Solvent assisted photochemical formation of a new keto[3,3]paracyclophane

Shin, Ho Suk; Moon, Da Yoon; An, Sejin; Park, Bong Ser

doi:10.1039/d2ob00660j

Cited by 2 publications

(1 citation statement)

References 51 publications

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“…Recently, it has been reported that a phenol‐linked phenacyl benzoate can be cyclized into a cyclophane through the well‐understood cleavage of benzoate as a photoremovable protecting group. [28] While the linker is similar in both studies, the macrocyclization to the [3.3]cyclophane through the reaction of an α‐acyl radical with a phenol [29] is markedly different to the route to the [3.2]cyclophane reported herein, which employs an ester group. In contrast to the well‐studied photochemistry of ketones and aldehydes (such as Norrish reactions, Paternò–Büchi reactions, electron transfer reactions and intermolecular hydrogen abstractions), [30] photochemical reactions with esters are rare.…”

Section: Resultsmentioning

confidence: 81%

A Photochemical Macrocyclization Route to Asymmetric Strained [3.2] Paracyclophanes

Haensch

Görls

Hertweck

2022

Chemistry A European J

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The intricate frameworks of paracyclophanes are an important target for synthesis since they are found in various chiral auxiliaries, solar cells, high-performance plastics, pharmaceuticals, and molecular machines. Whereas numerous methods exist for the preparation of symmetric paracyclophanes, protocols for the efficient synthesis of strained asymmetric scaffolds are limited. Here we report a remarkably simple photochemical route to strained [3.2]paracyclophanes starting from readily available educts. By way of NMR and Xray analyses, we discovered that UV-irradiation of an aromatic carboxylic ester tethered to a toluene moiety leads to the intramolecular formation of a new CÀ C bond, with loss of an alcohol. A systematic evaluation of the reaction conditions and substituents, as well as radical starter and triplet quenching experiments, point to a reaction mechanism involving an excited triplet state and hydrogen atom transfer. The new method proved to be robust and versatile enabling the synthesis of a range of cyclophanes with different substitutions, including an unusual diastereoisomer with two planar chiral centers, and thus proved to be a valuable addition to the synthetic toolbox.

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Section: Resultsmentioning

confidence: 81%

A Photochemical Macrocyclization Route to Asymmetric Strained [3.2] Paracyclophanes

Haensch

Görls

Hertweck

2022

Chemistry A European J

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Photochemical coupling reaction of phenacyl benzoate with acetone to form 1,4‐dicarbonyl compound enabled by charge transfer

Shin,

Park

2024

Bulletin Korean Chem Soc

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Photolysis of phenacyl benzoates tethered with a phenol or anisole in acetone resulted in the formation of 1,4‐dicarbonyl compounds, coupling products of the phenacyl moiety with acetone. The reaction occurs via electron and/or proton transfer from a triplet exciplex, leading to the formation of a phenacyl radical, which then adds to the enol form of acetone. The reaction also occurs in intermolecular fashion with external electron donors.

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Solvent assisted photochemical formation of a new keto[3,3]paracyclophane

Abstract: Photolysis of a phenacyl benzoate tethered with a phenol leads to a very efficient release of benzoic acid, which is suggested to occur by electron transfer and/or proton transfer from...

Cited by 2 publications

References 51 publications

A Photochemical Macrocyclization Route to Asymmetric Strained [3.2] Paracyclophanes

A Photochemical Macrocyclization Route to Asymmetric Strained [3.2] Paracyclophanes

Photochemical coupling reaction of phenacyl benzoate with acetone to form 1,4‐dicarbonyl compound enabled by charge transfer

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