Photoredoxkatalyse mit sichtbarem Licht

Abstract

Organische Umsetzungen, die durch sichtbares Licht ausgelöst werden, finden seit einigen Jahren immer größere Aufmerksamkeit. Insbesondere im Hinblick auf Kosten, Sicherheit, Verfügbarkeit und Umweltfreundlichkeit ist die Entwicklung solcher photokatalytischer Reaktionen zur effizienten Herstellung von Feinchemikalien höchst wünschenswert. In diesem Kurzaufsatz werden die jüngsten Fortschritte auf diesem sich schnell entwickelnden Forschungsgebiet erörtert.

Photochemical Transformations Accelerated in Continuous‐Flow Reactors: Basic Concepts and Applications

“…Hereby, incident light is absorbed by a catalyst or sensitizer and the electrons or energy are subsequently transferred to or accepted from an acceptor molecule, which can undergo a chemical transformation. [3][4][5] In the past several decades, the study of photochemical processes mainly involved research towards new product formation, reaction kinetics, and mechanisms. Despite the apparent advantages of photochemical transformations, implementation of this energy source in the large -scale production of chemicals has been largely neglected for a variety of reasons: [6] 1) Process complexity associated with photochemical processes leads to significant challenges for the proper reactor design and its modeling.…”

Photoredox Transformations with Dimeric Gold Complexes

“…[1,2] However, many organic compounds do not absorb sunlight or visible light, and the application of photochemistry in synthesis is therefore restricted. [6] During the last decade, several metal complexes, such as [Ru(bpy) 3 Cl 2 ] (1), [Ir(ppy) 2 (dtbbpy)PF 6 ] (2), and fac-[Ir-(ppy) 3 ] (3), have proven their potential in absorbing light and transforming it into electronic energy that can be used in organic synthesis to generate new CÀC, CÀN, and CÀO bonds through a single-electron-transfer (SET) process. [3] The inorganic complex [Ru(bpy) 3 Cl 2 ] (1) is one of the most used oneelectron photoredox catalysts for research in energy storage, water splitting, and photovoltaic devices.…”

Carboamination of Unactivated Alkenes through Three‐Component Radical Conjugate Addition

“…[16] As N-radical precursors,weused readily prepared aamido-oxy acids [17] where the N-protecting group can be varied and radical generation is known to be achieved by single electron oxidation using aredox catalyst. [18] We commenced the study by using the Cbz-protected Nradical precursor 1a in combination with 2-ethylbutene 2a and methyl vinyl ketone (3a)a pplying photoredox catalysis. Extensive experimentation revealed that the cascade is best conducted with Ir(dFCF 3 ppy) 2 (dtbbpy)PF 6 as the photocatalyst (PC,0 .5 mol %) in combination with Cs 2 CO 3 (1.5 equiv) and H 2 O(2equiv) as an additive in dichloromethane (DCM) at room temperature for 24 hours under blue light irradiation.…”