Free Radical Chemistry Enabled by Visible Light-Induced Electron Transfer.
Free Radical Chemistry Enabled by Visible Light-Induced Electron Transfer.
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可见光诱导电子转移的自由基化学。
DOI：
10.1021/acs.accounts.6b00270
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发表时间：
2016-10-18
影响因子：
18.3
通讯作者：
Stephenson, Corey R. J.
中科院分区：
文献类型：
--
作者：
Staveness, Daryl;Bosque, Irene;Stephenson, Corey R. J.
与经典的合成方法相比，利用可见光作为化学转化的驱动力通常提供了一种更环保的替代方案。过渡金属基光催化剂通常用于光氧化还原催化，与大多数有机基质不同，它可以在可见光光谱中有效吸收，允许正交激发。随后的激发态比基态催化剂更具还原性和氧化性，并与有机化学家可用的一些更强大的单电子氧化剂或还原剂竞争，但只需通过辐射即可获得。这一策略的好处已被证明在基础化学中特别有用，该领域传统上使用相当有毒和危险的试剂来产生所需的中间体。在这篇文章中，我们讨论了我们在基于自由基的成键和键断裂事件中利用可见光光氧化还原催化所做的努力，对于这些事件，几乎没有环境友好的替代方案。机械性的调查推动了我们在这一领域的贡献，既促进了所需的转变，也提供了新的、意想不到的机会。事实上，我们的(+)-醇溶蛋白C的全合成只有在阐明了各种三烷胺添加剂作为还原猝灭剂和H原子供体的双重行为的倾向之后才有可能。重要的是，虽然天然产物合成是我们探索这些光化学过程的最初动机的核心，但自那以后，我们已经证明了其在化学其他子领域的适用性，我们对流动技术的评估展示了将这些结果从实验室转化为中试规模的潜力。我们对光氧化还原催化的探索始于基本的方法学，提供了一种无锡还原脱卤化反应，将以前用于这种转化的各种危险试剂换成了可见光介导的常温条件。在这项工作的基础上，发展了一条通往原子转移自由基加成(ATRA)化学的新途径，使双键和三键都能够实现双重官能化。重要的是，我们还扩大了我们的产品组合，瞄准临床相关的支架。事实证明，通过使用大量可用的起始原料，光氧化还原催化有效地生成了高价值的含氟烷基，提供了进入三氟甲基化(杂)芳烃文库的途径，以及通过新颖的光化学自由基微笑重排获得了有趣的GEM-二氟苯基模体。最后，我们讨论了通过选择性C-O键裂解方法实现木质素可持续加工的光化学策略。收集这些努力的目的是要突出可见光介导的自由基化学影响各种工业部门的潜力。
Harnessing visible light as the driving force for chemical transformations generally offers a more environmentally friendly alternative compared with classical synthetic methodology. The transition metal-based photocatalysts commonly employed in photoredox catalysis absorb efficiently in the visible spectrum, unlike most organic substrates, allowing for orthogonal excitation. The subsequent excited states are both more reducing and more oxidizing than the ground state catalyst and are competitive with some of the more powerful single-electron oxidants or reductants available to organic chemists yet are simply accessed via irradiation. The benefits of this strategy have proven particularly useful in radical chemistry, a field that traditionally employs rather toxic and hazardous reagents to generate the desired intermediates. In this Account, we discuss our efforts to leverage visible light photoredox catalysis in radical-based bond-forming and bond-cleaving events for which few, if any, environmentally benign alternatives exist. Mechanistic investigations have driven our contributions in this field, for both facilitating desired transformations and offering new, unexpected opportunities. In fact, our total synthesis of (+)-gliocladin C was only possible upon elucidating the propensity for various trialkylamine additives to elicit a dual behavior as both a reductive quencher and a H-atom donor. Importantly, while natural product synthesis was central to our initial motivations to explore these photochemical processes, we have since demonstrated applicability within other subfields of chemistry, and our evaluation of flow technologies demonstrates the potential to translate these results from the bench to pilot scale. Our forays into photoredox catalysis began with fundamental methodology, providing a tin-free reductive dehalogenation that exchanged the gamut of hazardous reagents previously employed for such a transformation for visible light-mediated, ambient temperature conditions. Evolving from this work, a new avenue toward atom transfer radical addition (ATRA) chemistry was developed, enabling dual functionalization of both double and triple bonds. Importantly, we have also expanded our portfolio to target clinically relevant scaffolds. Photoredox catalysis proved effective in generating high value fluorinated alkyl radicals through the use of abundantly available starting materials, providing access to libraries of trifluoromethylated (hetero)arenes as well as intriguing gem-difluoro benzyl motifs via a novel photochemical radical Smiles rearrangement. Finally, we discuss a photochemical strategy toward sustainable lignin processing through selective C–O bond cleavage methodology. The collection of these efforts is meant to highlight the potential for visible light-mediated radical chemistry to impact a variety of industrial sectors.
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影响因子：
18.3
作者：
Beatty, Joel W.;Stephenson, Corey R. J.
通讯作者：
Stephenson, Corey R. J.
DOI：
10.1021/jo502288q
发表时间：
2014-12-05
期刊：
The Journal of organic chemistry
影响因子：
--
作者：
Douglas JJ;Cole KP;Stephenson CR
通讯作者：
Stephenson CR
影响因子：
--
作者：
FUKUZUMI, S;MOCHIZUKI, S;TANAKA, T
通讯作者：
TANAKA, T
影响因子：
5.7
作者：
Kim, Seonah;Chmely, Stephen C.;Beckham, Gregg T.
通讯作者：
Beckham, Gregg T.
影响因子：
7.3
作者：
Gillis, Eric P.;Eastman, Kyle J.;Meanwell, Nicholas A.
通讯作者：
Meanwell, Nicholas A.