Work

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

Year: 2026

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide 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 NR 2 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.

Source: The Journal of Organic Chemistry

DOI: 10.1021/acs.joc.6c00105

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

Institutions: St Petersburg University, University of Regensburg

Language: English

Topic: Coordination Chemistry and Organometallics

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funder: Deutsche Forschungsgemeinschaft