Flavin-photosensitized reactions of retinal and stilbene

Gordon-Walker, Ann; Radda, George K.

doi:10.1042/bj1200673e

Cited by 12 publications

(7 citation statements)

References 24 publications

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“…During the course of their investigations into the photochemistry of retinol derivatives in the presence of (−)-riboflavin, Walker and Radda discovered that the opposite directionality is observed (i.e., E → Z ) via sensitization in the presence of (−)-riboflavin (Vitamin B2) . The same group reported that the isomerization of stilbene can be achieved using several flavin-based derivatives . Inspired by these studies, Metternich and Gilmour developed a biomimetic isomerization in which cinnamyl derivatives serve as retinal chromophore surrogates .…”

Section: Geometric Isomerization Of Simple Alkenes Via Selective Ener...mentioning

confidence: 99%

“…163 The same group reported that the isomerization of stilbene can be achieved using several flavin-based derivatives. 164 Inspired by these studies, Metternich and Gilmour developed a biomimetic isomerization in which cinnamyl derivatives serve as retinal chromophore surrogates. 165 In an operationally simple protocol, inexpensive (−)-riboflavin was used as a photocatalyst under irradiation with violet LEDs (402 nm).…”

Section: Isomerization Of Cinnamyl Derivativesmentioning

confidence: 99%

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Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

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Geometrical E → Z alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and is enjoying a renaissance (Roth et al. Angew. Chem., Int. Ed. Engl. 1989 28, 1193–1207). This is a consequence of the fundamental stereochemical importance of Z-alkenes, juxtaposed with frustrations in thermal reactivity that are rooted in microscopic reversibility. Accessing excited state reactivity paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences in the photophysical behavior of the substrate and product chromophores: this provides a molecular basis for directionality. While direct irradiation is operationally simple, photosensitization via selective energy transfer enables augmentation of the alkene repertoire to include substrates that are not directly excited by photons. Through sustained innovation, an impressive portfolio of tailored small molecule catalysts with a range of triplet energies are now widely available to facilitate contra-thermodynamic and thermo-neutral isomerization reactions to generate Z-alkene fragments. This review is intended to serve as a practical guide covering the geometric isomerization of alkenes enabled by energy transfer catalysis from 2000 to 2020, and as a logical sequel to the excellent treatment by Dugave and Demange (Chem. Rev. 2003 103, 2475–2532). The mechanistic foundations underpinning isomerization selectivity are discussed together with induction models and rationales to explain the counterintuitive directionality of these processes in which very small energy differences distinguish substrate from product. Implications for subsequent stereospecific transformations, application in total synthesis, regioselective polyene isomerization, and spatiotemporal control of pre-existing alkene configuration in a broader sense are discussed.

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Section: Geometric Isomerization Of Simple Alkenes Via Selective Ener...mentioning

confidence: 99%

Section: Isomerization Of Cinnamyl Derivativesmentioning

confidence: 99%

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

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“…25 Studies towards the flavinphotosensitization of stilbene have been undertaken, but only the trans-cis isomerisation of stilbene has been observed. 26 An example of double bond oxidation by flavin sensitization is the oxidation of unsaturated fatty acids in MeCN that yielded hydroperoxides of fatty acids. It was proposed that the oxidation proceeds by a type II (singlet oxygen) mechanism.…”

Section: Oxidation Of Phenylenesmentioning

confidence: 99%

Visible light flavin photo-oxidation of methylbenzenes, styrenes and phenylacetic acids

Lechner

Kümmel

König

2010

Photochem Photobiol Sci

135

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We report the photocatalytic oxidation of benzylic carbon atoms under mild conditions using riboflavin tetraacetate as photocatalyst and blue-emitting LEDs (440 nm) as light source. Oxygen is the terminal oxidant and hydrogen peroxide appears as the only byproduct in most cases. The process oxidizes toluene derivatives, stilbenes, styrenes and phenylacetic acids to their corresponding benzaldehydes. A benzyl methyl ether and acylated benzyl amines are oxidized directly to the corresponding methyl ester or benzylimides. The mechanism of the reactions has been investigated and the results indicate that oxygen addition to benzyl radicals is a key step of the oxidation process in the case of phenylacetic acids.

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“…[17] Stilbene (2), a prototypical substrate for studying E/Z-isomerism (Figure 1), has been a focal point in both experimental and computational investigations. [18] Experimental and…”

Section: Limitations Of the Adiabatic Modelmentioning

confidence: 99%

Dynamic Vertical Triplet Energies: A metric for predicting triplet energy transfer

Popescu,

Paton

2024

Preprint

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Visible light energy transfer catalysis has emerged in recent years as an attractive synthetic method for accessing high-energy intermediates, leading to the discovery of novel reactivity modes inaccessible via thermal methods. Computational methods have played a crucial role in understanding and predicting energy transfer catalysis, bypassing the need for complex and laborious photophysical measurements. Specifically, adiabatic triplet energies have been used as a predictive tool in the design of substrates amenable to sensitization, as well as a mechanistic tool. However, this approach fails to accurately predict the likelihood of triplet energy to molecules that undergo large structural changes upon excitation, and provides qualitatively incorrect predictions of E/Z-isomerism under energy transfer catalysis. Here, we introduce a new metric, dynamic vertical triplet energies (DvTE), based on the evaluation of change in vertical energy gaps throughout direct dynamics trajectory simulations. This approach improves the predictive capabilities of density functional theory computations and provides further support for the "hot-band" mechanism of energy transfer. We demonstrate excellent performance, with R2 = 0.96 and a mean absolute error (MAE) of 2.1 kcal/mol, for a collection of 20 small organic molecules, whereas the traditional adiabatic model performs significantly worse (R2=0.58, MAE = 8.3 kcal/mol). We anticipate this approach will be valuable for predicting E/Z isomerization triplet energies, for which currently there is no available computational protocol.

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Flavin-photosensitized reactions of retinal and stilbene

Cited by 12 publications

References 24 publications

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Visible light flavin photo-oxidation of methylbenzenes, styrenes and phenylacetic acids

Dynamic Vertical Triplet Energies: A metric for predicting triplet energy transfer

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