Wu Jingjing, Wang Hui, Fang Huaquan, Wang Kevin C, Ghosh Deborin, Fasano Valerio, Noble Adam, Aggarwal Varinder K
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K.
J Am Chem Soc. 2025 Jun 11;147(23):19450-19457. doi: 10.1021/jacs.5c03864. Epub 2025 May 30.
Organic free radicals are commonly perceived to be highly reactive species with short lifetimes, yet there are many examples that defy this convention by displaying remarkable stability. Although these persistent radicals can be relatively unreactive in their ground states, photoexcitation can generate highly reactive excited states. Despite this, they have found limited application as reagents or catalysts in photochemical reactions. Here we report the identification of persistent boryl-bipyridine radicals that function as highly reducing photoredox catalysts. These radicals, which are generated by simply mixing a bipyridine with a diboron reagent, were found to possess excited state reduction potentials that rival the most powerful photoreductants reported to date. We show that this class of doublet state photoredox catalyst can promote borylations of alkyl bromides and various other transformations.
有机自由基通常被认为是具有短寿命的高活性物种，但有许多例子违背了这一传统观念，表现出显著的稳定性。尽管这些持久性自由基在基态下可能相对不活泼，但光激发可以产生高活性的激发态。尽管如此，它们在光化学反应中作为试剂或催化剂的应用却很有限。在此，我们报告了一种持久性硼基联吡啶自由基的鉴定，该自由基可作为高还原性光氧化还原催化剂。这些自由基通过简单地将联吡啶与二硼试剂混合而产生，发现其激发态还原电位可与迄今为止报道的最强光还原剂相媲美。我们表明，这类双重态光氧化还原催化剂可以促进溴代烷的硼化反应和各种其他转化反应。
