Biphasic photochemistry: micelle solutions as media for photochemical cycloadditions of enones

Berenjian, Nader; Mayo, P. De; Sturgeon, Mary-Ellen; Sydnes, Leiv K.; Weedon, Alan C.

doi:10.1139/v82-064

Cited by 49 publications

(36 citation statements)

References 10 publications

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“…For example, photocycloaddition of 3-n-butylcyclopentanone in the presence of heptenyl acetate in organic solvents gives a single adduct B (Scheme 6). [204][205][206] Irradiation of these two compounds solubilized in a potassium decanoate micelle yields a mixture of two adducts A and B in which the A is the major product and consistent with the notion that a micellar interface helps orient the reactant molecules (Figure 8). A few years ago, our group demonstrated that alkenes photostable in the solid state dimerize within cucurbiturils.…”

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confidence: 78%

Supramolecular photochemistry concepts highlighted with select examples

Ramamurthy

Mondal

2015

Journal of Photochemistry and Photobiology C: Photochemistry Re

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‗Supramolecular Photochemistry' (SP) deals with a study of the properties of molecules in their excited states where the medium plays a significant role. While ‗Molecular Photochemistry' (MP) deals with studies in isotropic solution, the SP deals with reactant molecules that interact weakly with their surroundings. The surroundings in general are highly organized assemblies such as crystals, liquid crystals, micelles, hostguest structures etc. The behavior of exited molecules in SP unlike in isotropic solution is controlled not only by their inherent electronic and steric properties but also by the immediate surroundings. The weak interactions that control the chemistry include van der Walls, hydrophobic, C-H-, - and several types of hydrogen bonds. In this review the uniqueness of SP compared to MP is highlighted with examples chosen from reactions in crystals, micelles and host-guest assemblies. In spite of distinctly different structures (crystals, micelles etc.) the influence of the medium could be understood on the basis of a model developed by G. M. J. Schmidt for photoreactions in crystals. The principles of reaction cavity model are briefly outlined in this review. There are a few important features that are specific to SP. For example, highly reactive molecules and intermediates could be stabilized in a confined environment; they enable phosphorescence to be observed at room temperature and favor chiral induction in photochemical reactions. Using such examples the uniqueness of SP is highlighted. The future of SP depends on developing efficient and unique catalytic photoreactions using easily available reaction ‗containers'. In addition, their value in artificial photosynthesis should be established for SP to occupy a center stage in the future.

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confidence: 78%

Supramolecular photochemistry concepts highlighted with select examples

Ramamurthy

Mondal

2015

Journal of Photochemistry and Photobiology C: Photochemistry Re

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“…Given the low combined yield for compounds 17 and 18 , it is likely that other dimerization products were formed but could not be isolated in a pure form. [2 + 2] Photodimerization, in a head-to-head fashion, is common for cyclopentenones, 23 while the regioselectivity of the intermolecular head-to-head double bond addition of a monosubstituted olefin to an enone has less precedence. 9d , 23d , 24 …”

Section: Resultsmentioning

confidence: 99%

Visible Light-Mediated Photochemical Reactions of 2-(2′-Alkenyloxy)cycloalk-2-enones

2020

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The title compounds were prepared, and their reactivity was studied upon sensitized irradiation at λ = 420 nm. Thioxanthen-9-one was employed as the sensitizer at a loading of 10 mol % in small-scale reactions and of 2.5 mol % on a larger scale. Cyclohex-2-enones substituted by a 2′-propenyloxy, 2′-butenyloxy, 2′-pentenyloxy, or 2′-methyl-2′-propenyloxy group in the 2-position gave the products of an intramolecular [2 + 2] photocycloadditon. The reaction proceeded with high regioselectivity (crossed product) and perfect diastereoselectivity (nine examples, 34–99% yield). If the olefin in the tether was trisubstituted (3′-methyl-2′-butenyloxy), no cycloaddition was observed. Rather, a cyclization with subsequent hydrogen abstraction occurred (three examples, 65–86% yield). The results are consistent with a reaction course via a triplet enone intermediate and the formation of a 1,4-diradical by an initial cyclization. The analogous cyclopent-2-enones were less prone to an intramolecular reaction. Instead, decomposition or intermolecular [2 + 2] photocycloaddition reactions prevailed. In the latter event, two main products were identified (three examples, 30–43% yield), resulting either from a head-to-head [2 + 2]-photodimerization or from a twofold [2 + 2] photocycloaddition of the enone to the olefin. The latter reaction sequence generated pentacyclic products with a central [1,5]dioxocane ring. The structure assignment of the two product types was corroborated by a single-crystal X-ray analysis.

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“…Vinylogous thioesters (A3, Q ¼ S) have been used less frequently in [2 þ 2]photocycloaddition as compared to their oxygen and nitrogen analogues [83]. More recent applications can be found in the above-mentioned study with chiral allenes [79].…”

Section: -Hetero-2-cyclohexenonesmentioning

confidence: 99%