Photocatalytic Synthesis of Stilbenes via Cross‐Coupling of Alkenyl Boronic Acids and Arenediazonium Tetrafluoroborate Salts

Meyer, Tim; Xu, Jian‐Xing; Rabeah, Jabor; Brückner, Angelika; Wu, Xiao‐Feng

doi:10.1002/cptc.202000061

Cited by 11 publications

(12 citation statements)

References 93 publications

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“…This is unusual given that catalyst quenching and the production of singlet oxygen is expected to occur. An example of Ru(bpy) 3 Cl 2 enabling stilbene isomerization has been reported by Wu and co-workers …”

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

confidence: 99%

“…Shortly after this report, Luo et al reported a related transformation using Katritzky salt as radical precursors . Similarly, Wu and co-workers reported the stereoselective synthesis of alkenes utilizing redox active diazonium salts 324 (Scheme , bottom) . The authors used this platform to develop a route to stilbene derivatives ( 326 ) starting from boronic acid 325 and using Ru(bpy) 3 Cl 2 as the photocatalyst.…”

Section: Catalysis-based Processes Capped With Alkene Isomerizationmentioning

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: Catalysis-based Processes Capped With Alkene Isomerizationmentioning

confidence: 99%

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

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“…Within this area, an irradiance between 100 and 120 mW cm −2 was measured. Comparing these values to those of typical irradiation setups [74–80] (4–80 mW cm −2 ), it becomes apparent that the PhotoFlexys reactor system provides a sufficient strong irradiance to reproduce a wide range of literature protocols. At this point, it should be noted that the irradiance values are measured in a sliced model and the total irradiance might double in the complete reactor.…”

Section: Resultsmentioning

confidence: 96%

“…A) Evolution of the reactor's internal temperature with and without cooling and its effect on the irradiance. B) Comparison of actinometry and radiometric measurements for evaluation of the available photon flux typical irradiation setups [74][75][76][77][78][79][80] (4-80 mW cm À 2 ), it becomes apparent that the PhotoFlexys reactor system provides a sufficient strong irradiance to reproduce a wide range of literature protocols. At this point, it should be noted that the irradiance values are measured in a sliced model and the total irradiance might double in the complete reactor.…”

Section: Reactor Characterizationmentioning

confidence: 99%

The PhotoFlexys: A Multi‐Purpose Reactor Platform to Simplify Process Intensification and Mechanistic Studies in Photochemistry

Rößler

Liauw

2021

Chemistry Methods

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Reactor technology plays a vital role in photochemistry since process efficiency and reproducibility largely depend on the used reactor design. Considering the diverse requirements for photochemical reactions, we have developed a multi-purpose reactor platform that aims for an equally efficient implementation of photochemical reactions under batch and continuous flow conditions. Interchangeable irradiation units and reactor functionalities reduce the necessary equipment for running photochemical reactions to a minimum. The versatility of the reactor platform has been tested on a variety of benchmark reactions under batch, multi-batch and continuous flow conditions. Uniting the strengths of the photoreactor platform with an in-situ monitoring approach permitted reliable kinetic and mechanistic studies.

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“…A different approach in the generation of radicals from boronic acids was presented in 2020 by Wu and co‐workers (Scheme 26). [54] They developed a convenient alternative to the traditionally employed methodologies to synthesize stilbenes, whose ubiquitous presence in natural and biologically active molecules is well recognized. In contrast to the usually employed quite harsh conditions, the authors proposed the employment of an organic photocatalyst (Eosin Y, PC5) in a mixture of EtOH and water at room temperature.…”

Section: Radical Generation Through An Oxidative Quenching Cyclementioning

confidence: 99%

Uncovering the Potential of Boronic Acid and Derivatives as Radical Source in Photo(electro)chemical Reactions

et al. 2022

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The chemistry of boron compounds has been profoundly investigated in the last decades, leading to ubiquity in many synthetic applications as well as biologically active molecules. Since the advent of photoredox catalysis, an upsurge in the discovery of suitable radical precursors has been witnessed, and boron is becoming a protagonist in this field. Despite many studies focused on trifluoroborates, the use of boronic acids and esters have received much less attention in this regard. Because of their high oxidation potential, the development of methods to enable their involvement in photocatalyzed reactions is only recent. Nonetheless, this review summarizes novel strategies developed to unlock their role as radical precursors in photochemical reactions and discloses the potential that boronic acids and esters own, when their intrinsic chemical properties are exploited.

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Photocatalytic Synthesis of Stilbenes via Cross‐Coupling of Alkenyl Boronic Acids and Arenediazonium Tetrafluoroborate Salts

Cited by 11 publications

References 93 publications

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

The PhotoFlexys: A Multi‐Purpose Reactor Platform to Simplify Process Intensification and Mechanistic Studies in Photochemistry

Uncovering the Potential of Boronic Acid and Derivatives as Radical Source in Photo(electro)chemical Reactions

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