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Farbstoffsensibilisierte Photoreaktionen von vinylogen Epoxycarbonylverbindungen
Author(s) -
Skorianetz Werner,
Ohloff Günther
Publication year - 1973
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19730560704
Subject(s) - chemistry , cyclopentanone , isomerization , ketone , photodissociation , photochemistry , fragmentation (computing) , peroxide , double bond , methyl ketone , medicinal chemistry , stereochemistry , organic chemistry , catalysis , computer science , operating system
On irradiation in the presence of dye sensitizers, vinylogous epoxy carbonyl compounds undergo a novel photofragmentation reaction, to give furyl ketones in good yields. The fragmentation process is probably preceded by trans ‐ cis isomerization of the double bond; in one case the cis ‐isomer could be isolated. In a side reaction epoxyenone 10 gives the cyclopentanone derivatives 13 and 14 by a [1, 2] shift of a methyl group. Similar dye sensitized photolysis of the endo ‐peroxide 2 also gives the corresponding furyl ketone 4 , and the corresponding vinylogous epoxyketone C is probably an intermediate in this transformation. The finding that dyes of relatively low triplet energies (∼ 30 kcal/mol) efficiently sensitize these reactions, and a certain wave length dependence suggest that the usual triplet mechanism cannot be involved.