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Updated: Aug 10, 2025

Metal-free Synthesis of Ynones from Acyl Chlorides and Potassium Alkynyltrifluoroborate Salts
Published on: February 24, 2015
Bromide-mediated, C2-selective, and oxygenative alkylation of pyridinium salts using alkenes and molecular oxygen
Dong Qiu1,2, Huiyang Liu1,2, Shuai Sun1
1State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, P. R. China. suyj@licp.cas.cn.
Abstract:
Herein, we report a bromide-mediated, C2-selective, and oxygenative alkylation of pyridinium salts using alkenes and O2 for the synthesis of important β-2-pyridyl ketones. Notably, a quaternary carbon center was successfully installed at the C2-position of pyridine and the resulting C2-substituents were highly functionalized. The intermediary cycloadduct was isolated and further transformed into the desired product, which indicated that this three-component reaction underwent a reaction cascade including dearomative cycloaddition and rearomative ring-opening oxygenation. Finally, the bromide-mediated mechanism was discussed and active Br(I) species were proposed to be generated in situ and promote the rearomative ring-opening oxygenation by halogen bond-assisted electron transfer.
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