BuLi, t-BuLi) toward the formation of 2,3-dihydro-4-dialkylaminopyridin-1-iums, isolated as air-stable triflates, which are remarkably resistant to oxidation and deprotonation. This stability is attributed to pronounced orbital interactions and charge delocalization between the NR2 group and the pyridinium core creating a vinylogous amidine structural motif. At the same time, triisopropylsilylation completely suppresses nucleophilic addition, enabling the first case of room-temperature C2 lithiation of the pyridine core. This difference in the reaction pathway originated from a dramatic decrease of the relative steric accessibility of C2(6) pyridine carbon atoms.



Involved Institutions


Details

Item typeArticle
Journal or Publication TitleThe Journal of Organic Chemistry
Publisher:ACS
Open Access Type:ACS Hybrid
Date25 June 2026
InstitutionsChemistry and Pharmacy > Institut für Organische Chemie
Chemistry and Pharmacy > Institut für Organische Chemie > Arbeitskreis Prof. Dr. Ruth Gschwind
Projects
Funded by: Deutsche Forschungsgemeinschaft (DFG) (426795949)
Identification Number
ValueType
10.1021/acs.joc.6c00105DOI
KeywordsAddition reactions, Chemical reactions, Nitrogen, Pyridines, Reagents
Dewey Decimal Classification500 Science > 540 Chemistry & allied sciences
StatusPublished
RefereedYes, this version has been refereed
Created at the University of RegensburgYes
URN of the UB Regensburgurn:nbn:de:bvb:355-epub-797497
Item ID79749

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