Die säurekatalysierte Isomerisierung von 7-Oxabicyclo[2.2.1]-heptadien- und Oxepin-Derivaten [1]

The acid catalyzed isomerization of several substituted oxanorbornadienes 4 and oxepines 10 - easily available from 4 by a photochemical and a consecutive thermal step - allows the synthesis of several highly substituted phenols and 2,4-cyclohexadienones in a straightforward manner and with good to excellent yields. The formation of the methoxycarbonyl-hexadienes 18e and 18f upon photolysis of 9e and 17f in methanol supports the structure elucidation. The relative importance of the McLAFFERTY and EMERY effects in the mass spectral degradation of methoxycarbonyl and methyl substituted phenols are discussed.