Clean and Easy Photochemistry

Ciana, Claire-Lise; Bochet, Christian G.

doi:10.2533/chimia.2007.650

Cited by 69 publications

(28 citation statements)

References 18 publications

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“…Dadurch werden ungewöhnliche Molekülgerüste zugänglich, deren ¾hnlichkeit mit den Substraten klein ist und deren Bildung Staunen hervorruft. [5] Als kleines Beispiel sei die Synthese des racemischen [6] (AE )-Cedrens (2) aus der Vorstufe 1 erwähnt (Schema 1). [7] Durch einen photochemischen Schlüsselschritt gelang in vier Schritten bei gleich bleibender Anzahl der Kohlenstoffatome der Aufbau eines vollkommen andersartigen Molekülskeletts.…”

Section: Einführungunclassified

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

2011

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Photochemische Reaktionen bereichern in signifikanter Weise das Repertoire zur Knüpfung von Kohlenstoff‐Kohlenstoff‐Bindungen und machen ungewöhnliche, auf herkömmlichem Weg nicht erhältliche Molekülgerüste zugänglich. In diesem Aufsatz werden die wichtigsten Umsetzungen der Photochemie vorgestellt, die auf breiter Front Einzug in die Naturstoffsynthese gehalten haben. Beispielhaft werden einzelne Totalsynthesen diskutiert, wobei besonderes Augenmerk auf den photochemischen Schlüsselschritt sowie dessen Stereoselektivität gerichtet ist. Dabei wird das photochemisch erzeugte Molekül in Relation zur Struktur des Naturstoffs gebracht, und Folgereaktionen werden, wo notwendig, illustriert und klassifiziert.

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Section: Einführungunclassified

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

2011

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“…Photochemical reactions considerably enlarge the spectrum of reactions which can be carried out within a compound family [1][2][3][4]. This behavior is due to the change of electronic configuration upon electronic excitation by light absorption [5,6].…”

Section: Introductionmentioning

confidence: 99%

Photochemically induced radical reactions with furanones

Oelgemöller

Hoffmann

2015

Pure and Applied Chemistry

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Radicals are easily generated via hydrogen transfer form secondary alcohols or tertiary amines using photochemical sensitization with ketones. They can subsequently add to the electron deficient double bond of furanones. The addition of the alcohols is particularly efficient. Therefore, this reaction was used to characterize and to compare the efficiency of different photochemical continuous flow microreactors. A range of micro-structured reactors were tested and their performances evaluated. The enclosed microchip enabled high space-time-yields but its microscopic dimensions limited its productivity. In contrast, the open microcapillary model showed a greater potential for scale-up and reactor optimization. A 10-microcapillary reactor was therefore constructed and utilized for typical R&D applications. Compared to the corresponding batch processes, the microreactor systems gave faster conversions, improved product qualities and higher yields. Similar reactions have also been carried out with electronically excited furanones and other α,β-unsaturated ketones. In this case, hydrogen is transferred directly to the excited olefin. This reaction part may occur either in one step, i.e., electron and proton are transferred simultaneously, or it may occur in two steps, i.e., the electron is transferred first and the proton follows. In the first case, a C-C bond is formed in the α position of the α,β-unsaturated carbonyl compound and in the second case this bond is formed in the β position. For the first reaction, the influence of stereochemical elements of the substrate on the regioselectivity of the hydrogen abstraction on the side chain has been studied.

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“…Photochemical reactions use photons as sustainable reagents for the construction of complex structures that cannot be obtained easily by thermal reactions [1][2][3][4]. Of these, [2+2] photocycloadditions are especially important for the generation of highly strained cyclobutanes [5,6].…”

Section: Introductionmentioning

confidence: 99%

Diastereoselective [2+2] Photocycloaddition of a Chiral Cyclohexenone with Ethylene in a Continuous Flow Microcapillary Reactor

et al. 2012

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The diastereoselective [2+2] photocycloaddition of ethylene to a chiral cyclohexenone was studied in a continuous flow microcapillary reactor. In all cases examined, the microcapillary reactor gave higher conversions and selectivity than the batch system, even after shorter irradiation times. These findings were explained by the superior temperature control, favorable light penetration, and generation of a gas-liquid slug flow with improved mass transfer in the microreactor.

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Clean and Easy Photochemistry

Cited by 69 publications

References 18 publications

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

Photochemically induced radical reactions with furanones

Diastereoselective [2+2] Photocycloaddition of a Chiral Cyclohexenone with Ethylene in a Continuous Flow Microcapillary Reactor

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