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Updated: Jun 2, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Gold(I)-Catalyzed Nucleophilic Propargylation of Azinium Ions via Hydroxydihydroazine Intermediates
Jack Smithson1,2, Luke O'Brien1,2, Kieran D Jones1,2
1The GlaxoSmithKline Carbon Neutral Laboratories for Sustainable Chemistry, University of Nottingham, Jubilee Campus, Triumph Road, Nottingham, NG7 2TU, UK.
Abstract:
The nucleophilic propargylation of azinium ions with a propargylboronate proceeds efficiently under gold(I) catalysis. A range of N-alkylated pyridinium, quinolinium, and pyrazinium ions undergo propargylation with good yields and high regioselectivities to give various functionalized 1,4-dihydropyridines, 1,2-dihydropyridines, 1,4-dihydroquinolines, 1,2-dihydroquinolines, and 4,5-dihydropyrazines. No allenylation side-products are observed. Density functional theory (DFT) calculations provided insight into the mechanisms of these reactions. Hydroxydihydroazine intermediates formed by the addition of LiOH to the azinium ions were found to be the reactive electrophiles in these reactions.
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