An asymmetric induction principle and biomimetics with photons via electron transfer

The interaction between an electronically excited photocatalyst and an organic molecule can result in the genertion of a diverse array of reactive intermediates that can be manipulated in a variety of ways to result in synthetically useful bond constructions. This Review summarizes dual-catalyst strategies that have been applied to synthetic photochemistry. Mechanistically distinct modes of photocatalysis are discussed, including photoinduced electron transfer, hydrogen atom transfer, and energy transfer. We focus upon the cooperative interactions of photocatalysts with redox mediators, Lewis and Brønsted acids, organocatalysts, enzymes, and transition metal complexes.

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“…109,110 Furthermore, a remote chiral auxiliary could be used to control the stereochemical outcome of the overall transformation. 111–113 …”

Section: Photoinduced Electron Transfermentioning

confidence: 99%

Dual Catalysis Strategies in Photochemical Synthesis

2016

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“…Longer cascades of cyclizations are more likely to involve precursors that contain repeating units, as exemplified by the cascade initiated by an unusual photoelectron transfer (PET) method (Scheme , top) 119. Although this cascade was started by initial formation of radical cation 86 from tetraene 85 , the domino cyclization was purely a radical process,120 and was applied to the synthesis of (±)‐stypoldione 87 . The three endo cyclizations were constrained by the three strategically placed methyl substituents in the original tetraene.…”

Section: Three‐stage and Longer Unimolecular Cascadesmentioning

confidence: 99%

Programming Organic Molecules: Design and Management of Organic Syntheses through Free-Radical Cascade Processes

McCarroll

Walton

2001

Angew. Chem. Int. Ed.

236

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Cascade, domino, or tandem processes, that link together two or more transformations in one pot, are increasing in popularity because they lead to improvements in synthetic efficiency and decreases in environmental impact. Not only do these cascades contain choice mechanistic gems but they also deliver compact and elegant syntheses of complex natural products. Longer cascades require more functional groups precisely configured within carefully designed initial molecular architectures. Such “purposeful” molecules can be thought of as chemical algorithms.This article surveys the phenomenal range of unimolecular free‐radical cascades. A convenient system for classifying free‐radical cascades is described that is useful for evaluating and comparing cascades and aids the design of synthetic routes to polycyclic structures.Double cyclization cascades lead to cyclopentylcyclopentane or bicyclo[3.3.0]octane derivatives. Precursors that contain a ring as a template have been used to control stereochemistry in syntheses of triquinanes and many related compounds. Of the cascades containing ring‐cleavage steps, the most useful are the ring expansions which have opened up new synthetic routes to medium ring polycycles.The key design features of three‐stage unimolecular free‐radical cascades that yielded steroid structures, are linear arrays of radical acceptor units associated with methyl groups distributed every fifth C‐atom in the precursor polyenes. Ring cleavage is the reverse of cyclization. In special, symmetrical structures, therefore, this led to sequences that were reversible, thus launching endlessly repeating cascades supported by delightfully fluxional structures. The science of “programming” organic molecules to achieve particular target structures is maturing rapidly. Coordination and classification of the welter of information in this area is intended to facilitate design and hence to extend the range and complexity of attainable structures.

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“…Not surprisingly, the high optical concentration power of this reactor afforded a significant reduction of the reaction time, compared with the 104 h required for the direct excitation of the substrate. However, the performance of this reactor design is linked to the presence of clear sky: in partially sunny or a cloudy day, low-tech flat-bed collectors have shown to be superior thanks to their ability to efficiently collect the diffuse component of solar irradiance [36, 37].…”

Section: Reactor Designsmentioning

confidence: 99%

Solar Photochemistry in Flow

Cambié

Noël

2018

Top Curr Chem (Z)

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In recent years, photochemistry has been a highly active research field. This renaissance is linked to the upsurge of photoredox catalysis, a versatile platform for synthetic methodologies using visible light photons as a traceless reagent. In contrast with UV, visible light constitutes almost half of the ground solar irradiance, making the use of solar light in chemistry a sustainable and viable possibility. However, the direct use of sunlight to power chemical reactions is still little explored. This can be explained by both the hurdles associated with solar radiation (e.g., its variability, irreproducibility, high IR content, etc.) and the need for a specialized photoreactor. Most of these issues can be tackled with technological solutions, and especially with the recourse to flow chemistry. Flow chemistry goes hand in hand with photochemistry thanks to the uniform irradiation it provides to the reaction. Furthermore, a continuous-flow reactor can be easily integrated with different solar collectors (including compound parabolic concentrators and luminescent solar concentrators) and constitutes the most efficient approach to solar photochemistry. After a description of the characteristics of the solar radiation relevant to chemistry, this chapter critically describes the different type of solar photoreactors and their applications in synthetic organic chemistry. Finally, an outlook on the future of solar photochemistry in flow is included.

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An asymmetric induction principle and biomimetics with photons via electron transfer

Abstract: Abstract

Cited by 32 publications

References 1 publication

Dual Catalysis Strategies in Photochemical Synthesis

Dual Catalysis Strategies in Photochemical Synthesis

Programming Organic Molecules: Design and Management of Organic Syntheses through Free-Radical Cascade Processes

Solar Photochemistry in Flow

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