提出了利用有机光氧化还原催化对电子中性芳烃和富电子芳烃进行胺化的机理研究。动力学和计算数据支持使用唑和伯胺亲核试剂对芳烃阳离子自由基进行限速亲核加成。这一发现与氟化物和醇盐离核剂一致,支持使用阳离子自由基加速亲核芳香取代(CRA-S N Ar)的统一机制图。电化学和时间分辨荧光光谱证实了溶剂在胺存在下选择性芳烃氧化中发挥的关键作用。通过光物理研究阐明了呫吨盐的合成局限性。提出了一种具有改善的周转数的替代催化剂支架。
Cobalt-catalysed C–H methylation for late-stage drug diversification
作者:Stig D. Friis、Magnus J. Johansson、Lutz Ackermann
DOI:10.1038/s41557-020-0475-7
日期:2020.6
despite its significance, accessing such analogues via derivatization at a late stage remains a pivotal challenge. In an effort to mitigate this major limitation, we here present a strategy for the cobalt-catalysed late-stage C–H methylation of structurally complex drug molecules. Enabling broad applicability, the transformation relies on a boron-based methyl source and takes advantage of inherently present
作者:Shengjun Ni、Matic Hribersek、Swarna K. Baddigam、Fredric J. L. Ingner、Andreas Orthaber、Paul J. Gates、Lukasz T. Pilarski
DOI:10.1002/anie.202010202
日期:2021.3.15
The mechanochemical, solvent‐free, highly regioselective, rhodium‐catalyzed C−Hmethylation of (hetero)arenes is reported. The reaction shows excellent functional‐group compatibility and is demonstrated to work for the late‐stage C−Hmethylation of biologically active compounds. The method requires no external heating and benefits from considerably shorter reaction times than previous solution‐based
Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication
作者:He Huang、Zack M. Strater、Michael Rauch、James Shee、Thomas J. Sisto、Colin Nuckolls、Tristan H. Lambert
DOI:10.1002/anie.201906381
日期:2019.9.16
electrophotocatalytic oxidation platform. This chemistry employs a trisaminocyclopropenium (TAC) ion catalyst, which is electrochemically oxidized to form a cyclopropenium radical dication intermediate. The radical dication undergoes photoexcitation with visible light to produce an excited-state species with oxidizing power (3.33 V vs. SCE) sufficient to oxidize benzene and halogenated benzenes via single-electron
可见光光催化和电催化是促进化学反应的两种强大策略。在这里,这两种模式结合在电光催化氧化平台中。该化学过程采用三氨基环丙烯 (TAC) 离子催化剂,通过电化学氧化形成环丙烯自由基阳离子中间体。自由基阳离子在可见光下进行光激发,产生具有氧化能力(3.33 V vs. SCE)的激发态物质,足以通过单电子转移(SET)氧化苯和卤代苯,从而导致 CH/NH 与唑类偶联。提供了光激发物质的强氧化行为的基本原理,同时通过顺式2,6-二甲基哌啶部分的特定构象合理化了催化剂的稳定性。
Nucleophilic Aromatic Substitution of Unactivated Fluoroarenes Enabled by Organic Photoredox Catalysis
作者:Vincent A. Pistritto、Megan E. Schutzbach-Horton、David A. Nicewicz
DOI:10.1021/jacs.0c09296
日期:2020.10.7
use of organic photoredox catalysis renders this method operationally simple under mild conditions and is amenable to various nucleophile classes, including azoles, amines, and carboxylic acids. Select fluorinated heterocycles can be functionalized using this method. In addition, the late-stage functionalization of pharmaceuticals is also presented. Computational studies demonstrate that the site selectivity
Unveiling Potent Photooxidation Behavior of Catalytic Photoreductants
作者:Karina Targos、Oliver P. Williams、Zachary K. Wickens
DOI:10.1021/jacs.1c00399
日期:2021.3.24
We describe a photocatalytic system that reveals latent photooxidant behavior from one of the most reducing conventional photoredox catalysts, N-phenylphenothiazine (PTH). This aerobic photochemical reaction engages difficult to oxidize feedstocks, such as benzene, in C(sp2)–N coupling reactions through direct oxidation. Mechanistic studies are consistent with activation of PTH via photooxidation and