Photochemically induced radical reactions with furanones

Oelgemöller, Michael, and Hoffmann, Norbert (2015) Photochemically induced radical reactions with furanones. Pure and Applied Chemistry, 87 (6). pp. 569-582.

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Abstract

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.

Item ID: 39124
Item Type: Article (Research - C1)
ISSN: 1365-3075
Keywords: C-H bond reactivity; flow reactor; micro reactor set up; photochemistry; radical reactions; stereoselectivity; XXV IUPAC Photochemistry
Funders: Australian Research Council (ARC), French Ministry of Research, Région Champagne-Ardenne, French Centre National de la Recherche Scientifique, Japan Society for Promotion of Science (JSPS), ADME/AGRICE, Ministry of Education, Science, Sport and Culture, Japan (MESSC), Tokuyama Science Foundation
Projects and Grants: ARC Discovery Project DP130100794, ADME/AGRICE Project 0601C0022, MESSC No. 19350021, Priority Area No. 19027033, MESSC No. 1902034, MESSC No. 20036038, MESSC No. 2110851
Date Deposited: 10 Jun 2015 04:33
FoR Codes: 03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030503 Organic Chemical Synthesis @ 40%
03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030504 Organic Green Chemistry @ 30%
03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030505 Physical Organic Chemistry @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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