Radical-cation-initiated Diels-Alder di- and trimerization of 3,4-dimethoxypropenylbenzene: stereochemical correlation with the lignans galbulin and isogalbulin
Oxidation of isoeugenol methyl ether in the system CF3COOH-CH2Cl2-PbO2 involves intermediate formation of (E)-3,4-(MeO)(2)C6H3(C) over dot H-CHCH3 radical cation whose further transformations follow two main dehydrotrimerization pathways, resulting in formation of two positional and two stereoisomeric products having a tricyclic skeleton.