Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis.
Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis.
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DOI：
10.1021/acs.accounts.5b00068
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发表时间：
2015-05-19
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：
Beatty, Joel W.;Stephenson, Corey R. J.
虽然使用可见光来驱动化学反应性对于开发环境友好的化学转化非常重要，但通常需要同时使用化学计量的电子供体或受体来控制这些系统的期望氧化还原行为。叔胺碱的低成本和普遍存在导致其在光氧化还原催化中作为还原性添加剂的广泛使用。在这种情况下，三烷基胺的早期使用集中在它们作为光催化剂的还原激发态猝灭剂的作用，这反过来提供了更高度还原的催化中间体。在这个帐户中，我们讨论了一些意见和思维过程，导致我们使用胺作为还原添加剂，以其作为复杂的底物和天然产物合成的中间体。我们小组早期尝试通过自由基中间体构建关键的碳-碳键，导致观察到一些三烷基胺在氧化还原活性光化学条件下容易表现为有效的氢原子供体。在20世纪70年代，80年代和90年代发表的深入的机理研究之后，这种理解反过来又允许通过合理调整胺组分来设计一些光化学方法的系统方法。最小化的胺添加剂的C-H donicity被发现，以促进所需的C-C键的形成在许多情况下，和随后的阐明胺的氧化还原命运引发了重新评估的胺的作用，从试剂的底物。叔胺在这些光化学系统中的反应性是复杂的，并且允许许多不一定相互排斥的机械可能性。单电子氧化、C-H夺取、去质子化和β-断裂的各种组合导致形成活性中间体，如α-氨基自由基和亚胺离子。这些过程已经在光化学文献中深入探讨，并导致了对基本体系中胺自由基阳离子行为的坚定的机械把握。利用这些瞬时物质的合成潜力代表了胺底物的受控官能化的持续挑战，因为这些机械可能性可能导致不期望的副产物形成或底物分解。叔胺的存在下，在许多生物碱，药物和农用化学品借给信任的潜在效用，这种化学在天然产物的合成，在这里，我们将讨论如何控制这些转换可能用于合成目的。
While the use of visible light to drive chemical reactivity is of high importance to the development of environmentally benign chemical transformations, the concomitant use of a stoichiometric electron donor or acceptor is often required to steer the desired redox behavior of these systems. The low-cost and ubiquity of tertiary amine bases has led to their widespread use as reductive additives in photoredox catalysis. Early use of trialkylamines in this context was focused on their role as reductive excited state quenchers of the photocatalyst, which in turn provides a more highly reducing catalytic intermediate. In this Account, we discuss some of the observations and thought processes that have led from our use of amines as reductive additives to their use as complex substrates and intermediates for natural product synthesis. Early attempts by our group to construct key carbon–carbon bonds via free-radical intermediates led to the observation that some trialkylamines readily behave as efficient hydrogen atom donors under redox-active photochemical conditions. In the wake of in-depth mechanistic studies published in the 1970s, 1980s and 1990s, this understanding has in turn allowed for a systematic approach to the design of a number of photochemical methodologies through rational tuning of the amine component. Minimization of the C–H donicity of the amine additive was found to promote desired C–C bond formation in a number of contexts, and subsequent elucidation of the amine’s redox fate has sparked a reevaluation of the amine’s role from that of reagent to that of substrate. The reactivity of tertiary amines in these photochemical systems is complex, and allows for a number of mechanistic possibilities that are not necessarily mutually exclusive. A variety of combinations of single-electron oxidation, C–H abstraction, deprotonation, and β-scission result in the formation of reactive intermediates such as α-amino radicals and iminium ions. These processes have been explored in depth in the photochemical literature and have resulted in a firm mechanistic grasp of the behavior of amine radical cations in fundamental systems. Harnessing the synthetic potential of these transient species represents an ongoing challenge for the controlled functionalization of amine substrates, because these mechanistic possibilities may result in undesired byproduct formation or substrate decomposition. The presence of tertiary amines in numerous alkaloids, pharmaceuticals, and agrochemicals lends credence to the potential utility of this chemistry in natural product synthesis, and herein we will discuss how these transformations might be controlled for synthetic purposes.
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DOI：
10.1126/science.1170777
发表时间：
2009-04-10
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Kim J;Ashenhurst JA;Movassaghi M
通讯作者：
Movassaghi M
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：
1.8
作者：
Cocquet, G;Rool, P;Ferroud, C
通讯作者：
Ferroud, C
影响因子：
2.7
作者：
Hu J;Wang J;Nguyen TH;Zheng N
通讯作者：
Zheng N