在此,我们报道了使用 TEMPO 衍生的烷氧基胺进行光氧化还原亲核(放射性)氟化,这是一类底物,可通过多种容易获得的羧酸、卤化物、烯烃、醇、醛、硼试剂和 C-H 一步获得债券。这种温和且通用的单电子途径提供了放射性标记的脂肪族氟化物,由于反应性不足和竞争性消除,应用传统的亲核取代技术通常无法获得这些氟化物。该光氧化还原过程的自动化还通过用户友好且市售的光氧化还原流反应器和放射合成平台进行了演示,因此加快了获得高摩尔活性 ( A m ) 的标记脂肪族氟化物的速度,以进行临床(前)评估。
Catalytic, Enantioselective Addition of Alkyl Radicals to Alkenes via Visible-Light-Activated Photoredox Catalysis with a Chiral Rhodium Complex
作者:Haohua Huo、Klaus Harms、Eric Meggers
DOI:10.1021/jacs.6b03399
日期:2016.6.8
An efficient enantioselective addition of alkyl radicals, oxidatively generated from organotrifluoroborates, to acceptor-substituted alkenes is catalyzed by a bis-cyclometalated rhodium catalyst (4 mol %) under photoredox conditions. The practical method provides yields up to 97% with excellent enantioselectivities up to 99% ee and can be classified as a redox neutral, electron-transfer-catalyzed reaction
Visible Light-Induced Selective Generation of Radicals from Organoborates by Photoredox Catalysis
作者:Yusuke Yasu、Takashi Koike、Munetaka Akita
DOI:10.1002/adsc.201200588
日期:2012.12.14
A new strategy for the generation of carbon-centered radicals via oxidation of alkyl-, allyl-, benzyl- and arylborates by visible-light-driven single electron transfer (SET) photoredoxcatalysis has been established. The generated radicals smoothly react with TEMPO and electron-deficient alkenes to afford CO and CC coupling products, respectively. In this radical initiating system, cyclic organo(triol)borates
structurally complex structures. During the past decade, directing groups have revolutionized molecular synthesis in terms of ortho-selective C–H activation. In sharp contrast, a selectivity switch that guides the typical ortho- to remote meta-C–H activation has thus far proven elusive. Herein, we describe the realization of such a concept for a robust selectivity control in rutheniumcatalysis. The distal
Continuous UV-Flow Microsystem for Efficient Radical Generation from Organotrifluoroborates by Photoredox Catalysis
作者:Nassim El Achi、Maël Penhoat、Youssef Bakkour、Christian Rolando、Laëtitia Chausset-Boissarie
DOI:10.1002/ejoc.201600728
日期:2016.9
An efficient continuous-flow protocol for C–O and C–C bond formation fromorganoborates by photoredoxcatalysis under UV irradiation was explored. The combination of a cyclometalated iridium photocatalyst, high-power UV light-emitting diode irradiation, and microreactor technology resulted in very efficient radicalgeneration. The flow device enabled determination of highly accurate kinetic data that
isocyanates at the benzylic position upon irradiation with visiblelight in the presence of an iridium photoredox catalyst, a bromide anion, and a nickel catalyst, producing N-substituted α-aryl amides. An analogous carbamoylation reaction of aliphatic C–H bonds of alkanes took place when UV light and a diaryl ketone were used instead of visiblelight and the iridium complex. The present reaction offers