Issue 8, 2024

A dearomatization–rearomatization strategy for construction of 4H-quinolizin-4-ones via C–H bond functionalization of pyridines

Abstract

Herein, based on a dearomatization–rearomatization strategy, a straightforward construction of poly-substituted and fused 4H-quinolizin-4-ones via direct ortho C–H bond functionalization of pyridines under metal-free conditions has been developed. This approach offers a convenient method for the modular synthesis of functionalized 4H-quinolizin-4-ones from simple pyridines, methyl 2-bromoacetates, and alkenes. Mechanistic studies indicated that the reaction included activation of pyridines to N-(2-methoxy-2-oxoethyl) pyridinium salts, dearomative [3 + 2] cycloaddition, and rearomative ring expansion processes. Notably, an aromatization-driven β cleavage of the relatively stable pyridine radical intermediate was proposed as a key process for the construction of the desired 4H-quinolizin-4-ones over the traditional indolizines.

Graphical abstract: A dearomatization–rearomatization strategy for construction of 4H-quinolizin-4-ones via C–H bond functionalization of pyridines

Supplementary files

Article information

Article type
Research Article
Submitted
30 Nov 2023
Accepted
24 Feb 2024
First published
26 Feb 2024

Org. Chem. Front., 2024,11, 2319-2325

A dearomatization–rearomatization strategy for construction of 4H-quinolizin-4-ones via C–H bond functionalization of pyridines

D. Qiu and Y. Su, Org. Chem. Front., 2024, 11, 2319 DOI: 10.1039/D3QO01990J

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