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Zum Mechanismus der photochemischen Dehydrocyclisierung von Diphenyläther / On the Mechanism of the Photochemical Dehydrocyclisation of Diphenylether

The photochemical cyclisation of diphenylether to dibenzofuran is scavenged by trans-1,3-pentadiene indicating that the triplet state of the ether is the reactive species. The intramolecular, kinetic isotope effects kʜ/kᴅ for the cyclisation of 2-deuteriodiphenyl ether and 1-phenoxy-4-pentadeuteriophenoxy-benzene are 1.12 ± 0.05 and 1.19 ± 0.05, respectively. A reaction scheme consisting of a photochemical cyclisation to 1 a, 9 a-dihydrodi-benzofuran followed by dehydrogenation to dibenzofuran is suggested.