由于所得烷氧基自由基容易断裂,分子间自由基加成到羰基上是困难的。迄今为止,酮的分子间自由基加成是构建季碳中心的一种有价值的方法,仍然是一项艰巨的合成挑战。在这里,我们报告了第一个可见光诱导的分子间烷基硼酸加成到 α-酮酸通过路易斯酸活化实现的。各种光谱测量和机械探测实验证实了原位硼配合物的形成,这有助于将各种烷基硼酸加成到羰基上,并防止新形成的 CC 键断裂。在室温下,仅在可见光照射下,无需任何额外试剂,即可由易得的烷基硼酸和酮酸合成不同取代的乳酸酯。这种硼活化方法可以扩展到作为自由基前体的烷基二氢吡啶与用于伯、仲和叔烷基自由基加成的外部硼试剂。在流动反应器中的无金属条件下,药学上有用的抗胆碱能前体很容易放大到数克。
A series of N,N′-dialkylated derivatives of (1R,2R)-cyclohexane-1,2-diamine were synthesized, and a new approach to the one-pot preparation of this type of amine was demonstrated. The prepared diamines were used as organocatalysts for the two-stepsynthesis of α-hydroxy γ-keto esters from arenes, chlorooxoacetates, and ketones; they were also used as chiral ligands for Meervein–Ponndorf–Verley reductions
Divergent Photocatalytic Reactions of α-Ketoesters under Triplet Sensitization and Photoredox Conditions
作者:Jian Zheng、Xiao Dong、Tehshik P. Yoon
DOI:10.1021/acs.orglett.0c02314
日期:2020.8.21
The long-lived triplet excited states of transition metal photocatalysts can activate organic substrates via either energy- or electron-transfer pathways, and the rates of these processes can be influenced by rational tuning of the reaction conditions. The characteristic reactive intermediates generated, however, are distinct and can exhibit very different reactivity patterns. This mechanistic diversity
Development of Decarboxylative Coupling Processes for the Synthesis of Azomethines and Ketones
作者:Florence Collet、Bingrui Song、Felix Rudolphi、Lukas J. Gooßen
DOI:10.1002/ejoc.201101103
日期:2011.11
redox-neutral decarboxylativecross-coupling reactions. Hydrogenation of the azomethine products leads to secondary amines. Alternatively, they can be hydrolyzed in situ to arylketones. The resulting ketonesynthesis via azomethine intermediates is also of interest as it gives higher yields at much lower temperatures than the direct decarboxylative coupling of α-oxo carboxylates with aryl halides.
作者:Kidd, Jesse B.、Fiala, Tahoe A.、Swords, Wesley B.、Park, Yerin、Meyer, Kent A.、Sanders, Kyana M.、Guzei, Ilia A.、Wright, John C.、Yoon, Tehshik P.
DOI:10.1021/jacs.4c02975
日期:——
electronic structure of their excited state and divert their reactivity toward alternate photoproducts. We show herein that a triplet rebound strategy enables the stereocontrolled reaction of an excited-state carbonyl compound in its native, unbound state. These studies have resulted in the development of the first highly enantioselective catalytic Paternò–Büchi reaction, catalyzed by a novel hydrogen-bonding
Paternò-Büchi 反应是羰基与烯烃的 [2 + 2] 光环加成反应,得到氧杂环丁烷。然而,这种经典光反应的对映选择性催化已被证明是一个长期存在的挑战。许多最先进的不对称光化学策略并不适合解决这个问题,因为羰基与布朗斯台德或路易斯酸性催化剂的相互作用可以改变其激发态的电子结构并将其反应性转向替代光产物。我们在此表明,三重态回弹策略能够实现激发态羰基化合物在其天然、未结合状态下的立体控制反应。这些研究开发出了第一个高度对映选择性催化 Paternò-Büchi 反应,该反应由新型氢键手性 Ir 光催化剂催化。
Bouveault, Bulletin de la Societe Chimique de France, 1897, vol. <3> 17, p. 941