本文报道了一种可见光驱动的胺阳离子自由基介导的氢原子转移策略,成功实现了烯基醛与溴代二氟乙酸酯的氟烷基化环化反应。该方法通过原位形成电子给体-受体（EDA）复合物,在温和条件下实现了醛到酮的直接转化,并构建了含氟取代的环状酮类化合物。反应具有优异的官能团兼容性、广泛的底物适用性以及良好的产率。机理研究表明,胺阳离子自由基能够快速攫取烷氧基自由基α碳上的氢原子,有效避免了竞争性的1,5-HAT副反应。
A visible-light-driven fluoroalkylative cyclization of alkenyl aldehydes is achieved via amine radical cation-mediated hydrogen atom transfer. The reaction proceeds through an in-situ-formed electron donor-acceptor (EDA) complex between DABCO and ethyl bromodifluoroacetate, which under 390 nm LED irradiation generates difluoroalkyl radicals and amine radical cations. The amine radical cation then effects a key HAT step, delivering fluorinated cyclic ketones while suppressing competitive 1,5-HAT pathways. This protocol operates under mild, metal-free, and photocatalyst-free conditions, exhibits broad functional group tolerance, and is compatible with diverse alkenyl aldehydes and fluoroalkyl precursors.
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