Characterizing chain processes in visible light photoredox catalysis

Cismesia, Megan A.; Yoon, Tehshik P.

doi:10.1039/c5sc02185e

Cited by 870 publications

(840 citation statements)

References 69 publications

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“…Pleasingly, in the presence of an aryl‐disulfide as H‐atom relay catalyst,18 and 2,6‐lutidine as the base, 5 a was obtained in 81 % yield, which, to the best of our knowledge, represents the first fully catalytic radical hydroimination of olefins. Control experiments established the requirement for 4 and continuous irradiation and the calculated quantum yield19 Φ =0.09 supports the photoredox nature of the process 16…”

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confidence: 59%

Photoredox Imino Functionalizations of Olefins

2017

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Shown herein is that polyfunctionalized nitrogen heterocycles can be easily prepared by a visible‐light‐mediated radical cascade process. This divergent strategy features the oxidative generation of iminyl radicals and subsequent cyclization/radical trapping, which allows the effective construction of highly functionalized heterocycles. The reactions proceed efficiently at room temperature, utilize an organic photocatalyst, use simple and readily available materials, and generate, in a single step, valuable building blocks that would be difficult to prepare by other methods.

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confidence: 59%

Photoredox Imino Functionalizations of Olefins

2017

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“…[23] For a more detailed investigation of reaction mechanisms, the tools of advanced spectroscopy, such as transient absorption spectroscopy and time-resolved or coupled methods, are applied. These enable a detailed understanding of the concatenated sequence of reaction steps of a photoinitiated reaction.…”

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confidence: 99%

Photocatalysis in Organic Synthesis – Past, Present, and Future

2017

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Abstract:The use of visible light as a catalyst in organic reactions has developed greatly in the last decade as a result of the increasing urge to implement energy-efficient and green processes and through the availability of light-emitting diodesThe use of visible light to promote organic transformations has developed enormously over the last decade. Several factors have come together to make this possible: An increased awareness for optimizing the energy efficiency of reactions even on the laboratory scale identifies visible light as an ideal reagent.[1]Technological progress and broad commercial availability of light-emitting diodes that are able to provide high-intensity visible light in a narrow wavelength range for all colors have made ideal cheap and energy-efficient light sources available for photocatalysis. At the same time, advances in flow chemistry [2] and the use of transparent flow reactors in photocatalysis has helped to overcome challenges in the upscaling and reproducibility of photochemical reactions, which are important aspects for any larger-scale industrial application.Classical photochemistry using ultraviolet light for the direct excitation of organic compounds is an established and highly developed field of chemistry with a historical development spanning more than a century.[3] However, the discipline has remained, in the perception of many organic chemists, a special technique that is not easy to apply. This perception has changed with the use of visible light, photoredox catalysts, and sensitizers. The reaction setup in the synthesis lab does not differ much from that of typical thermal chemistry, with the exception of the light source. As visible light has lower energy than ultraviolet irradiation usually applied in classical photochemistry, in many cases the reactions are selective, more predictable, and easier to control. Many visible-light-mediated [a]

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“…Mechanistic investigations proved that this reaction is not a chain mechanism on the basis of the determined quantum yield (Φ = 0.33). [21] Moreover, the proton for the final protonation step comes from the solvent, as confirmed by labeling experiments.…”

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confidence: 72%