Visible-light induced photocatalyst-free synthesis of β-enaminones.

Authors

Zhiqin Zhang, Yuxuan Li, Xirui Zhang, Jiajing Tan, Hongguang Du, Ning Chen

Published in

Organic & biomolecular chemistry. Apr 22, 2025. Epub Apr 22, 2025.

Abstract

An environmentally friendly and efficient synthesis of β-enaminones through photo-acylation of vinyl azides is described herein, utilizing 4-acyl-1,4-dihydropyridines (4-acyl-1,4-DHPs) as dual-function reagents. These reagents simultaneously serve as reductants and radical initiators. The method accommodates a broad range of vinyl azides, demonstrating excellent functional group tolerance and enabling potential application. Comprehensive mechanistic exploration was conducted employing TEMPO trapping, on-off experiments, and isotopic labelling studies. Key to our understanding was the integration of dual-parameter Hammett analysis and kinetic isotope effect (KIE) studies. The Hammett analysis, using quadratic linear regression with dual radical parameters, σ_mb and σ_jj·, highlighted the involvement of radical mechanisms and anionic intermediates. In conjunction with KIE studies, these analyses revealed that the rate-limiting step in the transformation is the single-electron reduction of the conjugated enamine radical to the corresponding anion. This finding offers valuable insights into the reaction dynamics and could guide the development of related synthetic strategies.

PMID:
40260470
Bibliographic data and abstract were imported from PubMed on 22 Apr 2025.

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